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15 <h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES
16 Programming HOWTO</a></h1>
18 <h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep
21 <div class="AFFILIATION">
23 <p class="ADDRESS"><code class="EMAIL"><<a href=
24 "mailto:ppadala@gmail.com">ppadala@gmail.com</a>></code>
29 <p class="PUBDATE">v1.9, 2005-06-20<br></p>
31 <div class="REVHISTORY">
32 <table width="100%" border="0" summary="revisions">
34 <th align="left" valign="top" colspan="3"><b>Revision
40 <td align="left">Revision 2.0</td>
41 <td align="left">2022-12-03</td>
42 <td align="left">Revised by: dickey</td>
46 <td align="left" colspan="3">Fixes for the sample
47 programs, Correct documentation errata.</td>
51 <td align="left">Revision 1.9</td>
52 <td align="left">2005-06-20</td>
53 <td align="left">Revised by: ppadala</td>
57 <td align="left" colspan="3">The license has been
58 changed to the MIT-style license used by NCURSES. Note
59 that the programs are also re-licensed under this.</td>
63 <td align="left">Revision 1.8</td>
64 <td align="left">2005-06-17</td>
65 <td align="left">Revised by: ppadala</td>
69 <td align="left" colspan="3">Lots of updates. Added
70 references and perl examples. Changes to examples. Many
71 grammatical and stylistic changes to the content.
72 Changes to NCURSES history.</td>
76 <td align="left">Revision 1.7.1</td>
77 <td align="left">2002-06-25</td>
78 <td align="left">Revised by: ppadala</td>
82 <td align="left" colspan="3">Added a README file for
83 building and instructions for building from
88 <td align="left">Revision 1.7</td>
89 <td align="left">2002-06-25</td>
90 <td align="left">Revised by: ppadala</td>
94 <td align="left" colspan="3">Added "Other formats"
95 section and made a lot of fancy changes to the
96 programs. Inlining of programs is gone.</td>
100 <td align="left">Revision 1.6.1</td>
101 <td align="left">2002-02-24</td>
102 <td align="left">Revised by: ppadala</td>
106 <td align="left" colspan="3">Removed the old Changelog
107 section, cleaned the makefiles</td>
111 <td align="left">Revision 1.6</td>
112 <td align="left">2002-02-16</td>
113 <td align="left">Revised by: ppadala</td>
117 <td align="left" colspan="3">Corrected a lot of
118 spelling mistakes, added ACS variables section</td>
122 <td align="left">Revision 1.5</td>
123 <td align="left">2002-01-05</td>
124 <td align="left">Revised by: ppadala</td>
128 <td align="left" colspan="3">Changed structure to
129 present proper TOC</td>
133 <td align="left">Revision 1.3.1</td>
134 <td align="left">2001-07-26</td>
135 <td align="left">Revised by: ppadala</td>
139 <td align="left" colspan="3">Corrected maintainers
140 paragraph, Corrected stable release number</td>
144 <td align="left">Revision 1.3</td>
145 <td align="left">2001-07-24</td>
146 <td align="left">Revised by: ppadala</td>
150 <td align="left" colspan="3">Added copyright notices to
151 main document (LDP license) and programs (GPL),
152 Corrected printw_example.</td>
156 <td align="left">Revision 1.2</td>
157 <td align="left">2001-06-05</td>
158 <td align="left">Revised by: ppadala</td>
162 <td align="left" colspan="3">Incorporated ravi's
163 changes. Mainly to introduction, menu, form, justforfun
168 <td align="left">Revision 1.1</td>
169 <td align="left">2001-05-22</td>
170 <td align="left">Revised by: ppadala</td>
174 <td align="left" colspan="3">Added "a word about
175 window" section, Added scanw_example.</td>
181 <div class="ABSTRACT">
182 <a name="AEN72" id="AEN72"></a>
183 <p><span class="emphasis"><i class="EMPHASIS">This
184 document is intended to be an "All in One" guide for
185 programming with ncurses and its sister libraries. We
186 graduate from a simple "Hello World" program to more
187 complex form manipulation. No prior experience in ncurses
188 is assumed. Send comments to <a href=
189 "mailto:ppadala@gmail.com" target="_top">this
190 address</a></i></span>
200 <dt><b>Table of Contents</b>
203 <dt>1. <a href="#INTRO">Introduction</a></dt>
207 <dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt>
209 <dt>1.2. <a href="#WHATCANWEDO">What we can do with
212 <dt>1.3. <a href="#WHERETOGETIT">Where to get
215 <dt>1.4. <a href="#PURPOSE">Purpose/Scope of the
218 <dt>1.5. <a href="#ABOUTPROGRAMS">About the
221 <dt>1.6. <a href="#OTHERFORMATS">Other Formats of the
226 <dt>1.6.1. <a href="#LISTFORMATS">Readily available
227 formats from tldp.org</a></dt>
229 <dt>1.6.2. <a href="#BUILDSOURCE">Building from
234 <dt>1.7. <a href="#CREDITS">Credits</a></dt>
236 <dt>1.8. <a href="#WISHLIST">Wish List</a></dt>
238 <dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt>
242 <dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt>
246 <dt>2.1. <a href="#COMPILECURSES">Compiling With the
247 NCURSES Library</a></dt>
249 <dt>2.2. <a href="#DISSECTION">Dissection</a></dt>
253 <dt>2.2.1. <a href="#ABOUT-INITSCR">About
256 <dt>2.2.2. <a href="#MYST-REFRESH">The mysterious
259 <dt>2.2.3. <a href="#ABOUT-ENDWIN">About
266 <dt>3. <a href="#GORY">The Gory Details</a></dt>
268 <dt>4. <a href="#INIT">Initialization</a></dt>
272 <dt>4.1. <a href="#ABOUTINIT">Initialization
275 <dt>4.2. <a href="#RAWCBREAK">raw() and
278 <dt>4.3. <a href="#ECHONOECHO">echo() and
281 <dt>4.4. <a href="#KEYPAD">keypad()</a></dt>
283 <dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt>
285 <dt>4.6. <a href="#MISCINIT">Miscellaneous
286 Initialization functions</a></dt>
288 <dt>4.7. <a href="#INITEX">An Example</a></dt>
292 <dt>5. <a href="#AWORDWINDOWS">A Word about
295 <dt>6. <a href="#PRINTW">Output functions</a></dt>
299 <dt>6.1. <a href="#ADDCHCLASS">addch() class of
302 <dt>6.2. <a href="#AEN303">mvaddch(), waddch() and
305 <dt>6.3. <a href="#PRINTWCLASS">printw() class of
310 <dt>6.3.1. <a href="#PRINTWMVPRINTW">printw() and
313 <dt>6.3.2. <a href="#WPRINTWMVWPRINTW">wprintw()
314 and mvwprintw</a></dt>
316 <dt>6.3.3. <a href="#VWPRINTW">vw_printw()</a></dt>
318 <dt>6.3.4. <a href="#SIMPLEPRINTWEX">A Simple
319 printw example</a></dt>
323 <dt>6.4. <a href="#ADDSTRCLASS">addstr() class of
326 <dt>6.5. <a href="#ACAUTION">A word of caution</a></dt>
330 <dt>7. <a href="#SCANW">Input functions</a></dt>
334 <dt>7.1. <a href="#GETCHCLASS">getch() class of
337 <dt>7.2. <a href="#SCANWCLASS">scanw() class of
342 <dt>7.2.1. <a href="#SCANWMVSCANW">scanw() and
345 <dt>7.2.2. <a href="#WSCANWMVWSCANW">wscanw() and
348 <dt>7.2.3. <a href="#VWSCANW">vw_scanw()</a></dt>
352 <dt>7.3. <a href="#GETSTRCLASS">getstr() class of
355 <dt>7.4. <a href="#GETSTREX">Some examples</a></dt>
359 <dt>8. <a href="#ATTRIB">Attributes</a></dt>
363 <dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt>
365 <dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs
368 <dt>8.3. <a href="#ATTRGET">attr_get()</a></dt>
370 <dt>8.4. <a href="#ATTRFUNCS">attr_ functions</a></dt>
372 <dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt>
374 <dt>8.6. <a href="#CHGAT">chgat() functions</a></dt>
378 <dt>9. <a href="#WINDOWS">Windows</a></dt>
382 <dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt>
384 <dt>9.2. <a href="#LETBEWINDOW">Let there be a Window
387 <dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt>
389 <dt>9.4. <a href="#OTHERSTUFF">The other stuff in the
392 <dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border
397 <dt>10. <a href="#COLOR">Colors</a></dt>
401 <dt>10.1. <a href="#COLORBASICS">The basics</a></dt>
403 <dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color
406 <dt>10.3. <a href="#COLORCONTENT">Color
411 <dt>11. <a href="#KEYS">Interfacing with the key
416 <dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt>
418 <dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage
423 <dt>12. <a href="#MOUSE">Interfacing with the
428 <dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt>
430 <dt>12.2. <a href="#GETTINGEVENTS">Getting the
433 <dt>12.3. <a href="#MOUSETOGETHER">Putting it all
436 <dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous
441 <dt>13. <a href="#SCREEN">Screen Manipulation</a></dt>
445 <dt>13.1. <a href="#GETYX">getyx() functions</a></dt>
447 <dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt>
449 <dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt>
453 <dt>14. <a href="#MISC">Miscellaneous features</a></dt>
457 <dt>14.1. <a href="#CURSSET">curs_set()</a></dt>
459 <dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving
462 <dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt>
466 <dt>15. <a href="#OTHERLIB">Other libraries</a></dt>
468 <dt>16. <a href="#PANELS">Panel Library</a></dt>
472 <dt>16.1. <a href="#PANELBASICS">The Basics</a></dt>
474 <dt>16.2. <a href="#COMPILEPANELS">Compiling With the
475 Panels Library</a></dt>
477 <dt>16.3. <a href="#PANELBROWSING">Panel Window
480 <dt>16.4. <a href="#USERPTRUSING">Using User
483 <dt>16.5. <a href="#PANELMOVERESIZE">Moving and
484 Resizing Panels</a></dt>
486 <dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing
489 <dt>16.7. <a href="#PANELABOVE">panel_above() and
490 panel_below() Functions</a></dt>
494 <dt>17. <a href="#MENUS">Menus Library</a></dt>
498 <dt>17.1. <a href="#MENUBASICS">The Basics</a></dt>
500 <dt>17.2. <a href="#COMPILEMENUS">Compiling With the
501 Menu Library</a></dt>
503 <dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work
504 horse of the menu system</a></dt>
506 <dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt>
508 <dt>17.5. <a href="#SCROLLMENUS">Scrolling
511 <dt>17.6. <a href="#MULTICOLUMN">Multi Columnar
514 <dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued
517 <dt>17.8. <a href="#MENUOPT">Menu Options</a></dt>
519 <dt>17.9. <a href="#MENUUSERPTR">The useful User
524 <dt>18. <a href="#FORMS">Forms Library</a></dt>
528 <dt>18.1. <a href="#FORMBASICS">The Basics</a></dt>
530 <dt>18.2. <a href="#COMPILEFORMS">Compiling With the
531 Forms Library</a></dt>
533 <dt>18.3. <a href="#PLAYFIELDS">Playing with
538 <dt>18.3.1. <a href="#FETCHINFO">Fetching Size and
539 Location of Field</a></dt>
541 <dt>18.3.2. <a href="#MOVEFIELD">Moving the
544 <dt>18.3.3. <a href="#JUSTIFYFIELD">Field
545 Justification</a></dt>
547 <dt>18.3.4. <a href="#FIELDDISPATTRIB">Field
548 Display Attributes</a></dt>
550 <dt>18.3.5. <a href="#FIELDOPTIONBITS">Field Option
553 <dt>18.3.6. <a href="#FIELDSTATUS">Field
556 <dt>18.3.7. <a href="#FIELDUSERPTR">Field User
560 "#VARIABLESIZEFIELDS">Variable-Sized
565 <dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt>
567 <dt>18.5. <a href="#FILEDVALIDATE">Field
570 <dt>18.6. <a href="#FORMDRIVER">Form Driver: The work
571 horse of the forms system</a></dt>
575 <dt>18.6.1. <a href="#PAGENAVREQ">Page Navigation
578 <dt>18.6.2. <a href="#INTERFIELDNAVREQ">Inter-Field
579 Navigation Requests</a></dt>
581 <dt>18.6.3. <a href="#INTRAFIELDNAVREQ">Intra-Field
582 Navigation Requests</a></dt>
584 <dt>18.6.4. <a href="#SCROLLREQ">Scrolling
587 <dt>18.6.5. <a href="#EDITREQ">Editing
590 <dt>18.6.6. <a href="#ORDERREQ">Order
593 <dt>18.6.7. <a href="#APPLICCOMMANDS">Application
600 <dt>19. <a href="#TOOLS">Tools and Widget
605 <dt>19.1. <a href="#CDK">CDK (Curses Development
610 <dt>19.1.1. <a href="#WIDGETLIST">Widget
613 <dt>19.1.2. <a href="#CDKATTRACT">Some Attractive
617 "#CDKCONCLUSION">Conclusion</a></dt>
621 <dt>19.2. <a href="#DIALOG">The dialog</a></dt>
623 <dt>19.3. <a href="#PERLCURSES">Perl Curses Modules
624 CURSES::FORM and CURSES::WIDGETS</a></dt>
628 <dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt>
632 <dt>20.1. <a href="#GAMEOFLIFE">The Game of
635 <dt>20.2. <a href="#MAGIC">Magic Square</a></dt>
637 <dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt>
639 <dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt>
641 <dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt>
643 <dt>20.6. <a href="#TT">Typing Tutor</a></dt>
647 <dt>21. <a href="#REF">References</a></dt>
652 <h2 class="SECT1"><a name="INTRO" id="INTRO">1.
653 Introduction</a></h2>
655 <p>In the olden days of teletype terminals, terminals were
656 away from computers and were connected to them through serial
657 cables. The terminals could be configured by sending a series
658 of bytes. All the capabilities (such as moving the cursor to
659 a new location, erasing part of the screen, scrolling the
660 screen, changing modes, etc.) of terminals could be accessed
661 through these series of bytes. These control seeuqnces are
662 usually called escape sequences, because they start with an
663 escape(0x1B) character. Even today, with proper emulation, we
664 can send escape sequences to the emulator and achieve the
665 same effect on a terminal window.</p>
667 <p>Suppose you wanted to print a line in color. Try typing
668 this on your console.</p>
670 <pre class="PROGRAMLISTING">echo "^[[0;31;40mIn Color"</pre>
671 <p>The first character is an escape character, which looks
672 like two characters ^ and [. To be able to print it, you have
673 to press CTRL+V and then the ESC key. All the others are
674 normal printable characters. You should be able to see the
675 string "In Color" in red. It stays that way and to revert
676 back to the original mode type this.</p>
678 <pre class="PROGRAMLISTING">echo "^[[0;37;40m"</pre>
679 <p>Now, what do these magic characters mean? Difficult to
680 comprehend? They might even be different for different
681 terminals. So the designers of UNIX invented a mechanism
682 named <tt class="LITERAL">termcap</tt>. It is a file that
683 lists all the capabilities of a particular terminal, along
684 with the escape sequences needed to achieve a particular
685 effect. In the later years, this was replaced by <tt class=
686 "LITERAL">terminfo</tt>. Without delving too much into
687 details, this mechanism allows application programs to query
688 the terminfo database and obtain the control characters to be
689 sent to a terminal or terminal emulator.</p>
694 <h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is
697 <p>You might be wondering, what the import of all this
698 technical gibberish is. In the above scenario, every
699 application program is supposed to query the terminfo and
700 perform the necessary stuff (sending control characters,
701 etc.). It soon became difficult to manage this complexity
702 and this gave birth to 'CURSES'. Curses is a pun on the
703 name "cursor optimization". The Curses library forms a
704 wrapper over working with raw terminal codes, and provides
705 highly flexible and efficient API (Application Programming
706 Interface). It provides functions to move the cursor,
707 create windows, produce colors, play with mouse, etc. The
708 application programs need not worry about the underlying
709 terminal capabilities.</p>
711 <p>So what is NCURSES? NCURSES is a clone of the original
712 System V Release 4.0 (SVr4) curses. It is a freely
713 distributable library, fully compatible with older version
714 of curses. In short, it is a library of functions that
715 manages an application's display on character-cell
716 terminals. In the remainder of the document, the terms
717 curses and ncurses are used interchangeably.</p>
719 <p>A detailed history of NCURSES can be found in the NEWS
720 file from the source distribution. The current package is
721 maintained by <a href="mailto:dickey@invisible-island.net"
722 target="_top">Thomas Dickey</a>. You can contact the
723 maintainers at <a href="mailto:bug-ncurses@gnu.org" target=
724 "_top">bug-ncurses@gnu.org</a>.</p>
730 <h3 class="SECT2"><a name="WHATCANWEDO" id=
731 "WHATCANWEDO">1.2. What we can do with NCURSES</a></h3>
733 <p>NCURSES not only creates a wrapper over terminal
734 capabilities, but also gives a robust framework to create
735 nice looking UI (User Interface)s in text mode. It provides
736 functions to create windows, etc. Its sister libraries
737 panel, menu and form provide an extension to the basic
738 curses library. These libraries usually come along with
739 curses. One can create applications that contain multiple
740 windows, menus, panels and forms. Windows can be managed
741 independently, can provide 'scrollability' and even can be
744 <p>Menus provide the user with an easy command selection
745 option. Forms allow the creation of easy-to-use data entry
746 and display windows. Panels extend the capabilities of
747 ncurses to deal with overlapping and stacked windows.</p>
749 <p>These are just some of the basic things we can do with
750 ncurses. As we move along, We will see all the capabilities
751 of these libraries.</p>
757 <h3 class="SECT2"><a name="WHERETOGETIT" id=
758 "WHERETOGETIT">1.3. Where to get it</a></h3>
760 <p>All right, now that you know what you can do with
761 ncurses, you must be rearing to get started. NCURSES is
762 usually shipped with your installation. In case you don't
763 have the library or want to compile it on your own, read
766 <p><span class="emphasis"><i class="EMPHASIS">Compiling the
770 <p>NCURSES can be obtained from <a href=
771 "ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target=
772 "_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a>
773 or any of the ftp sites mentioned in <a href=
774 "https://www.gnu.org/order/ftp.html" target=
775 "_top">https://www.gnu.org/order/ftp.html</a>.</p>
777 <p>Read the README and INSTALL files for details on to how
778 to install it. It usually involves the following
782 "PROGRAMLISTING"> tar zxvf ncurses<version>.tar.gz # unzip and untar the archive
783 cd ncurses<version> # cd to the directory
784 ./configure # configure the build according to your
787 su root # become root
788 make install # install it</pre>
789 <p><span class="emphasis"><i class="EMPHASIS">Using the
793 <p>NCURSES RPM can be found and downloaded from <a href=
794 "https://rpmfind.net" target="_top">https://rpmfind.net</a>
795 . The RPM can be installed with the following command after
799 "PROGRAMLISTING"> rpm -i <downloaded rpm></pre>
805 <h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4.
806 Purpose/Scope of the document</a></h3>
808 <p>This document is intended to be a "All in One" guide for
809 programming with ncurses and its sister libraries. We
810 graduate from a simple "Hello World" program to more
811 complex form manipulation. No prior experience in ncurses
812 is assumed. The writing is informal, but a lot of detail is
813 provided for each of the examples.</p>
819 <h3 class="SECT2"><a name="ABOUTPROGRAMS" id=
820 "ABOUTPROGRAMS">1.5. About the Programs</a></h3>
822 <p>All the programs in the document are available in zipped
824 "https://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz"
825 target="_top">here</a>. Unzip and untar it. The directory
826 structure looks like this.</p>
828 <pre class="PROGRAMLISTING">ncurses
830 |----> JustForFun -- just for fun programs
831 |----> basics -- basic programs
832 |----> demo -- output files go into this directory after make
834 | |----> exe -- exe files of all example programs
835 |----> forms -- programs related to form library
836 |----> menus -- programs related to menus library
837 |----> panels -- programs related to panels library
838 |----> perl -- perl equivalents of the examples (contributed
839 | by Anuradha Ratnaweera)
840 |----> Makefile -- the top level Makefile
841 |----> README -- the top level README file. contains instructions
842 |----> COPYING -- copyright notice</pre>
843 <p>The individual directories contain the following
847 "PROGRAMLISTING">Description of files in each directory
848 --------------------------------------
851 |----> hanoi.c -- The Towers of Hanoi Solver
852 |----> life.c -- The Game of Life demo
853 |----> magic.c -- An Odd Order Magic Square builder
854 |----> queens.c -- The famous N-Queens Solver
855 |----> shuffle.c -- A fun game, if you have time to kill
856 |----> tt.c -- A very trivial typing tutor
860 |----> acs_vars.c -- ACS_ variables example
861 |----> hello_world.c -- Simple "Hello World" Program
862 |----> init_func_example.c -- Initialization functions example
863 |----> key_code.c -- Shows the scan code of the key pressed
864 |----> mouse_menu.c -- A menu accessible by mouse
865 |----> other_border.c -- Shows usage of other border functions apa
867 |----> printw_example.c -- A very simple printw() example
868 |----> scanw_example.c -- A very simple getstr() example
869 |----> simple_attr.c -- A program that can print a c file with
870 | -- comments in attribute
871 |----> simple_color.c -- A simple example demonstrating colors
872 |----> simple_key.c -- A menu accessible with keyboard UP, DOWN
874 |----> temp_leave.c -- Demonstrates temporarily leaving curses mode
875 |----> win_border.c -- Shows Creation of windows and borders
876 |----> with_chgat.c -- chgat() usage example
880 |----> form_attrib.c -- Usage of field attributes
881 |----> form_options.c -- Usage of field options
882 |----> form_simple.c -- A simple form example
883 |----> form_win.c -- Demo of windows associated with forms
887 |----> menu_attrib.c -- Usage of menu attributes
888 |----> menu_item_data.c -- Usage of item_name(), etc. functions
889 |----> menu_multi_column.c -- Creates multi columnar menus
890 |----> menu_scroll.c -- Demonstrates scrolling capability of menus
891 |----> menu_simple.c -- A simple menu accessed by arrow keys
892 |----> menu_toggle.c -- Creates multi valued menus and explains
894 |----> menu_userptr.c -- Usage of user pointer
895 |----> menu_win.c -- Demo of windows associated with menus
899 |----> panel_browse.c -- Panel browsing through tab. Usage of user
901 |----> panel_hide.c -- Hiding and Un hiding of panels
902 |----> panel_resize.c -- Moving and resizing of panels
903 |----> panel_simple.c -- A simple panel example
906 |----> 01-10.pl -- Perl equivalents of first ten example programs</pre>
907 <p>There is a top level Makefile included in the main
908 directory. It builds all the files and puts the
909 ready-to-use exes in demo/exe directory. You can also do
910 selective make by going into the corresponding directory.
911 Each directory contains a README file explaining the
912 purpose of each c file in the directory.</p>
914 <p>For every example, I have included path name for the
915 file relative to the examples directory.</p>
917 <p>If you prefer browsing individual programs, point your
919 "https://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/"
921 "_top">https://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p>
923 <p>All the programs are released under the same license
924 that is used by ncurses (MIT-style). This gives you the
925 ability to do pretty much anything other than claiming them
926 as yours. Feel free to use them in your programs as
933 <h3 class="SECT2"><a name="OTHERFORMATS" id=
934 "OTHERFORMATS">1.6. Other Formats of the document</a></h3>
936 <p>This howto is also available in various other formats on
937 the tldp.org site. Here are the links to other formats of
943 <h4 class="SECT3"><a name="LISTFORMATS" id=
944 "LISTFORMATS">1.6.1. Readily available formats from
950 "https://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf"
951 target="_top">Acrobat PDF Format</a></p>
956 "https://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz"
957 target="_top">PostScript Format</a></p>
962 "https://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz"
963 target="_top">In Multiple HTML pages</a></p>
968 "https://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html"
969 target="_top">In One big HTML format</a></p>
977 <h4 class="SECT3"><a name="BUILDSOURCE" id=
978 "BUILDSOURCE">1.6.2. Building from source</a></h4>
980 <p>If above links are broken or if you want to experiment
981 with sgml read on.</p>
984 "PROGRAMLISTING"> Get both the source and the tar,gzipped programs, available at
985 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
986 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml
987 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
988 NCURSES-HOWTO/ncurses_programs.tar.gz
990 Unzip ncurses_programs.tar.gz with
991 tar zxvf ncurses_programs.tar.gz
993 Use jade to create various formats. For example if you just want to create
994 the multiple html files, you would use
995 jade -t sgml -i html -d <path to docbook html stylesheet>
996 NCURSES-Programming-HOWTO.sgml
997 to get pdf, first create a single html file of the HOWTO with
998 jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks
999 NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html
1000 then use htmldoc to get pdf file with
1001 htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf>
1002 NCURSES-ONE-BIG-FILE.html
1003 for ps, you would use
1004 htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps>
1005 NCURSES-ONE-BIG-FILE.html</pre>
1007 "https://www.tldp.org/LDP/LDP-Author-Guide/" target=
1008 "_top">LDP Author guide</a> for more details. If all else
1009 fails, mail me at <a href="ppadala@gmail.com" target=
1010 "_top">ppadala@gmail.com</a></p>
1017 <h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7.
1020 <p>I thank <a href="mailto:sharath_1@usa.net" target=
1021 "_top">Sharath</a> and Emre Akbas for helping me with few
1022 sections. The introduction was initially written by
1023 sharath. I rewrote it with few excerpts taken from his
1024 initial work. Emre helped in writing printw and scanw
1027 <p>Perl equivalents of the example programs are contributed
1028 by <a href="mailto:Aratnaweera@virtusa.com" target=
1029 "_top">Anuradha Ratnaweera</a>.</p>
1031 <p>Then comes <a href="mailto:parimi@ece.arizona.edu"
1032 target="_top">Ravi Parimi</a>, my dearest friend, who has
1033 been on this project before even one line was written. He
1034 constantly bombarded me with suggestions and patiently
1035 reviewed the whole text. He also checked each program on
1036 Linux and Solaris.</p>
1042 <h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8.
1045 <p>This is the wish list, in the order of priority. If you
1046 have a wish or you want to work on completing the wish,
1047 mail <a href="mailto:ppadala@gmail.com" target=
1052 <p>Add examples to last parts of forms section.</p>
1056 <p>Prepare a Demo showing all the programs and allow
1057 the user to browse through description of each program.
1058 Let the user compile and see the program in action. A
1059 dialog based interface is preferred.</p>
1063 <p>Add debug info. _tracef, _tracemouse stuff.</p>
1067 <p>Accessing termcap, terminfo using functions provided
1068 by ncurses package.</p>
1072 <p>Working on two terminals simultaneously.</p>
1076 <p>Add more stuff to miscellaneous section.</p>
1084 <h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9.
1087 <p>Copyright © 2001 by Pradeep Padala.</p>
1089 <p>Permission is hereby granted, free of charge, to any
1090 person obtaining a copy of this software and associated
1091 documentation files (the "Software"), to deal in the
1092 Software without restriction, including without limitation
1093 the rights to use, copy, modify, merge, publish,
1094 distribute, distribute with modifications, sublicense,
1095 and/or sell copies of the Software, and to permit persons
1096 to whom the Software is furnished to do so, subject to the
1097 following conditions:</p>
1099 <p>The above copyright notice and this permission notice
1100 shall be included in all copies or substantial portions of
1103 <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
1104 ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
1105 THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
1106 PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE
1107 COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
1108 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
1109 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
1110 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</p>
1112 <p>Except as contained in this notice, the name(s) of the
1113 above copyright holders shall not be used in advertising or
1114 otherwise to promote the sale, use or other dealings in
1115 this Software without prior written authorization.</p>
1122 <h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2.
1123 Hello World !!!</a></h2>
1125 <p>Welcome to the world of curses. Before we plunge into the
1126 library and look into its various features, let's write a
1127 simple program and say hello to the world.</p>
1132 <h3 class="SECT2"><a name="COMPILECURSES" id=
1133 "COMPILECURSES">2.1. Compiling With the NCURSES Library</a></h3>
1135 <p>To use ncurses library functions, you have to include
1136 ncurses.h in your programs. To link the program with
1137 ncurses the flag -lncurses should be added.</p>
1139 <pre class="PROGRAMLISTING"> #include <ncurses.h>
1144 compile and link: gcc <program file> -lncurses</pre>
1145 <div class="EXAMPLE">
1146 <a name="BHW" id="BHW"></a>
1147 <p><b>Example 1. The Hello World !!! Program</b>
1150 <pre class="PROGRAMLISTING"><span class=
1151 "INLINEMEDIAOBJECT">#include <curses.h>
1155 initscr(); /* Start curses mode */
1156 printw("Hello World !!!"); /* Print Hello World */
1157 refresh(); /* Print it on to the real screen */
1158 getch(); /* Wait for user input */
1159 endwin(); /* End curses mode */
1169 <h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2.
1172 <p>The above program prints "Hello World !!!" to the screen
1173 and exits. This program shows how to initialize curses and
1174 do screen manipulation and end curses mode. Let's dissect
1175 it line by line.</p>
1180 <h4 class="SECT3"><a name="ABOUT-INITSCR" id=
1181 "ABOUT-INITSCR">2.2.1. About initscr()</a></h4>
1183 <p>The function initscr() initializes the terminal in
1184 curses mode. In some implementations, it clears the
1185 screen and presents a blank screen. To do any screen
1186 manipulation using curses package this has to be called
1187 first. This function initializes the curses system and
1188 allocates memory for our present window (called
1189 <tt class="LITERAL">stdscr</tt>) and some other
1190 data-structures. Under extreme cases this function might
1191 fail due to insufficient memory to allocate memory for
1192 curses library's data structures.</p>
1194 <p>After this is done, we can do a variety of
1195 initializations to customize our curses settings. These
1196 details will be explained <a href="#INIT">later</a> .</p>
1202 <h4 class="SECT3"><a name="MYST-REFRESH" id=
1203 "MYST-REFRESH">2.2.2. The mysterious refresh()</a></h4>
1205 <p>The next line printw prints the string "Hello World
1206 !!!" on to the screen. This function is analogous to
1207 normal printf in all respects except that it prints the
1208 data on a window called stdscr at the current (y,x)
1209 co-ordinates. Since our present co-ordinates are at 0,0
1210 the string is printed at the left hand corner of the
1213 <p>This brings us to that mysterious refresh(). Well,
1214 when we called printw the data is actually written to an
1215 imaginary window, which is not updated on the screen yet.
1216 The job of printw is to update a few flags and data
1217 structures and write the data to a buffer corresponding
1218 to stdscr. In order to show it on the screen, we need to
1219 call refresh() and tell the curses system to dump the
1220 contents on the screen.</p>
1222 <p>The philosophy behind all this is to allow the
1223 programmer to do multiple updates on the imaginary screen
1224 or windows and do a refresh once all his screen update is
1225 done. refresh() checks the window and updates only the
1226 portion which has been changed. This improves performance
1227 and offers greater flexibility too. But, it is sometimes
1228 frustrating to beginners. A common mistake committed by
1229 beginners is to forget to call refresh() after they did
1230 some update through printw() class of functions. I still
1231 forget to add it sometimes :-)</p>
1237 <h4 class="SECT3"><a name="ABOUT-ENDWIN" id=
1238 "ABOUT-ENDWIN">2.2.3. About endwin()</a></h4>
1240 <p>And finally don't forget to end the curses mode.
1241 Otherwise your terminal might behave strangely after the
1242 program quits. endwin() frees the memory taken by curses
1243 sub-system and its data structures and puts the terminal
1244 in normal mode. This function must be called after you
1245 are done with the curses mode.</p>
1253 <h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory
1256 <p>Now that we have seen how to write a simple curses program
1257 let's get into the details. There are many functions that
1258 help customize what you see on screen and many features which
1259 can be put to full use.</p>
1261 <p>Here we go...</p>
1267 <h2 class="SECT1"><a name="INIT" id="INIT">4.
1268 Initialization</a></h2>
1270 <p>We now know that to initialize curses system the function
1271 initscr() has to be called. There are functions which can be
1272 called after this initialization to customize our curses
1273 session. We may ask the curses system to set the terminal in
1274 raw mode or initialize color or initialize the mouse, etc.
1275 Let's discuss some of the functions that are normally called
1276 immediately after initscr();</p>
1281 <h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1.
1282 Initialization functions</a></h3>
1288 <h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2.
1289 raw() and cbreak()</a></h3>
1291 <p>Normally the terminal driver buffers the characters a
1292 user types until a new line or carriage return is
1293 encountered. But most programs require that the characters
1294 be available as soon as the user types them. The above two
1295 functions are used to disable line buffering. The
1296 difference between these two functions is in the way
1297 control characters like suspend (CTRL-Z), interrupt and
1298 quit (CTRL-C) are passed to the program. In the raw() mode
1299 these characters are directly passed to the program without
1300 generating a signal. In the <tt class=
1301 "LITERAL">cbreak()</tt> mode these control characters are
1302 interpreted as any other character by the terminal driver.
1303 I personally prefer to use raw() as I can exercise greater
1304 control over what the user does.</p>
1310 <h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3.
1311 echo() and noecho()</a></h3>
1313 <p>These functions control the echoing of characters typed
1314 by the user to the terminal. <tt class=
1315 "LITERAL">noecho()</tt> switches off echoing. The reason
1316 you might want to do this is to gain more control over
1317 echoing or to suppress unnecessary echoing while taking
1318 input from the user through the getch(), etc. functions.
1319 Most of the interactive programs call <tt class=
1320 "LITERAL">noecho()</tt> at initialization and do the
1321 echoing of characters in a controlled manner. It gives the
1322 programmer the flexibility of echoing characters at any
1323 place in the window without updating current (y,x)
1330 <h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4.
1333 <p>This is my favorite initialization function. It enables
1334 the reading of function keys like F1, F2, arrow keys, etc.
1335 Almost every interactive program enables this, as arrow
1336 keys are a major part of any User Interface. Do <tt class=
1337 "LITERAL">keypad(stdscr, TRUE)</tt> to enable this feature
1338 for the regular screen (stdscr). You will learn more about
1339 key management in later sections of this document.</p>
1345 <h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5.
1346 halfdelay()</a></h3>
1348 <p>This function, though not used very often, is a useful
1349 one at times. halfdelay()is called to enable the half-delay
1350 mode, which is similar to the cbreak() mode in that
1351 characters typed are immediately available to program.
1352 However, it waits for 'X' tenths of a second for input and
1353 then returns ERR, if no input is available. 'X' is the
1354 timeout value passed to the function halfdelay(). This
1355 function is useful when you want to ask the user for input,
1356 and if he doesn't respond with in certain time, we can do
1357 some thing else. One possible example is a timeout at the
1358 password prompt.</p>
1364 <h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6.
1365 Miscellaneous Initialization functions</a></h3>
1367 <p>There are few more functions which are called at
1368 initialization to customize curses behavior. They are not
1369 used as extensively as those mentioned above. Some of them
1370 are explained where appropriate.</p>
1376 <h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An
1379 <p>Let's write a program which will clarify the usage of
1380 these functions.</p>
1382 <div class="EXAMPLE">
1383 <a name="BINFU" id="BINFU"></a>
1384 <p><b>Example 2. Initialization Function Usage
1388 <pre class="PROGRAMLISTING"><span class=
1389 "INLINEMEDIAOBJECT">#include <curses.h>
1394 initscr(); /* Start curses mode */
1395 raw(); /* Line buffering disabled */
1396 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
1397 noecho(); /* Don't echo() while we do getch */
1399 printw("Type any character to see it in bold\n");
1400 ch = getch(); /* If raw() hadn't been called
1401 * we have to press enter before it
1402 * gets to the program */
1403 if(ch == KEY_F(1)) /* Without keypad enabled this will */
1404 printw("F1 Key pressed");/* not get to us either */
1405 /* Without noecho() some ugly escape
1406 * characters might have been printed
1409 { printw("The pressed key is ");
1414 refresh(); /* Print it on to the real screen */
1415 getch(); /* Wait for user input */
1416 endwin(); /* End curses mode */
1422 <p>This program is self-explanatory. But I used functions
1423 which aren't explained yet. The function <tt class=
1424 "LITERAL">getch()</tt> is used to get a character from
1425 user. It is equivalent to normal <tt class=
1426 "LITERAL">getchar()</tt> except that we can disable the
1427 line buffering to avoid <enter> after input. Look for
1428 more about <tt class="LITERAL">getch()</tt>and reading keys
1429 in the <a href="#KEYS">key management section</a> . The
1430 functions attron and attroff are used to switch some
1431 attributes on and off respectively. In the example I used
1432 them to print the character in bold. These functions are
1433 explained in detail later.</p>
1440 <h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5.
1441 A Word about Windows</a></h2>
1443 <p>Before we plunge into the myriad ncurses functions, let me
1444 clear few things about windows. Windows are explained in
1445 detail in following <a href="#WINDOWS">sections</a></p>
1447 <p>A Window is an imaginary screen defined by curses system.
1448 A window does not mean a bordered window which you usually
1449 see on Win9X platforms. When curses is initialized, it
1450 creates a default window named <tt class=
1451 "LITERAL">stdscr</tt> which represents your 80x25 (or the
1452 size of window in which you are running) screen. If you are
1453 doing simple tasks like printing few strings, reading input,
1454 etc., you can safely use this single window for all of your
1455 purposes. You can also create windows and call functions
1456 which explicitly work on the specified window.</p>
1458 <p>For example, if you call</p>
1460 <pre class="PROGRAMLISTING"> printw("Hi There !!!");
1462 <p>It prints the string on stdscr at the present cursor
1463 position. Similarly the call to refresh(), works on stdscr
1466 <p>Say you have created <a href="#WINDOWS">windows</a> then
1467 you have to call a function with a 'w' added to the usual
1470 <pre class="PROGRAMLISTING"> wprintw(win, "Hi There !!!");
1471 wrefresh(win);</pre>
1472 <p>As you will see in the rest of the document, naming of
1473 functions follow the same convention. For each function there
1474 usually are three more functions.</p>
1477 "PROGRAMLISTING"> printw(string); /* Print on stdscr at present cursor position */
1478 mvprintw(y, x, string);/* Move to (y, x) then print string */
1479 wprintw(win, string); /* Print on window win at present cursor position */
1481 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */
1482 /* co-ordinates and then print */</pre>
1483 <p>Usually the w-less functions are macros which expand to
1484 corresponding w-function with stdscr as the window
1491 <h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
1494 <p>I guess you can't wait any more to see some action. Back
1495 to our odyssey of curses functions. Now that curses is
1496 initialized, let's interact with world.</p>
1498 <p>There are three classes of functions which you can use to
1499 do output on screen.</p>
1503 <p>addch() class: Print single character with
1508 <p>printw() class: Print formatted output similar to
1513 <p>addstr() class: Print strings</p>
1517 <p>These functions can be used interchangeably and it is a
1518 matter of style as to which class is used. Let's see each one
1524 <h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1.
1525 addch() class of functions</a></h3>
1527 <p>These functions put a single character into the current
1528 cursor location and advance the position of the cursor. You
1529 can give the character to be printed but they usually are
1530 used to print a character with some attributes. Attributes
1531 are explained in detail in later <a href=
1532 "#ATTRIB">sections</a> of the document. If a character is
1533 associated with an attribute(bold, reverse video etc.),
1534 when curses prints the character, it is printed in that
1537 <p>In order to combine a character with some attributes,
1538 you have two options:</p>
1542 <p>By OR'ing a single character with the desired
1543 attribute macros. These attribute macros could be found
1544 in the header file <tt class="LITERAL">ncurses.h</tt>.
1545 For example, you want to print a character ch(of type
1546 char) bold and underlined, you would call addch() as
1550 "PROGRAMLISTING"> addch(ch | A_BOLD | A_UNDERLINE);</pre>
1554 <p>By using functions like <tt class=
1555 "LITERAL">attrset(),attron(),attroff()</tt>. These
1556 functions are explained in the <a href=
1557 "#ATTRIB">Attributes</a> section. Briefly, they
1558 manipulate the current attributes of the given window.
1559 Once set, the character printed in the window are
1560 associated with the attributes until it is turned
1565 <p>Additionally, <tt class="LITERAL">curses</tt> provides
1566 some special characters for character-based graphics. You
1567 can draw tables, horizontal or vertical lines, etc. You can
1568 find all available characters in the header file <tt class=
1569 "LITERAL">ncurses.h</tt>. Try looking for macros beginning
1570 with <tt class="LITERAL">ACS_</tt> in this file.</p>
1576 <h3 class="SECT2"><a name="AEN303" id="AEN303">6.2.
1577 mvaddch(), waddch() and mvwaddch()</a></h3>
1579 <p><tt class="LITERAL">mvaddch()</tt> is used to move the
1580 cursor to a given point, and then print. Thus, the
1584 "PROGRAMLISTING"> move(row,col); /* moves the cursor to row<span class="emphasis"><i class="EMPHASIS">th</i></span> row and col<span class="emphasis"><i class="EMPHASIS">th</i></span> column */
1585 addch(ch);</pre>can be replaced by
1587 <pre class="PROGRAMLISTING"> mvaddch(row,col,ch);</pre>
1588 <p><tt class="LITERAL">waddch()</tt> is similar to
1589 <tt class="LITERAL">addch()</tt>, except that it adds a
1590 character into the given window. (Note that <tt class=
1591 "LITERAL">addch()</tt> adds a character into the window
1592 <tt class="LITERAL">stdscr</tt>.)</p>
1594 <p>In a similar fashion <tt class="LITERAL">mvwaddch()</tt>
1595 function is used to add a character into the given window
1596 at the given coordinates.</p>
1598 <p>Now, we are familiar with the basic output function
1599 <tt class="LITERAL">addch()</tt>. But, if we want to print
1600 a string, it would be very annoying to print it character
1601 by character. Fortunately, <tt class="LITERAL">ncurses</tt>
1602 provides <tt class="LITERAL">printf</tt><span class=
1603 "emphasis"><i class="EMPHASIS">-like</i></span> or
1604 <tt class="LITERAL">puts</tt><span class=
1605 "emphasis"><i class="EMPHASIS">-like</i></span>
1612 <h3 class="SECT2"><a name="PRINTWCLASS" id=
1613 "PRINTWCLASS">6.3. printw() class of functions</a></h3>
1615 <p>These functions are similar to <tt class=
1616 "LITERAL">printf()</tt> with the added capability of
1617 printing at any position on the screen.</p>
1622 <h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
1623 "PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
1625 <p>These two functions work much like <tt class=
1626 "LITERAL">printf()</tt>. <tt class=
1627 "LITERAL">mvprintw()</tt> can be used to move the cursor
1628 to a position and then print. If you want to move the
1629 cursor first and then print using <tt class=
1630 "LITERAL">printw()</tt> function, use <tt class=
1631 "LITERAL">move()</tt> first and then use <tt class=
1632 "LITERAL">printw()</tt> though I see no point why one
1633 should avoid using <tt class="LITERAL">mvprintw()</tt>,
1634 you have the flexibility to manipulate.</p>
1640 <h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
1641 "WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4>
1643 <p>These two functions are similar to above two except
1644 that they print in the corresponding window given as
1651 <h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
1652 vw_printw()</a></h4>
1654 <p>This function is similar to <tt class=
1655 "LITERAL">vprintf()</tt>. This can be used when variable
1656 number of arguments are to be printed.</p>
1662 <h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
1663 "SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
1665 <div class="EXAMPLE">
1666 <a name="BPREX" id="BPREX"></a>
1667 <p><b>Example 3. A Simple printw example</b>
1670 <pre class="PROGRAMLISTING"><span class=
1671 "INLINEMEDIAOBJECT">#include <curses.h>
1672 #include <string.h>
1676 char mesg[]="Just a string"; /* message to be appeared on the screen */
1677 int row,col; /* to store the number of rows and *
1678 * the number of columns of the screen */
1679 initscr(); /* start the curses mode */
1680 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1681 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1682 /* print the message at the center of the screen */
1683 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
1684 printw("Try resizing your window(if possible) and then run this program again");
1693 <p>Above program demonstrates how easy it is to use
1694 <tt class="LITERAL">printw</tt>. You just feed the
1695 coordinates and the message to be appeared on the screen,
1696 then it does what you want.</p>
1698 <p>The above program introduces us to a new function
1699 <tt class="LITERAL">getmaxyx()</tt>, a macro defined in
1700 <tt class="LITERAL">ncurses.h</tt>. It gives the number
1701 of columns and the number of rows in a given window.
1702 <tt class="LITERAL">getmaxyx()</tt> does this by updating
1703 the variables given to it. Since <tt class=
1704 "LITERAL">getmaxyx()</tt> is not a function we don't pass
1705 pointers to it, we just give two integer variables.</p>
1712 <h3 class="SECT2"><a name="ADDSTRCLASS" id=
1713 "ADDSTRCLASS">6.4. addstr() class of functions</a></h3>
1715 <p><tt class="LITERAL">addstr()</tt> is used to put a
1716 character string into a given window. This function is
1717 similar to calling <tt class="LITERAL">addch()</tt> once
1718 for each character in a given string. This is true for all
1719 output functions. There are other functions from this
1720 family such as <tt class=
1721 "LITERAL">mvaddstr(),mvwaddstr()</tt> and <tt class=
1722 "LITERAL">waddstr()</tt>, which obey the naming convention
1723 of curses.(e.g. mvaddstr() is similar to the respective
1724 calls move() and then addstr().) Another function of this
1725 family is addnstr(), which takes an integer parameter(say
1726 n) additionally. This function puts at most n characters
1727 into the screen. If n is negative, then the entire string
1734 <h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A
1735 word of caution</a></h3>
1737 <p>All these functions take y co-ordinate first and then x
1738 in their arguments. A common mistake by beginners is to
1739 pass x,y in that order. If you are doing too many
1740 manipulations of (y,x) co-ordinates, think of dividing the
1741 screen into windows and manipulate each one separately.
1742 Windows are explained in the <a href="#WINDOWS">windows</a>
1750 <h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
1753 <p>Well, printing without taking input, is boring. Let's see
1754 functions which allow us to get input from user. These
1755 functions also can be divided into three categories.</p>
1759 <p>getch() class: Get a character</p>
1763 <p>scanw() class: Get formatted input</p>
1767 <p>getstr() class: Get strings</p>
1774 <h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1.
1775 getch() class of functions</a></h3>
1777 <p>These functions read a single character from the
1778 terminal. But there are several subtle facts to consider.
1779 For example if you don't use the function cbreak(), curses
1780 will not read your input characters contiguously but will
1781 begin read them only after a new line or an EOF is
1782 encountered. In order to avoid this, the cbreak() function
1783 must used so that characters are immediately available to
1784 your program. Another widely used function is noecho(). As
1785 the name suggests, when this function is set (used), the
1786 characters that are keyed in by the user will not show up
1787 on the screen. The two functions cbreak() and noecho() are
1788 typical examples of key management. Functions of this genre
1789 are explained in the <a href="#KEYS">key management
1796 <h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2.
1797 scanw() class of functions</a></h3>
1799 <p>These functions are similar to <tt class=
1800 "LITERAL">scanf()</tt> with the added capability of getting
1801 the input from any location on the screen.</p>
1806 <h4 class="SECT3"><a name="SCANWMVSCANW" id=
1807 "SCANWMVSCANW">7.2.1. scanw() and mvscanw</a></h4>
1809 <p>The usage of these functions is similar to that of
1810 <tt class="LITERAL">sscanf()</tt>, where the line to be
1811 scanned is provided by <tt class="LITERAL">wgetstr()</tt>
1812 function. That is, these functions call to <tt class=
1813 "LITERAL">wgetstr()</tt> function(explained below) and
1814 uses the resulting line for a scan.</p>
1820 <h4 class="SECT3"><a name="WSCANWMVWSCANW" id=
1821 "WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4>
1823 <p>These are similar to above two functions except that
1824 they read from a window, which is supplied as one of the
1825 arguments to these functions.</p>
1831 <h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3.
1834 <p>This function is similar to <tt class=
1835 "LITERAL">vscanf()</tt>. This can be used when a variable
1836 number of arguments are to be scanned.</p>
1843 <h3 class="SECT2"><a name="GETSTRCLASS" id=
1844 "GETSTRCLASS">7.3. getstr() class of functions</a></h3>
1846 <p>These functions are used to get strings from the
1847 terminal. In essence, this function performs the same task
1848 as would be achieved by a series of calls to <tt class=
1849 "LITERAL">getch()</tt> until a newline, carriage return, or
1850 end-of-file is received. The resulting string of characters
1851 are pointed to by <tt class="LITERAL">str</tt>, which is a
1852 character pointer provided by the user.</p>
1858 <h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4.
1859 Some examples</a></h3>
1861 <div class="EXAMPLE">
1862 <a name="BSCEX" id="BSCEX"></a>
1863 <p><b>Example 4. A Simple scanw example</b>
1866 <pre class="PROGRAMLISTING"><span class=
1867 "INLINEMEDIAOBJECT">#include <curses.h>
1868 #include <string.h>
1872 char mesg[]="Enter a string: "; /* message to be appeared on the screen */
1874 int row,col; /* to store the number of rows and *
1875 * the number of columns of the screen */
1876 initscr(); /* start the curses mode */
1877 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1878 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1879 /* print the message at the center of the screen */
1881 mvprintw(LINES - 2, 0, "You Entered: %s", str);
1894 <h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8.
1897 <p>We have seen an example of how attributes can be used to
1898 print characters with some special effects. Attributes, when
1899 set prudently, can present information in an easy,
1900 understandable manner. The following program takes a C file
1901 as input and prints the file with comments in bold. Scan
1902 through the code.</p>
1904 <div class="EXAMPLE">
1905 <a name="BSIAT" id="BSIAT"></a>
1906 <p><b>Example 5. A Simple Attributes example</b>
1909 <pre class="PROGRAMLISTING"><span class=
1910 "INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */
1911 #include <curses.h>
1912 #include <stdlib.h>
1914 int main(int argc, char *argv[])
1916 int ch, prev, row, col;
1923 printf("Usage: %s <a c file name>\n", argv[0]);
1926 fp = fopen(argv[1], "r");
1929 perror("Cannot open input file");
1932 initscr(); /* Start curses mode */
1933 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */
1934 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */
1936 getyx(stdscr, y, x); /* get the current cursor position */
1937 if(y == (row - 1)) /* are we are at the end of the screen */
1939 printw("<-Press Any Key->"); /* tell the user to press a key */
1941 clear(); /* clear the screen */
1942 move(0, 0); /* start at the beginning of the screen */
1944 if(prev == '/' && ch == '*') /* If it is / and * then only
1947 attron(A_BOLD); /* cut bold on */
1948 getyx(stdscr, y, x); /* get the current cursor position */
1949 move(y, x - 1); /* back up one space */
1950 printw("%c%c", '/', ch); /* The actual printing is done here */
1955 if(prev == '*' && ch == '/')
1956 attroff(A_BOLD); /* Switch it off once we got *
1960 endwin(); /* End curses mode */
1966 <p>Don't worry about all those initialization and other crap.
1967 Concentrate on the while loop. It reads each character in the
1968 file and searches for the pattern /*. Once it spots the
1969 pattern, it switches the BOLD attribute on with <tt class=
1970 "LITERAL">attron()</tt> . When we get the pattern */ it is
1971 switched off by <tt class="LITERAL">attroff()</tt> .</p>
1973 <p>The above program also introduces us to two useful
1974 functions <tt class="LITERAL">getyx()</tt> and <tt class=
1975 "LITERAL">move()</tt>. The first function gets the
1976 co-ordinates of the present cursor into the variables y, x.
1977 Since getyx() is a macro we don't have to pass pointers to
1978 variables. The function <tt class="LITERAL">move()</tt> moves
1979 the cursor to the co-ordinates given to it.</p>
1981 <p>The above program is really a simple one which doesn't do
1982 much. On these lines one could write a more useful program
1983 which reads a C file, parses it and prints it in different
1984 colors. One could even extend it to other languages as
1990 <h3 class="SECT2"><a name="ATTRIBDETAILS" id=
1991 "ATTRIBDETAILS">8.1. The details</a></h3>
1993 <p>Let's get into more details of attributes. The functions
1994 <tt class="LITERAL">attron(), attroff(), attrset()</tt> ,
1995 and their sister functions <tt class=
1996 "LITERAL">attr_get()</tt>, etc. can be used to switch
1997 attributes on/off , get attributes and produce a colorful
2000 <p>The functions attron and attroff take a bit-mask of
2001 attributes and switch them on or off, respectively. The
2002 following video attributes, which are defined in
2003 <curses.h> can be passed to these functions.</p>
2005 <pre class="PROGRAMLISTING">
2006 A_NORMAL Normal display (no highlight)
2007 A_STANDOUT Best highlighting mode of the terminal.
2008 A_UNDERLINE Underlining
2009 A_REVERSE Reverse video
2012 A_BOLD Extra bright or bold
2013 A_PROTECT Protected mode
2014 A_INVIS Invisible or blank mode
2015 A_ALTCHARSET Alternate character set
2016 A_CHARTEXT Bit-mask to extract a character
2017 COLOR_PAIR(n) Color-pair number n
2019 <p>The last one is the most colorful one :-) Colors are
2020 explained in the <a href="#color" target="_top">next
2023 <p>We can OR(|) any number of above attributes to get a
2024 combined effect. If you wanted reverse video with blinking
2025 characters you can use</p>
2028 "PROGRAMLISTING"> attron(A_REVERSE | A_BLINK);</pre>
2034 <h3 class="SECT2"><a name="ATTRONVSATTRSET" id=
2035 "ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3>
2037 <p>Then what is the difference between attron() and
2038 attrset()? attrset sets the attributes of window whereas
2039 attron just switches on the attribute given to it. So
2040 attrset() fully overrides whatever attributes the window
2041 previously had and sets it to the new attribute(s).
2042 Similarly attroff() just switches off the attribute(s)
2043 given to it as an argument. This gives us the flexibility
2044 of managing attributes easily.But if you use them
2045 carelessly you may loose track of what attributes the
2046 window has and garble the display. This is especially true
2047 while managing menus with colors and highlighting. So
2048 decide on a consistent policy and stick to it. You can
2049 always use <tt class="LITERAL">standend()</tt> which is
2050 equivalent to <tt class="LITERAL">attrset(A_NORMAL)</tt>
2051 which turns off all attributes and brings you to normal
2058 <h3 class="SECT2"><a name="ATTRGET" id="ATTRGET">8.3.
2061 <p>The function attr_get() gets the current attributes and
2062 color pair of the window. Though we might not use this as
2063 often as the above functions, this is useful in scanning
2064 areas of screen. Say we wanted to do some complex update on
2065 screen and we are not sure what attribute each character is
2066 associated with. Then this function can be used with either
2067 attrset or attron to produce the desired effect.</p>
2073 <h3 class="SECT2"><a name="ATTRFUNCS" id="ATTRFUNCS">8.4.
2074 attr_ functions</a></h3>
2076 <p>There are series of functions like attr_set(), attr_on,
2077 etc. These are similar to above functions except that they
2078 take parameters of type <tt class=
2079 "LITERAL">attr_t</tt>.</p>
2085 <h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5.
2086 wattr functions</a></h3>
2088 <p>For each of the above functions we have a corresponding
2089 function with 'w' which operates on a particular window.
2090 The above functions operate on stdscr.</p>
2096 <h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat()
2099 <p>The function chgat() is listed in the end of the man
2100 page curs_attr. It actually is a useful one. This function
2101 can be used to set attributes for a group of characters
2102 without moving. I mean it !!! without moving the cursor :-)
2103 It changes the attributes of a given number of characters
2104 starting at the current cursor location.</p>
2106 <p>We can give -1 as the character count to update till end
2107 of line. If you want to change attributes of characters
2108 from current position to end of line, just use this.</p>
2111 "PROGRAMLISTING"> chgat(-1, A_REVERSE, 0, NULL);</pre>
2112 <p>This function is useful when changing attributes for
2113 characters that are already on the screen. Move to the
2114 character from which you want to change and change the
2117 <p>Other functions wchgat(), mvchgat(), wchgat() behave
2118 similarly except that the w functions operate on the
2119 particular window. The mv functions first move the cursor
2120 then perform the work given to them. Actually chgat is a
2121 macro which is replaced by a wchgat() with stdscr as the
2122 window. Most of the "w-less" functions are macros.</p>
2124 <div class="EXAMPLE">
2125 <a name="BWICH" id="BWICH"></a>
2126 <p><b>Example 6. Chgat() Usage example</b>
2129 <pre class="PROGRAMLISTING"><span class=
2130 "INLINEMEDIAOBJECT">#include <curses.h>
2132 int main(int argc, char *argv[])
2133 { initscr(); /* Start curses mode */
2134 start_color(); /* Start color functionality */
2136 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2137 printw("A Big string which i didn't care to type fully ");
2138 mvchgat(0, 0, -1, A_BLINK, 1, NULL);
2140 * First two parameters specify the position at which to start
2141 * Third parameter number of characters to update. -1 means till
2143 * Forth parameter is the normal attribute you wanted to give
2145 * Fifth is the color index. It is the index given during init_pair()
2146 * use 0 if you didn't want color
2147 * Sixth one is always NULL
2151 endwin(); /* End curses mode */
2156 <p>This example also introduces us to the color world of
2157 curses. Colors will be explained in detail later. Use 0 for
2165 <h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9.
2168 <p>Windows form the most important concept in curses. You
2169 have seen the standard window stdscr above where all the
2170 functions implicitly operated on this window. Now to make
2171 design even a simplest GUI, you need to resort to windows.
2172 The main reason you may want to use windows is to manipulate
2173 parts of the screen separately, for better efficiency, by
2174 updating only the windows that need to be changed and for a
2175 better design. I would say the last reason is the most
2176 important in going for windows. You should always strive for
2177 a better and easy-to-manage design in your programs. If you
2178 are writing big, complex GUIs this is of pivotal importance
2179 before you start doing anything.</p>
2184 <h3 class="SECT2"><a name="WINDOWBASICS" id=
2185 "WINDOWBASICS">9.1. The basics</a></h3>
2187 <p>A Window can be created by calling the function
2188 <tt class="LITERAL">newwin()</tt>. It doesn't create any
2189 thing on the screen actually. It allocates memory for a
2190 structure to manipulate the window and updates the
2191 structure with data regarding the window such as its size,
2192 beginy, beginx, etc. Hence in curses, a window is just an
2193 abstraction of an imaginary window, which can be
2194 manipulated independent of other parts of screen. The
2195 function newwin() returns a pointer to structure WINDOW,
2196 which can be passed to window related functions such as
2197 wprintw(), etc. Finally the window can be destroyed with
2198 delwin(). It will deallocate the memory associated with the
2199 window structure.</p>
2205 <h3 class="SECT2"><a name="LETBEWINDOW" id=
2206 "LETBEWINDOW">9.2. Let there be a Window !!!</a></h3>
2208 <p>What fun is it, if a window is created and we can't see
2209 it. So the fun part begins by displaying the window. The
2210 function <tt class="LITERAL">box()</tt> can be used to draw
2211 a border around the window. Let's explore these functions
2212 in more detail in this example.</p>
2214 <div class="EXAMPLE">
2215 <a name="BWIBO" id="BWIBO"></a>
2216 <p><b>Example 7. Window Border example</b>
2219 <pre class="PROGRAMLISTING"><span class=
2220 "INLINEMEDIAOBJECT">#include <curses.h>
2222 WINDOW *create_newwin(int height, int width, int starty, int startx);
2223 void destroy_win(WINDOW *local_win);
2225 int main(int argc, char *argv[])
2227 int startx, starty, width, height;
2230 initscr(); /* Start curses mode */
2231 cbreak(); /* Line buffering disabled, Pass on
2232 * everty thing to me */
2233 keypad(stdscr, TRUE); /* I need that nifty F1 */
2237 starty = (LINES - height) / 2; /* Calculating for a center placement */
2238 startx = (COLS - width) / 2; /* of the window */
2239 printw("Press F1 to exit");
2241 my_win = create_newwin(height, width, starty, startx);
2243 while((ch = getch()) != KEY_F(1))
2246 destroy_win(my_win);
2247 my_win = create_newwin(height, width, starty,--startx);
2250 destroy_win(my_win);
2251 my_win = create_newwin(height, width, starty,++startx);
2254 destroy_win(my_win);
2255 my_win = create_newwin(height, width, --starty,startx);
2258 destroy_win(my_win);
2259 my_win = create_newwin(height, width, ++starty,startx);
2264 endwin(); /* End curses mode */
2268 WINDOW *create_newwin(int height, int width, int starty, int startx)
2269 { WINDOW *local_win;
2271 local_win = newwin(height, width, starty, startx);
2272 box(local_win, 0 , 0); /* 0, 0 gives default characters
2273 * for the vertical and horizontal
2275 wrefresh(local_win); /* Show that box */
2280 void destroy_win(WINDOW *local_win)
2282 /* box(local_win, ' ', ' '); : This won't produce the desired
2283 * result of erasing the window. It will leave its four corners
2284 * and so an ugly remnant of window.
2286 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' ');
2287 /* The parameters taken are
2288 * 1. win: the window on which to operate
2289 * 2. ls: character to be used for the left side of the window
2290 * 3. rs: character to be used for the right side of the window
2291 * 4. ts: character to be used for the top side of the window
2292 * 5. bs: character to be used for the bottom side of the window
2293 * 6. tl: character to be used for the top left corner of the window
2294 * 7. tr: character to be used for the top right corner of the window
2295 * 8. bl: character to be used for the bottom left corner of the window
2296 * 9. br: character to be used for the bottom right corner of the window
2298 wrefresh(local_win);
2307 <h3 class="SECT2"><a name="BORDEREXEXPL" id=
2308 "BORDEREXEXPL">9.3. Explanation</a></h3>
2310 <p>Don't scream. I know it is a big example. But I have to
2311 explain some important things here :-). This program
2312 creates a rectangular window that can be moved with left,
2313 right, up, down arrow keys. It repeatedly creates and
2314 destroys windows as user press a key. Don't go beyond the
2315 screen limits. Checking for those limits is left as an
2316 exercise for the reader. Let's dissect it by line by
2319 <p>The <tt class="LITERAL">create_newwin()</tt> function
2320 creates a window with <tt class="LITERAL">newwin()</tt> and
2321 displays a border around it with box. The function
2322 <tt class="LITERAL">destroy_win()</tt> first erases the
2323 window from screen by painting a border with ' ' character
2324 and then calling <tt class="LITERAL">delwin()</tt> to
2325 deallocate memory related to it. Depending on the key the
2326 user presses, starty or startx is changed and a new window
2329 <p>In the destroy_win, as you can see, I used wborder
2330 instead of box. The reason is written in the comments (You
2331 missed it. I know. Read the code :-)). wborder draws a
2332 border around the window with the characters given to it as
2333 the 4 corner points and the 4 lines. To put it clearly, if
2334 you have called wborder as below:</p>
2337 "PROGRAMLISTING"> wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');</pre>
2338 <p>it produces something like</p>
2340 <pre class="PROGRAMLISTING"> +------------+
2347 +------------+</pre>
2353 <h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4.
2354 The other stuff in the example</a></h3>
2356 <p>You can also see in the above examples, that I have used
2357 the variables COLS, LINES which are initialized to the
2358 screen sizes after initscr(). They can be useful in finding
2359 screen dimensions and finding the center co-ordinate of the
2360 screen as above. The function <tt class=
2361 "LITERAL">getch()</tt> as usual gets the key from keyboard
2362 and according to the key it does the corresponding work.
2363 This type of switch- case is very common in any GUI based
2370 <h3 class="SECT2"><a name="OTHERBORDERFUNCS" id=
2371 "OTHERBORDERFUNCS">9.5. Other Border functions</a></h3>
2373 <p>Above program is grossly inefficient in that with each
2374 press of a key, a window is destroyed and another is
2375 created. So let's write a more efficient program which uses
2376 other border related functions.</p>
2378 <p>The following program uses <tt class=
2379 "LITERAL">mvhline()</tt> and <tt class=
2380 "LITERAL">mvvline()</tt> to achieve similar effect. These
2381 two functions are simple. They create a horizontal or
2382 vertical line of the specified length at the specified
2385 <div class="EXAMPLE">
2386 <a name="BOTBO" id="BOTBO"></a>
2387 <p><b>Example 8. More border functions</b>
2390 <pre class="PROGRAMLISTING"><span class=
2391 "INLINEMEDIAOBJECT">#include <curses.h>
2393 typedef struct _win_border_struct {
2394 chtype ls, rs, ts, bs,
2398 typedef struct _WIN_struct {
2405 void init_win_params(WIN *p_win);
2406 void print_win_params(WIN *p_win);
2407 void create_box(WIN *win, bool flag);
2409 int main(int argc, char *argv[])
2413 initscr(); /* Start curses mode */
2414 start_color(); /* Start the color functionality */
2415 cbreak(); /* Line buffering disabled, Pass on
2416 * everty thing to me */
2417 keypad(stdscr, TRUE); /* I need that nifty F1 */
2419 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2421 /* Initialize the window parameters */
2422 init_win_params(&win);
2423 print_win_params(&win);
2425 attron(COLOR_PAIR(1));
2426 printw("Press F1 to exit");
2428 attroff(COLOR_PAIR(1));
2430 create_box(&win, TRUE);
2431 while((ch = getch()) != KEY_F(1))
2434 create_box(&win, FALSE);
2436 create_box(&win, TRUE);
2439 create_box(&win, FALSE);
2441 create_box(&win, TRUE);
2444 create_box(&win, FALSE);
2446 create_box(&win, TRUE);
2449 create_box(&win, FALSE);
2451 create_box(&win, TRUE);
2455 endwin(); /* End curses mode */
2458 void init_win_params(WIN *p_win)
2460 p_win->height = 3;
2461 p_win->width = 10;
2462 p_win->starty = (LINES - p_win->height)/2;
2463 p_win->startx = (COLS - p_win->width)/2;
2465 p_win->border.ls = '|';
2466 p_win->border.rs = '|';
2467 p_win->border.ts = '-';
2468 p_win->border.bs = '-';
2469 p_win->border.tl = '+';
2470 p_win->border.tr = '+';
2471 p_win->border.bl = '+';
2472 p_win->border.br = '+';
2475 void print_win_params(WIN *p_win)
2478 mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty,
2479 p_win->width, p_win->height);
2483 void create_box(WIN *p_win, bool flag)
2487 x = p_win->startx;
2488 y = p_win->starty;
2489 w = p_win->width;
2490 h = p_win->height;
2493 { mvaddch(y, x, p_win->border.tl);
2494 mvaddch(y, x + w, p_win->border.tr);
2495 mvaddch(y + h, x, p_win->border.bl);
2496 mvaddch(y + h, x + w, p_win->border.br);
2497 mvhline(y, x + 1, p_win->border.ts, w - 1);
2498 mvhline(y + h, x + 1, p_win->border.bs, w - 1);
2499 mvvline(y + 1, x, p_win->border.ls, h - 1);
2500 mvvline(y + 1, x + w, p_win->border.rs, h - 1);
2504 for(j = y; j <= y + h; ++j)
2505 for(i = x; i <= x + w; ++i)
2518 <h2 class="SECT1"><a name="COLOR" id="COLOR">10. Colors</a></h2>
2521 <h3 class="SECT2"><a name="COLORBASICS" id=
2522 "COLORBASICS">10.1. The basics</a></h3>
2524 <p>Life seems dull with no colors. Curses has a nice
2525 mechanism to handle colors. Let's get into the thick of the
2526 things with a small program.</p>
2528 <div class="EXAMPLE">
2529 <a name="BSICO" id="BSICO"></a>
2530 <p><b>Example 9. A Simple Color example</b>
2533 <pre class="PROGRAMLISTING"><span class=
2534 "INLINEMEDIAOBJECT">#include <stdlib.h>
2535 #include <string.h>
2536 #include <curses.h>
2538 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string);
2539 int main(int argc, char *argv[])
2540 { initscr(); /* Start curses mode */
2541 if(has_colors() == FALSE)
2543 printf("Your terminal does not support color\n");
2546 start_color(); /* Start color */
2547 init_pair(1, COLOR_RED, COLOR_BLACK);
2549 attron(COLOR_PAIR(1));
2550 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ...");
2551 attroff(COLOR_PAIR(1));
2555 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string)
2569 length = strlen(string);
2570 temp = (width - length)/ 2;
2571 x = startx + (int)temp;
2572 mvwprintw(win, y, x, "%s", string);
2578 <p>As you can see, to start using color, you should first
2579 call the function <tt class="LITERAL">start_color()</tt>.
2580 After that, you can use color capabilities of your
2581 terminals using various functions. To find out whether a
2582 terminal has color capabilities or not, you can use
2583 <tt class="LITERAL">has_colors()</tt> function, which
2584 returns FALSE if the terminal does not support color.</p>
2586 <p>Curses initializes all the colors supported by terminal
2587 when start_color() is called. These can be accessed by the
2588 define constants like <tt class="LITERAL">COLOR_BLACK</tt>
2589 , etc. Now to actually start using colors, you have to
2590 define pairs. Colors are always used in pairs. That means
2591 you have to use the function <tt class=
2592 "LITERAL">init_pair()</tt> to define the foreground and
2593 background for the pair number you give. After that that
2594 pair number can be used as a normal attribute with
2595 <tt class="LITERAL">COLOR_PAIR()</tt>function. This may
2596 seem to be cumbersome at first. But this elegant solution
2597 allows us to manage color pairs very easily. To appreciate
2598 it, you have to look into the the source code of "dialog",
2599 a utility for displaying dialog boxes from shell scripts.
2600 The developers have defined foreground and background
2601 combinations for all the colors they might need and
2602 initialized at the beginning. This makes it very easy to
2603 set attributes just by accessing a pair which we already
2604 have defined as a constant.</p>
2606 <p>The following colors are defined in <tt class=
2607 "LITERAL">curses.h</tt>. You can use these as parameters
2608 for various color functions.</p>
2610 <pre class="PROGRAMLISTING"> COLOR_BLACK 0
2623 <h3 class="SECT2"><a name="CHANGECOLORDEFS" id=
2624 "CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3>
2626 <p>The function <tt class="LITERAL">init_color()</tt>can be
2627 used to change the rgb values for the colors defined by
2628 curses initially. Say you wanted to lighten the intensity
2629 of red color by a minuscule. Then you can use this function
2633 "PROGRAMLISTING"> init_color(COLOR_RED, 700, 0, 0);
2634 /* param 1 : color name
2635 * param 2, 3, 4 : rgb content min = 0, max = 1000 */</pre>
2636 <p>If your terminal cannot change the color definitions,
2637 the function returns ERR. The function <tt class=
2638 "LITERAL">can_change_color()</tt> can be used to find out
2639 whether the terminal has the capability of changing color
2640 content or not. The rgb content is scaled from 0 to 1000.
2641 Initially RED color is defined with content 1000(r), 0(g),
2648 <h3 class="SECT2"><a name="COLORCONTENT" id=
2649 "COLORCONTENT">10.3. Color Content</a></h3>
2651 <p>The functions <tt class="LITERAL">color_content()</tt>
2652 and <tt class="LITERAL">pair_content()</tt> can be used to
2653 find the color content and foreground, background
2654 combination for the pair.</p>
2661 <h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing
2662 with the key board</a></h2>
2665 <h3 class="SECT2"><a name="KEYSBASICS" id=
2666 "KEYSBASICS">11.1. The Basics</a></h3>
2668 <p>No GUI is complete without a strong user interface and
2669 to interact with the user, a curses program should be
2670 sensitive to key presses or the mouse actions done by the
2671 user. Let's deal with the keys first.</p>
2673 <p>As you have seen in almost all of the above examples, it
2674 is very easy to get key input from the user. A simple way
2675 of getting key presses is to use <tt class=
2676 "LITERAL">getch()</tt> function. The cbreak mode should be
2677 enabled to read keys when you are interested in reading
2678 individual key hits rather than complete lines of text
2679 (which usually end with a carriage return). keypad should
2680 be enabled to get the Functions keys, arrow keys, etc. See
2681 the initialization section for details.</p>
2683 <p><tt class="LITERAL">getch()</tt> returns an integer
2684 corresponding to the key pressed. If it is a normal
2685 character, the integer value will be equivalent to the
2686 character. Otherwise it returns a number which can be
2687 matched with the constants defined in <tt class=
2688 "LITERAL">curses.h</tt>. For example if the user presses
2689 F1, the integer returned is 265. This can be checked using
2690 the macro KEY_F() defined in curses.h. This makes reading
2691 keys portable and easy to manage.</p>
2693 <p>For example, if you call getch() like this</p>
2695 <pre class="PROGRAMLISTING"> int ch;
2698 <p>getch() will wait for the user to press a key, (unless
2699 you specified a timeout) and when user presses a key, the
2700 corresponding integer is returned. Then you can check the
2701 value returned with the constants defined in curses.h to
2702 match against the keys you want.</p>
2704 <p>The following code piece will do that job.</p>
2706 <pre class="PROGRAMLISTING"> if(ch == KEY_LEFT)
2707 printw("Left arrow is pressed\n");</pre>
2708 <p>Let's write a small program which creates a menu which
2709 can be navigated by up and down arrows.</p>
2715 <h3 class="SECT2"><a name="SIMPLEKEYEX" id=
2716 "SIMPLEKEYEX">11.2. A Simple Key Usage example</a></h3>
2718 <div class="EXAMPLE">
2719 <a name="BSIKE" id="BSIKE"></a>
2720 <p><b>Example 10. A Simple Key Usage example</b>
2723 <pre class="PROGRAMLISTING"><span class=
2724 "INLINEMEDIAOBJECT">#include <curses.h>
2739 int n_choices = sizeof(choices) / sizeof(char *);
2740 void print_menu(WINDOW *menu_win, int highlight);
2751 cbreak(); /* Line buffering disabled. pass on everything */
2752 startx = (80 - WIDTH) / 2;
2753 starty = (24 - HEIGHT) / 2;
2755 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2756 keypad(menu_win, TRUE);
2757 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice");
2759 print_menu(menu_win, highlight);
2761 { c = wgetch(menu_win);
2765 highlight = n_choices;
2770 if(highlight == n_choices)
2779 mvprintw(24, 0, "Character pressed is = %3d Hopefully it can be printed as '%c'", c, c);
2783 print_menu(menu_win, highlight);
2784 if(choice != 0) /* User did a choice come out of the infinite loop */
2787 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]);
2794 void print_menu(WINDOW *menu_win, int highlight)
2800 box(menu_win, 0, 0);
2801 for(i = 0; i < n_choices; ++i)
2802 { if(highlight == i + 1) /* High light the present choice */
2803 { wattron(menu_win, A_REVERSE);
2804 mvwprintw(menu_win, y, x, "%s", choices[i]);
2805 wattroff(menu_win, A_REVERSE);
2808 mvwprintw(menu_win, y, x, "%s", choices[i]);
2821 <h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing
2822 with the mouse</a></h2>
2824 <p>Now that you have seen how to get keys, lets do the same
2825 thing from mouse. Usually each UI allows the user to interact
2826 with both keyboard and mouse.</p>
2831 <h3 class="SECT2"><a name="MOUSEBASICS" id=
2832 "MOUSEBASICS">12.1. The Basics</a></h3>
2834 <p>Before you do any thing else, the events you want to
2835 receive have to be enabled with <tt class=
2836 "LITERAL">mousemask()</tt>.</p>
2839 "PROGRAMLISTING"> mousemask( mmask_t newmask, /* The events you want to listen to */
2840 mmask_t *oldmask) /* The old events mask */</pre>
2841 <p>The first parameter to above function is a bit mask of
2842 events you would like to listen. By default, all the events
2843 are turned off. The bit mask <tt class=
2844 "LITERAL">ALL_MOUSE_EVENTS</tt> can be used to get all the
2847 <p>The following are all the event masks:</p>
2849 <pre class="PROGRAMLISTING"> Name Description
2850 ---------------------------------------------------------------------
2851 BUTTON1_PRESSED mouse button 1 down
2852 BUTTON1_RELEASED mouse button 1 up
2853 BUTTON1_CLICKED mouse button 1 clicked
2854 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
2855 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
2856 BUTTON2_PRESSED mouse button 2 down
2857 BUTTON2_RELEASED mouse button 2 up
2858 BUTTON2_CLICKED mouse button 2 clicked
2859 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
2860 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
2861 BUTTON3_PRESSED mouse button 3 down
2862 BUTTON3_RELEASED mouse button 3 up
2863 BUTTON3_CLICKED mouse button 3 clicked
2864 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
2865 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
2866 BUTTON4_PRESSED mouse button 4 down
2867 BUTTON4_RELEASED mouse button 4 up
2868 BUTTON4_CLICKED mouse button 4 clicked
2869 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
2870 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
2871 BUTTON_SHIFT shift was down during button state change
2872 BUTTON_CTRL control was down during button state change
2873 BUTTON_ALT alt was down during button state change
2874 ALL_MOUSE_EVENTS report all button state changes
2875 REPORT_MOUSE_POSITION report mouse movement</pre>
2881 <h3 class="SECT2"><a name="GETTINGEVENTS" id=
2882 "GETTINGEVENTS">12.2. Getting the events</a></h3>
2884 <p>Once a class of mouse events have been enabled, getch()
2885 class of functions return KEY_MOUSE every time some mouse
2886 event happens. Then the mouse event can be retrieved with
2887 <tt class="LITERAL">getmouse()</tt>.</p>
2889 <p>The code approximately looks like this:</p>
2891 <pre class="PROGRAMLISTING"> MEVENT event;
2895 if(getmouse(&event) == OK)
2896 . /* Do some thing with the event */
2899 <p>getmouse() returns the event into the pointer given to
2900 it. It is a structure which contains</p>
2902 <pre class="PROGRAMLISTING"> typedef struct
2904 short id; /* ID to distinguish multiple devices */
2905 int x, y, z; /* event coordinates */
2906 mmask_t bstate; /* button state bits */
2908 <p>The <tt class="LITERAL">bstate</tt> is the main variable
2909 we are interested in. It tells the button state of the
2912 <p>Then with a code snippet like the following, we can find
2913 out what happened.</p>
2916 "PROGRAMLISTING"> if(event.bstate & BUTTON1_PRESSED)
2917 printw("Left Button Pressed");</pre>
2923 <h3 class="SECT2"><a name="MOUSETOGETHER" id=
2924 "MOUSETOGETHER">12.3. Putting it all Together</a></h3>
2926 <p>That's pretty much interfacing with mouse. Let's create
2927 the same menu and enable mouse interaction. To make things
2928 simpler, key handling is removed.</p>
2930 <div class="EXAMPLE">
2931 <a name="BMOME" id="BMOME"></a>
2932 <p><b>Example 11. Access the menu with mouse !!!</b>
2935 <pre class="PROGRAMLISTING"><span class=
2936 "INLINEMEDIAOBJECT">#include <string.h>
2937 #include <curses.h>
2945 char *choices[] = { "Choice 1",
2952 int n_choices = sizeof(choices) / sizeof(char *);
2954 void print_menu(WINDOW *menu_win, int highlight);
2955 void report_choice(int mouse_x, int mouse_y, int *p_choice);
2958 { int c, choice = 0;
2962 /* Initialize curses */
2966 cbreak(); //Line buffering disabled. pass on everything
2968 /* Try to put the window in the middle of screen */
2969 startx = (80 - WIDTH) / 2;
2970 starty = (24 - HEIGHT) / 2;
2973 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
2977 /* Print the menu for the first time */
2978 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2979 print_menu(menu_win, 1);
2980 /* Get all the mouse events */
2981 mousemask(ALL_MOUSE_EVENTS, NULL);
2984 { c = wgetch(menu_win);
2987 if(getmouse(&event) == OK)
2988 { /* When the user clicks left mouse button */
2989 if(event.bstate & BUTTON1_PRESSED)
2990 { report_choice(event.x + 1, event.y + 1, &choice);
2991 if(choice == -1) //Exit chosen
2993 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
2997 print_menu(menu_win, choice);
3006 void print_menu(WINDOW *menu_win, int highlight)
3012 box(menu_win, 0, 0);
3013 for(i = 0; i < n_choices; ++i)
3014 { if(highlight == i + 1)
3015 { wattron(menu_win, A_REVERSE);
3016 mvwprintw(menu_win, y, x, "%s", choices[i]);
3017 wattroff(menu_win, A_REVERSE);
3020 mvwprintw(menu_win, y, x, "%s", choices[i]);
3026 /* Report the choice according to mouse position */
3027 void report_choice(int mouse_x, int mouse_y, int *p_choice)
3033 for(choice = 0; choice < n_choices; ++choice)
3034 if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice]))
3035 { if(choice == n_choices - 1)
3038 *p_choice = choice + 1;
3048 <h3 class="SECT2"><a name="MISCMOUSEFUNCS" id=
3049 "MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3>
3051 <p>The functions mouse_trafo() and wmouse_trafo() can be
3052 used to convert to mouse co-ordinates to screen relative
3053 co-ordinates. See curs_mouse(3X) man page for details.</p>
3055 <p>The mouseinterval function sets the maximum time (in
3056 thousands of a second) that can elapse between press and
3057 release events in order for them to be recognized as a
3058 click. This function returns the previous interval value.
3059 The default is one fifth of a second.</p>
3066 <h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen
3067 Manipulation</a></h2>
3069 <p>In this section, we will look into some functions, which
3070 allow us to manage the screen efficiently and to write some
3071 fancy programs. This is especially important in writing
3077 <h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx()
3080 <p>The function <tt class="LITERAL">getyx()</tt> can be
3081 used to find out the present cursor co-ordinates. It will
3082 fill the values of x and y co-ordinates in the arguments
3083 given to it. Since getyx() is a macro you don't have to
3084 pass the address of the variables. It can be called as</p>
3086 <pre class="PROGRAMLISTING"> getyx(win, y, x);
3087 /* win: window pointer
3088 * y, x: y, x co-ordinates will be put into this variables
3090 <p>The function getparyx() gets the beginning co-ordinates
3091 of the sub window relative to the main window. This is some
3092 times useful to update a sub window. When designing fancy
3093 stuff like writing multiple menus, it becomes difficult to
3094 store the menu positions, their first option co-ordinates,
3095 etc. A simple solution to this problem, is to create menus
3096 in sub windows and later find the starting co-ordinates of
3097 the menus by using getparyx().</p>
3099 <p>The functions getbegyx() and getmaxyx() store current
3100 window's beginning and maximum co-ordinates. These
3101 functions are useful in the same way as above in managing
3102 the windows and sub windows effectively.</p>
3108 <h3 class="SECT2"><a name="SCREENDUMP" id=
3109 "SCREENDUMP">13.2. Screen Dumping</a></h3>
3111 <p>While writing games, some times it becomes necessary to
3112 store the state of the screen and restore it back to the
3113 same state. The function scr_dump() can be used to dump the
3114 screen contents to a file given as an argument. Later it
3115 can be restored by scr_restore function. These two simple
3116 functions can be used effectively to maintain a fast moving
3117 game with changing scenarios.</p>
3123 <h3 class="SECT2"><a name="WINDOWDUMP" id=
3124 "WINDOWDUMP">13.3. Window Dumping</a></h3>
3126 <p>To store and restore windows, the functions <tt class=
3127 "LITERAL">putwin()</tt> and <tt class=
3128 "LITERAL">getwin()</tt> can be used. <tt class=
3129 "LITERAL">putwin()</tt> puts the present window state into
3130 a file, which can be later restored by <tt class=
3131 "LITERAL">getwin()</tt>.</p>
3133 <p>The function <tt class="LITERAL">copywin()</tt> can be
3134 used to copy a window completely onto another window. It
3135 takes the source and destination windows as parameters and
3136 according to the rectangle specified, it copies the
3137 rectangular region from source to destination window. Its
3138 last parameter specifies whether to overwrite or just
3139 overlay the contents on to the destination window. If this
3140 argument is true, then the copying is non-destructive.</p>
3147 <h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous
3150 <p>Now you know enough features to write a good curses
3151 program, with all bells and whistles. There are some
3152 miscellaneous functions which are useful in various cases.
3153 Let's go headlong into some of those.</p>
3158 <h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1.
3161 <p>This function can be used to make the cursor invisible.
3162 The parameter to this function should be</p>
3164 <pre class="PROGRAMLISTING"> 0 : invisible or
3166 2 : very visible.</pre>
3172 <h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2.
3173 Temporarily Leaving Curses mode</a></h3>
3175 <p>Some times you may want to get back to cooked mode
3176 (normal line buffering mode) temporarily. In such a case
3177 you will first need to save the tty modes with a call to
3178 <tt class="LITERAL">def_prog_mode()</tt> and then call
3179 <tt class="LITERAL">endwin()</tt> to end the curses mode.
3180 This will leave you in the original tty mode. To get back
3181 to curses once you are done, call <tt class=
3182 "LITERAL">reset_prog_mode()</tt> . This function returns
3183 the tty to the state stored by <tt class=
3184 "LITERAL">def_prog_mode()</tt>. Then do refresh(), and you
3185 are back to the curses mode. Here is an example showing the
3186 sequence of things to be done.</p>
3188 <div class="EXAMPLE">
3189 <a name="BTELE" id="BTELE"></a>
3190 <p><b>Example 12. Temporarily Leaving Curses Mode</b>
3193 <pre class="PROGRAMLISTING"><span class=
3194 "INLINEMEDIAOBJECT">#include <stdlib.h>
3195 #include <curses.h>
3199 initscr(); /* Start curses mode */
3200 printw("Hello World !!!\n"); /* Print Hello World */
3201 refresh(); /* Print it on to the real screen */
3202 def_prog_mode(); /* Save the tty modes */
3203 endwin(); /* End curses mode temporarily */
3204 system("/bin/sh"); /* Do whatever you like in cooked mode */
3205 reset_prog_mode(); /* Return to the previous tty mode*/
3206 /* stored by def_prog_mode() */
3207 refresh(); /* Do refresh() to restore the */
3208 /* Screen contents */
3209 printw("Another String\n"); /* Back to curses use the full */
3210 refresh(); /* capabilities of curses */
3211 endwin(); /* End curses mode */
3221 <h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_
3224 <p>If you have ever programmed in DOS, you know about those
3225 nifty characters in extended character set. They are
3226 printable only on some terminals. NCURSES functions like
3227 <tt class="LITERAL">box()</tt> use these characters. All
3228 these variables start with ACS meaning alternative
3229 character set. You might have noticed me using these
3230 characters in some of the programs above. Here is an
3231 example showing all the characters.</p>
3233 <div class="EXAMPLE">
3234 <a name="BACSVARS" id="BACSVARS"></a>
3235 <p><b>Example 13. ACS Variables Example</b>
3238 <pre class="PROGRAMLISTING"><span class=
3239 "INLINEMEDIAOBJECT">#include <curses.h>
3245 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n");
3246 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n");
3247 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n");
3248 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n");
3249 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n");
3250 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n");
3251 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n");
3252 printw("Horizontal line "); addch(ACS_HLINE); printw("\n");
3253 printw("Vertical line "); addch(ACS_VLINE); printw("\n");
3254 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n");
3255 printw("Scan Line 1 "); addch(ACS_S1); printw("\n");
3256 printw("Scan Line 3 "); addch(ACS_S3); printw("\n");
3257 printw("Scan Line 7 "); addch(ACS_S7); printw("\n");
3258 printw("Scan Line 9 "); addch(ACS_S9); printw("\n");
3259 printw("Diamond "); addch(ACS_DIAMOND); printw("\n");
3260 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n");
3261 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n");
3262 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n");
3263 printw("Bullet "); addch(ACS_BULLET); printw("\n");
3264 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n");
3265 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n");
3266 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n");
3267 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n");
3268 printw("Board of squares "); addch(ACS_BOARD); printw("\n");
3269 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n");
3270 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n");
3271 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n");
3272 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n");
3273 printw("Pi "); addch(ACS_PI); printw("\n");
3274 printw("Not equal "); addch(ACS_NEQUAL); printw("\n");
3275 printw("UK pound sign "); addch(ACS_STERLING); printw("\n");
3290 <h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other
3293 <p>Apart from the curses library, there are few text mode
3294 libraries, which provide more functionality and a lot of
3295 features. The following sections explain three standard
3296 libraries which are usually distributed along with
3303 <h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel
3306 <p>Now that you are proficient in curses, you wanted to do
3307 some thing big. You created a lot of overlapping windows to
3308 give a professional windows-type look. Unfortunately, it soon
3309 becomes difficult to manage these. The multiple refreshes,
3310 updates plunge you into a nightmare. The overlapping windows
3311 create blotches, whenever you forget to refresh the windows
3312 in the proper order.</p>
3314 <p>Don't despair. There is an elegant solution provided in
3315 panels library. In the words of developers of ncurses</p>
3317 <p><span class="emphasis"><i class="EMPHASIS">When your
3318 interface design is such that windows may dive deeper into
3319 the visibility stack or pop to the top at runtime, the
3320 resulting book-keeping can be tedious and difficult to get
3321 right. Hence the panels library.</i></span>
3324 <p>If you have lot of overlapping windows, then panels
3325 library is the way to go. It obviates the need of doing
3326 series of wnoutrefresh(), doupdate() and relieves the burden
3327 of doing it correctly(bottom up). The library maintains
3328 information about the order of windows, their overlapping and
3329 update the screen properly. So why wait? Let's take a close
3330 peek into panels.</p>
3335 <h3 class="SECT2"><a name="PANELBASICS" id=
3336 "PANELBASICS">16.1. The Basics</a></h3>
3338 <p>Panel object is a window that is implicitly treated as
3339 part of a deck including all other panel objects. The deck
3340 is treated as a stack with the top panel being completely
3341 visible and the other panels may or may not be obscured
3342 according to their positions. So the basic idea is to
3343 create a stack of overlapping panels and use panels library
3344 to display them correctly. There is a function similar to
3345 refresh() which, when called , displays panels in the
3346 correct order. Functions are provided to hide or show
3347 panels, move panels, change its size, etc. The overlapping
3348 problem is managed by the panels library during all the
3349 calls to these functions.</p>
3351 <p>The general flow of a panel program goes like this:</p>
3355 <p>Create the windows (with newwin()) to be attached to
3360 <p>Create panels with the chosen visibility order.
3361 Stack them up according to the desired visibility. The
3362 function new_panel() is used to created panels.</p>
3366 <p>Call update_panels() to write the panels to the
3367 virtual screen in correct visibility order. Do a
3368 doupdate() to show it on the screen.</p>
3372 <p>Mainpulate the panels with show_panel(),
3373 hide_panel(), move_panel(), etc. Make use of helper
3374 functions like panel_hidden() and panel_window(). Make
3375 use of user pointer to store custom data for a panel.
3376 Use the functions set_panel_userptr() and
3377 panel_userptr() to set and get the user pointer for a
3382 <p>When you are done with the panel use del_panel() to
3383 delete the panel.</p>
3387 <p>Let's make the concepts clear, with some programs. The
3388 following is a simple program which creates 3 overlapping
3389 panels and shows them on the screen.</p>
3395 <h3 class="SECT2"><a name="COMPILEPANELS" id=
3396 "COMPILEPANELS">16.2. Compiling With the Panels Library</a></h3>
3398 <p>To use panels library functions, you have to include
3399 panel.h and to link the program with panels library the
3400 flag -lpanel should be added along with -lncurses in that
3403 <pre class="PROGRAMLISTING"> #include <panel.h>
3408 compile and link: gcc <program file> -lpanel -lncurses</pre>
3409 <div class="EXAMPLE">
3410 <a name="PPASI" id="PPASI"></a>
3411 <p><b>Example 14. Panel basics</b>
3414 <pre class="PROGRAMLISTING"><span class=
3415 "INLINEMEDIAOBJECT">#include <panel.h>
3418 { WINDOW *my_wins[3];
3419 PANEL *my_panels[3];
3420 int lines = 10, cols = 40, y = 2, x = 4, i;
3426 /* Create windows for the panels */
3427 my_wins[0] = newwin(lines, cols, y, x);
3428 my_wins[1] = newwin(lines, cols, y + 1, x + 5);
3429 my_wins[2] = newwin(lines, cols, y + 2, x + 10);
3432 * Create borders around the windows so that you can see the effect
3435 for(i = 0; i < 3; ++i)
3436 box(my_wins[i], 0, 0);
3438 /* Attach a panel to each window */ /* Order is bottom up */
3439 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3440 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3441 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3443 /* Update the stacking order. 2nd panel will be on top */
3446 /* Show it on the screen */
3455 <p>As you can see, above program follows a simple flow as
3456 explained. The windows are created with newwin() and then
3457 they are attached to panels with new_panel(). As we attach
3458 one panel after another, the stack of panels gets updated.
3459 To put them on screen update_panels() and doupdate() are
3466 <h3 class="SECT2"><a name="PANELBROWSING" id=
3467 "PANELBROWSING">16.3. Panel Window Browsing</a></h3>
3469 <p>A slightly complicated example is given below. This
3470 program creates 3 windows which can be cycled through using
3471 tab. Have a look at the code.</p>
3473 <div class="EXAMPLE">
3474 <a name="PPABR" id="PPABR"></a>
3475 <p><b>Example 15. Panel Window Browsing Example</b>
3478 <pre class="PROGRAMLISTING"><span class=
3479 "INLINEMEDIAOBJECT">#include <string.h>
3480 #include <panel.h>
3485 void init_wins(WINDOW **wins, int n);
3486 void win_show(WINDOW *win, char *label, int label_color);
3487 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3490 { WINDOW *my_wins[3];
3491 PANEL *my_panels[3];
3495 /* Initialize curses */
3500 keypad(stdscr, TRUE);
3502 /* Initialize all the colors */
3503 init_pair(1, COLOR_RED, COLOR_BLACK);
3504 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3505 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3506 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3508 init_wins(my_wins, 3);
3510 /* Attach a panel to each window */ /* Order is bottom up */
3511 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3512 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3513 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3515 /* Set up the user pointers to the next panel */
3516 set_panel_userptr(my_panels[0], my_panels[1]);
3517 set_panel_userptr(my_panels[1], my_panels[2]);
3518 set_panel_userptr(my_panels[2], my_panels[0]);
3520 /* Update the stacking order. 2nd panel will be on top */
3523 /* Show it on the screen */
3524 attron(COLOR_PAIR(4));
3525 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3526 attroff(COLOR_PAIR(4));
3530 while((ch = getch()) != KEY_F(1))
3533 top = (PANEL *)panel_userptr(top);
3544 /* Put all the windows */
3545 void init_wins(WINDOW **wins, int n)
3551 for(i = 0; i < n; ++i)
3552 { wins[i] = newwin(NLINES, NCOLS, y, x);
3553 sprintf(label, "Window Number %d", i + 1);
3554 win_show(wins[i], label, i + 1);
3560 /* Show the window with a border and a label */
3561 void win_show(WINDOW *win, char *label, int label_color)
3562 { int startx, starty, height, width;
3564 getbegyx(win, starty, startx);
3565 getmaxyx(win, height, width);
3568 mvwaddch(win, 2, 0, ACS_LTEE);
3569 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3570 mvwaddch(win, 2, width - 1, ACS_RTEE);
3572 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3575 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3589 length = strlen(string);
3590 temp = (width - length)/ 2;
3591 x = startx + (int)temp;
3592 wattron(win, color);
3593 mvwprintw(win, y, x, "%s", string);
3594 wattroff(win, color);
3603 <h3 class="SECT2"><a name="USERPTRUSING" id=
3604 "USERPTRUSING">16.4. Using User Pointers</a></h3>
3606 <p>In the above example I used user pointers to find out
3607 the next window in the cycle. We can attach custom
3608 information to the panel by specifying a user pointer,
3609 which can point to any information you want to store. In
3610 this case I stored the pointer to the next panel in the
3611 cycle. User pointer for a panel can be set with the
3612 function <tt class="LITERAL">set_panel_userptr()</tt>. It
3613 can be accessed using the function <tt class=
3614 "LITERAL">panel_userptr()</tt> which will return the user
3615 pointer for the panel given as argument. After finding the
3616 next panel in the cycle, it is brought to the top by the
3617 function top_panel(). This function brings the panel given
3618 as argument to the top of the panel stack.</p>
3624 <h3 class="SECT2"><a name="PANELMOVERESIZE" id=
3625 "PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3>
3627 <p>The function <tt class="LITERAL">move_panel()</tt> can
3628 be used to move a panel to the desired location. It does
3629 not change the position of the panel in the stack. Make
3630 sure that you use move_panel() instead mvwin() on the
3631 window associated with the panel.</p>
3633 <p>Resizing a panel is slightly complex. There is no
3634 straight forward function just to resize the window
3635 associated with a panel. A solution to resize a panel is to
3636 create a new window with the desired sizes, change the
3637 window associated with the panel using replace_panel().
3638 Don't forget to delete the old window. The window
3639 associated with a panel can be found by using the function
3642 <p>The following program shows these concepts, in
3643 supposedly simple program. You can cycle through the window
3644 with <TAB> as usual. To resize or move the active
3645 panel press 'r' for resize 'm' for moving. Then use arrow
3646 keys to resize or move it to the desired way and press
3647 enter to end your resizing or moving. This example makes
3648 use of user data to get the required data to do the
3651 <div class="EXAMPLE">
3652 <a name="PPARE" id="PPARE"></a>
3653 <p><b>Example 16. Panel Moving and Resizing example</b>
3656 <pre class="PROGRAMLISTING"><span class=
3657 "INLINEMEDIAOBJECT">#include <stdlib.h>
3658 #include <string.h>
3659 #include <panel.h>
3661 typedef struct _PANEL_DATA {
3671 void init_wins(WINDOW **wins, int n);
3672 void win_show(WINDOW *win, char *label, int label_color);
3673 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3674 void set_user_ptrs(PANEL **panels, int n);
3677 { WINDOW *my_wins[3];
3678 PANEL *my_panels[3];
3681 WINDOW *temp_win, *old_win;
3683 int newx, newy, neww, newh;
3684 int size = FALSE, move = FALSE;
3686 /* Initialize curses */
3691 keypad(stdscr, TRUE);
3693 /* Initialize all the colors */
3694 init_pair(1, COLOR_RED, COLOR_BLACK);
3695 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3696 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3697 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3699 init_wins(my_wins, 3);
3701 /* Attach a panel to each window */ /* Order is bottom up */
3702 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3703 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3704 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3706 set_user_ptrs(my_panels, 3);
3707 /* Update the stacking order. 2nd panel will be on top */
3710 /* Show it on the screen */
3711 attron(COLOR_PAIR(4));
3712 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3713 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3714 attroff(COLOR_PAIR(4));
3717 stack_top = my_panels[2];
3718 top = (PANEL_DATA *)panel_userptr(stack_top);
3723 while((ch = getch()) != KEY_F(1))
3726 top = (PANEL_DATA *)panel_userptr(stack_top);
3727 top_panel(top->next);
3728 stack_top = top->next;
3729 top = (PANEL_DATA *)panel_userptr(stack_top);
3735 case 'r': /* Re-Size*/
3737 attron(COLOR_PAIR(4));
3738 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing");
3740 attroff(COLOR_PAIR(4));
3742 case 'm': /* Move */
3743 attron(COLOR_PAIR(4));
3744 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving");
3746 attroff(COLOR_PAIR(4));
3781 case 10: /* Enter */
3786 { old_win = panel_window(stack_top);
3787 temp_win = newwin(newh, neww, newy, newx);
3788 replace_panel(stack_top, temp_win);
3789 win_show(temp_win, top->label, top->label_color);
3794 { move_panel(stack_top, newy, newx);
3800 attron(COLOR_PAIR(4));
3801 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3802 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3803 attroff(COLOR_PAIR(4));
3812 /* Put all the windows */
3813 void init_wins(WINDOW **wins, int n)
3819 for(i = 0; i < n; ++i)
3820 { wins[i] = newwin(NLINES, NCOLS, y, x);
3821 sprintf(label, "Window Number %d", i + 1);
3822 win_show(wins[i], label, i + 1);
3828 /* Set the PANEL_DATA structures for individual panels */
3829 void set_user_ptrs(PANEL **panels, int n)
3835 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA));
3837 for(i = 0;i < n; ++i)
3838 { win = panel_window(panels[i]);
3839 getbegyx(win, y, x);
3840 getmaxyx(win, h, w);
3845 sprintf(temp, "Window Number %d", i + 1);
3846 strcpy(ptrs[i].label, temp);
3847 ptrs[i].label_color = i + 1;
3849 ptrs[i].next = panels[0];
3851 ptrs[i].next = panels[i + 1];
3852 set_panel_userptr(panels[i], &ptrs[i]);
3856 /* Show the window with a border and a label */
3857 void win_show(WINDOW *win, char *label, int label_color)
3858 { int startx, starty, height, width;
3860 getbegyx(win, starty, startx);
3861 getmaxyx(win, height, width);
3864 mvwaddch(win, 2, 0, ACS_LTEE);
3865 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3866 mvwaddch(win, 2, width - 1, ACS_RTEE);
3868 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3871 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3885 length = strlen(string);
3886 temp = (width - length)/ 2;
3887 x = startx + (int)temp;
3888 wattron(win, color);
3889 mvwprintw(win, y, x, "%s", string);
3890 wattroff(win, color);
3895 <p>Concentrate on the main while loop. Once it finds out
3896 the type of key pressed, it takes appropriate action. If
3897 'r' is pressed resizing mode is started. After this the new
3898 sizes are updated as the user presses the arrow keys. When
3899 the user presses <ENTER> present selection ends and
3900 panel is resized by using the concept explained. While in
3901 resizing mode the program doesn't show how the window is
3902 getting resized. It is left as an exercise to the reader to
3903 print a dotted border while it gets resized to a new
3906 <p>When the user presses 'm' the move mode starts. This is
3907 a bit simpler than resizing. As the arrow keys are pressed
3908 the new position is updated and pressing of <ENTER>
3909 causes the panel to be moved by calling the function
3912 <p>In this program the user data which is represented as
3913 PANEL_DATA, plays very important role in finding the
3914 associated information with a panel. As written in the
3915 comments, the PANEL_DATA stores the panel sizes, label,
3916 label color and a pointer to the next panel in the
3923 <h3 class="SECT2"><a name="PANELSHOWHIDE" id=
3924 "PANELSHOWHIDE">16.6. Hiding and Showing Panels</a></h3>
3926 <p>A Panel can be hidden by using the function
3927 hide_panel(). This function merely removes it form the
3928 stack of panels, thus hiding it on the screen once you do
3929 update_panels() and doupdate(). It doesn't destroy the
3930 PANEL structure associated with the hidden panel. It can be
3931 shown again by using the show_panel() function.</p>
3933 <p>The following program shows the hiding of panels. Press
3934 'a' or 'b' or 'c' to show or hide first, second and third
3935 windows respectively. It uses a user data with a small
3936 variable hide, which keeps track of whether the window is
3937 hidden or not. For some reason the function <tt class=
3938 "LITERAL">panel_hidden()</tt> which tells whether a panel
3939 is hidden or not is not working. A bug report was also
3940 presented by Michael Andres <a href=
3941 "http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/"
3942 target="_top">here</a></p>
3944 <div class="EXAMPLE">
3945 <a name="PPAHI" id="PPAHI"></a>
3946 <p><b>Example 17. Panel Hiding and Showing example</b>
3949 <pre class="PROGRAMLISTING"><span class=
3950 "INLINEMEDIAOBJECT">#include <string.h>
3951 #include <panel.h>
3953 typedef struct _PANEL_DATA {
3954 int hide; /* TRUE if panel is hidden */
3960 void init_wins(WINDOW **wins, int n);
3961 void win_show(WINDOW *win, char *label, int label_color);
3962 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3965 { WINDOW *my_wins[3];
3966 PANEL *my_panels[3];
3967 PANEL_DATA panel_datas[3];
3971 /* Initialize curses */
3976 keypad(stdscr, TRUE);
3978 /* Initialize all the colors */
3979 init_pair(1, COLOR_RED, COLOR_BLACK);
3980 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3981 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3982 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3984 init_wins(my_wins, 3);
3986 /* Attach a panel to each window */ /* Order is bottom up */
3987 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3988 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3989 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3991 /* Initialize panel data saying that nothing is hidden */
3992 panel_datas[0].hide = FALSE;
3993 panel_datas[1].hide = FALSE;
3994 panel_datas[2].hide = FALSE;
3996 set_panel_userptr(my_panels[0], &panel_datas[0]);
3997 set_panel_userptr(my_panels[1], &panel_datas[1]);
3998 set_panel_userptr(my_panels[2], &panel_datas[2]);
4000 /* Update the stacking order. 2nd panel will be on top */
4003 /* Show it on the screen */
4004 attron(COLOR_PAIR(4));
4005 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)");
4006 mvprintw(LINES - 2, 0, "F1 to Exit");
4008 attroff(COLOR_PAIR(4));
4011 while((ch = getch()) != KEY_F(1))
4014 temp = (PANEL_DATA *)panel_userptr(my_panels[0]);
4015 if(temp->hide == FALSE)
4016 { hide_panel(my_panels[0]);
4017 temp->hide = TRUE;
4020 { show_panel(my_panels[0]);
4021 temp->hide = FALSE;
4025 temp = (PANEL_DATA *)panel_userptr(my_panels[1]);
4026 if(temp->hide == FALSE)
4027 { hide_panel(my_panels[1]);
4028 temp->hide = TRUE;
4031 { show_panel(my_panels[1]);
4032 temp->hide = FALSE;
4036 temp = (PANEL_DATA *)panel_userptr(my_panels[2]);
4037 if(temp->hide == FALSE)
4038 { hide_panel(my_panels[2]);
4039 temp->hide = TRUE;
4042 { show_panel(my_panels[2]);
4043 temp->hide = FALSE;
4054 /* Put all the windows */
4055 void init_wins(WINDOW **wins, int n)
4061 for(i = 0; i < n; ++i)
4062 { wins[i] = newwin(NLINES, NCOLS, y, x);
4063 sprintf(label, "Window Number %d", i + 1);
4064 win_show(wins[i], label, i + 1);
4070 /* Show the window with a border and a label */
4071 void win_show(WINDOW *win, char *label, int label_color)
4072 { int startx, starty, height, width;
4074 getbegyx(win, starty, startx);
4075 getmaxyx(win, height, width);
4078 mvwaddch(win, 2, 0, ACS_LTEE);
4079 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
4080 mvwaddch(win, 2, width - 1, ACS_RTEE);
4082 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
4085 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4099 length = strlen(string);
4100 temp = (width - length)/ 2;
4101 x = startx + (int)temp;
4102 wattron(win, color);
4103 mvwprintw(win, y, x, "%s", string);
4104 wattroff(win, color);
4113 <h3 class="SECT2"><a name="PANELABOVE" id=
4114 "PANELABOVE">16.7. panel_above() and panel_below()
4117 <p>The functions <tt class="LITERAL">panel_above()</tt> and
4118 <tt class="LITERAL">panel_below()</tt> can be used to find
4119 out the panel above and below a panel. If the argument to
4120 these functions is NULL, then they return a pointer to
4121 bottom panel and top panel respectively.</p>
4128 <h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus
4131 <p>The menus library provides a nice extension to basic
4132 curses, through which you can create menus. It provides a set
4133 of functions to create menus. But they have to be customized
4134 to give a nicer look, with colors, etc. Let's get into the
4137 <p>A menu is a screen display that assists the user to choose
4138 some subset of a given set of items. To put it simple, a menu
4139 is a collection of items from which one or more items can be
4140 chosen. Some readers might not be aware of multiple item
4141 selection capability. Menu library provides functionality to
4142 write menus from which the user can chose more than one item
4143 as the preferred choice. This is dealt with in a later
4144 section. Now it is time for some rudiments.</p>
4149 <h3 class="SECT2"><a name="MENUBASICS" id=
4150 "MENUBASICS">17.1. The Basics</a></h3>
4152 <p>To create menus, you first create items, and then post
4153 the menu to the display. After that, all the processing of
4154 user responses is done in an elegant function menu_driver()
4155 which is the work horse of any menu program.</p>
4157 <p>The general flow of control of a menu program looks like
4162 <p>Initialize curses</p>
4166 <p>Create items using new_item(). You can specify a
4167 name and description for the items.</p>
4171 <p>Create the menu with new_menu() by specifying the
4172 items to be attached with.</p>
4176 <p>Post the menu with menu_post() and refresh the
4181 <p>Process the user requests with a loop and do
4182 necessary updates to menu with menu_driver.</p>
4186 <p>Unpost the menu with menu_unpost()</p>
4190 <p>Free the memory allocated to menu by free_menu()</p>
4194 <p>Free the memory allocated to the items with
4203 <p>Let's see a program which prints a simple menu and
4204 updates the current selection with up, down arrows.</p>
4210 <h3 class="SECT2"><a name="COMPILEMENUS" id=
4211 "COMPILEMENUS">17.2. Compiling With the Menu Library</a></h3>
4213 <p>To use menu library functions, you have to include
4214 menu.h and to link the program with menu library the flag
4215 -lmenu should be added along with -lncurses in that
4218 <pre class="PROGRAMLISTING"> #include <menu.h>
4223 compile and link: gcc <program file> -lmenu -lncurses</pre>
4224 <div class="EXAMPLE">
4225 <a name="MMESI" id="MMESI"></a>
4226 <p><b>Example 18. Menu Basics</b>
4229 <pre class="PROGRAMLISTING"><span class=
4230 "INLINEMEDIAOBJECT">#include <stdlib.h>
4231 #include <curses.h>
4232 #include <menu.h>
4234 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4256 keypad(stdscr, TRUE);
4258 n_choices = ARRAY_SIZE(choices);
4259 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4261 for(i = 0; i < n_choices; ++i)
4262 my_items[i] = new_item(choices[i], choices[i]);
4263 my_items[n_choices] = (ITEM *)NULL;
4265 my_menu = new_menu((ITEM **)my_items);
4266 mvprintw(LINES - 2, 0, "F1 to Exit");
4270 while((c = getch()) != KEY_F(1))
4273 menu_driver(my_menu, REQ_DOWN_ITEM);
4276 menu_driver(my_menu, REQ_UP_ITEM);
4281 free_item(my_items[0]);
4282 free_item(my_items[1]);
4289 <p>This program demonstrates the basic concepts involved in
4290 creating a menu using menus library. First we create the
4291 items using new_item() and then attach them to the menu
4292 with new_menu() function. After posting the menu and
4293 refreshing the screen, the main processing loop starts. It
4294 reads user input and takes corresponding action. The
4295 function menu_driver() is the main work horse of the menu
4296 system. The second parameter to this function tells what's
4297 to be done with the menu. According to the parameter,
4298 menu_driver() does the corresponding task. The value can be
4299 either a menu navigational request, an ascii character, or
4300 a KEY_MOUSE special key associated with a mouse event.</p>
4302 <p>The menu_driver accepts following navigational
4306 "PROGRAMLISTING"> REQ_LEFT_ITEM Move left to an item.
4307 REQ_RIGHT_ITEM Move right to an item.
4308 REQ_UP_ITEM Move up to an item.
4309 REQ_DOWN_ITEM Move down to an item.
4310 REQ_SCR_ULINE Scroll up a line.
4311 REQ_SCR_DLINE Scroll down a line.
4312 REQ_SCR_DPAGE Scroll down a page.
4313 REQ_SCR_UPAGE Scroll up a page.
4314 REQ_FIRST_ITEM Move to the first item.
4315 REQ_LAST_ITEM Move to the last item.
4316 REQ_NEXT_ITEM Move to the next item.
4317 REQ_PREV_ITEM Move to the previous item.
4318 REQ_TOGGLE_ITEM Select/deselect an item.
4319 REQ_CLEAR_PATTERN Clear the menu pattern buffer.
4320 REQ_BACK_PATTERN Delete the previous character from the pattern buffer.
4321 REQ_NEXT_MATCH Move to the next item matching the pattern match.
4322 REQ_PREV_MATCH Move to the previous item matching the pattern match. </pre>
4323 <p>Don't get overwhelmed by the number of options. We will
4324 see them slowly one after another. The options of interest
4325 in this example are REQ_UP_ITEM and REQ_DOWN_ITEM. These
4326 two options when passed to menu_driver, menu driver updates
4327 the current item to one item up or down respectively.</p>
4333 <h3 class="SECT2"><a name="MENUDRIVER" id=
4334 "MENUDRIVER">17.3. Menu Driver: The work horse of the menu
4337 <p>As you have seen in the above example, menu_driver plays
4338 an important role in updating the menu. It is very
4339 important to understand various options it takes and what
4340 they do. As explained above, the second parameter to
4341 menu_driver() can be either a navigational request, a
4342 printable character or a KEY_MOUSE key. Let's dissect the
4343 different navigational requests.</p>
4347 <p><span class="emphasis"><i class=
4348 "EMPHASIS">REQ_LEFT_ITEM and REQ_RIGHT_ITEM</i></span>
4351 <p>A Menu can be displayed with multiple columns for
4352 more than one item. This can be done by using the
4353 <tt class="LITERAL">menu_format()</tt>function. When a
4354 multi columnar menu is displayed these requests cause
4355 the menu driver to move the current selection to left
4360 <p><span class="emphasis"><i class=
4361 "EMPHASIS">REQ_UP_ITEM and REQ_DOWN_ITEM</i></span>
4364 <p>These two options you have seen in the above
4365 example. These options when given, makes the
4366 menu_driver to move the current selection to an item up
4371 <p><span class="emphasis"><i class="EMPHASIS">REQ_SCR_*
4375 <p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE,
4376 REQ_SCR_DPAGE, REQ_SCR_UPAGE are related to scrolling.
4377 If all the items in the menu cannot be displayed in the
4378 menu sub window, then the menu is scrollable. These
4379 requests can be given to the menu_driver to do the
4380 scrolling either one line up, down or one page down or
4381 up respectively.</p>
4385 <p><span class="emphasis"><i class=
4386 "EMPHASIS">REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM
4387 and REQ_PREV_ITEM</i></span>
4390 <p>These requests are self explanatory.</p>
4394 <p><span class="emphasis"><i class=
4395 "EMPHASIS">REQ_TOGGLE_ITEM</i></span>
4398 <p>This request when given, toggles the present
4399 selection. This option is to be used only in a multi
4400 valued menu. So to use this request the option
4401 O_ONEVALUE must be off. This option can be made off or
4402 on with set_menu_opts().</p>
4406 <p><span class="emphasis"><i class="EMPHASIS">Pattern
4410 <p>Every menu has an associated pattern buffer, which
4411 is used to find the nearest match to the ascii
4412 characters entered by the user. Whenever ascii
4413 characters are given to menu_driver, it puts in to the
4414 pattern buffer. It also tries to find the nearest match
4415 to the pattern in the items list and moves current
4416 selection to that item. The request REQ_CLEAR_PATTERN
4417 clears the pattern buffer. The request REQ_BACK_PATTERN
4418 deletes the previous character in the pattern buffer.
4419 In case the pattern matches more than one item then the
4420 matched items can be cycled through REQ_NEXT_MATCH and
4421 REQ_PREV_MATCH which move the current selection to the
4422 next and previous matches respectively.</p>
4426 <p><span class="emphasis"><i class="EMPHASIS">Mouse
4430 <p>In case of KEY_MOUSE requests, according to the
4431 mouse position an action is taken accordingly. The
4432 action to be taken is explained in the man page as,</p>
4434 <pre class="PROGRAMLISTING"><span class=
4435 "emphasis"><i class=
4436 "EMPHASIS"> If the second argument is the KEY_MOUSE special key, the
4437 associated mouse event is translated into one of the above
4438 pre-defined requests. Currently only clicks in the user
4439 window (e.g. inside the menu display area or the decora­
4440 tion window) are handled. If you click above the display
4441 region of the menu, a REQ_SCR_ULINE is generated, if you
4442 doubleclick a REQ_SCR_UPAGE is generated and if you
4443 tripleclick a REQ_FIRST_ITEM is generated. If you click
4444 below the display region of the menu, a REQ_SCR_DLINE is
4445 generated, if you doubleclick a REQ_SCR_DPAGE is generated
4446 and if you tripleclick a REQ_LAST_ITEM is generated. If
4447 you click at an item inside the display area of the menu,
4448 the menu cursor is positioned to that item.</i></span></pre>
4452 <p>Each of the above requests will be explained in the
4453 following lines with several examples whenever
4460 <h3 class="SECT2"><a name="MENUWINDOWS" id=
4461 "MENUWINDOWS">17.4. Menu Windows</a></h3>
4463 <p>Every menu created is associated with a window and a sub
4464 window. The menu window displays any title or border
4465 associated with the menu. The menu sub window displays the
4466 menu items currently available for selection. But we didn't
4467 specify any window or sub window in the simple example.
4468 When a window is not specified, stdscr is taken as the main
4469 window, and then menu system calculates the sub window size
4470 required for the display of items. Then items are displayed
4471 in the calculated sub window. So let's play with these
4472 windows and display a menu with a border and a title.</p>
4474 <div class="EXAMPLE">
4475 <a name="MMEWI" id="MMEWI"></a>
4476 <p><b>Example 19. Menu Windows Usage example</b>
4479 <pre class="PROGRAMLISTING"><span class=
4480 "INLINEMEDIAOBJECT">#include <stdlib.h>
4481 #include <string.h>
4482 #include <menu.h>
4484 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4495 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4501 WINDOW *my_menu_win;
4504 /* Initialize curses */
4509 keypad(stdscr, TRUE);
4510 init_pair(1, COLOR_RED, COLOR_BLACK);
4513 n_choices = ARRAY_SIZE(choices);
4514 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4515 for(i = 0; i < n_choices; ++i)
4516 my_items[i] = new_item(choices[i], choices[i]);
4519 my_menu = new_menu((ITEM **)my_items);
4521 /* Create the window to be associated with the menu */
4522 my_menu_win = newwin(10, 40, 4, 4);
4523 keypad(my_menu_win, TRUE);
4525 /* Set main window and sub window */
4526 set_menu_win(my_menu, my_menu_win);
4527 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4529 /* Set menu mark to the string " * " */
4530 set_menu_mark(my_menu, " * ");
4532 /* Print a border around the main window and print a title */
4533 box(my_menu_win, 0, 0);
4534 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4535 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4536 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4537 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4538 mvprintw(LINES - 2, 0, "F1 to exit");
4543 wrefresh(my_menu_win);
4545 while((c = wgetch(my_menu_win)) != KEY_F(1))
4548 menu_driver(my_menu, REQ_DOWN_ITEM);
4551 menu_driver(my_menu, REQ_UP_ITEM);
4554 wrefresh(my_menu_win);
4557 /* Unpost and free all the memory taken up */
4558 unpost_menu(my_menu);
4560 for(i = 0; i < n_choices; ++i)
4561 free_item(my_items[i]);
4565 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4579 length = strlen(string);
4580 temp = (width - length)/ 2;
4581 x = startx + (int)temp;
4582 wattron(win, color);
4583 mvwprintw(win, y, x, "%s", string);
4584 wattroff(win, color);
4589 <p>This example creates a menu with a title, border, a
4590 fancy line separating title and the items. As you can see,
4591 in order to attach a window to a menu the function
4592 set_menu_win() has to be used. Then we attach the sub
4593 window also. This displays the items in the sub window. You
4594 can also set the mark string which gets displayed to the
4595 left of the selected item with set_menu_mark().</p>
4601 <h3 class="SECT2"><a name="SCROLLMENUS" id=
4602 "SCROLLMENUS">17.5. Scrolling Menus</a></h3>
4604 <p>If the sub window given for a window is not big enough
4605 to show all the items, then the menu will be scrollable.
4606 When you are on the last item in the present list, if you
4607 send REQ_DOWN_ITEM, it gets translated into REQ_SCR_DLINE
4608 and the menu scrolls by one item. You can manually give
4609 REQ_SCR_ operations to do scrolling. Let's see how it can
4612 <div class="EXAMPLE">
4613 <a name="MMESC" id="MMESC"></a>
4614 <p><b>Example 20. Scrolling Menus example</b>
4617 <pre class="PROGRAMLISTING"><span class=
4618 "INLINEMEDIAOBJECT">#include <stdlib.h>
4619 #include <string.h>
4620 #include <curses.h>
4621 #include <menu.h>
4623 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4640 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4646 WINDOW *my_menu_win;
4649 /* Initialize curses */
4654 keypad(stdscr, TRUE);
4655 init_pair(1, COLOR_RED, COLOR_BLACK);
4656 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4659 n_choices = ARRAY_SIZE(choices);
4660 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4661 for(i = 0; i < n_choices; ++i)
4662 my_items[i] = new_item(choices[i], choices[i]);
4665 my_menu = new_menu((ITEM **)my_items);
4667 /* Create the window to be associated with the menu */
4668 my_menu_win = newwin(10, 40, 4, 4);
4669 keypad(my_menu_win, TRUE);
4671 /* Set main window and sub window */
4672 set_menu_win(my_menu, my_menu_win);
4673 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4674 set_menu_format(my_menu, 5, 1);
4676 /* Set menu mark to the string " * " */
4677 set_menu_mark(my_menu, " * ");
4679 /* Print a border around the main window and print a title */
4680 box(my_menu_win, 0, 0);
4681 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4682 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4683 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4684 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4688 wrefresh(my_menu_win);
4690 attron(COLOR_PAIR(2));
4691 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scroll down or up a page of items");
4692 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)");
4693 attroff(COLOR_PAIR(2));
4696 while((c = wgetch(my_menu_win)) != KEY_F(1))
4699 menu_driver(my_menu, REQ_DOWN_ITEM);
4702 menu_driver(my_menu, REQ_UP_ITEM);
4705 menu_driver(my_menu, REQ_SCR_DPAGE);
4708 menu_driver(my_menu, REQ_SCR_UPAGE);
4711 wrefresh(my_menu_win);
4714 /* Unpost and free all the memory taken up */
4715 unpost_menu(my_menu);
4717 for(i = 0; i < n_choices; ++i)
4718 free_item(my_items[i]);
4722 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4736 length = strlen(string);
4737 temp = (width - length)/ 2;
4738 x = startx + (int)temp;
4739 wattron(win, color);
4740 mvwprintw(win, y, x, "%s", string);
4741 wattroff(win, color);
4746 <p>This program is self-explanatory. In this example the
4747 number of choices has been increased to ten, which is
4748 larger than our sub window size which can hold 6 items.
4749 This message has to be explicitly conveyed to the menu
4750 system with the function set_menu_format(). In here we
4751 specify the number of rows and columns we want to be
4752 displayed for a single page. We can specify any number of
4753 items to be shown, in the rows variables, if it is less
4754 than the height of the sub window. If the key pressed by
4755 the user is a PAGE UP or PAGE DOWN, the menu is scrolled a
4756 page due to the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE)
4757 given to menu_driver().</p>
4763 <h3 class="SECT2"><a name="MULTICOLUMN" id=
4764 "MULTICOLUMN">17.6. Multi Columnar Menus</a></h3>
4766 <p>In the above example you have seen how to use the
4767 function set_menu_format(). I didn't mention what the cols
4768 variable (third parameter) does. Well, If your sub window
4769 is wide enough, you can opt to display more than one item
4770 per row. This can be specified in the cols variable. To
4771 make things simpler, the following example doesn't show
4772 descriptions for the items.</p>
4774 <div class="EXAMPLE">
4775 <a name="MMEMUCO" id="MMEMUCO"></a>
4776 <p><b>Example 21. Milt Columnar Menus Example</b>
4779 <pre class="PROGRAMLISTING"><span class=
4780 "INLINEMEDIAOBJECT">#include <stdlib.h>
4781 #include <curses.h>
4782 #include <menu.h>
4784 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4788 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5",
4789 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10",
4790 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15",
4791 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20",
4800 WINDOW *my_menu_win;
4803 /* Initialize curses */
4808 keypad(stdscr, TRUE);
4809 init_pair(1, COLOR_RED, COLOR_BLACK);
4810 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4813 n_choices = ARRAY_SIZE(choices);
4814 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4815 for(i = 0; i < n_choices; ++i)
4816 my_items[i] = new_item(choices[i], choices[i]);
4819 my_menu = new_menu((ITEM **)my_items);
4821 /* Set menu option not to show the description */
4822 menu_opts_off(my_menu, O_SHOWDESC);
4824 /* Create the window to be associated with the menu */
4825 my_menu_win = newwin(10, 70, 4, 4);
4826 keypad(my_menu_win, TRUE);
4828 /* Set main window and sub window */
4829 set_menu_win(my_menu, my_menu_win);
4830 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1));
4831 set_menu_format(my_menu, 5, 3);
4832 set_menu_mark(my_menu, " * ");
4834 /* Print a border around the main window and print a title */
4835 box(my_menu_win, 0, 0);
4837 attron(COLOR_PAIR(2));
4838 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll");
4839 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)");
4840 attroff(COLOR_PAIR(2));
4845 wrefresh(my_menu_win);
4847 while((c = wgetch(my_menu_win)) != KEY_F(1))
4850 menu_driver(my_menu, REQ_DOWN_ITEM);
4853 menu_driver(my_menu, REQ_UP_ITEM);
4856 menu_driver(my_menu, REQ_LEFT_ITEM);
4859 menu_driver(my_menu, REQ_RIGHT_ITEM);
4862 menu_driver(my_menu, REQ_SCR_DPAGE);
4865 menu_driver(my_menu, REQ_SCR_UPAGE);
4868 wrefresh(my_menu_win);
4871 /* Unpost and free all the memory taken up */
4872 unpost_menu(my_menu);
4874 for(i = 0; i < n_choices; ++i)
4875 free_item(my_items[i]);
4880 <p>Watch the function call to set_menu_format(). It
4881 specifies the number of columns to be 3, thus displaying 3
4882 items per row. We have also switched off the showing
4883 descriptions with the function menu_opts_off(). There are
4884 couple of functions set_menu_opts(), menu_opts_on() and
4885 menu_opts() which can be used to manipulate menu options.
4886 The following menu options can be specified.</p>
4888 <pre class="PROGRAMLISTING"> O_ONEVALUE
4889 Only one item can be selected for this menu.
4892 Display the item descriptions when the menu is
4896 Display the menu in row-major order.
4899 Ignore the case when pattern-matching.
4902 Move the cursor to within the item name while pat­
4906 Don't wrap around next-item and previous-item,
4907 requests to the other end of the menu.</pre>
4908 <p>All options are on by default. You can switch specific
4909 attributes on or off with menu_opts_on() and
4910 menu_opts_off() functions. You can also use set_menu_opts()
4911 to directly specify the options. The argument to this
4912 function should be a OR ed value of some of those above
4913 constants. The function menu_opts() can be used to find out
4914 a menu's present options.</p>
4920 <h3 class="SECT2"><a name="MULTIVALUEMENUS" id=
4921 "MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3>
4923 <p>You might be wondering what if you switch off the option
4924 O_ONEVALUE. Then the menu becomes multi-valued. That means
4925 you can select more than one item. This brings us to the
4926 request REQ_TOGGLE_ITEM. Let's see it in action.</p>
4928 <div class="EXAMPLE">
4929 <a name="MMETO" id="MMETO"></a>
4930 <p><b>Example 22. Multi Valued Menus example</b>
4933 <pre class="PROGRAMLISTING"><span class=
4934 "INLINEMEDIAOBJECT">#include <stdlib.h>
4935 #include <string.h>
4936 #include <curses.h>
4937 #include <menu.h>
4939 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4960 /* Initialize curses */
4964 keypad(stdscr, TRUE);
4966 /* Initialize items */
4967 n_choices = ARRAY_SIZE(choices);
4968 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4969 for(i = 0; i < n_choices; ++i)
4970 my_items[i] = new_item(choices[i], choices[i]);
4971 my_items[n_choices] = (ITEM *)NULL;
4973 my_menu = new_menu((ITEM **)my_items);
4975 /* Make the menu multi valued */
4976 menu_opts_off(my_menu, O_ONEVALUE);
4978 mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item.");
4979 mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)");
4983 while((c = getch()) != KEY_F(1))
4986 menu_driver(my_menu, REQ_DOWN_ITEM);
4989 menu_driver(my_menu, REQ_UP_ITEM);
4992 menu_driver(my_menu, REQ_TOGGLE_ITEM);
4994 case 10: /* Enter */
4998 items = menu_items(my_menu);
5000 for(i = 0; i < item_count(my_menu); ++i)
5001 if(item_value(items[i]) == TRUE)
5002 { strcat(temp, item_name(items[i]));
5007 mvprintw(20, 0, temp);
5014 free_item(my_items[0]);
5015 free_item(my_items[1]);
5022 <p>Whew, A lot of new functions. Let's take them one after
5023 another. Firstly, the REQ_TOGGLE_ITEM. In a multi-valued
5024 menu, the user should be allowed to select or un select
5025 more than one item. The request REQ_TOGGLE_ITEM toggles the
5026 present selection. In this case when space is pressed
5027 REQ_TOGGLE_ITEM request is sent to menu_driver to achieve
5030 <p>Now when the user presses <ENTER> we show the
5031 items he presently selected. First we find out the items
5032 associated with the menu using the function menu_items().
5033 Then we loop through the items to find out if the item is
5034 selected or not. The function item_value() returns TRUE if
5035 an item is selected. The function item_count() returns the
5036 number of items in the menu. The item name can be found
5037 with item_name(). You can also find the description
5038 associated with an item using item_description().</p>
5044 <h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu
5047 <p>Well, by this time you must be itching for some
5048 difference in your menu, with lots of functionality. I
5049 know. You want Colors !!!. You want to create nice menus
5050 similar to those text mode <a href=
5051 "http://www.jersey.net/~debinjoe/games/" target="_top">dos
5052 games</a>. The functions set_menu_fore() and
5053 set_menu_back() can be used to change the attribute of the
5054 selected item and unselected item. The names are
5055 misleading. They don't change menu's foreground or
5056 background which would have been useless.</p>
5058 <p>The function set_menu_grey() can be used to set the
5059 display attribute for the non-selectable items in the menu.
5060 This brings us to the interesting option for an item the
5061 one and only O_SELECTABLE. We can turn it off by the
5062 function item_opts_off() and after that that item is not
5063 selectable. It is like a grayed item in those fancy windows
5064 menus. Let's put these concepts in practice with this
5067 <div class="EXAMPLE">
5068 <a name="MMEAT" id="MMEAT"></a>
5069 <p><b>Example 23. Menu Options example</b>
5072 <pre class="PROGRAMLISTING"><span class=
5073 "INLINEMEDIAOBJECT">#include <stdlib.h>
5074 #include <menu.h>
5076 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5097 /* Initialize curses */
5102 keypad(stdscr, TRUE);
5103 init_pair(1, COLOR_RED, COLOR_BLACK);
5104 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5105 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5107 /* Initialize items */
5108 n_choices = ARRAY_SIZE(choices);
5109 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5110 for(i = 0; i < n_choices; ++i)
5111 my_items[i] = new_item(choices[i], choices[i]);
5112 my_items[n_choices] = (ITEM *)NULL;
5113 item_opts_off(my_items[3], O_SELECTABLE);
5114 item_opts_off(my_items[6], O_SELECTABLE);
5117 my_menu = new_menu((ITEM **)my_items);
5119 /* Set fore ground and back ground of the menu */
5120 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE);
5121 set_menu_back(my_menu, COLOR_PAIR(2));
5122 set_menu_grey(my_menu, COLOR_PAIR(3));
5125 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5126 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5130 while((c = getch()) != KEY_F(1))
5133 menu_driver(my_menu, REQ_DOWN_ITEM);
5136 menu_driver(my_menu, REQ_UP_ITEM);
5138 case 10: /* Enter */
5141 mvprintw(20, 0, "Item selected is : %s",
5142 item_name(current_item(my_menu)));
5143 pos_menu_cursor(my_menu);
5147 unpost_menu(my_menu);
5148 for(i = 0; i < n_choices; ++i)
5149 free_item(my_items[i]);
5160 <h3 class="SECT2"><a name="MENUUSERPTR" id=
5161 "MENUUSERPTR">17.9. The useful User Pointer</a></h3>
5163 <p>We can associate a user pointer with each item in the
5164 menu. It works the same way as user pointer in panels. It
5165 is not touched by menu system. You can store any thing you
5166 like in that. I usually use it to store the function to be
5167 executed when the menu option is chosen (It is selected and
5168 may be the user pressed <ENTER>);</p>
5170 <div class="EXAMPLE">
5171 <a name="MMEUS" id="MMEUS"></a>
5172 <p><b>Example 24. Menu User Pointer Usage</b>
5175 <pre class="PROGRAMLISTING"><span class=
5176 "INLINEMEDIAOBJECT">#include <stdlib.h>
5177 #include <curses.h>
5178 #include <menu.h>
5180 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5193 void func(char *name);
5202 /* Initialize curses */
5207 keypad(stdscr, TRUE);
5208 init_pair(1, COLOR_RED, COLOR_BLACK);
5209 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5210 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5212 /* Initialize items */
5213 n_choices = ARRAY_SIZE(choices);
5214 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5215 for(i = 0; i < n_choices; ++i)
5216 { my_items[i] = new_item(choices[i], choices[i]);
5217 /* Set the user pointer */
5218 set_item_userptr(my_items[i], func);
5220 my_items[n_choices] = (ITEM *)NULL;
5223 my_menu = new_menu((ITEM **)my_items);
5226 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5227 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5231 while((c = getch()) != KEY_F(1))
5234 menu_driver(my_menu, REQ_DOWN_ITEM);
5237 menu_driver(my_menu, REQ_UP_ITEM);
5239 case 10: /* Enter */
5243 cur = current_item(my_menu);
5244 p = item_userptr(cur);
5245 p((char *)item_name(cur));
5246 pos_menu_cursor(my_menu);
5252 unpost_menu(my_menu);
5253 for(i = 0; i < n_choices; ++i)
5254 free_item(my_items[i]);
5259 void func(char *name)
5262 mvprintw(20, 0, "Item selected is : %s", name);
5271 <h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms
5274 <p>Well. If you have seen those forms on web pages which take
5275 input from users and do various kinds of things, you might be
5276 wondering how would any one create such forms in text mode
5277 display. It is quite difficult to write those nifty forms in
5278 plain ncurses. Forms library tries to provide a basic frame
5279 work to build and maintain forms with ease. It has lot of
5280 features(functions) which manage validation, dynamic
5281 expansion of fields, etc. Let's see it in full flow.</p>
5283 <p>A form is a collection of fields; each field can be either
5284 a label(static text) or a data-entry location. The forms also
5285 library provides functions to divide forms into multiple
5291 <h3 class="SECT2"><a name="FORMBASICS" id=
5292 "FORMBASICS">18.1. The Basics</a></h3>
5294 <p>Forms are created in much the same way as menus. First
5295 the fields related to the form are created with
5296 new_field(). You can set options for the fields, so that
5297 they can be displayed with some fancy attributes, validated
5298 before the field looses focus, etc. Then the fields are
5299 attached to form. After this, the form can be posted to
5300 display and is ready to receive inputs. On the similar
5301 lines to menu_driver(), the form is manipulated with
5302 form_driver(). We can send requests to form_driver to move
5303 focus to a certain field, move cursor to end of the field
5304 etc. After the user enters values in the fields and
5305 validation done, form can be unposted and memory allocated
5308 <p>The general flow of control of a forms program looks
5313 <p>Initialize curses</p>
5317 <p>Create fields using new_field(). You can specify the
5318 height and width of the field, and its position on the
5323 <p>Create the forms with new_form() by specifying the
5324 fields to be attached with.</p>
5328 <p>Post the form with form_post() and refresh the
5333 <p>Process the user requests with a loop and do
5334 necessary updates to form with form_driver.</p>
5338 <p>Unpost the menu with form_unpost()</p>
5342 <p>Free the memory allocated to menu by free_form()</p>
5346 <p>Free the memory allocated to the items with
5355 <p>As you can see, working with forms library is much
5356 similar to handling menu library. The following examples
5357 will explore various aspects of form processing. Let's
5358 start the journey with a simple example. first.</p>
5364 <h3 class="SECT2"><a name="COMPILEFORMS" id=
5365 "COMPILEFORMS">18.2. Compiling With the Forms Library</a></h3>
5367 <p>To use forms library functions, you have to include
5368 form.h and to link the program with forms library the flag
5369 -lform should be added along with -lncurses in that
5372 <pre class="PROGRAMLISTING"> #include <form.h>
5377 compile and link: gcc <program file> -lform -lncurses</pre>
5378 <div class="EXAMPLE">
5379 <a name="FFOSI" id="FFOSI"></a>
5380 <p><b>Example 25. Forms Basics</b>
5383 <pre class="PROGRAMLISTING"><span class=
5384 "INLINEMEDIAOBJECT">#include <form.h>
5391 /* Initialize curses */
5395 keypad(stdscr, TRUE);
5397 /* Initialize the fields */
5398 field[0] = new_field(1, 10, 4, 18, 0, 0);
5399 field[1] = new_field(1, 10, 6, 18, 0, 0);
5402 /* Set field options */
5403 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */
5404 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5405 /* Field is filled up */
5406 set_field_back(field[1], A_UNDERLINE);
5407 field_opts_off(field[1], O_AUTOSKIP);
5409 /* Create the form and post it */
5410 my_form = new_form(field);
5414 mvprintw(4, 10, "Value 1:");
5415 mvprintw(6, 10, "Value 2:");
5418 /* Loop through to get user requests */
5419 while((ch = getch()) != KEY_F(1))
5422 /* Go to next field */
5423 form_driver(my_form, REQ_NEXT_FIELD);
5424 /* Go to the end of the present buffer */
5425 /* Leaves nicely at the last character */
5426 form_driver(my_form, REQ_END_LINE);
5429 /* Go to previous field */
5430 form_driver(my_form, REQ_PREV_FIELD);
5431 form_driver(my_form, REQ_END_LINE);
5434 /* If this is a normal character, it gets */
5436 form_driver(my_form, ch);
5441 /* Un post form and free the memory */
5442 unpost_form(my_form);
5444 free_field(field[0]);
5445 free_field(field[1]);
5452 <p>Above example is pretty straight forward. It creates two
5453 fields with <tt class="LITERAL">new_field()</tt>.
5454 new_field() takes height, width, starty, startx, number of
5455 offscreen rows and number of additional working buffers.
5456 The fifth argument number of offscreen rows specifies how
5457 much of the field to be shown. If it is zero, the entire
5458 field is always displayed otherwise the form will be
5459 scrollable when the user accesses not displayed parts of
5460 the field. The forms library allocates one buffer per field
5461 to store the data user enters. Using the last parameter to
5462 new_field() we can specify it to allocate some additional
5463 buffers. These can be used for any purpose you like.</p>
5465 <p>After creating the fields, back ground attribute of both
5466 of them is set to an underscore with set_field_back(). The
5467 AUTOSKIP option is turned off using field_opts_off(). If
5468 this option is turned on, focus will move to the next field
5469 in the form once the active field is filled up
5472 <p>After attaching the fields to the form, it is posted.
5473 Here on, user inputs are processed in the while loop, by
5474 making corresponding requests to form_driver. The details
5475 of all the requests to the form_driver() are explained
5482 <h3 class="SECT2"><a name="PLAYFIELDS" id=
5483 "PLAYFIELDS">18.3. Playing with Fields</a></h3>
5485 <p>Each form field is associated with a lot of attributes.
5486 They can be manipulated to get the required effect and to
5487 have fun !!!. So why wait?</p>
5492 <h4 class="SECT3"><a name="FETCHINFO" id=
5493 "FETCHINFO">18.3.1. Fetching Size and Location of
5496 <p>The parameters we have given at the time of creation
5497 of a field can be retrieved with field_info(). It returns
5498 height, width, starty, startx, number of offscreen rows,
5499 and number of additional buffers into the parameters
5500 given to it. It is a sort of inverse of new_field().</p>
5503 "PROGRAMLISTING">int field_info( FIELD *field, /* field from which to fetch */
5504 int *height, *int width, /* field size */
5505 int *top, int *left, /* upper left corner */
5506 int *offscreen, /* number of offscreen rows */
5507 int *nbuf); /* number of working buffers */</pre>
5513 <h4 class="SECT3"><a name="MOVEFIELD" id=
5514 "MOVEFIELD">18.3.2. Moving the field</a></h4>
5516 <p>The location of the field can be moved to a different
5517 position with move_field().</p>
5520 "PROGRAMLISTING">int move_field( FIELD *field, /* field to alter */
5521 int top, int left); /* new upper-left corner */</pre>
5522 <p>As usual, the changed position can be queried with
5529 <h4 class="SECT3"><a name="JUSTIFYFIELD" id=
5530 "JUSTIFYFIELD">18.3.3. Field Justification</a></h4>
5532 <p>The justification to be done for the field can be
5533 fixed using the function set_field_just().</p>
5536 "PROGRAMLISTING"> int set_field_just(FIELD *field, /* field to alter */
5537 int justmode); /* mode to set */
5538 int field_just(FIELD *field); /* fetch justify mode of field */</pre>
5539 <p>The justification mode valued accepted and returned by
5540 these functions are NO_JUSTIFICATION, JUSTIFY_RIGHT,
5541 JUSTIFY_LEFT, or JUSTIFY_CENTER.</p>
5547 <h4 class="SECT3"><a name="FIELDDISPATTRIB" id=
5548 "FIELDDISPATTRIB">18.3.4. Field Display Attributes</a></h4>
5550 <p>As you have seen, in the above example, display
5551 attribute for the fields can be set with set_field_fore()
5552 and setfield_back(). These functions set foreground and
5553 background attribute of the fields. You can also specify
5554 a pad character which will be filled in the unfilled
5555 portion of the field. The pad character is set with a
5556 call to set_field_pad(). Default pad value is a space.
5557 The functions field_fore(), field_back, field_pad() can
5558 be used to query the present foreground, background
5559 attributes and pad character for the field. The following
5560 list gives the usage of functions.</p>
5563 "PROGRAMLISTING"> int set_field_fore(FIELD *field, /* field to alter */
5564 chtype attr); /* attribute to set */
5566 chtype field_fore(FIELD *field); /* field to query */
5567 /* returns foreground attribute */
5569 int set_field_back(FIELD *field, /* field to alter */
5570 chtype attr); /* attribute to set */
5572 chtype field_back(FIELD *field); /* field to query */
5573 /* returns background attribute */
5575 int set_field_pad(FIELD *field, /* field to alter */
5576 int pad); /* pad character to set */
5578 chtype field_pad(FIELD *field); /* field to query */
5579 /* returns present pad character */ </pre>
5580 <p>Though above functions seem quite simple, using colors
5581 with set_field_fore() may be frustrating in the
5582 beginning. Let me first explain about foreground and
5583 background attributes of a field. The foreground
5584 attribute is associated with the character. That means a
5585 character in the field is printed with the attribute you
5586 have set with set_field_fore(). Background attribute is
5587 the attribute used to fill background of field, whether
5588 any character is there or not. So what about colors?
5589 Since colors are always defined in pairs, what is the
5590 right way to display colored fields? Here's an example
5591 clarifying color attributes.</p>
5593 <div class="EXAMPLE">
5594 <a name="FFOAT" id="FFOAT"></a>
5595 <p><b>Example 26. Form Attributes example</b>
5598 <pre class="PROGRAMLISTING"><span class=
5599 "INLINEMEDIAOBJECT">#include <form.h>
5606 /* Initialize curses */
5611 keypad(stdscr, TRUE);
5613 /* Initialize few color pairs */
5614 init_pair(1, COLOR_WHITE, COLOR_BLUE);
5615 init_pair(2, COLOR_WHITE, COLOR_BLUE);
5617 /* Initialize the fields */
5618 field[0] = new_field(1, 10, 4, 18, 0, 0);
5619 field[1] = new_field(1, 10, 6, 18, 0, 0);
5622 /* Set field options */
5623 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */
5624 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */
5625 /* are printed in white */
5626 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5627 /* Field is filled up */
5628 set_field_back(field[1], A_UNDERLINE);
5629 field_opts_off(field[1], O_AUTOSKIP);
5631 /* Create the form and post it */
5632 my_form = new_form(field);
5636 set_current_field(my_form, field[0]); /* Set focus to the colored field */
5637 mvprintw(4, 10, "Value 1:");
5638 mvprintw(6, 10, "Value 2:");
5639 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5642 /* Loop through to get user requests */
5643 while((ch = getch()) != KEY_F(1))
5646 /* Go to next field */
5647 form_driver(my_form, REQ_NEXT_FIELD);
5648 /* Go to the end of the present buffer */
5649 /* Leaves nicely at the last character */
5650 form_driver(my_form, REQ_END_LINE);
5653 /* Go to previous field */
5654 form_driver(my_form, REQ_PREV_FIELD);
5655 form_driver(my_form, REQ_END_LINE);
5658 /* If this is a normal character, it gets */
5660 form_driver(my_form, ch);
5665 /* Un post form and free the memory */
5666 unpost_form(my_form);
5668 free_field(field[0]);
5669 free_field(field[1]);
5676 <p>Play with the color pairs and try to understand the
5677 foreground and background attributes. In my programs
5678 using color attributes, I usually set only the background
5679 with set_field_back(). Curses simply doesn't allow
5680 defining individual color attributes.</p>
5686 <h4 class="SECT3"><a name="FIELDOPTIONBITS" id=
5687 "FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4>
5689 <p>There is also a large collection of field option bits
5690 you can set to control various aspects of forms
5691 processing. You can manipulate them with these
5695 "PROGRAMLISTING">int set_field_opts(FIELD *field, /* field to alter */
5696 int attr); /* attribute to set */
5698 int field_opts_on(FIELD *field, /* field to alter */
5699 int attr); /* attributes to turn on */
5701 int field_opts_off(FIELD *field, /* field to alter */
5702 int attr); /* attributes to turn off */
5704 int field_opts(FIELD *field); /* field to query */ </pre>
5705 <p>The function set_field_opts() can be used to directly
5706 set attributes of a field or you can choose to switch a
5707 few attributes on and off with field_opts_on() and
5708 field_opts_off() selectively. Anytime you can query the
5709 attributes of a field with field_opts(). The following is
5710 the list of available options. By default, all options
5713 <div class="VARIABLELIST">
5718 <p>Controls whether the field is visible on the
5719 screen. Can be used during form processing to hide
5720 or pop up fields depending on the value of parent
5727 <p>Controls whether the field is active during
5728 forms processing (i.e. visited by form navigation
5729 keys). Can be used to make labels or derived fields
5730 with buffer values alterable by the forms
5731 application, not the user.</p>
5737 <p>Controls whether data is displayed during field
5738 entry. If this option is turned off on a field, the
5739 library will accept and edit data in that field,
5740 but it will not be displayed and the visible field
5741 cursor will not move. You can turn off the O_PUBLIC
5742 bit to define password fields.</p>
5748 <p>Controls whether the field's data can be
5749 modified. When this option is off, all editing
5750 requests except <tt class=
5751 "LITERAL">REQ_PREV_CHOICE</tt> and <tt class=
5752 "LITERAL">REQ_NEXT_CHOICE</tt>will fail. Such
5753 read-only fields may be useful for help
5760 <p>Controls word-wrapping in multi-line fields.
5761 Normally, when any character of a (blank-separated)
5762 word reaches the end of the current line, the
5763 entire word is wrapped to the next line (assuming
5764 there is one). When this option is off, the word
5765 will be split across the line break.</p>
5771 <p>Controls field blanking. When this option is on,
5772 entering a character at the first field position
5773 erases the entire field (except for the
5774 just-entered character).</p>
5780 <p>Controls automatic skip to next field when this
5781 one fills. Normally, when the forms user tries to
5782 type more data into a field than will fit, the
5783 editing location jumps to next field. When this
5784 option is off, the user's cursor will hang at the
5785 end of the field. This option is ignored in dynamic
5786 fields that have not reached their size limit.</p>
5792 <p>Controls whether validation is applied to blank
5793 fields. Normally, it is not; the user can leave a
5794 field blank without invoking the usual validation
5795 check on exit. If this option is off on a field,
5796 exit from it will invoke a validation check.</p>
5802 <p>Controls whether validation occurs on every
5803 exit, or only after the field is modified. Normally
5804 the latter is true. Setting O_PASSOK may be useful
5805 if your field's validation function may change
5806 during forms processing.</p>
5812 <p>Controls whether the field is fixed to its
5813 initial dimensions. If you turn this off, the field
5814 becomes dynamic and will stretch to fit entered
5820 <p>A field's options cannot be changed while the field is
5821 currently selected. However, options may be changed on
5822 posted fields that are not current.</p>
5824 <p>The option values are bit-masks and can be composed
5825 with logical-or in the obvious way. You have seen the
5826 usage of switching off O_AUTOSKIP option. The following
5827 example clarifies usage of some more options. Other
5828 options are explained where appropriate.</p>
5830 <div class="EXAMPLE">
5831 <a name="FFOOP" id="FFOOP"></a>
5832 <p><b>Example 27. Field Options Usage example</b>
5835 <pre class="PROGRAMLISTING"><span class=
5836 "INLINEMEDIAOBJECT">#include <form.h>
5845 { FIELD *field[N_FIELDS];
5849 /* Initialize curses */
5853 keypad(stdscr, TRUE);
5855 /* Initialize the fields */
5856 for(i = 0; i < N_FIELDS - 1; ++i)
5857 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0);
5858 field[N_FIELDS - 1] = NULL;
5860 /* Set field options */
5861 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */
5863 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */
5864 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/
5865 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */
5866 /* after last character is entered */
5868 /* Create the form and post it */
5869 my_form = new_form(field);
5873 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */
5874 set_field_buffer(field[0], 0, "This is a static Field");
5875 /* Initialize the field */
5876 mvprintw(STARTY, STARTX - 10, "Field 1:");
5877 mvprintw(STARTY + 2, STARTX - 10, "Field 2:");
5880 /* Loop through to get user requests */
5881 while((ch = getch()) != KEY_F(1))
5884 /* Go to next field */
5885 form_driver(my_form, REQ_NEXT_FIELD);
5886 /* Go to the end of the present buffer */
5887 /* Leaves nicely at the last character */
5888 form_driver(my_form, REQ_END_LINE);
5891 /* Go to previous field */
5892 form_driver(my_form, REQ_PREV_FIELD);
5893 form_driver(my_form, REQ_END_LINE);
5896 /* If this is a normal character, it gets */
5898 form_driver(my_form, ch);
5903 /* Un post form and free the memory */
5904 unpost_form(my_form);
5906 free_field(field[0]);
5907 free_field(field[1]);
5914 <p>This example, though useless, shows the usage of
5915 options. If used properly, they can present information
5916 very effectively in a form. The second field being not
5917 O_PUBLIC, does not show the characters you are
5924 <h4 class="SECT3"><a name="FIELDSTATUS" id=
5925 "FIELDSTATUS">18.3.6. Field Status</a></h4>
5927 <p>The field status specifies whether the field has got
5928 edited or not. It is initially set to FALSE and when user
5929 enters something and the data buffer gets modified it
5930 becomes TRUE. So a field's status can be queried to find
5931 out whether it has been modified or not. The following
5932 functions can assist in those operations.</p>
5935 "PROGRAMLISTING">int set_field_status(FIELD *field, /* field to alter */
5936 int status); /* status to set */
5938 int field_status(FIELD *field); /* fetch status of field */</pre>
5939 <p>It is better to check the field's status only after
5940 after leaving the field, as data buffer might not have
5941 been updated yet as the validation is still due. To
5942 guarantee that right status is returned, call
5943 field_status() either (1) in the field's exit validation
5944 check routine, (2) from the field's or form's
5945 initialization or termination hooks, or (3) just after a
5946 REQ_VALIDATION request has been processed by the forms
5953 <h4 class="SECT3"><a name="FIELDUSERPTR" id=
5954 "FIELDUSERPTR">18.3.7. Field User Pointer</a></h4>
5956 <p>Every field structure contains one pointer that can be
5957 used by the user for various purposes. It is not touched
5958 by forms library and can be used for any purpose by the
5959 user. The following functions set and fetch user
5963 "PROGRAMLISTING">int set_field_userptr(FIELD *field,
5964 char *userptr); /* the user pointer you wish to associate */
5965 /* with the field */
5967 char *field_userptr(FIELD *field); /* fetch user pointer of the field */</pre>
5973 <h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id=
5974 "VARIABLESIZEFIELDS">18.3.8. Variable-Sized Fields</a></h4>
5976 <p>If you want a dynamically changing field with variable
5977 width, this is the feature you want to put to full use.
5978 This will allow the user to enter more data than the
5979 original size of the field and let the field grow.
5980 According to the field orientation it will scroll
5981 horizontally or vertically to incorporate the new
5984 <p>To make a field dynamically growable, the option
5985 O_STATIC should be turned off. This can be done with
5989 "PROGRAMLISTING"> field_opts_off(field_pointer, O_STATIC);</pre>
5990 <p>But it is usually not advisable to allow a field to
5991 grow infinitely. You can set a maximum limit to the
5992 growth of the field with</p>
5995 "PROGRAMLISTING">int set_max_field(FIELD *field, /* Field on which to operate */
5996 int max_growth); /* maximum growth allowed for the field */</pre>
5997 <p>The field info for a dynamically growable field can be
6001 "PROGRAMLISTING">int dynamic_field_info( FIELD *field, /* Field on which to operate */
6002 int *prows, /* number of rows will be filled in this */
6003 int *pcols, /* number of columns will be filled in this*/
6004 int *pmax) /* maximum allowable growth will be filled */
6005 /* in this */</pre>Though field_info
6006 work as usual, it is advisable to use this function to get the
6007 proper attributes of a dynamically growable field.
6008 <p>Recall the library routine new_field; a new field
6009 created with height set to one will be defined to be a
6010 one line field. A new field created with height greater
6011 than one will be defined to be a multi line field.</p>
6013 <p>A one line field with O_STATIC turned off (dynamically
6014 growable field) will contain a single fixed row, but the
6015 number of columns can increase if the user enters more
6016 data than the initial field will hold. The number of
6017 columns displayed will remain fixed and the additional
6018 data will scroll horizontally.</p>
6020 <p>A multi line field with O_STATIC turned off
6021 (dynamically growable field) will contain a fixed number
6022 of columns, but the number of rows can increase if the
6023 user enters more data than the initial field will hold.
6024 The number of rows displayed will remain fixed and the
6025 additional data will scroll vertically.</p>
6027 <p>The above two paragraphs pretty much describe a
6028 dynamically growable field's behavior. The way other
6029 parts of forms library behaves is described below:</p>
6033 <p>The field option O_AUTOSKIP will be ignored if the
6034 option O_STATIC is off and there is no maximum growth
6035 specified for the field. Currently, O_AUTOSKIP
6036 generates an automatic REQ_NEXT_FIELD form driver
6037 request when the user types in the last character
6038 position of a field. On a growable field with no
6039 maximum growth specified, there is no last character
6040 position. If a maximum growth is specified, the
6041 O_AUTOSKIP option will work as normal if the field
6042 has grown to its maximum size.</p>
6046 <p>The field justification will be ignored if the
6047 option O_STATIC is off. Currently, set_field_just can
6048 be used to JUSTIFY_LEFT, JUSTIFY_RIGHT,
6049 JUSTIFY_CENTER the contents of a one line field. A
6050 growable one line field will, by definition, grow and
6051 scroll horizontally and may contain more data than
6052 can be justified. The return from field_just will be
6057 <p>The overloaded form driver request REQ_NEW_LINE
6058 will operate the same way regardless of the
6059 O_NL_OVERLOAD form option if the field option
6060 O_STATIC is off and there is no maximum growth
6061 specified for the field. Currently, if the form
6062 option O_NL_OVERLOAD is on, REQ_NEW_LINE implicitly
6063 generates a REQ_NEXT_FIELD if called from the last
6064 line of a field. If a field can grow without bound,
6065 there is no last line, so REQ_NEW_LINE will never
6066 implicitly generate a REQ_NEXT_FIELD. If a maximum
6067 growth limit is specified and the O_NL_OVERLOAD form
6068 option is on, REQ_NEW_LINE will only implicitly
6069 generate REQ_NEXT_FIELD if the field has grown to its
6070 maximum size and the user is on the last line.</p>
6074 <p>The library call dup_field will work as usual; it
6075 will duplicate the field, including the current
6076 buffer size and contents of the field being
6077 duplicated. Any specified maximum growth will also be
6082 <p>The library call link_field will work as usual; it
6083 will duplicate all field attributes and share buffers
6084 with the field being linked. If the O_STATIC field
6085 option is subsequently changed by a field sharing
6086 buffers, how the system reacts to an attempt to enter
6087 more data into the field than the buffer will
6088 currently hold will depend on the setting of the
6089 option in the current field.</p>
6093 <p>The library call field_info will work as usual;
6094 the variable nrow will contain the value of the
6095 original call to new_field. The user should use
6096 dynamic_field_info, described above, to query the
6097 current size of the buffer.</p>
6101 <p>Some of the above points make sense only after
6102 explaining form driver. We will be looking into that in
6103 next few sections.</p>
6110 <h3 class="SECT2"><a name="FORMWINDOWS" id=
6111 "FORMWINDOWS">18.4. Form Windows</a></h3>
6113 <p>The form windows concept is pretty much similar to menu
6114 windows. Every form is associated with a main window and a
6115 sub window. The form main window displays any title or
6116 border associated or whatever the user wishes. Then the sub
6117 window contains all the fields and displays them according
6118 to their position. This gives the flexibility of
6119 manipulating fancy form displaying very easily.</p>
6121 <p>Since this is pretty much similar to menu windows, I am
6122 providing an example with out much explanation. The
6123 functions are similar and they work the same way.</p>
6125 <div class="EXAMPLE">
6126 <a name="FFOWI" id="FFOWI"></a>
6127 <p><b>Example 28. Form Windows Example</b>
6130 <pre class="PROGRAMLISTING"><span class=
6131 "INLINEMEDIAOBJECT">#include <string.h>
6132 #include <form.h>
6134 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
6140 WINDOW *my_form_win;
6143 /* Initialize curses */
6148 keypad(stdscr, TRUE);
6150 /* Initialize few color pairs */
6151 init_pair(1, COLOR_RED, COLOR_BLACK);
6153 /* Initialize the fields */
6154 field[0] = new_field(1, 10, 6, 1, 0, 0);
6155 field[1] = new_field(1, 10, 8, 1, 0, 0);
6158 /* Set field options */
6159 set_field_back(field[0], A_UNDERLINE);
6160 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
6161 /* Field is filled up */
6162 set_field_back(field[1], A_UNDERLINE);
6163 field_opts_off(field[1], O_AUTOSKIP);
6165 /* Create the form and post it */
6166 my_form = new_form(field);
6168 /* Calculate the area required for the form */
6169 scale_form(my_form, &rows, &cols);
6171 /* Create the window to be associated with the form */
6172 my_form_win = newwin(rows + 4, cols + 4, 4, 4);
6173 keypad(my_form_win, TRUE);
6175 /* Set main window and sub window */
6176 set_form_win(my_form, my_form_win);
6177 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2));
6179 /* Print a border around the main window and print a title */
6180 box(my_form_win, 0, 0);
6181 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1));
6184 wrefresh(my_form_win);
6186 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
6189 /* Loop through to get user requests */
6190 while((ch = wgetch(my_form_win)) != KEY_F(1))
6193 /* Go to next field */
6194 form_driver(my_form, REQ_NEXT_FIELD);
6195 /* Go to the end of the present buffer */
6196 /* Leaves nicely at the last character */
6197 form_driver(my_form, REQ_END_LINE);
6200 /* Go to previous field */
6201 form_driver(my_form, REQ_PREV_FIELD);
6202 form_driver(my_form, REQ_END_LINE);
6205 /* If this is a normal character, it gets */
6207 form_driver(my_form, ch);
6212 /* Un post form and free the memory */
6213 unpost_form(my_form);
6215 free_field(field[0]);
6216 free_field(field[1]);
6222 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
6236 length = strlen(string);
6237 temp = (width - length)/ 2;
6238 x = startx + (int)temp;
6239 wattron(win, color);
6240 mvwprintw(win, y, x, "%s", string);
6241 wattroff(win, color);
6250 <h3 class="SECT2"><a name="FILEDVALIDATE" id=
6251 "FILEDVALIDATE">18.5. Field Validation</a></h3>
6253 <p>By default, a field will accept any data input by the
6254 user. It is possible to attach validation to the field.
6255 Then any attempt by the user to leave the field, while it
6256 contains data that doesn't match the validation type will
6257 fail. Some validation types also have a character-validity
6258 check for each time a character is entered in the
6261 <p>Validation can be attached to a field with the following
6265 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6266 FIELDTYPE *ftype, /* type to associate */
6267 ...); /* additional arguments*/</pre>Once
6268 set, the validation type for a field can be queried with
6271 "PROGRAMLISTING">FIELDTYPE *field_type(FIELD *field); /* field to query */</pre>
6272 <p>The form driver validates the data in a field only when
6273 data is entered by the end-user. Validation does not occur
6278 <p>the application program changes the field value by
6279 calling set_field_buffer.</p>
6283 <p>linked field values are changed indirectly -- by
6284 changing the field to which they are linked</p>
6288 <p>The following are the pre-defined validation types. You
6289 can also specify custom validation, though it is a bit
6290 tricky and cumbersome.</p>
6292 <h1 class="BRIDGEHEAD"><a name="AEN1074" id=
6293 "AEN1074"></a>TYPE_ALPHA</h1>
6295 <p>This field type accepts alphabetic data; no blanks, no
6296 digits, no special characters (this is checked at
6297 character-entry time). It is set up with:</p>
6300 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6301 TYPE_ALPHA, /* type to associate */
6302 int width); /* minimum width of field */</pre>
6303 <p>The width argument sets a minimum width of data. The
6304 user has to enter at-least width number of characters
6305 before he can leave the field. Typically you'll want to set
6306 this to the field width; if it is greater than the field
6307 width, the validation check will always fail. A minimum
6308 width of zero makes field completion optional.</p>
6310 <h1 class="BRIDGEHEAD"><a name="AEN1078" id=
6311 "AEN1078"></a>TYPE_ALNUM</h1>
6313 <p>This field type accepts alphabetic data and digits; no
6314 blanks, no special characters (this is checked at
6315 character-entry time). It is set up with:</p>
6318 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6319 TYPE_ALNUM, /* type to associate */
6320 int width); /* minimum width of field */</pre>
6321 <p>The width argument sets a minimum width of data. As with
6322 TYPE_ALPHA, typically you'll want to set this to the field
6323 width; if it is greater than the field width, the
6324 validation check will always fail. A minimum width of zero
6325 makes field completion optional.</p>
6327 <h1 class="BRIDGEHEAD"><a name="AEN1082" id=
6328 "AEN1082"></a>TYPE_ENUM</h1>
6330 <p>This type allows you to restrict a field's values to be
6331 among a specified set of string values (for example, the
6332 two-letter postal codes for U.S. states). It is set up
6336 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6337 TYPE_ENUM, /* type to associate */
6338 char **valuelist; /* list of possible values */
6339 int checkcase; /* case-sensitive? */
6340 int checkunique); /* must specify uniquely? */</pre>
6341 <p>The valuelist parameter must point at a NULL-terminated
6342 list of valid strings. The checkcase argument, if true,
6343 makes comparison with the string case-sensitive.</p>
6345 <p>When the user exits a TYPE_ENUM field, the validation
6346 procedure tries to complete the data in the buffer to a
6347 valid entry. If a complete choice string has been entered,
6348 it is of course valid. But it is also possible to enter a
6349 prefix of a valid string and have it completed for you.</p>
6351 <p>By default, if you enter such a prefix and it matches
6352 more than one value in the string list, the prefix will be
6353 completed to the first matching value. But the checkunique
6354 argument, if true, requires prefix matches to be unique in
6355 order to be valid.</p>
6357 <p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests
6358 can be particularly useful with these fields.</p>
6360 <h1 class="BRIDGEHEAD"><a name="AEN1089" id=
6361 "AEN1089"></a>TYPE_INTEGER</h1>
6363 <p>This field type accepts an integer. It is set up as
6367 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6368 TYPE_INTEGER, /* type to associate */
6369 int padding, /* # places to zero-pad to */
6370 int vmin, int vmax); /* valid range */</pre>
6371 <p>Valid characters consist of an optional leading minus
6372 and digits. The range check is performed on exit. If the
6373 range maximum is less than or equal to the minimum, the
6374 range is ignored.</p>
6376 <p>If the value passes its range check, it is padded with
6377 as many leading zero digits as necessary to meet the
6378 padding argument.</p>
6380 <p>A TYPE_INTEGER value buffer can conveniently be
6381 interpreted with the C library function atoi(3).</p>
6383 <h1 class="BRIDGEHEAD"><a name="AEN1095" id=
6384 "AEN1095"></a>TYPE_NUMERIC</h1>
6386 <p>This field type accepts a decimal number. It is set up
6390 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6391 TYPE_NUMERIC, /* type to associate */
6392 int padding, /* # places of precision */
6393 int vmin, int vmax); /* valid range */</pre>
6394 <p>Valid characters consist of an optional leading minus
6395 and digits. possibly including a decimal point. The range
6396 check is performed on exit. If the range maximum is less
6397 than or equal to the minimum, the range is ignored.</p>
6399 <p>If the value passes its range check, it is padded with
6400 as many trailing zero digits as necessary to meet the
6401 padding argument.</p>
6403 <p>A TYPE_NUMERIC value buffer can conveniently be
6404 interpreted with the C library function atof(3).</p>
6406 <h1 class="BRIDGEHEAD"><a name="AEN1101" id=
6407 "AEN1101"></a>TYPE_REGEXP</h1>
6409 <p>This field type accepts data matching a regular
6410 expression. It is set up as follows:</p>
6413 "PROGRAMLISTING">int set_field_type(FIELD *field, /* field to alter */
6414 TYPE_REGEXP, /* type to associate */
6415 char *regexp); /* expression to match */</pre>
6416 <p>The syntax for regular expressions is that of
6417 regcomp(3). The check for regular-expression match is
6418 performed on exit.</p>
6424 <h3 class="SECT2"><a name="FORMDRIVER" id=
6425 "FORMDRIVER">18.6. Form Driver: The work horse of the forms
6428 <p>As in the menu system, form_driver() plays a very
6429 important role in forms system. All types of requests to
6430 forms system should be funneled through form_driver().</p>
6433 "PROGRAMLISTING">int form_driver(FORM *form, /* form on which to operate */
6434 int request) /* form request code */</pre>
6435 <p>As you have seen some of the examples above, you have to
6436 be in a loop looking for user input and then decide whether
6437 it is a field data or a form request. The form requests are
6438 then passed to form_driver() to do the work.</p>
6440 <p>The requests roughly can be divided into following
6441 categories. Different requests and their usage is explained
6447 <h4 class="SECT3"><a name="PAGENAVREQ" id=
6448 "PAGENAVREQ">18.6.1. Page Navigation Requests</a></h4>
6450 <p>These requests cause page-level moves through the
6451 form, triggering display of a new form screen. A form can
6452 be made of multiple pages. If you have a big form with
6453 lot of fields and logical sections, then you can divide
6454 the form into pages. The function set_new_page() to set a
6455 new page at the field specified.</p>
6458 "PROGRAMLISTING">int set_new_page(FIELD *field,/* Field at which page break to be set or unset */
6459 bool new_page_flag); /* should be TRUE to put a break */</pre>
6460 <p>The following requests allow you to move to different
6465 <p><span class="emphasis"><i class=
6466 "EMPHASIS">REQ_NEXT_PAGE</i></span> Move to the next
6471 <p><span class="emphasis"><i class=
6472 "EMPHASIS">REQ_PREV_PAGE</i></span> Move to the
6473 previous form page.</p>
6477 <p><span class="emphasis"><i class=
6478 "EMPHASIS">REQ_FIRST_PAGE</i></span> Move to the
6479 first form page.</p>
6483 <p><span class="emphasis"><i class=
6484 "EMPHASIS">REQ_LAST_PAGE</i></span> Move to the last
6489 <p>These requests treat the list as cyclic; that is,
6490 REQ_NEXT_PAGE from the last page goes to the first, and
6491 REQ_PREV_PAGE from the first page goes to the last.</p>
6497 <h4 class="SECT3"><a name="INTERFIELDNAVREQ" id=
6498 "INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation
6501 <p>These requests handle navigation between fields on the
6506 <p><span class="emphasis"><i class=
6507 "EMPHASIS">REQ_NEXT_FIELD</i></span> Move to next
6512 <p><span class="emphasis"><i class=
6513 "EMPHASIS">REQ_PREV_FIELD</i></span> Move to previous
6518 <p><span class="emphasis"><i class=
6519 "EMPHASIS">REQ_FIRST_FIELD</i></span> Move to the
6524 <p><span class="emphasis"><i class=
6525 "EMPHASIS">REQ_LAST_FIELD</i></span> Move to the last
6530 <p><span class="emphasis"><i class=
6531 "EMPHASIS">REQ_SNEXT_FIELD</i></span> Move to sorted
6536 <p><span class="emphasis"><i class=
6537 "EMPHASIS">REQ_SPREV_FIELD</i></span> Move to sorted
6542 <p><span class="emphasis"><i class=
6543 "EMPHASIS">REQ_SFIRST_FIELD</i></span> Move to the
6544 sorted first field.</p>
6548 <p><span class="emphasis"><i class=
6549 "EMPHASIS">REQ_SLAST_FIELD</i></span> Move to the
6550 sorted last field.</p>
6554 <p><span class="emphasis"><i class=
6555 "EMPHASIS">REQ_LEFT_FIELD</i></span> Move left to
6560 <p><span class="emphasis"><i class=
6561 "EMPHASIS">REQ_RIGHT_FIELD</i></span> Move right to
6566 <p><span class="emphasis"><i class=
6567 "EMPHASIS">REQ_UP_FIELD</i></span> Move up to
6572 <p><span class="emphasis"><i class=
6573 "EMPHASIS">REQ_DOWN_FIELD</i></span> Move down to
6578 <p>These requests treat the list of fields on a page as
6579 cyclic; that is, REQ_NEXT_FIELD from the last field goes
6580 to the first, and REQ_PREV_FIELD from the first field
6581 goes to the last. The order of the fields for these (and
6582 the REQ_FIRST_FIELD and REQ_LAST_FIELD requests) is
6583 simply the order of the field pointers in the form array
6584 (as set up by new_form() or set_form_fields()</p>
6586 <p>It is also possible to traverse the fields as if they
6587 had been sorted in screen-position order, so the sequence
6588 goes left-to-right and top-to-bottom. To do this, use the
6589 second group of four sorted-movement requests.</p>
6591 <p>Finally, it is possible to move between fields using
6592 visual directions up, down, right, and left. To
6593 accomplish this, use the third group of four requests.
6594 Note, however, that the position of a form for purposes
6595 of these requests is its upper-left corner.</p>
6597 <p>For example, suppose you have a multi-line field B,
6598 and two single-line fields A and C on the same line with
6599 B, with A to the left of B and C to the right of B. A
6600 REQ_MOVE_RIGHT from A will go to B only if A, B, and C
6601 all share the same first line; otherwise it will skip
6608 <h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id=
6609 "INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation
6612 <p>These requests drive movement of the edit cursor
6613 within the currently selected field.</p>
6617 <p><span class="emphasis"><i class=
6618 "EMPHASIS">REQ_NEXT_CHAR</i></span> Move to next
6623 <p><span class="emphasis"><i class=
6624 "EMPHASIS">REQ_PREV_CHAR</i></span> Move to previous
6629 <p><span class="emphasis"><i class=
6630 "EMPHASIS">REQ_NEXT_LINE</i></span> Move to next
6635 <p><span class="emphasis"><i class=
6636 "EMPHASIS">REQ_PREV_LINE</i></span> Move to previous
6641 <p><span class="emphasis"><i class=
6642 "EMPHASIS">REQ_NEXT_WORD</i></span> Move to next
6647 <p><span class="emphasis"><i class=
6648 "EMPHASIS">REQ_PREV_WORD</i></span> Move to previous
6653 <p><span class="emphasis"><i class=
6654 "EMPHASIS">REQ_BEG_FIELD</i></span> Move to beginning
6659 <p><span class="emphasis"><i class=
6660 "EMPHASIS">REQ_END_FIELD</i></span> Move to end of
6665 <p><span class="emphasis"><i class=
6666 "EMPHASIS">REQ_BEG_LINE</i></span> Move to beginning
6671 <p><span class="emphasis"><i class=
6672 "EMPHASIS">REQ_END_LINE</i></span> Move to end of
6677 <p><span class="emphasis"><i class=
6678 "EMPHASIS">REQ_LEFT_CHAR</i></span> Move left in
6683 <p><span class="emphasis"><i class=
6684 "EMPHASIS">REQ_RIGHT_CHAR</i></span> Move right in
6689 <p><span class="emphasis"><i class=
6690 "EMPHASIS">REQ_UP_CHAR</i></span> Move up in
6695 <p><span class="emphasis"><i class=
6696 "EMPHASIS">REQ_DOWN_CHAR</i></span> Move down in
6701 <p>Each word is separated from the previous and next
6702 characters by whitespace. The commands to move to
6703 beginning and end of line or field look for the first or
6704 last non-pad character in their ranges.</p>
6710 <h4 class="SECT3"><a name="SCROLLREQ" id=
6711 "SCROLLREQ">18.6.4. Scrolling Requests</a></h4>
6713 <p>Fields that are dynamic and have grown and fields
6714 explicitly created with offscreen rows are scrollable.
6715 One-line fields scroll horizontally; multi-line fields
6716 scroll vertically. Most scrolling is triggered by editing
6717 and intra-field movement (the library scrolls the field
6718 to keep the cursor visible). It is possible to explicitly
6719 request scrolling with the following requests:</p>
6723 <p><span class="emphasis"><i class=
6724 "EMPHASIS">REQ_SCR_FLINE</i></span> Scroll vertically
6729 <p><span class="emphasis"><i class=
6730 "EMPHASIS">REQ_SCR_BLINE</i></span> Scroll vertically
6731 backward a line.</p>
6735 <p><span class="emphasis"><i class=
6736 "EMPHASIS">REQ_SCR_FPAGE</i></span> Scroll vertically
6741 <p><span class="emphasis"><i class=
6742 "EMPHASIS">REQ_SCR_BPAGE</i></span> Scroll vertically
6743 backward a page.</p>
6747 <p><span class="emphasis"><i class=
6748 "EMPHASIS">REQ_SCR_FHPAGE</i></span> Scroll
6749 vertically forward half a page.</p>
6753 <p><span class="emphasis"><i class=
6754 "EMPHASIS">REQ_SCR_BHPAGE</i></span> Scroll
6755 vertically backward half a page.</p>
6759 <p><span class="emphasis"><i class=
6760 "EMPHASIS">REQ_SCR_FCHAR</i></span> Scroll
6761 horizontally forward a character.</p>
6765 <p><span class="emphasis"><i class=
6766 "EMPHASIS">REQ_SCR_BCHAR</i></span> Scroll
6767 horizontally backward a character.</p>
6771 <p><span class="emphasis"><i class=
6772 "EMPHASIS">REQ_SCR_HFLINE</i></span> Scroll
6773 horizontally one field width forward.</p>
6777 <p><span class="emphasis"><i class=
6778 "EMPHASIS">REQ_SCR_HBLINE</i></span> Scroll
6779 horizontally one field width backward.</p>
6783 <p><span class="emphasis"><i class=
6784 "EMPHASIS">REQ_SCR_HFHALF</i></span> Scroll
6785 horizontally one half field width forward.</p>
6789 <p><span class="emphasis"><i class=
6790 "EMPHASIS">REQ_SCR_HBHALF</i></span> Scroll
6791 horizontally one half field width backward.</p>
6795 <p>For scrolling purposes, a page of a field is the
6796 height of its visible part.</p>
6802 <h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5.
6803 Editing Requests</a></h4>
6805 <p>When you pass the forms driver an ASCII character, it
6806 is treated as a request to add the character to the
6807 field's data buffer. Whether this is an insertion or a
6808 replacement depends on the field's edit mode (insertion
6811 <p>The following requests support editing the field and
6812 changing the edit mode:</p>
6816 <p><span class="emphasis"><i class=
6817 "EMPHASIS">REQ_INS_MODE</i></span> Set insertion
6822 <p><span class="emphasis"><i class=
6823 "EMPHASIS">REQ_OVL_MODE</i></span> Set overlay
6828 <p><span class="emphasis"><i class=
6829 "EMPHASIS">REQ_NEW_LINE</i></span> New line request
6830 (see below for explanation).</p>
6834 <p><span class="emphasis"><i class=
6835 "EMPHASIS">REQ_INS_CHAR</i></span> Insert space at
6836 character location.</p>
6840 <p><span class="emphasis"><i class=
6841 "EMPHASIS">REQ_INS_LINE</i></span> Insert blank line
6842 at character location.</p>
6846 <p><span class="emphasis"><i class=
6847 "EMPHASIS">REQ_DEL_CHAR</i></span> Delete character
6852 <p><span class="emphasis"><i class=
6853 "EMPHASIS">REQ_DEL_PREV</i></span> Delete previous
6858 <p><span class="emphasis"><i class=
6859 "EMPHASIS">REQ_DEL_LINE</i></span> Delete line at
6864 <p><span class="emphasis"><i class=
6865 "EMPHASIS">REQ_DEL_WORD</i></span> Delete word at
6870 <p><span class="emphasis"><i class=
6871 "EMPHASIS">REQ_CLR_EOL</i></span> Clear to end of
6876 <p><span class="emphasis"><i class=
6877 "EMPHASIS">REQ_CLR_EOF</i></span> Clear to end of
6882 <p><span class="emphasis"><i class=
6883 "EMPHASIS">REQ_CLR_FIELD</i></span> Clear entire
6888 <p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV
6889 requests is complicated and partly controlled by a pair
6890 of forms options. The special cases are triggered when
6891 the cursor is at the beginning of a field, or on the last
6892 line of the field.</p>
6894 <p>First, we consider REQ_NEW_LINE:</p>
6896 <p>The normal behavior of REQ_NEW_LINE in insert mode is
6897 to break the current line at the position of the edit
6898 cursor, inserting the portion of the current line after
6899 the cursor as a new line following the current and moving
6900 the cursor to the beginning of that new line (you may
6901 think of this as inserting a newline in the field
6904 <p>The normal behavior of REQ_NEW_LINE in overlay mode is
6905 to clear the current line from the position of the edit
6906 cursor to end of line. The cursor is then moved to the
6907 beginning of the next line.</p>
6909 <p>However, REQ_NEW_LINE at the beginning of a field, or
6910 on the last line of a field, instead does a
6911 REQ_NEXT_FIELD. O_NL_OVERLOAD option is off, this special
6912 action is disabled.</p>
6914 <p>Now, let us consider REQ_DEL_PREV:</p>
6916 <p>The normal behavior of REQ_DEL_PREV is to delete the
6917 previous character. If insert mode is on, and the cursor
6918 is at the start of a line, and the text on that line will
6919 fit on the previous one, it instead appends the contents
6920 of the current line to the previous one and deletes the
6921 current line (you may think of this as deleting a newline
6922 from the field buffer).</p>
6924 <p>However, REQ_DEL_PREV at the beginning of a field is
6925 instead treated as a REQ_PREV_FIELD.</p>
6927 <p>If the O_BS_OVERLOAD option is off, this special
6928 action is disabled and the forms driver just returns
6929 E_REQUEST_DENIED.</p>
6935 <h4 class="SECT3"><a name="ORDERREQ" id=
6936 "ORDERREQ">18.6.6. Order Requests</a></h4>
6938 <p>If the type of your field is ordered, and has
6939 associated functions for getting the next and previous
6940 values of the type from a given value, there are requests
6941 that can fetch that value into the field buffer:</p>
6945 <p><span class="emphasis"><i class=
6946 "EMPHASIS">REQ_NEXT_CHOICE</i></span> Place the
6947 successor value of the current value in the
6952 <p><span class="emphasis"><i class=
6953 "EMPHASIS">REQ_PREV_CHOICE</i></span> Place the
6954 predecessor value of the current value in the
6959 <p>Of the built-in field types, only TYPE_ENUM has
6960 built-in successor and predecessor functions. When you
6961 define a field type of your own (see Custom Validation
6962 Types), you can associate our own ordering functions.</p>
6968 <h4 class="SECT3"><a name="APPLICCOMMANDS" id=
6969 "APPLICCOMMANDS">18.6.7. Application Commands</a></h4>
6971 <p>Form requests are represented as integers above the
6972 curses value greater than KEY_MAX and less than or equal
6973 to the constant MAX_COMMAND. A value within this range
6974 gets ignored by form_driver(). So this can be used for
6975 any purpose by the application. It can be treated as an
6976 application specific action and take corresponding
6985 <h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and
6986 Widget Libraries</a></h2>
6988 <p>Now that you have seen the capabilities of ncurses and its
6989 sister libraries, you are rolling your sleeves up and gearing
6990 for a project that heavily manipulates screen. But wait.. It
6991 can be pretty difficult to write and maintain complex GUI
6992 widgets in plain ncurses or even with the additional
6993 libraries. There are some ready-to-use tools and widget
6994 libraries that can be used instead of writing your own
6995 widgets. You can use some of them, get ideas from the code,
6996 or even extend them.</p>
7001 <h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses
7002 Development Kit)</a></h3>
7004 <p>In the author's words</p>
7006 <p><span class="emphasis"><i class="EMPHASIS">CDK stands
7007 for 'Curses Development Kit' and it currently contains 21
7008 ready to use widgets which facilitate the speedy
7009 development of full screen curses programs.</i></span>
7012 <p>The kit provides some useful widgets, which can be used
7013 in your programs directly. It is pretty well written and
7014 the documentation is very good. The examples in the
7015 examples directory can be a good place to start for
7016 beginners. The CDK can be downloaded from <a href=
7017 "https://invisible-island.net/cdk/" target=
7018 "_top">https://invisible-island.net/cdk/</a> . Follow the
7019 instructions in README file to install it.</p>
7024 <h4 class="SECT3"><a name="WIDGETLIST" id=
7025 "WIDGETLIST">19.1.1. Widget List</a></h4>
7027 <p>The following is the list of widgets provided with cdk
7028 and their description.</p>
7031 "PROGRAMLISTING">Widget Type Quick Description
7032 ===========================================================================
7033 Alphalist Allows a user to select from a list of words, with
7034 the ability to narrow the search list by typing in a
7035 few characters of the desired word.
7036 Buttonbox This creates a multiple button widget.
7037 Calendar Creates a little simple calendar widget.
7038 Dialog Prompts the user with a message, and the user
7039 can pick an answer from the buttons provided.
7040 Entry Allows the user to enter various types of information.
7041 File Selector A file selector built from Cdk base widgets. This
7042 example shows how to create more complicated widgets
7043 using the Cdk widget library.
7044 Graph Draws a graph.
7045 Histogram Draws a histogram.
7046 Item List Creates a pop up field which allows the user to select
7047 one of several choices in a small field. Very useful
7048 for things like days of the week or month names.
7049 Label Displays messages in a pop up box, or the label can be
7050 considered part of the screen.
7051 Marquee Displays a message in a scrolling marquee.
7052 Matrix Creates a complex matrix with lots of options.
7053 Menu Creates a pull-down menu interface.
7054 Multiple Line Entry A multiple line entry field. Very useful
7055 for long fields. (like a description
7057 Radio List Creates a radio button list.
7058 Scale Creates a numeric scale. Used for allowing a user to
7059 pick a numeric value and restrict them to a range of
7061 Scrolling List Creates a scrolling list/menu list.
7062 Scrolling Window Creates a scrolling log file viewer. Can add
7063 information into the window while its running.
7064 A good widget for displaying the progress of
7065 something. (akin to a console window)
7066 Selection List Creates a multiple option selection list.
7067 Slider Akin to the scale widget, this widget provides a
7068 visual slide bar to represent the numeric value.
7069 Template Creates a entry field with character sensitive
7070 positions. Used for pre-formatted fields like
7071 dates and phone numbers.
7072 Viewer This is a file/information viewer. Very useful
7073 when you need to display loads of information.
7074 ===========================================================================</pre>
7075 <p>A few of the widgets are modified by Thomas Dickey in
7076 recent versions.</p>
7082 <h4 class="SECT3"><a name="CDKATTRACT" id=
7083 "CDKATTRACT">19.1.2. Some Attractive Features</a></h4>
7085 <p>Apart from making our life easier with readily usable
7086 widgets, cdk solves one frustrating problem with printing
7087 multi colored strings, justified strings elegantly.
7088 Special formatting tags can be embedded in the strings
7089 which are passed to CDK functions. For Example</p>
7091 <p>If the string</p>
7094 "PROGRAMLISTING">"</B/1>This line should have a yellow foreground and a blue
7095 background.<!1>"</pre>
7096 <p>given as a parameter to newCDKLabel(), it prints the
7097 line with yellow foreground and blue background. There
7098 are other tags available for justifying string, embedding
7099 special drawing characters, etc. Please refer to the man
7100 page cdk_display(3X) for details. The man page explains
7101 the usage with nice examples.</p>
7107 <h4 class="SECT3"><a name="CDKCONCLUSION" id=
7108 "CDKCONCLUSION">19.1.3. Conclusion</a></h4>
7110 <p>All in all, CDK is a well-written package of widgets,
7111 which if used properly can form a strong frame work for
7112 developing complex GUI.</p>
7119 <h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The
7122 <p>Long long ago, in September 1994, when few people knew
7123 linux, Jeff Tranter wrote an <a href=
7124 "http://www2.linuxjournal.com/lj-issues/issue5/2807.html"
7125 target="_top">article</a> on dialog in Linux Journal. He
7126 starts the article with these words..</p>
7128 <p><span class="emphasis"><i class="EMPHASIS">Linux is
7129 based on the Unix operating system, but also features a
7130 number of unique and useful kernel features and application
7131 programs that often go beyond what is available under Unix.
7132 One little-known gem is "dialog", a utility for creating
7133 professional-looking dialog boxes from within shell
7134 scripts. This article presents a tutorial introduction to
7135 the dialog utility, and shows examples of how and where it
7136 can be used</i></span>
7139 <p>As he explains, dialog is a real gem in making
7140 professional-looking dialog boxes with ease. It creates a
7141 variety of dialog boxes, menus, check lists, etc. It is
7142 usually installed by default. If not, you can download it
7143 from <a href="https://invisible-island.net/dialog/" target=
7144 "_top">Thomas Dickey</a>'s site.</p>
7146 <p>The above-mentioned article gives a very good overview
7147 of its uses and capabilities. The man page has more
7148 details. It can be used in variety of situations. One good
7149 example is building of linux kernel in text mode. Linux
7150 kernel uses a modified version of dialog tailored for its
7153 <p>dialog was initially designed to be used with shell
7154 scripts. If you want to use its functionality in a c
7155 program, then you can use libdialog. The documentation
7156 regarding this is sparse. Definitive reference is the
7157 dialog.h header file which comes with the library. You may
7158 need to hack here and there to get the required output. The
7159 source is easily customizable. I have used it on a number
7160 of occasions by modifying the code.</p>
7166 <h3 class="SECT2"><a name="PERLCURSES" id=
7167 "PERLCURSES">19.3. Perl Curses Modules CURSES::FORM and
7168 CURSES::WIDGETS</a></h3>
7170 <p>The perl module Curses, Curses::Form and Curses::Widgets
7171 give access to curses from perl. If you have curses and
7172 basic perl is installed, you can get these modules from
7173 <a href="http://www.cpan.org/modules/01modules.index.html"
7174 target="_top">CPAN All Modules page</a>. Get the three
7175 zipped modules in the Curses category. Once installed you
7176 can use these modules from perl scripts like any other
7177 module. For more information on perl modules see perlmod
7178 man page. The above modules come with good documentation
7179 and they have some demo scripts to test the functionality.
7180 Though the widgets provided are very rudimentary, these
7181 modules provide good access to curses library from
7184 <p>Some of my code examples are converted to perl by
7185 Anuradha Ratnaweera and they are available in the
7186 <tt class="LITERAL">perl</tt> directory.</p>
7188 <p>For more information see man pages Curses(3) ,
7189 Curses::Form(3) and Curses::Widgets(3). These pages are
7190 installed only when the above modules are acquired and
7198 <h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20.
7199 Just For Fun !!!</a></h2>
7201 <p>This section contains few programs written by me just for
7202 fun. They don't signify a better programming practice or the
7203 best way of using ncurses. They are provided here so as to
7204 allow beginners to get ideas and add more programs to this
7205 section. If you have written a couple of nice, simple
7206 programs in curses and want them to included here, contact
7207 <a href="mailto:ppadala@gmail.com" target="_top">me</a>.</p>
7212 <h3 class="SECT2"><a name="GAMEOFLIFE" id=
7213 "GAMEOFLIFE">20.1. The Game of Life</a></h3>
7215 <p>Game of life is a wonder of math. In <a href=
7216 "http://www.math.com/students/wonders/life/life.html"
7217 target="_top">Paul Callahan</a>'s words</p>
7219 <pre class="PROGRAMLISTING"><span class="emphasis"><i class=
7220 "EMPHASIS">The Game of Life (or simply Life) is not a game in the conventional sense. There
7221 are no players, and no winning or losing. Once the "pieces" are placed in the
7222 starting position, the rules determine everything that happens later.
7223 Nevertheless, Life is full of surprises! In most cases, it is impossible to look
7224 at a starting position (or pattern) and see what will happen in the future. The
7225 only way to find out is to follow the rules of the game.</i></span></pre>
7226 <p>This program starts with a simple inverted U pattern and
7227 shows how wonderful life works. There is a lot of room for
7228 improvement in the program. You can let the user enter
7229 pattern of his choice or even take input from a file. You
7230 can also change rules and play with a lot of variations.
7231 Search on <a href="https://www.google.com" target=
7232 "_top">google</a> for interesting information on game of
7235 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7236 JustForFun/life.c</i></span>
7243 <h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic
7246 <p>Magic Square, another wonder of math, is very simple to
7247 understand but very difficult to make. In a magic square
7248 sum of the numbers in each row, each column is equal. Even
7249 diagonal sum can be equal. There are many variations which
7250 have special properties.</p>
7252 <p>This program creates a simple magic square of odd
7255 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7256 JustForFun/magic.c</i></span>
7263 <h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers
7266 <p>The famous towers of hanoi solver. The aim of the game
7267 is to move the disks on the first peg to last peg, using
7268 middle peg as a temporary stay. The catch is not to place a
7269 larger disk over a small disk at any time.</p>
7271 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7272 JustForFun/hanoi.c</i></span>
7279 <h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens
7282 <p>The objective of the famous N-Queen puzzle is to put N
7283 queens on a N X N chess board without attacking each
7286 <p>This program solves it with a simple backtracking
7289 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7290 JustForFun/queens.c</i></span>
7297 <h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5.
7300 <p>A fun game, if you have time to kill.</p>
7302 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7303 JustForFun/shuffle.c</i></span>
7310 <h3 class="SECT2"><a name="TT" id="TT">20.6. Typing
7313 <p>A simple typing tutor, I created more out of need than
7314 for ease of use. If you know how to put your fingers
7315 correctly on the keyboard, but lack practice, this can be
7318 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7319 JustForFun/tt.c</i></span>
7327 <h2 class="SECT1"><a name="REF" id="REF">21. References</a></h2>
7331 <p>NCURSES man pages</p>
7335 <p>NCURSES FAQ at <a href=
7336 "https://invisible-island.net/ncurses/ncurses.faq.html"
7338 "_top">https://invisible-island.net/ncurses/ncurses.faq.html</a></p>
7342 <p>Writing programs with NCURSES by Eric Raymond and Zeyd
7343 M. Ben-Halim at <a href=
7344 "https://invisible-island.net/ncurses/ncurses-intro.html"
7346 "_top">https://invisible-island.net/ncurses/ncurses-intro.html</a>
7347 - somewhat obsolete. I was inspired by this document and
7348 the structure of this HOWTO follows from the original
projects / ncurses.git / blob