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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 1.9</td>
41 <td align="left">2005-06-20</td>
42 <td align="left">Revised by: ppadala</td>
46 <td align="left" colspan="3">The license has been
47 changed to the MIT-style license used by NCURSES. Note
48 that the programs are also re-licensed under this.</td>
52 <td align="left">Revision 1.8</td>
53 <td align="left">2005-06-17</td>
54 <td align="left">Revised by: ppadala</td>
58 <td align="left" colspan="3">Lots of updates. Added
59 references and perl examples. Changes to examples. Many
60 grammatical and stylistic changes to the content.
61 Changes to NCURSES history.</td>
65 <td align="left">Revision 1.7.1</td>
66 <td align="left">2002-06-25</td>
67 <td align="left">Revised by: ppadala</td>
71 <td align="left" colspan="3">Added a README file for
72 building and instructions for building from
77 <td align="left">Revision 1.7</td>
78 <td align="left">2002-06-25</td>
79 <td align="left">Revised by: ppadala</td>
83 <td align="left" colspan="3">Added "Other formats"
84 section and made a lot of fancy changes to the
85 programs. Inlining of programs is gone.</td>
89 <td align="left">Revision 1.6.1</td>
90 <td align="left">2002-02-24</td>
91 <td align="left">Revised by: ppadala</td>
95 <td align="left" colspan="3">Removed the old Changelog
96 section, cleaned the makefiles</td>
100 <td align="left">Revision 1.6</td>
101 <td align="left">2002-02-16</td>
102 <td align="left">Revised by: ppadala</td>
106 <td align="left" colspan="3">Corrected a lot of
107 spelling mistakes, added ACS variables section</td>
111 <td align="left">Revision 1.5</td>
112 <td align="left">2002-01-05</td>
113 <td align="left">Revised by: ppadala</td>
117 <td align="left" colspan="3">Changed structure to
118 present proper TOC</td>
122 <td align="left">Revision 1.3.1</td>
123 <td align="left">2001-07-26</td>
124 <td align="left">Revised by: ppadala</td>
128 <td align="left" colspan="3">Corrected maintainers
129 paragraph, Corrected stable release number</td>
133 <td align="left">Revision 1.3</td>
134 <td align="left">2001-07-24</td>
135 <td align="left">Revised by: ppadala</td>
139 <td align="left" colspan="3">Added copyright notices to
140 main document (LDP license) and programs (GPL),
141 Corrected printw_example.</td>
145 <td align="left">Revision 1.2</td>
146 <td align="left">2001-06-05</td>
147 <td align="left">Revised by: ppadala</td>
151 <td align="left" colspan="3">Incorporated ravi's
152 changes. Mainly to introduction, menu, form, justforfun
157 <td align="left">Revision 1.1</td>
158 <td align="left">2001-05-22</td>
159 <td align="left">Revised by: ppadala</td>
163 <td align="left" colspan="3">Added "a word about
164 window" section, Added scanw_example.</td>
170 <div class="ABSTRACT">
171 <a name="AEN67" id="AEN67"></a>
172 <p><span class="emphasis"><i class="EMPHASIS">This
173 document is intended to be an "All in One" guide for
174 programming with ncurses and its sister libraries. We
175 graduate from a simple "Hello World" program to more
176 complex form manipulation. No prior experience in ncurses
177 is assumed. Send comments to <a href=
178 "mailto:ppadala@gmail.com" target="_top">this
179 address</a></i></span>
189 <dt><b>Table of Contents</b>
192 <dt>1. <a href="#INTRO">Introduction</a></dt>
196 <dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt>
198 <dt>1.2. <a href="#WHATCANWEDO">What we can do with
201 <dt>1.3. <a href="#WHERETOGETIT">Where to get
204 <dt>1.4. <a href="#PURPOSE">Purpose/Scope of the
207 <dt>1.5. <a href="#ABOUTPROGRAMS">About the
210 <dt>1.6. <a href="#OTHERFORMATS">Other Formats of the
215 <dt>1.6.1. <a href="#LISTFORMATS">Readily available
216 formats from tldp.org</a></dt>
218 <dt>1.6.2. <a href="#BUILDSOURCE">Building from
223 <dt>1.7. <a href="#CREDITS">Credits</a></dt>
225 <dt>1.8. <a href="#WISHLIST">Wish List</a></dt>
227 <dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt>
231 <dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt>
235 <dt>2.1. <a href="#COMPILECURSES">Compiling With the
236 NCURSES Library</a></dt>
238 <dt>2.2. <a href="#DISSECTION">Dissection</a></dt>
242 <dt>2.2.1. <a href="#ABOUT-INITSCR">About
245 <dt>2.2.2. <a href="#MYST-REFRESH">The mysterious
248 <dt>2.2.3. <a href="#ABOUT-ENDWIN">About
255 <dt>3. <a href="#GORY">The Gory Details</a></dt>
257 <dt>4. <a href="#INIT">Initialization</a></dt>
261 <dt>4.1. <a href="#ABOUTINIT">Initialization
264 <dt>4.2. <a href="#RAWCBREAK">raw() and
267 <dt>4.3. <a href="#ECHONOECHO">echo() and
270 <dt>4.4. <a href="#KEYPAD">keypad()</a></dt>
272 <dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt>
274 <dt>4.6. <a href="#MISCINIT">Miscellaneous
275 Initialization functions</a></dt>
277 <dt>4.7. <a href="#INITEX">An Example</a></dt>
281 <dt>5. <a href="#AWORDWINDOWS">A Word about
284 <dt>6. <a href="#PRINTW">Output functions</a></dt>
288 <dt>6.1. <a href="#ADDCHCLASS">addch() class of
291 <dt>6.2. <a href="#AEN298">mvaddch(), waddch() and
294 <dt>6.3. <a href="#PRINTWCLASS">printw() class of
299 <dt>6.3.1. <a href="#PRINTWMVPRINTW">printw() and
302 <dt>6.3.2. <a href="#WPRINTWMVWPRINTW">wprintw()
303 and mvwprintw</a></dt>
305 <dt>6.3.3. <a href="#VWPRINTW">vw_printw()</a></dt>
307 <dt>6.3.4. <a href="#SIMPLEPRINTWEX">A Simple
308 printw example</a></dt>
312 <dt>6.4. <a href="#ADDSTRCLASS">addstr() class of
315 <dt>6.5. <a href="#ACAUTION">A word of caution</a></dt>
319 <dt>7. <a href="#SCANW">Input functions</a></dt>
323 <dt>7.1. <a href="#GETCHCLASS">getch() class of
326 <dt>7.2. <a href="#SCANWCLASS">scanw() class of
331 <dt>7.2.1. <a href="#SCANWMVSCANW">scanw() and
334 <dt>7.2.2. <a href="#WSCANWMVWSCANW">wscanw() and
337 <dt>7.2.3. <a href="#VWSCANW">vw_scanw()</a></dt>
341 <dt>7.3. <a href="#GETSTRCLASS">getstr() class of
344 <dt>7.4. <a href="#GETSTREX">Some examples</a></dt>
348 <dt>8. <a href="#ATTRIB">Attributes</a></dt>
352 <dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt>
354 <dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs
357 <dt>8.3. <a href="#ATTRGET">attr_get()</a></dt>
359 <dt>8.4. <a href="#ATTRFUNCS">attr_ functions</a></dt>
361 <dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt>
363 <dt>8.6. <a href="#CHGAT">chgat() functions</a></dt>
367 <dt>9. <a href="#WINDOWS">Windows</a></dt>
371 <dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt>
373 <dt>9.2. <a href="#LETBEWINDOW">Let there be a Window
376 <dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt>
378 <dt>9.4. <a href="#OTHERSTUFF">The other stuff in the
381 <dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border
386 <dt>10. <a href="#COLOR">Colors</a></dt>
390 <dt>10.1. <a href="#COLORBASICS">The basics</a></dt>
392 <dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color
395 <dt>10.3. <a href="#COLORCONTENT">Color
400 <dt>11. <a href="#KEYS">Interfacing with the key
405 <dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt>
407 <dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage
412 <dt>12. <a href="#MOUSE">Interfacing with the
417 <dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt>
419 <dt>12.2. <a href="#GETTINGEVENTS">Getting the
422 <dt>12.3. <a href="#MOUSETOGETHER">Putting it all
425 <dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous
430 <dt>13. <a href="#SCREEN">Screen Manipulation</a></dt>
434 <dt>13.1. <a href="#GETYX">getyx() functions</a></dt>
436 <dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt>
438 <dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt>
442 <dt>14. <a href="#MISC">Miscellaneous features</a></dt>
446 <dt>14.1. <a href="#CURSSET">curs_set()</a></dt>
448 <dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving
451 <dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt>
455 <dt>15. <a href="#OTHERLIB">Other libraries</a></dt>
457 <dt>16. <a href="#PANELS">Panel Library</a></dt>
461 <dt>16.1. <a href="#PANELBASICS">The Basics</a></dt>
463 <dt>16.2. <a href="#COMPILEPANELS">Compiling With the
464 Panels Library</a></dt>
466 <dt>16.3. <a href="#PANELBROWSING">Panel Window
469 <dt>16.4. <a href="#USERPTRUSING">Using User
472 <dt>16.5. <a href="#PANELMOVERESIZE">Moving and
473 Resizing Panels</a></dt>
475 <dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing
478 <dt>16.7. <a href="#PANELABOVE">panel_above() and
479 panel_below() Functions</a></dt>
483 <dt>17. <a href="#MENUS">Menus Library</a></dt>
487 <dt>17.1. <a href="#MENUBASICS">The Basics</a></dt>
489 <dt>17.2. <a href="#COMPILEMENUS">Compiling With the
490 Menu Library</a></dt>
492 <dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work
493 horse of the menu system</a></dt>
495 <dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt>
497 <dt>17.5. <a href="#SCROLLMENUS">Scrolling
500 <dt>17.6. <a href="#MULTICOLUMN">Multi Columnar
503 <dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued
506 <dt>17.8. <a href="#MENUOPT">Menu Options</a></dt>
508 <dt>17.9. <a href="#MENUUSERPTR">The useful User
513 <dt>18. <a href="#FORMS">Forms Library</a></dt>
517 <dt>18.1. <a href="#FORMBASICS">The Basics</a></dt>
519 <dt>18.2. <a href="#COMPILEFORMS">Compiling With the
520 Forms Library</a></dt>
522 <dt>18.3. <a href="#PLAYFIELDS">Playing with
527 <dt>18.3.1. <a href="#FETCHINFO">Fetching Size and
528 Location of Field</a></dt>
530 <dt>18.3.2. <a href="#MOVEFIELD">Moving the
533 <dt>18.3.3. <a href="#JUSTIFYFIELD">Field
534 Justification</a></dt>
536 <dt>18.3.4. <a href="#FIELDDISPATTRIB">Field
537 Display Attributes</a></dt>
539 <dt>18.3.5. <a href="#FIELDOPTIONBITS">Field Option
542 <dt>18.3.6. <a href="#FIELDSTATUS">Field
545 <dt>18.3.7. <a href="#FIELDUSERPTR">Field User
549 "#VARIABLESIZEFIELDS">Variable-Sized
554 <dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt>
556 <dt>18.5. <a href="#FILEDVALIDATE">Field
559 <dt>18.6. <a href="#FORMDRIVER">Form Driver: The work
560 horse of the forms system</a></dt>
564 <dt>18.6.1. <a href="#PAGENAVREQ">Page Navigation
567 <dt>18.6.2. <a href="#INTERFIELDNAVREQ">Inter-Field
568 Navigation Requests</a></dt>
570 <dt>18.6.3. <a href="#INTRAFIELDNAVREQ">Intra-Field
571 Navigation Requests</a></dt>
573 <dt>18.6.4. <a href="#SCROLLREQ">Scrolling
576 <dt>18.6.5. <a href="#EDITREQ">Editing
579 <dt>18.6.6. <a href="#ORDERREQ">Order
582 <dt>18.6.7. <a href="#APPLICCOMMANDS">Application
589 <dt>19. <a href="#TOOLS">Tools and Widget
594 <dt>19.1. <a href="#CDK">CDK (Curses Development
599 <dt>19.1.1. <a href="#WIDGETLIST">Widget
602 <dt>19.1.2. <a href="#CDKATTRACT">Some Attractive
606 "#CDKCONCLUSION">Conclusion</a></dt>
610 <dt>19.2. <a href="#DIALOG">The dialog</a></dt>
612 <dt>19.3. <a href="#PERLCURSES">Perl Curses Modules
613 CURSES::FORM and CURSES::WIDGETS</a></dt>
617 <dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt>
621 <dt>20.1. <a href="#GAMEOFLIFE">The Game of
624 <dt>20.2. <a href="#MAGIC">Magic Square</a></dt>
626 <dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt>
628 <dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt>
630 <dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt>
632 <dt>20.6. <a href="#TT">Typing Tutor</a></dt>
636 <dt>21. <a href="#REF">References</a></dt>
641 <h2 class="SECT1"><a name="INTRO" id="INTRO">1.
642 Introduction</a></h2>
644 <p>In the olden days of teletype terminals, terminals were
645 away from computers and were connected to them through serial
646 cables. The terminals could be configured by sending a series
647 of bytes. All the capabilities (such as moving the cursor to
648 a new location, erasing part of the screen, scrolling the
649 screen, changing modes etc.) of terminals could be accessed
650 through these series of bytes. These control seeuqnces are
651 usually called escape sequences, because they start with an
652 escape(0x1B) character. Even today, with proper emulation, we
653 can send escape sequences to the emulator and achieve the
654 same effect on a terminal window.</p>
656 <p>Suppose you wanted to print a line in color. Try typing
657 this on your console.</p>
659 <pre class="PROGRAMLISTING">
660 echo "^[[0;31;40mIn Color"
662 <p>The first character is an escape character, which looks
663 like two characters ^ and [. To be able to print it, you have
664 to press CTRL+V and then the ESC key. All the others are
665 normal printable characters. You should be able to see the
666 string "In Color" in red. It stays that way and to revert
667 back to the original mode type this.</p>
669 <pre class="PROGRAMLISTING">
672 <p>Now, what do these magic characters mean? Difficult to
673 comprehend? They might even be different for different
674 terminals. So the designers of UNIX invented a mechanism
675 named <tt class="LITERAL">termcap</tt>. It is a file that
676 lists all the capabilities of a particular terminal, along
677 with the escape sequences needed to achieve a particular
678 effect. In the later years, this was replaced by <tt class=
679 "LITERAL">terminfo</tt>. Without delving too much into
680 details, this mechanism allows application programs to query
681 the terminfo database and obtain the control characters to be
682 sent to a terminal or terminal emulator.</p>
687 <h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is
690 <p>You might be wondering, what the import of all this
691 technical gibberish is. In the above scenario, every
692 application program is supposed to query the terminfo and
693 perform the necessary stuff (sending control characters
694 etc.). It soon became difficult to manage this complexity
695 and this gave birth to 'CURSES'. Curses is a pun on the
696 name "cursor optimization". The Curses library forms a
697 wrapper over working with raw terminal codes, and provides
698 highly flexible and efficient API (Application Programming
699 Interface). It provides functions to move the cursor,
700 create windows, produce colors, play with mouse etc. The
701 application programs need not worry about the underlying
702 terminal capabilities.</p>
704 <p>So what is NCURSES? NCURSES is a clone of the original
705 System V Release 4.0 (SVr4) curses. It is a freely
706 distributable library, fully compatible with older version
707 of curses. In short, it is a library of functions that
708 manages an application's display on character-cell
709 terminals. In the remainder of the document, the terms
710 curses and ncurses are used interchangeably.</p>
712 <p>A detailed history of NCURSES can be found in the NEWS
713 file from the source distribution. The current package is
714 maintained by <a href="mailto:dickey@his.com" target=
715 "_top">Thomas Dickey</a>. You can contact the maintainers
716 at <a href="mailto:bug-ncurses@gnu.org" target=
717 "_top">bug-ncurses@gnu.org</a>.</p>
723 <h3 class="SECT2"><a name="WHATCANWEDO" id=
724 "WHATCANWEDO">1.2. What we can do with NCURSES</a></h3>
726 <p>NCURSES not only creates a wrapper over terminal
727 capabilities, but also gives a robust framework to create
728 nice looking UI (User Interface)s in text mode. It provides
729 functions to create windows etc. Its sister libraries
730 panel, menu and form provide an extension to the basic
731 curses library. These libraries usually come along with
732 curses. One can create applications that contain multiple
733 windows, menus, panels and forms. Windows can be managed
734 independently, can provide 'scrollability' and even can be
737 <p>Menus provide the user with an easy command selection
738 option. Forms allow the creation of easy-to-use data entry
739 and display windows. Panels extend the capabilities of
740 ncurses to deal with overlapping and stacked windows.</p>
742 <p>These are just some of the basic things we can do with
743 ncurses. As we move along, We will see all the capabilities
744 of these libraries.</p>
750 <h3 class="SECT2"><a name="WHERETOGETIT" id=
751 "WHERETOGETIT">1.3. Where to get it</a></h3>
753 <p>All right, now that you know what you can do with
754 ncurses, you must be rearing to get started. NCURSES is
755 usually shipped with your installation. In case you don't
756 have the library or want to compile it on your own, read
759 <p><span class="emphasis"><i class="EMPHASIS">Compiling the
763 <p>NCURSES can be obtained from <a href=
764 "ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target=
765 "_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a>
766 or any of the ftp sites mentioned in <a href=
767 "http://www.gnu.org/order/ftp.html" target=
768 "_top">http://www.gnu.org/order/ftp.html</a>.</p>
770 <p>Read the README and INSTALL files for details on to how
771 to install it. It usually involves the following
774 <pre class="PROGRAMLISTING">
775 tar zxvf ncurses<version>.tar.gz # unzip and untar the archive
776 cd ncurses<version> # cd to the directory
777 ./configure # configure the build according to your
780 su root # become root
781 make install # install it
783 <p><span class="emphasis"><i class="EMPHASIS">Using the
787 <p>NCURSES RPM can be found and downloaded from <a href=
788 "http://rpmfind.net" target="_top">http://rpmfind.net</a> .
789 The RPM can be installed with the following command after
792 <pre class="PROGRAMLISTING">
793 rpm -i <downloaded rpm>
800 <h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4.
801 Purpose/Scope of the document</a></h3>
803 <p>This document is intended to be a "All in One" guide for
804 programming with ncurses and its sister libraries. We
805 graduate from a simple "Hello World" program to more
806 complex form manipulation. No prior experience in ncurses
807 is assumed. The writing is informal, but a lot of detail is
808 provided for each of the examples.</p>
814 <h3 class="SECT2"><a name="ABOUTPROGRAMS" id=
815 "ABOUTPROGRAMS">1.5. About the Programs</a></h3>
817 <p>All the programs in the document are available in zipped
819 "http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz"
820 target="_top">here</a>. Unzip and untar it. The directory
821 structure looks like this.</p>
823 <pre class="PROGRAMLISTING">
826 |----> JustForFun -- just for fun programs
827 |----> basics -- basic programs
828 |----> demo -- output files go into this directory after make
830 | |----> exe -- exe files of all example programs
831 |----> forms -- programs related to form library
832 |----> menus -- programs related to menus library
833 |----> panels -- programs related to panels library
834 |----> perl -- perl equivalents of the examples (contributed
835 | by Anuradha Ratnaweera)
836 |----> Makefile -- the top level Makefile
837 |----> README -- the top level README file. contains instructions
838 |----> COPYING -- copyright notice
840 <p>The individual directories contain the following
843 <pre class="PROGRAMLISTING">
844 Description of files in each directory
845 --------------------------------------
848 |----> hanoi.c -- The Towers of Hanoi Solver
849 |----> life.c -- The Game of Life demo
850 |----> magic.c -- An Odd Order Magic Square builder
851 |----> queens.c -- The famous N-Queens Solver
852 |----> shuffle.c -- A fun game, if you have time to kill
853 |----> tt.c -- A very trivial typing tutor
857 |----> acs_vars.c -- ACS_ variables example
858 |----> hello_world.c -- Simple "Hello World" Program
859 |----> init_func_example.c -- Initialization functions example
860 |----> key_code.c -- Shows the scan code of the key pressed
861 |----> mouse_menu.c -- A menu accessible by mouse
862 |----> other_border.c -- Shows usage of other border functions apa
864 |----> printw_example.c -- A very simple printw() example
865 |----> scanw_example.c -- A very simple getstr() example
866 |----> simple_attr.c -- A program that can print a c file with
867 | -- comments in attribute
868 |----> simple_color.c -- A simple example demonstrating colors
869 |----> simple_key.c -- A menu accessible with keyboard UP, DOWN
871 |----> temp_leave.c -- Demonstrates temporarily leaving curses mode
872 |----> win_border.c -- Shows Creation of windows and borders
873 |----> with_chgat.c -- chgat() usage example
877 |----> form_attrib.c -- Usage of field attributes
878 |----> form_options.c -- Usage of field options
879 |----> form_simple.c -- A simple form example
880 |----> form_win.c -- Demo of windows associated with forms
884 |----> menu_attrib.c -- Usage of menu attributes
885 |----> menu_item_data.c -- Usage of item_name() etc.. functions
886 |----> menu_multi_column.c -- Creates multi columnar menus
887 |----> menu_scroll.c -- Demonstrates scrolling capability of menus
888 |----> menu_simple.c -- A simple menu accessed by arrow keys
889 |----> menu_toggle.c -- Creates multi valued menus and explains
891 |----> menu_userptr.c -- Usage of user pointer
892 |----> menu_win.c -- Demo of windows associated with menus
896 |----> panel_browse.c -- Panel browsing through tab. Usage of user
898 |----> panel_hide.c -- Hiding and Un hiding of panels
899 |----> panel_resize.c -- Moving and resizing of panels
900 |----> panel_simple.c -- A simple panel example
903 |----> 01-10.pl -- Perl equivalents of first ten example programs
905 <p>There is a top level Makefile included in the main
906 directory. It builds all the files and puts the
907 ready-to-use exes in demo/exe directory. You can also do
908 selective make by going into the corresponding directory.
909 Each directory contains a README file explaining the
910 purpose of each c file in the directory.</p>
912 <p>For every example, I have included path name for the
913 file relative to the examples directory.</p>
915 <p>If you prefer browsing individual programs, point your
917 "http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/"
919 "_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p>
921 <p>All the programs are released under the same license
922 that is used by ncurses (MIT-style). This gives you the
923 ability to do pretty much anything other than claiming them
924 as yours. Feel free to use them in your programs as
931 <h3 class="SECT2"><a name="OTHERFORMATS" id=
932 "OTHERFORMATS">1.6. Other Formats of the document</a></h3>
934 <p>This howto is also availabe in various other formats on
935 the tldp.org site. Here are the links to other formats of
941 <h4 class="SECT3"><a name="LISTFORMATS" id=
942 "LISTFORMATS">1.6.1. Readily available formats from
948 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf"
949 target="_top">Acrobat PDF Format</a></p>
954 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz"
955 target="_top">PostScript Format</a></p>
960 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz"
961 target="_top">In Multiple HTML pages</a></p>
966 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html"
967 target="_top">In One big HTML format</a></p>
975 <h4 class="SECT3"><a name="BUILDSOURCE" id=
976 "BUILDSOURCE">1.6.2. Building from source</a></h4>
978 <p>If above links are broken or if you want to experiment
979 with sgml read on.</p>
981 <pre class="PROGRAMLISTING">
982 Get both the source and the tar,gzipped programs, available at
983 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
984 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml
985 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
986 NCURSES-HOWTO/ncurses_programs.tar.gz
988 Unzip ncurses_programs.tar.gz with
989 tar zxvf ncurses_programs.tar.gz
991 Use jade to create various formats. For example if you just want to create
992 the multiple html files, you would use
993 jade -t sgml -i html -d <path to docbook html stylesheet>
994 NCURSES-Programming-HOWTO.sgml
995 to get pdf, first create a single html file of the HOWTO with
996 jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks
997 NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html
998 then use htmldoc to get pdf file with
999 htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf>
1000 NCURSES-ONE-BIG-FILE.html
1001 for ps, you would use
1002 htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps>
1003 NCURSES-ONE-BIG-FILE.html
1006 "http://www.tldp.org/LDP/LDP-Author-Guide/" target=
1007 "_top">LDP Author guide</a> for more details. If all else
1008 failes, mail me at <a href="ppadala@gmail.com" target=
1009 "_top">ppadala@gmail.com</a></p>
1016 <h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7.
1019 <p>I thank <a href="mailto:sharath_1@usa.net" target=
1020 "_top">Sharath</a> and Emre Akbas for helping me with few
1021 sections. The introduction was initially written by
1022 sharath. I rewrote it with few excerpts taken from his
1023 initial work. Emre helped in writing printw and scanw
1026 <p>Perl equivalents of the example programs are contributed
1027 by <a href="mailto:Aratnaweera@virtusa.com" target=
1028 "_top">Anuradha Ratnaweera</a>.</p>
1030 <p>Then comes <a href="mailto:parimi@ece.arizona.edu"
1031 target="_top">Ravi Parimi</a>, my dearest friend, who has
1032 been on this project before even one line was written. He
1033 constantly bombarded me with suggestions and patiently
1034 reviewed the whole text. He also checked each program on
1035 Linux and Solaris.</p>
1041 <h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8.
1044 <p>This is the wish list, in the order of priority. If you
1045 have a wish or you want to work on completing the wish,
1046 mail <a href="mailto:ppadala@gmail.com" target=
1051 <p>Add examples to last parts of forms section.</p>
1055 <p>Prepare a Demo showing all the programs and allow
1056 the user to browse through description of each program.
1057 Let the user compile and see the program in action. A
1058 dialog based interface is preferred.</p>
1062 <p>Add debug info. _tracef, _tracemouse stuff.</p>
1066 <p>Accessing termcap, terminfo using functions provided
1067 by ncurses package.</p>
1071 <p>Working on two terminals simultaneously.</p>
1075 <p>Add more stuff to miscellaneous section.</p>
1083 <h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9.
1086 <p>Copyright © 2001 by Pradeep Padala.</p>
1088 <p>Permission is hereby granted, free of charge, to any
1089 person obtaining a copy of this software and associated
1090 documentation files (the "Software"), to deal in the
1091 Software without restriction, including without limitation
1092 the rights to use, copy, modify, merge, publish,
1093 distribute, distribute with modifications, sublicense,
1094 and/or sell copies of the Software, and to permit persons
1095 to whom the Software is furnished to do so, subject to the
1096 following conditions:</p>
1098 <p>The above copyright notice and this permission notice
1099 shall be included in all copies or substantial portions of
1102 <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
1103 ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
1104 THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
1105 PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE
1106 COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
1107 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
1108 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
1109 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</p>
1111 <p>Except as contained in this notice, the name(s) of the
1112 above copyright holders shall not be used in advertising or
1113 otherwise to promote the sale, use or other dealings in
1114 this Software without prior written authorization.</p>
1121 <h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2.
1122 Hello World !!!</a></h2>
1124 <p>Welcome to the world of curses. Before we plunge into the
1125 library and look into its various features, let's write a
1126 simple program and say hello to the world.</p>
1131 <h3 class="SECT2"><a name="COMPILECURSES" id=
1132 "COMPILECURSES">2.1. Compiling With the NCURSES Library</a></h3>
1134 <p>To use ncurses library functions, you have to include
1135 ncurses.h in your programs. To link the program with
1136 ncurses the flag -lncurses should be added.</p>
1138 <pre class="PROGRAMLISTING">
1139 #include <ncurses.h>
1144 compile and link: gcc <program file> -lncurses
1146 <div class="EXAMPLE">
1147 <a name="BHW" id="BHW"></a>
1148 <p><b>Example 1. The Hello World !!! Program</b>
1151 <pre class="PROGRAMLISTING">
1152 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
1156 initscr(); /* Start curses mode */
1157 printw("Hello World !!!"); /* Print Hello World */
1158 refresh(); /* Print it on to the real screen */
1159 getch(); /* Wait for user input */
1160 endwin(); /* End curses mode */
1171 <h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2.
1174 <p>The above program prints "Hello World !!!" to the screen
1175 and exits. This program shows how to initialize curses and
1176 do screen manipulation and end curses mode. Let's dissect
1177 it line by line.</p>
1182 <h4 class="SECT3"><a name="ABOUT-INITSCR" id=
1183 "ABOUT-INITSCR">2.2.1. About initscr()</a></h4>
1185 <p>The function initscr() initializes the terminal in
1186 curses mode. In some implementations, it clears the
1187 screen and presents a blank screen. To do any screen
1188 manipulation using curses package this has to be called
1189 first. This function initializes the curses system and
1190 allocates memory for our present window (called
1191 <tt class="LITERAL">stdscr</tt>) and some other
1192 data-structures. Under extreme cases this function might
1193 fail due to insufficient memory to allocate memory for
1194 curses library's data structures.</p>
1196 <p>After this is done, we can do a variety of
1197 initializations to customize our curses settings. These
1198 details will be explained <a href="#INIT">later</a> .</p>
1204 <h4 class="SECT3"><a name="MYST-REFRESH" id=
1205 "MYST-REFRESH">2.2.2. The mysterious refresh()</a></h4>
1207 <p>The next line printw prints the string "Hello World
1208 !!!" on to the screen. This function is analogous to
1209 normal printf in all respects except that it prints the
1210 data on a window called stdscr at the current (y,x)
1211 co-ordinates. Since our present co-ordinates are at 0,0
1212 the string is printed at the left hand corner of the
1215 <p>This brings us to that mysterious refresh(). Well,
1216 when we called printw the data is actually written to an
1217 imaginary window, which is not updated on the screen yet.
1218 The job of printw is to update a few flags and data
1219 structures and write the data to a buffer corresponding
1220 to stdscr. In order to show it on the screen, we need to
1221 call refresh() and tell the curses system to dump the
1222 contents on the screen.</p>
1224 <p>The philosophy behind all this is to allow the
1225 programmer to do multiple updates on the imaginary screen
1226 or windows and do a refresh once all his screen update is
1227 done. refresh() checks the window and updates only the
1228 portion which has been changed. This improves performance
1229 and offers greater flexibility too. But, it is sometimes
1230 frustrating to beginners. A common mistake committed by
1231 beginners is to forget to call refresh() after they did
1232 some update through printw() class of functions. I still
1233 forget to add it sometimes :-)</p>
1239 <h4 class="SECT3"><a name="ABOUT-ENDWIN" id=
1240 "ABOUT-ENDWIN">2.2.3. About endwin()</a></h4>
1242 <p>And finally don't forget to end the curses mode.
1243 Otherwise your terminal might behave strangely after the
1244 program quits. endwin() frees the memory taken by curses
1245 sub-system and its data structures and puts the terminal
1246 in normal mode. This function must be called after you
1247 are done with the curses mode.</p>
1255 <h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory
1258 <p>Now that we have seen how to write a simple curses program
1259 let's get into the details. There are many functions that
1260 help customize what you see on screen and many features which
1261 can be put to full use.</p>
1263 <p>Here we go...</p>
1269 <h2 class="SECT1"><a name="INIT" id="INIT">4.
1270 Initialization</a></h2>
1272 <p>We now know that to initialize curses system the function
1273 initscr() has to be called. There are functions which can be
1274 called after this initialization to customize our curses
1275 session. We may ask the curses system to set the terminal in
1276 raw mode or initialize color or initialize the mouse etc..
1277 Let's discuss some of the functions that are normally called
1278 immediately after initscr();</p>
1283 <h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1.
1284 Initialization functions</a></h3>
1290 <h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2.
1291 raw() and cbreak()</a></h3>
1293 <p>Normally the terminal driver buffers the characters a
1294 user types until a new line or carriage return is
1295 encountered. But most programs require that the characters
1296 be available as soon as the user types them. The above two
1297 functions are used to disable line buffering. The
1298 difference between these two functions is in the way
1299 control characters like suspend (CTRL-Z), interrupt and
1300 quit (CTRL-C) are passed to the program. In the raw() mode
1301 these characters are directly passed to the program without
1302 generating a signal. In the <tt class=
1303 "LITERAL">cbreak()</tt> mode these control characters are
1304 interpreted as any other character by the terminal driver.
1305 I personally prefer to use raw() as I can exercise greater
1306 control over what the user does.</p>
1312 <h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3.
1313 echo() and noecho()</a></h3>
1315 <p>These functions control the echoing of characters typed
1316 by the user to the terminal. <tt class=
1317 "LITERAL">noecho()</tt> switches off echoing. The reason
1318 you might want to do this is to gain more control over
1319 echoing or to suppress unnecessary echoing while taking
1320 input from the user through the getch() etc. functions.
1321 Most of the interactive programs call <tt class=
1322 "LITERAL">noecho()</tt> at initialization and do the
1323 echoing of characters in a controlled manner. It gives the
1324 programmer the flexibility of echoing characters at any
1325 place in the window without updating current (y,x)
1332 <h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4.
1335 <p>This is my favorite initialization function. It enables
1336 the reading of function keys like F1, F2, arrow keys etc.
1337 Almost every interactive program enables this, as arrow
1338 keys are a major part of any User Interface. Do <tt class=
1339 "LITERAL">keypad(stdscr, TRUE)</tt> to enable this feature
1340 for the regular screen (stdscr). You will learn more about
1341 key management in later sections of this document.</p>
1347 <h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5.
1348 halfdelay()</a></h3>
1350 <p>This function, though not used very often, is a useful
1351 one at times. halfdelay()is called to enable the half-delay
1352 mode, which is similar to the cbreak() mode in that
1353 characters typed are immediately available to program.
1354 However, it waits for 'X' tenths of a second for input and
1355 then returns ERR, if no input is available. 'X' is the
1356 timeout value passed to the function halfdelay(). This
1357 function is useful when you want to ask the user for input,
1358 and if he doesn't respond with in certain time, we can do
1359 some thing else. One possible example is a timeout at the
1360 password prompt.</p>
1366 <h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6.
1367 Miscellaneous Initialization functions</a></h3>
1369 <p>There are few more functions which are called at
1370 initialization to customize curses behavior. They are not
1371 used as extensively as those mentioned above. Some of them
1372 are explained where appropriate.</p>
1378 <h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An
1381 <p>Let's write a program which will clarify the usage of
1382 these functions.</p>
1384 <div class="EXAMPLE">
1385 <a name="BINFU" id="BINFU"></a>
1386 <p><b>Example 2. Initialization Function Usage
1390 <pre class="PROGRAMLISTING">
1391 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
1396 initscr(); /* Start curses mode */
1397 raw(); /* Line buffering disabled */
1398 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
1399 noecho(); /* Don't echo() while we do getch */
1401 printw("Type any character to see it in bold\n");
1402 ch = getch(); /* If raw() hadn't been called
1403 * we have to press enter before it
1404 * gets to the program */
1405 if(ch == KEY_F(1)) /* Without keypad enabled this will */
1406 printw("F1 Key pressed");/* not get to us either */
1407 /* Without noecho() some ugly escape
1408 * charachters might have been printed
1411 { printw("The pressed key is ");
1416 refresh(); /* Print it on to the real screen */
1417 getch(); /* Wait for user input */
1418 endwin(); /* End curses mode */
1425 <p>This program is self-explanatory. But I used functions
1426 which aren't explained yet. The function <tt class=
1427 "LITERAL">getch()</tt> is used to get a character from
1428 user. It is equivalent to normal <tt class=
1429 "LITERAL">getchar()</tt> except that we can disable the
1430 line buffering to avoid <enter> after input. Look for
1431 more about <tt class="LITERAL">getch()</tt>and reading keys
1432 in the <a href="#KEYS">key management section</a> . The
1433 functions attron and attroff are used to switch some
1434 attributes on and off respectively. In the example I used
1435 them to print the character in bold. These functions are
1436 explained in detail later.</p>
1443 <h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5.
1444 A Word about Windows</a></h2>
1446 <p>Before we plunge into the myriad ncurses functions, let me
1447 clear few things about windows. Windows are explained in
1448 detail in following <a href="#WINDOWS">sections</a></p>
1450 <p>A Window is an imaginary screen defined by curses system.
1451 A window does not mean a bordered window which you usually
1452 see on Win9X platforms. When curses is initialized, it
1453 creates a default window named <tt class=
1454 "LITERAL">stdscr</tt> which represents your 80x25 (or the
1455 size of window in which you are running) screen. If you are
1456 doing simple tasks like printing few strings, reading input
1457 etc., you can safely use this single window for all of your
1458 purposes. You can also create windows and call functions
1459 which explicitly work on the specified window.</p>
1461 <p>For example, if you call</p>
1463 <pre class="PROGRAMLISTING">
1464 printw("Hi There !!!");
1467 <p>It prints the string on stdscr at the present cursor
1468 position. Similarly the call to refresh(), works on stdscr
1471 <p>Say you have created <a href="#WINDOWS">windows</a> then
1472 you have to call a function with a 'w' added to the usual
1475 <pre class="PROGRAMLISTING">
1476 wprintw(win, "Hi There !!!");
1479 <p>As you will see in the rest of the document, naming of
1480 functions follow the same convention. For each function there
1481 usually are three more functions.</p>
1483 <pre class="PROGRAMLISTING">
1484 printw(string); /* Print on stdscr at present cursor position */
1485 mvprintw(y, x, string);/* Move to (y, x) then print string */
1486 wprintw(win, string); /* Print on window win at present cursor position */
1488 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */
1489 /* co-ordinates and then print */
1491 <p>Usually the w-less functions are macros which expand to
1492 corresponding w-function with stdscr as the window
1499 <h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
1502 <p>I guess you can't wait any more to see some action. Back
1503 to our odyssey of curses functions. Now that curses is
1504 initialized, let's interact with world.</p>
1506 <p>There are three classes of functions which you can use to
1507 do output on screen.</p>
1511 <p>addch() class: Print single character with
1516 <p>printw() class: Print formatted output similar to
1521 <p>addstr() class: Print strings</p>
1525 <p>These functions can be used interchangeably and it is a
1526 matter of style as to which class is used. Let's see each one
1532 <h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1.
1533 addch() class of functions</a></h3>
1535 <p>These functions put a single character into the current
1536 cursor location and advance the position of the cursor. You
1537 can give the character to be printed but they usually are
1538 used to print a character with some attributes. Attributes
1539 are explained in detail in later <a href=
1540 "#ATTRIB">sections</a> of the document. If a character is
1541 associated with an attribute(bold, reverse video etc.),
1542 when curses prints the character, it is printed in that
1545 <p>In order to combine a character with some attributes,
1546 you have two options:</p>
1550 <p>By OR'ing a single character with the desired
1551 attribute macros. These attribute macros could be found
1552 in the header file <tt class="LITERAL">ncurses.h</tt>.
1553 For example, you want to print a character ch(of type
1554 char) bold and underlined, you would call addch() as
1557 <pre class="PROGRAMLISTING">
1558 addch(ch | A_BOLD | A_UNDERLINE);
1563 <p>By using functions like <tt class=
1564 "LITERAL">attrset(),attron(),attroff()</tt>. These
1565 functions are explained in the <a href=
1566 "#ATTRIB">Attributes</a> section. Briefly, they
1567 manipulate the current attributes of the given window.
1568 Once set, the character printed in the window are
1569 associated with the attributes until it is turned
1574 <p>Additionally, <tt class="LITERAL">curses</tt> provides
1575 some special characters for character-based graphics. You
1576 can draw tables, horizontal or vertical lines, etc. You can
1577 find all avaliable characters in the header file <tt class=
1578 "LITERAL">ncurses.h</tt>. Try looking for macros beginning
1579 with <tt class="LITERAL">ACS_</tt> in this file.</p>
1585 <h3 class="SECT2"><a name="AEN298" id="AEN298">6.2.
1586 mvaddch(), waddch() and mvwaddch()</a></h3>
1588 <p><tt class="LITERAL">mvaddch()</tt> is used to move the
1589 cursor to a given point, and then print. Thus, the
1592 <pre class="PROGRAMLISTING">
1593 move(row,col); /* moves the cursor to row<span class=
1594 "emphasis"><i class=
1595 "EMPHASIS">th</i></span> row and col<span class="emphasis"><i class="EMPHASIS">th</i></span> column */
1597 </pre>can be replaced by
1599 <pre class="PROGRAMLISTING">
1600 mvaddch(row,col,ch);
1602 <p><tt class="LITERAL">waddch()</tt> is similar to
1603 <tt class="LITERAL">addch()</tt>, except that it adds a
1604 character into the given window. (Note that <tt class=
1605 "LITERAL">addch()</tt> adds a character into the window
1606 <tt class="LITERAL">stdscr</tt>.)</p>
1608 <p>In a similar fashion <tt class="LITERAL">mvwaddch()</tt>
1609 function is used to add a character into the given window
1610 at the given coordinates.</p>
1612 <p>Now, we are familiar with the basic output function
1613 <tt class="LITERAL">addch()</tt>. But, if we want to print
1614 a string, it would be very annoying to print it character
1615 by character. Fortunately, <tt class="LITERAL">ncurses</tt>
1616 provides <tt class="LITERAL">printf</tt><span class=
1617 "emphasis"><i class="EMPHASIS">-like</i></span> or
1618 <tt class="LITERAL">puts</tt><span class=
1619 "emphasis"><i class="EMPHASIS">-like</i></span>
1626 <h3 class="SECT2"><a name="PRINTWCLASS" id=
1627 "PRINTWCLASS">6.3. printw() class of functions</a></h3>
1629 <p>These functions are similar to <tt class=
1630 "LITERAL">printf()</tt> with the added capability of
1631 printing at any position on the screen.</p>
1636 <h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
1637 "PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
1639 <p>These two functions work much like <tt class=
1640 "LITERAL">printf()</tt>. <tt class=
1641 "LITERAL">mvprintw()</tt> can be used to move the cursor
1642 to a position and then print. If you want to move the
1643 cursor first and then print using <tt class=
1644 "LITERAL">printw()</tt> function, use <tt class=
1645 "LITERAL">move()</tt> first and then use <tt class=
1646 "LITERAL">printw()</tt> though I see no point why one
1647 should avoid using <tt class="LITERAL">mvprintw()</tt>,
1648 you have the flexibility to manipulate.</p>
1654 <h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
1655 "WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4>
1657 <p>These two functions are similar to above two except
1658 that they print in the corresponding window given as
1665 <h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
1666 vw_printw()</a></h4>
1668 <p>This function is similar to <tt class=
1669 "LITERAL">vprintf()</tt>. This can be used when variable
1670 number of arguments are to be printed.</p>
1676 <h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
1677 "SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
1679 <div class="EXAMPLE">
1680 <a name="BPREX" id="BPREX"></a>
1681 <p><b>Example 3. A Simple printw example</b>
1684 <pre class="PROGRAMLISTING">
1686 "INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1687 #include <string.h>
1691 char mesg[]="Just a string"; /* message to be appeared on the screen */
1692 int row,col; /* to store the number of rows and *
1693 * the number of colums of the screen */
1694 initscr(); /* start the curses mode */
1695 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1696 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1697 /* print the message at the center of the screen */
1698 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
1699 printw("Try resizing your window(if possible) and then run this program again");
1709 <p>Above program demonstrates how easy it is to use
1710 <tt class="LITERAL">printw</tt>. You just feed the
1711 coordinates and the message to be appeared on the screen,
1712 then it does what you want.</p>
1714 <p>The above program introduces us to a new function
1715 <tt class="LITERAL">getmaxyx()</tt>, a macro defined in
1716 <tt class="LITERAL">ncurses.h</tt>. It gives the number
1717 of columns and the number of rows in a given window.
1718 <tt class="LITERAL">getmaxyx()</tt> does this by updating
1719 the variables given to it. Since <tt class=
1720 "LITERAL">getmaxyx()</tt> is not a function we don't pass
1721 pointers to it, we just give two integer variables.</p>
1728 <h3 class="SECT2"><a name="ADDSTRCLASS" id=
1729 "ADDSTRCLASS">6.4. addstr() class of functions</a></h3>
1731 <p><tt class="LITERAL">addstr()</tt> is used to put a
1732 character string into a given window. This function is
1733 similar to calling <tt class="LITERAL">addch()</tt> once
1734 for each character in a given string. This is true for all
1735 output functions. There are other functions from this
1736 family such as <tt class=
1737 "LITERAL">mvaddstr(),mvwaddstr()</tt> and <tt class=
1738 "LITERAL">waddstr()</tt>, which obey the naming convention
1739 of curses.(e.g. mvaddstr() is similar to the respective
1740 calls move() and then addstr().) Another function of this
1741 family is addnstr(), which takes an integer parameter(say
1742 n) additionally. This function puts at most n characters
1743 into the screen. If n is negative, then the entire string
1750 <h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A
1751 word of caution</a></h3>
1753 <p>All these functions take y co-ordinate first and then x
1754 in their arguments. A common mistake by beginners is to
1755 pass x,y in that order. If you are doing too many
1756 manipulations of (y,x) co-ordinates, think of dividing the
1757 screen into windows and manipulate each one separately.
1758 Windows are explained in the <a href="#WINDOWS">windows</a>
1766 <h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
1769 <p>Well, printing without taking input, is boring. Let's see
1770 functions which allow us to get input from user. These
1771 functions also can be divided into three categories.</p>
1775 <p>getch() class: Get a character</p>
1779 <p>scanw() class: Get formatted input</p>
1783 <p>getstr() class: Get strings</p>
1790 <h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1.
1791 getch() class of functions</a></h3>
1793 <p>These functions read a single character from the
1794 terminal. But there are several subtle facts to consider.
1795 For example if you don't use the function cbreak(), curses
1796 will not read your input characters contiguously but will
1797 begin read them only after a new line or an EOF is
1798 encountered. In order to avoid this, the cbreak() function
1799 must used so that characters are immediately available to
1800 your program. Another widely used function is noecho(). As
1801 the name suggests, when this function is set (used), the
1802 characters that are keyed in by the user will not show up
1803 on the screen. The two functions cbreak() and noecho() are
1804 typical examples of key management. Functions of this genre
1805 are explained in the <a href="#KEYS">key management
1812 <h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2.
1813 scanw() class of functions</a></h3>
1815 <p>These functions are similar to <tt class=
1816 "LITERAL">scanf()</tt> with the added capability of getting
1817 the input from any location on the screen.</p>
1822 <h4 class="SECT3"><a name="SCANWMVSCANW" id=
1823 "SCANWMVSCANW">7.2.1. scanw() and mvscanw</a></h4>
1825 <p>The usage of these functions is similar to that of
1826 <tt class="LITERAL">sscanf()</tt>, where the line to be
1827 scanned is provided by <tt class="LITERAL">wgetstr()</tt>
1828 function. That is, these functions call to <tt class=
1829 "LITERAL">wgetstr()</tt> function(explained below) and
1830 uses the resulting line for a scan.</p>
1836 <h4 class="SECT3"><a name="WSCANWMVWSCANW" id=
1837 "WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4>
1839 <p>These are similar to above two functions except that
1840 they read from a window, which is supplied as one of the
1841 arguments to these functions.</p>
1847 <h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3.
1850 <p>This function is similar to <tt class=
1851 "LITERAL">vscanf()</tt>. This can be used when a variable
1852 number of arguments are to be scanned.</p>
1859 <h3 class="SECT2"><a name="GETSTRCLASS" id=
1860 "GETSTRCLASS">7.3. getstr() class of functions</a></h3>
1862 <p>These functions are used to get strings from the
1863 terminal. In essence, this function performs the same task
1864 as would be achieved by a series of calls to <tt class=
1865 "LITERAL">getch()</tt> until a newline, carriage return, or
1866 end-of-file is received. The resulting string of characters
1867 are pointed to by <tt class="LITERAL">str</tt>, which is a
1868 character pointer provided by the user.</p>
1874 <h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4.
1875 Some examples</a></h3>
1877 <div class="EXAMPLE">
1878 <a name="BSCEX" id="BSCEX"></a>
1879 <p><b>Example 4. A Simple scanw example</b>
1882 <pre class="PROGRAMLISTING">
1884 "INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1885 #include <string.h>
1889 char mesg[]="Enter a string: "; /* message to be appeared on the screen */
1891 int row,col; /* to store the number of rows and *
1892 * the number of colums of the screen */
1893 initscr(); /* start the curses mode */
1894 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1895 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1896 /* print the message at the center of the screen */
1898 mvprintw(LINES - 2, 0, "You Entered: %s", str);
1912 <h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8.
1915 <p>We have seen an example of how attributes can be used to
1916 print characters with some special effects. Attributes, when
1917 set prudently, can present information in an easy,
1918 understandable manner. The following program takes a C file
1919 as input and prints the file with comments in bold. Scan
1920 through the code.</p>
1922 <div class="EXAMPLE">
1923 <a name="BSIAT" id="BSIAT"></a>
1924 <p><b>Example 5. A Simple Attributes example</b>
1927 <pre class="PROGRAMLISTING">
1929 "INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */
1930 #include <ncurses.h>
1931 #include <stdlib.h>
1933 int main(int argc, char *argv[])
1935 int ch, prev, row, col;
1942 printf("Usage: %s <a c file name>\n", argv[0]);
1945 fp = fopen(argv[1], "r");
1948 perror("Cannot open input file");
1951 initscr(); /* Start curses mode */
1952 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */
1953 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */
1955 getyx(stdscr, y, x); /* get the current curser position */
1956 if(y == (row - 1)) /* are we are at the end of the screen */
1958 printw("<-Press Any Key->"); /* tell the user to press a key */
1960 clear(); /* clear the screen */
1961 move(0, 0); /* start at the beginning of the screen */
1963 if(prev == '/' && ch == '*') /* If it is / and * then only
1966 attron(A_BOLD); /* cut bold on */
1967 getyx(stdscr, y, x); /* get the current curser position */
1968 move(y, x - 1); /* back up one space */
1969 printw("%c%c", '/', ch); /* The actual printing is done here */
1974 if(prev == '*' && ch == '/')
1975 attroff(A_BOLD); /* Switch it off once we got *
1979 endwin(); /* End curses mode */
1986 <p>Don't worry about all those initialization and other crap.
1987 Concentrate on the while loop. It reads each character in the
1988 file and searches for the pattern /*. Once it spots the
1989 pattern, it switches the BOLD attribute on with <tt class=
1990 "LITERAL">attron()</tt> . When we get the pattern */ it is
1991 switched off by <tt class="LITERAL">attroff()</tt> .</p>
1993 <p>The above program also introduces us to two useful
1994 functions <tt class="LITERAL">getyx()</tt> and <tt class=
1995 "LITERAL">move()</tt>. The first function gets the
1996 co-ordinates of the present cursor into the variables y, x.
1997 Since getyx() is a macro we don't have to pass pointers to
1998 variables. The function <tt class="LITERAL">move()</tt> moves
1999 the cursor to the co-ordinates given to it.</p>
2001 <p>The above program is really a simple one which doesn't do
2002 much. On these lines one could write a more useful program
2003 which reads a C file, parses it and prints it in different
2004 colors. One could even extend it to other languages as
2010 <h3 class="SECT2"><a name="ATTRIBDETAILS" id=
2011 "ATTRIBDETAILS">8.1. The details</a></h3>
2013 <p>Let's get into more details of attributes. The functions
2014 <tt class="LITERAL">attron(), attroff(), attrset()</tt> ,
2015 and their sister functions <tt class=
2016 "LITERAL">attr_get()</tt> etc.. can be used to switch
2017 attributes on/off , get attributes and produce a colorful
2020 <p>The functions attron and attroff take a bit-mask of
2021 attributes and switch them on or off, respectively. The
2022 following video attributes, which are defined in
2023 <curses.h> can be passed to these functions.</p>
2025 <pre class="PROGRAMLISTING">
2027 A_NORMAL Normal display (no highlight)
2028 A_STANDOUT Best highlighting mode of the terminal.
2029 A_UNDERLINE Underlining
2030 A_REVERSE Reverse video
2033 A_BOLD Extra bright or bold
2034 A_PROTECT Protected mode
2035 A_INVIS Invisible or blank mode
2036 A_ALTCHARSET Alternate character set
2037 A_CHARTEXT Bit-mask to extract a character
2038 COLOR_PAIR(n) Color-pair number n
2041 <p>The last one is the most colorful one :-) Colors are
2042 explained in the <a href="#color" target="_top">next
2045 <p>We can OR(|) any number of above attributes to get a
2046 combined effect. If you wanted reverse video with blinking
2047 characters you can use</p>
2049 <pre class="PROGRAMLISTING">
2050 attron(A_REVERSE | A_BLINK);
2057 <h3 class="SECT2"><a name="ATTRONVSATTRSET" id=
2058 "ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3>
2060 <p>Then what is the difference between attron() and
2061 attrset()? attrset sets the attributes of window whereas
2062 attron just switches on the attribute given to it. So
2063 attrset() fully overrides whatever attributes the window
2064 previously had and sets it to the new attribute(s).
2065 Similarly attroff() just switches off the attribute(s)
2066 given to it as an argument. This gives us the flexibility
2067 of managing attributes easily.But if you use them
2068 carelessly you may loose track of what attributes the
2069 window has and garble the display. This is especially true
2070 while managing menus with colors and highlighting. So
2071 decide on a consistent policy and stick to it. You can
2072 always use <tt class="LITERAL">standend()</tt> which is
2073 equivalent to <tt class="LITERAL">attrset(A_NORMAL)</tt>
2074 which turns off all attributes and brings you to normal
2081 <h3 class="SECT2"><a name="ATTRGET" id="ATTRGET">8.3.
2084 <p>The function attr_get() gets the current attributes and
2085 color pair of the window. Though we might not use this as
2086 often as the above functions, this is useful in scanning
2087 areas of screen. Say we wanted to do some complex update on
2088 screen and we are not sure what attribute each character is
2089 associated with. Then this function can be used with either
2090 attrset or attron to produce the desired effect.</p>
2096 <h3 class="SECT2"><a name="ATTRFUNCS" id="ATTRFUNCS">8.4.
2097 attr_ functions</a></h3>
2099 <p>There are series of functions like attr_set(), attr_on
2100 etc.. These are similar to above functions except that they
2101 take parameters of type <tt class=
2102 "LITERAL">attr_t</tt>.</p>
2108 <h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5.
2109 wattr functions</a></h3>
2111 <p>For each of the above functions we have a corresponding
2112 function with 'w' which operates on a particular window.
2113 The above functions operate on stdscr.</p>
2119 <h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat()
2122 <p>The function chgat() is listed in the end of the man
2123 page curs_attr. It actually is a useful one. This function
2124 can be used to set attributes for a group of characters
2125 without moving. I mean it !!! without moving the cursor :-)
2126 It changes the attributes of a given number of characters
2127 starting at the current cursor location.</p>
2129 <p>We can give -1 as the character count to update till end
2130 of line. If you want to change attributes of characters
2131 from current position to end of line, just use this.</p>
2133 <pre class="PROGRAMLISTING">
2134 chgat(-1, A_REVERSE, 0, NULL);
2136 <p>This function is useful when changing attributes for
2137 characters that are already on the screen. Move to the
2138 character from which you want to change and change the
2141 <p>Other functions wchgat(), mvchgat(), wchgat() behave
2142 similarly except that the w functions operate on the
2143 particular window. The mv functions first move the cursor
2144 then perform the work given to them. Actually chgat is a
2145 macro which is replaced by a wchgat() with stdscr as the
2146 window. Most of the "w-less" functions are macros.</p>
2148 <div class="EXAMPLE">
2149 <a name="BWICH" id="BWICH"></a>
2150 <p><b>Example 6. Chgat() Usage example</b>
2153 <pre class="PROGRAMLISTING">
2154 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2156 int main(int argc, char *argv[])
2157 { initscr(); /* Start curses mode */
2158 start_color(); /* Start color functionality */
2160 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2161 printw("A Big string which i didn't care to type fully ");
2162 mvchgat(0, 0, -1, A_BLINK, 1, NULL);
2164 * First two parameters specify the position at which to start
2165 * Third parameter number of characters to update. -1 means till
2167 * Forth parameter is the normal attribute you wanted to give
2169 * Fifth is the color index. It is the index given during init_pair()
2170 * use 0 if you didn't want color
2171 * Sixth one is always NULL
2175 endwin(); /* End curses mode */
2181 <p>This example also introduces us to the color world of
2182 curses. Colors will be explained in detail later. Use 0 for
2190 <h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9.
2193 <p>Windows form the most important concept in curses. You
2194 have seen the standard window stdscr above where all the
2195 functions implicitly operated on this window. Now to make
2196 design even a simplest GUI, you need to resort to windows.
2197 The main reason you may want to use windows is to manipulate
2198 parts of the screen separately, for better efficiency, by
2199 updating only the windows that need to be changed and for a
2200 better design. I would say the last reason is the most
2201 important in going for windows. You should always strive for
2202 a better and easy-to-manage design in your programs. If you
2203 are writing big, complex GUIs this is of pivotal importance
2204 before you start doing anything.</p>
2209 <h3 class="SECT2"><a name="WINDOWBASICS" id=
2210 "WINDOWBASICS">9.1. The basics</a></h3>
2212 <p>A Window can be created by calling the function
2213 <tt class="LITERAL">newwin()</tt>. It doesn't create any
2214 thing on the screen actually. It allocates memory for a
2215 structure to manipulate the window and updates the
2216 structure with data regarding the window such as its size,
2217 beginy, beginx etc. Hence in curses, a window is just an
2218 abstraction of an imaginary window, which can be
2219 manipulated independent of other parts of screen. The
2220 function newwin() returns a pointer to structure WINDOW,
2221 which can be passed to window related functions like
2222 wprintw() etc.. Finally the window can be destroyed with
2223 delwin(). It will deallocate the memory associated with the
2224 window structure.</p>
2230 <h3 class="SECT2"><a name="LETBEWINDOW" id=
2231 "LETBEWINDOW">9.2. Let there be a Window !!!</a></h3>
2233 <p>What fun is it, if a window is created and we can't see
2234 it. So the fun part begins by displaying the window. The
2235 function <tt class="LITERAL">box()</tt> can be used to draw
2236 a border around the window. Let's explore these functions
2237 in more detail in this example.</p>
2239 <div class="EXAMPLE">
2240 <a name="BWIBO" id="BWIBO"></a>
2241 <p><b>Example 7. Window Border example</b>
2244 <pre class="PROGRAMLISTING">
2245 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2247 WINDOW *create_newwin(int height, int width, int starty, int startx);
2248 void destroy_win(WINDOW *local_win);
2250 int main(int argc, char *argv[])
2252 int startx, starty, width, height;
2255 initscr(); /* Start curses mode */
2256 cbreak(); /* Line buffering disabled, Pass on
2257 * everty thing to me */
2258 keypad(stdscr, TRUE); /* I need that nifty F1 */
2262 starty = (LINES - height) / 2; /* Calculating for a center placement */
2263 startx = (COLS - width) / 2; /* of the window */
2264 printw("Press F1 to exit");
2266 my_win = create_newwin(height, width, starty, startx);
2268 while((ch = getch()) != KEY_F(1))
2271 destroy_win(my_win);
2272 my_win = create_newwin(height, width, starty,--startx);
2275 destroy_win(my_win);
2276 my_win = create_newwin(height, width, starty,++startx);
2279 destroy_win(my_win);
2280 my_win = create_newwin(height, width, --starty,startx);
2283 destroy_win(my_win);
2284 my_win = create_newwin(height, width, ++starty,startx);
2289 endwin(); /* End curses mode */
2293 WINDOW *create_newwin(int height, int width, int starty, int startx)
2294 { WINDOW *local_win;
2296 local_win = newwin(height, width, starty, startx);
2297 box(local_win, 0 , 0); /* 0, 0 gives default characters
2298 * for the vertical and horizontal
2300 wrefresh(local_win); /* Show that box */
2305 void destroy_win(WINDOW *local_win)
2307 /* box(local_win, ' ', ' '); : This won't produce the desired
2308 * result of erasing the window. It will leave its four corners
2309 * and so an ugly remnant of window.
2311 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' ');
2312 /* The parameters taken are
2313 * 1. win: the window on which to operate
2314 * 2. ls: character to be used for the left side of the window
2315 * 3. rs: character to be used for the right side of the window
2316 * 4. ts: character to be used for the top side of the window
2317 * 5. bs: character to be used for the bottom side of the window
2318 * 6. tl: character to be used for the top left corner of the window
2319 * 7. tr: character to be used for the top right corner of the window
2320 * 8. bl: character to be used for the bottom left corner of the window
2321 * 9. br: character to be used for the bottom right corner of the window
2323 wrefresh(local_win);
2333 <h3 class="SECT2"><a name="BORDEREXEXPL" id=
2334 "BORDEREXEXPL">9.3. Explanation</a></h3>
2336 <p>Don't scream. I know it is a big example. But I have to
2337 explain some important things here :-). This program
2338 creates a rectangular window that can be moved with left,
2339 right, up, down arrow keys. It repeatedly creates and
2340 destroys windows as user press a key. Don't go beyond the
2341 screen limits. Checking for those limits is left as an
2342 exercise for the reader. Let's dissect it by line by
2345 <p>The <tt class="LITERAL">create_newwin()</tt> function
2346 creates a window with <tt class="LITERAL">newwin()</tt> and
2347 displays a border around it with box. The function
2348 <tt class="LITERAL">destroy_win()</tt> first erases the
2349 window from screen by painting a border with ' ' character
2350 and then calling <tt class="LITERAL">delwin()</tt> to
2351 deallocate memory related to it. Depending on the key the
2352 user presses, starty or startx is changed and a new window
2355 <p>In the destroy_win, as you can see, I used wborder
2356 instead of box. The reason is written in the comments (You
2357 missed it. I know. Read the code :-)). wborder draws a
2358 border around the window with the characters given to it as
2359 the 4 corner points and the 4 lines. To put it clearly, if
2360 you have called wborder as below:</p>
2362 <pre class="PROGRAMLISTING">
2363 wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');
2365 <p>it produces some thing like</p>
2367 <pre class="PROGRAMLISTING">
2382 <h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4.
2383 The other stuff in the example</a></h3>
2385 <p>You can also see in the above examples, that I have used
2386 the variables COLS, LINES which are initialized to the
2387 screen sizes after initscr(). They can be useful in finding
2388 screen dimensions and finding the center co-ordinate of the
2389 screen as above. The function <tt class=
2390 "LITERAL">getch()</tt> as usual gets the key from keyboard
2391 and according to the key it does the corresponding work.
2392 This type of switch- case is very common in any GUI based
2399 <h3 class="SECT2"><a name="OTHERBORDERFUNCS" id=
2400 "OTHERBORDERFUNCS">9.5. Other Border functions</a></h3>
2402 <p>Above program is grossly inefficient in that with each
2403 press of a key, a window is destroyed and another is
2404 created. So let's write a more efficient program which uses
2405 other border related functions.</p>
2407 <p>The following program uses <tt class=
2408 "LITERAL">mvhline()</tt> and <tt class=
2409 "LITERAL">mvvline()</tt> to achieve similar effect. These
2410 two functions are simple. They create a horizontal or
2411 vertical line of the specified length at the specified
2414 <div class="EXAMPLE">
2415 <a name="BOTBO" id="BOTBO"></a>
2416 <p><b>Example 8. More border functions</b>
2419 <pre class="PROGRAMLISTING">
2420 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2422 typedef struct _win_border_struct {
2423 chtype ls, rs, ts, bs,
2427 typedef struct _WIN_struct {
2434 void init_win_params(WIN *p_win);
2435 void print_win_params(WIN *p_win);
2436 void create_box(WIN *win, bool flag);
2438 int main(int argc, char *argv[])
2442 initscr(); /* Start curses mode */
2443 start_color(); /* Start the color functionality */
2444 cbreak(); /* Line buffering disabled, Pass on
2445 * everty thing to me */
2446 keypad(stdscr, TRUE); /* I need that nifty F1 */
2448 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2450 /* Initialize the window parameters */
2451 init_win_params(&win);
2452 print_win_params(&win);
2454 attron(COLOR_PAIR(1));
2455 printw("Press F1 to exit");
2457 attroff(COLOR_PAIR(1));
2459 create_box(&win, TRUE);
2460 while((ch = getch()) != KEY_F(1))
2463 create_box(&win, FALSE);
2465 create_box(&win, TRUE);
2468 create_box(&win, FALSE);
2470 create_box(&win, TRUE);
2473 create_box(&win, FALSE);
2475 create_box(&win, TRUE);
2478 create_box(&win, FALSE);
2480 create_box(&win, TRUE);
2484 endwin(); /* End curses mode */
2487 void init_win_params(WIN *p_win)
2489 p_win->height = 3;
2490 p_win->width = 10;
2491 p_win->starty = (LINES - p_win->height)/2;
2492 p_win->startx = (COLS - p_win->width)/2;
2494 p_win->border.ls = '|';
2495 p_win->border.rs = '|';
2496 p_win->border.ts = '-';
2497 p_win->border.bs = '-';
2498 p_win->border.tl = '+';
2499 p_win->border.tr = '+';
2500 p_win->border.bl = '+';
2501 p_win->border.br = '+';
2504 void print_win_params(WIN *p_win)
2507 mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty,
2508 p_win->width, p_win->height);
2512 void create_box(WIN *p_win, bool flag)
2516 x = p_win->startx;
2517 y = p_win->starty;
2518 w = p_win->width;
2519 h = p_win->height;
2522 { mvaddch(y, x, p_win->border.tl);
2523 mvaddch(y, x + w, p_win->border.tr);
2524 mvaddch(y + h, x, p_win->border.bl);
2525 mvaddch(y + h, x + w, p_win->border.br);
2526 mvhline(y, x + 1, p_win->border.ts, w - 1);
2527 mvhline(y + h, x + 1, p_win->border.bs, w - 1);
2528 mvvline(y + 1, x, p_win->border.ls, h - 1);
2529 mvvline(y + 1, x + w, p_win->border.rs, h - 1);
2533 for(j = y; j <= y + h; ++j)
2534 for(i = x; i <= x + w; ++i)
2548 <h2 class="SECT1"><a name="COLOR" id="COLOR">10. Colors</a></h2>
2551 <h3 class="SECT2"><a name="COLORBASICS" id=
2552 "COLORBASICS">10.1. The basics</a></h3>
2554 <p>Life seems dull with no colors. Curses has a nice
2555 mechanism to handle colors. Let's get into the thick of the
2556 things with a small program.</p>
2558 <div class="EXAMPLE">
2559 <a name="BSICO" id="BSICO"></a>
2560 <p><b>Example 9. A Simple Color example</b>
2563 <pre class="PROGRAMLISTING">
2564 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2566 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string);
2567 int main(int argc, char *argv[])
2568 { initscr(); /* Start curses mode */
2569 if(has_colors() == FALSE)
2571 printf("Your terminal does not support color\n");
2574 start_color(); /* Start color */
2575 init_pair(1, COLOR_RED, COLOR_BLACK);
2577 attron(COLOR_PAIR(1));
2578 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ...");
2579 attroff(COLOR_PAIR(1));
2583 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string)
2597 length = strlen(string);
2598 temp = (width - length)/ 2;
2599 x = startx + (int)temp;
2600 mvwprintw(win, y, x, "%s", string);
2607 <p>As you can see, to start using color, you should first
2608 call the function <tt class="LITERAL">start_color()</tt>.
2609 After that, you can use color capabilities of your
2610 terminals using various functions. To find out whether a
2611 terminal has color capabilities or not, you can use
2612 <tt class="LITERAL">has_colors()</tt> function, which
2613 returns FALSE if the terminal does not support color.</p>
2615 <p>Curses initializes all the colors supported by terminal
2616 when start_color() is called. These can be accessed by the
2617 define constants like <tt class="LITERAL">COLOR_BLACK</tt>
2618 etc. Now to actually start using colors, you have to define
2619 pairs. Colors are always used in pairs. That means you have
2620 to use the function <tt class="LITERAL">init_pair()</tt> to
2621 define the foreground and background for the pair number
2622 you give. After that that pair number can be used as a
2623 normal attribute with <tt class=
2624 "LITERAL">COLOR_PAIR()</tt>function. This may seem to be
2625 cumbersome at first. But this elegant solution allows us to
2626 manage color pairs very easily. To appreciate it, you have
2627 to look into the the source code of "dialog", a utility for
2628 displaying dialog boxes from shell scripts. The developers
2629 have defined foreground and background combinations for all
2630 the colors they might need and initialized at the
2631 beginning. This makes it very easy to set attributes just
2632 by accessing a pair which we already have defined as a
2635 <p>The following colors are defined in <tt class=
2636 "LITERAL">curses.h</tt>. You can use these as parameters
2637 for various color functions.</p>
2639 <pre class="PROGRAMLISTING">
2654 <h3 class="SECT2"><a name="CHANGECOLORDEFS" id=
2655 "CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3>
2657 <p>The function <tt class="LITERAL">init_color()</tt>can be
2658 used to change the rgb values for the colors defined by
2659 curses initially. Say you wanted to lighten the intensity
2660 of red color by a minuscule. Then you can use this function
2663 <pre class="PROGRAMLISTING">
2664 init_color(COLOR_RED, 700, 0, 0);
2665 /* param 1 : color name
2666 * param 2, 3, 4 : rgb content min = 0, max = 1000 */
2668 <p>If your terminal cannot change the color definitions,
2669 the function returns ERR. The function <tt class=
2670 "LITERAL">can_change_color()</tt> can be used to find out
2671 whether the terminal has the capability of changing color
2672 content or not. The rgb content is scaled from 0 to 1000.
2673 Initially RED color is defined with content 1000(r), 0(g),
2680 <h3 class="SECT2"><a name="COLORCONTENT" id=
2681 "COLORCONTENT">10.3. Color Content</a></h3>
2683 <p>The functions <tt class="LITERAL">color_content()</tt>
2684 and <tt class="LITERAL">pair_content()</tt> can be used to
2685 find the color content and foreground, background
2686 combination for the pair.</p>
2693 <h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing
2694 with the key board</a></h2>
2697 <h3 class="SECT2"><a name="KEYSBASICS" id=
2698 "KEYSBASICS">11.1. The Basics</a></h3>
2700 <p>No GUI is complete without a strong user interface and
2701 to interact with the user, a curses program should be
2702 sensitive to key presses or the mouse actions done by the
2703 user. Let's deal with the keys first.</p>
2705 <p>As you have seen in almost all of the above examples, it
2706 is very easy to get key input from the user. A simple way
2707 of getting key presses is to use <tt class=
2708 "LITERAL">getch()</tt> function. The cbreak mode should be
2709 enabled to read keys when you are interested in reading
2710 individual key hits rather than complete lines of text
2711 (which usually end with a carriage return). keypad should
2712 be enabled to get the Functions keys, arrow keys etc. See
2713 the initialization section for details.</p>
2715 <p><tt class="LITERAL">getch()</tt> returns an integer
2716 corresponding to the key pressed. If it is a normal
2717 character, the integer value will be equivalent to the
2718 character. Otherwise it returns a number which can be
2719 matched with the constants defined in <tt class=
2720 "LITERAL">curses.h</tt>. For example if the user presses
2721 F1, the integer returned is 265. This can be checked using
2722 the macro KEY_F() defined in curses.h. This makes reading
2723 keys portable and easy to manage.</p>
2725 <p>For example, if you call getch() like this</p>
2727 <pre class="PROGRAMLISTING">
2732 <p>getch() will wait for the user to press a key, (unless
2733 you specified a timeout) and when user presses a key, the
2734 corresponding integer is returned. Then you can check the
2735 value returned with the constants defined in curses.h to
2736 match against the keys you want.</p>
2738 <p>The following code piece will do that job.</p>
2740 <pre class="PROGRAMLISTING">
2742 printw("Left arrow is pressed\n");
2744 <p>Let's write a small program which creates a menu which
2745 can be navigated by up and down arrows.</p>
2751 <h3 class="SECT2"><a name="SIMPLEKEYEX" id=
2752 "SIMPLEKEYEX">11.2. A Simple Key Usage example</a></h3>
2754 <div class="EXAMPLE">
2755 <a name="BSIKE" id="BSIKE"></a>
2756 <p><b>Example 10. A Simple Key Usage example</b>
2759 <pre class="PROGRAMLISTING">
2760 <span class="INLINEMEDIAOBJECT">#include <stdio.h>
2761 #include <ncurses.h>
2776 int n_choices = sizeof(choices) / sizeof(char *);
2777 void print_menu(WINDOW *menu_win, int highlight);
2788 cbreak(); /* Line buffering disabled. pass on everything */
2789 startx = (80 - WIDTH) / 2;
2790 starty = (24 - HEIGHT) / 2;
2792 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2793 keypad(menu_win, TRUE);
2794 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice");
2796 print_menu(menu_win, highlight);
2798 { c = wgetch(menu_win);
2802 highlight = n_choices;
2807 if(highlight == n_choices)
2816 mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c);
2820 print_menu(menu_win, highlight);
2821 if(choice != 0) /* User did a choice come out of the infinite loop */
2824 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]);
2831 void print_menu(WINDOW *menu_win, int highlight)
2837 box(menu_win, 0, 0);
2838 for(i = 0; i < n_choices; ++i)
2839 { if(highlight == i + 1) /* High light the present choice */
2840 { wattron(menu_win, A_REVERSE);
2841 mvwprintw(menu_win, y, x, "%s", choices[i]);
2842 wattroff(menu_win, A_REVERSE);
2845 mvwprintw(menu_win, y, x, "%s", choices[i]);
2859 <h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing
2860 with the mouse</a></h2>
2862 <p>Now that you have seen how to get keys, lets do the same
2863 thing from mouse. Usually each UI allows the user to interact
2864 with both keyboard and mouse.</p>
2869 <h3 class="SECT2"><a name="MOUSEBASICS" id=
2870 "MOUSEBASICS">12.1. The Basics</a></h3>
2872 <p>Before you do any thing else, the events you want to
2873 receive have to be enabled with <tt class=
2874 "LITERAL">mousemask()</tt>.</p>
2876 <pre class="PROGRAMLISTING">
2877 mousemask( mmask_t newmask, /* The events you want to listen to */
2878 mmask_t *oldmask) /* The old events mask */
2880 <p>The first parameter to above function is a bit mask of
2881 events you would like to listen. By default, all the events
2882 are turned off. The bit mask <tt class=
2883 "LITERAL">ALL_MOUSE_EVENTS</tt> can be used to get all the
2886 <p>The following are all the event masks:</p>
2888 <pre class="PROGRAMLISTING">
2890 ---------------------------------------------------------------------
2891 BUTTON1_PRESSED mouse button 1 down
2892 BUTTON1_RELEASED mouse button 1 up
2893 BUTTON1_CLICKED mouse button 1 clicked
2894 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
2895 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
2896 BUTTON2_PRESSED mouse button 2 down
2897 BUTTON2_RELEASED mouse button 2 up
2898 BUTTON2_CLICKED mouse button 2 clicked
2899 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
2900 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
2901 BUTTON3_PRESSED mouse button 3 down
2902 BUTTON3_RELEASED mouse button 3 up
2903 BUTTON3_CLICKED mouse button 3 clicked
2904 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
2905 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
2906 BUTTON4_PRESSED mouse button 4 down
2907 BUTTON4_RELEASED mouse button 4 up
2908 BUTTON4_CLICKED mouse button 4 clicked
2909 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
2910 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
2911 BUTTON_SHIFT shift was down during button state change
2912 BUTTON_CTRL control was down during button state change
2913 BUTTON_ALT alt was down during button state change
2914 ALL_MOUSE_EVENTS report all button state changes
2915 REPORT_MOUSE_POSITION report mouse movement
2922 <h3 class="SECT2"><a name="GETTINGEVENTS" id=
2923 "GETTINGEVENTS">12.2. Getting the events</a></h3>
2925 <p>Once a class of mouse events have been enabled, getch()
2926 class of functions return KEY_MOUSE every time some mouse
2927 event happens. Then the mouse event can be retrieved with
2928 <tt class="LITERAL">getmouse()</tt>.</p>
2930 <p>The code approximately looks like this:</p>
2932 <pre class="PROGRAMLISTING">
2937 if(getmouse(&event) == OK)
2938 . /* Do some thing with the event */
2942 <p>getmouse() returns the event into the pointer given to
2943 it. It is a structure which contains</p>
2945 <pre class="PROGRAMLISTING">
2948 short id; /* ID to distinguish multiple devices */
2949 int x, y, z; /* event coordinates */
2950 mmask_t bstate; /* button state bits */
2953 <p>The <tt class="LITERAL">bstate</tt> is the main variable
2954 we are interested in. It tells the button state of the
2957 <p>Then with a code snippet like the following, we can find
2958 out what happened.</p>
2960 <pre class="PROGRAMLISTING">
2961 if(event.bstate & BUTTON1_PRESSED)
2962 printw("Left Button Pressed");
2969 <h3 class="SECT2"><a name="MOUSETOGETHER" id=
2970 "MOUSETOGETHER">12.3. Putting it all Together</a></h3>
2972 <p>That's pretty much interfacing with mouse. Let's create
2973 the same menu and enable mouse interaction. To make things
2974 simpler, key handling is removed.</p>
2976 <div class="EXAMPLE">
2977 <a name="BMOME" id="BMOME"></a>
2978 <p><b>Example 11. Access the menu with mouse !!!</b>
2981 <pre class="PROGRAMLISTING">
2982 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2990 char *choices[] = { "Choice 1",
2997 int n_choices = sizeof(choices) / sizeof(char *);
2999 void print_menu(WINDOW *menu_win, int highlight);
3000 void report_choice(int mouse_x, int mouse_y, int *p_choice);
3003 { int c, choice = 0;
3007 /* Initialize curses */
3011 cbreak(); //Line buffering disabled. pass on everything
3013 /* Try to put the window in the middle of screen */
3014 startx = (80 - WIDTH) / 2;
3015 starty = (24 - HEIGHT) / 2;
3018 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
3022 /* Print the menu for the first time */
3023 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
3024 print_menu(menu_win, 1);
3025 /* Get all the mouse events */
3026 mousemask(ALL_MOUSE_EVENTS, NULL);
3029 { c = wgetch(menu_win);
3032 if(getmouse(&event) == OK)
3033 { /* When the user clicks left mouse button */
3034 if(event.bstate & BUTTON1_PRESSED)
3035 { report_choice(event.x + 1, event.y + 1, &choice);
3036 if(choice == -1) //Exit chosen
3038 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
3042 print_menu(menu_win, choice);
3051 void print_menu(WINDOW *menu_win, int highlight)
3057 box(menu_win, 0, 0);
3058 for(i = 0; i < n_choices; ++i)
3059 { if(highlight == i + 1)
3060 { wattron(menu_win, A_REVERSE);
3061 mvwprintw(menu_win, y, x, "%s", choices[i]);
3062 wattroff(menu_win, A_REVERSE);
3065 mvwprintw(menu_win, y, x, "%s", choices[i]);
3071 /* Report the choice according to mouse position */
3072 void report_choice(int mouse_x, int mouse_y, int *p_choice)
3078 for(choice = 0; choice < n_choices; ++choice)
3079 if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice]))
3080 { if(choice == n_choices - 1)
3083 *p_choice = choice + 1;
3094 <h3 class="SECT2"><a name="MISCMOUSEFUNCS" id=
3095 "MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3>
3097 <p>The functions mouse_trafo() and wmouse_trafo() can be
3098 used to convert to mouse co-ordinates to screen relative
3099 co-ordinates. See curs_mouse(3X) man page for details.</p>
3101 <p>The mouseinterval function sets the maximum time (in
3102 thousands of a second) that can elapse between press and
3103 release events in order for them to be recognized as a
3104 click. This function returns the previous interval value.
3105 The default is one fifth of a second.</p>
3112 <h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen
3113 Manipulation</a></h2>
3115 <p>In this section, we will look into some functions, which
3116 allow us to manage the screen efficiently and to write some
3117 fancy programs. This is especially important in writing
3123 <h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx()
3126 <p>The function <tt class="LITERAL">getyx()</tt> can be
3127 used to find out the present cursor co-ordinates. It will
3128 fill the values of x and y co-ordinates in the arguments
3129 given to it. Since getyx() is a macro you don't have to
3130 pass the address of the variables. It can be called as</p>
3132 <pre class="PROGRAMLISTING">
3134 /* win: window pointer
3135 * y, x: y, x co-ordinates will be put into this variables
3138 <p>The function getparyx() gets the beginning co-ordinates
3139 of the sub window relative to the main window. This is some
3140 times useful to update a sub window. When designing fancy
3141 stuff like writing multiple menus, it becomes difficult to
3142 store the menu positions, their first option co-ordinates
3143 etc. A simple solution to this problem, is to create menus
3144 in sub windows and later find the starting co-ordinates of
3145 the menus by using getparyx().</p>
3147 <p>The functions getbegyx() and getmaxyx() store current
3148 window's beginning and maximum co-ordinates. These
3149 functions are useful in the same way as above in managing
3150 the windows and sub windows effectively.</p>
3156 <h3 class="SECT2"><a name="SCREENDUMP" id=
3157 "SCREENDUMP">13.2. Screen Dumping</a></h3>
3159 <p>While writing games, some times it becomes necessary to
3160 store the state of the screen and restore it back to the
3161 same state. The function scr_dump() can be used to dump the
3162 screen contents to a file given as an argument. Later it
3163 can be restored by scr_restore function. These two simple
3164 functions can be used effectively to maintain a fast moving
3165 game with changing scenarios.</p>
3171 <h3 class="SECT2"><a name="WINDOWDUMP" id=
3172 "WINDOWDUMP">13.3. Window Dumping</a></h3>
3174 <p>To store and restore windows, the functions <tt class=
3175 "LITERAL">putwin()</tt> and <tt class=
3176 "LITERAL">getwin()</tt> can be used. <tt class=
3177 "LITERAL">putwin()</tt> puts the present window state into
3178 a file, which can be later restored by <tt class=
3179 "LITERAL">getwin()</tt>.</p>
3181 <p>The function <tt class="LITERAL">copywin()</tt> can be
3182 used to copy a window completely onto another window. It
3183 takes the source and destination windows as parameters and
3184 according to the rectangle specified, it copies the
3185 rectangular region from source to destination window. Its
3186 last parameter specifies whether to overwrite or just
3187 overlay the contents on to the destination window. If this
3188 argument is true, then the copying is non-destructive.</p>
3195 <h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous
3198 <p>Now you know enough features to write a good curses
3199 program, with all bells and whistles. There are some
3200 miscellaneous functions which are useful in various cases.
3201 Let's go headlong into some of those.</p>
3206 <h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1.
3209 <p>This function can be used to make the cursor invisible.
3210 The parameter to this function should be</p>
3212 <pre class="PROGRAMLISTING">
3222 <h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2.
3223 Temporarily Leaving Curses mode</a></h3>
3225 <p>Some times you may want to get back to cooked mode
3226 (normal line buffering mode) temporarily. In such a case
3227 you will first need to save the tty modes with a call to
3228 <tt class="LITERAL">def_prog_mode()</tt> and then call
3229 <tt class="LITERAL">endwin()</tt> to end the curses mode.
3230 This will leave you in the original tty mode. To get back
3231 to curses once you are done, call <tt class=
3232 "LITERAL">reset_prog_mode()</tt> . This function returns
3233 the tty to the state stored by <tt class=
3234 "LITERAL">def_prog_mode()</tt>. Then do refresh(), and you
3235 are back to the curses mode. Here is an example showing the
3236 sequence of things to be done.</p>
3238 <div class="EXAMPLE">
3239 <a name="BTELE" id="BTELE"></a>
3240 <p><b>Example 12. Temporarily Leaving Curses Mode</b>
3243 <pre class="PROGRAMLISTING">
3244 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
3248 initscr(); /* Start curses mode */
3249 printw("Hello World !!!\n"); /* Print Hello World */
3250 refresh(); /* Print it on to the real screen */
3251 def_prog_mode(); /* Save the tty modes */
3252 endwin(); /* End curses mode temporarily */
3253 system("/bin/sh"); /* Do whatever you like in cooked mode */
3254 reset_prog_mode(); /* Return to the previous tty mode*/
3255 /* stored by def_prog_mode() */
3256 refresh(); /* Do refresh() to restore the */
3257 /* Screen contents */
3258 printw("Another String\n"); /* Back to curses use the full */
3259 refresh(); /* capabilities of curses */
3260 endwin(); /* End curses mode */
3271 <h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_
3274 <p>If you have ever programmed in DOS, you know about those
3275 nifty characters in extended character set. They are
3276 printable only on some terminals. NCURSES functions like
3277 <tt class="LITERAL">box()</tt> use these characters. All
3278 these variables start with ACS meaning alternative
3279 character set. You might have noticed me using these
3280 characters in some of the programs above. Here's an example
3281 showing all the characters.</p>
3283 <div class="EXAMPLE">
3284 <a name="BACSVARS" id="BACSVARS"></a>
3285 <p><b>Example 13. ACS Variables Example</b>
3288 <pre class="PROGRAMLISTING">
3289 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
3295 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n");
3296 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n");
3297 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n");
3298 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n");
3299 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n");
3300 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n");
3301 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n");
3302 printw("Horizontal line "); addch(ACS_HLINE); printw("\n");
3303 printw("Vertical line "); addch(ACS_VLINE); printw("\n");
3304 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n");
3305 printw("Scan Line 1 "); addch(ACS_S1); printw("\n");
3306 printw("Scan Line 3 "); addch(ACS_S3); printw("\n");
3307 printw("Scan Line 7 "); addch(ACS_S7); printw("\n");
3308 printw("Scan Line 9 "); addch(ACS_S9); printw("\n");
3309 printw("Diamond "); addch(ACS_DIAMOND); printw("\n");
3310 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n");
3311 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n");
3312 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n");
3313 printw("Bullet "); addch(ACS_BULLET); printw("\n");
3314 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n");
3315 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n");
3316 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n");
3317 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n");
3318 printw("Board of squares "); addch(ACS_BOARD); printw("\n");
3319 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n");
3320 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n");
3321 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n");
3322 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n");
3323 printw("Pi "); addch(ACS_PI); printw("\n");
3324 printw("Not equal "); addch(ACS_NEQUAL); printw("\n");
3325 printw("UK pound sign "); addch(ACS_STERLING); printw("\n");
3341 <h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other
3344 <p>Apart from the curses library, there are few text mode
3345 libraries, which provide more functionality and a lot of
3346 features. The following sections explain three standard
3347 libraries which are usually distributed along with
3354 <h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel
3357 <p>Now that you are proficient in curses, you wanted to do
3358 some thing big. You created a lot of overlapping windows to
3359 give a professional windows-type look. Unfortunately, it soon
3360 becomes difficult to manage these. The multiple refreshes,
3361 updates plunge you into a nightmare. The overlapping windows
3362 create blotches, whenever you forget to refresh the windows
3363 in the proper order.</p>
3365 <p>Don't despair. There's an elegant solution provided in
3366 panels library. In the words of developers of ncurses</p>
3368 <p><span class="emphasis"><i class="EMPHASIS">When your
3369 interface design is such that windows may dive deeper into
3370 the visibility stack or pop to the top at runtime, the
3371 resulting book-keeping can be tedious and difficult to get
3372 right. Hence the panels library.</i></span>
3375 <p>If you have lot of overlapping windows, then panels
3376 library is the way to go. It obviates the need of doing
3377 series of wnoutrefresh(), doupdate() and relieves the burden
3378 of doing it correctly(bottom up). The library maintains
3379 information about the order of windows, their overlapping and
3380 update the screen properly. So why wait? Let's take a close
3381 peek into panels.</p>
3386 <h3 class="SECT2"><a name="PANELBASICS" id=
3387 "PANELBASICS">16.1. The Basics</a></h3>
3389 <p>Panel object is a window that is implicitly treated as
3390 part of a deck including all other panel objects. The deck
3391 is treated as a stack with the top panel being completely
3392 visible and the other panels may or may not be obscured
3393 according to their positions. So the basic idea is to
3394 create a stack of overlapping panels and use panels library
3395 to display them correctly. There is a function similar to
3396 refresh() which, when called , displays panels in the
3397 correct order. Functions are provided to hide or show
3398 panels, move panels, change its size etc.. The overlapping
3399 problem is managed by the panels library during all the
3400 calls to these functions.</p>
3402 <p>The general flow of a panel program goes like this:</p>
3406 <p>Create the windows (with newwin()) to be attached to
3411 <p>Create panels with the chosen visibility order.
3412 Stack them up according to the desired visibility. The
3413 function new_panel() is used to created panels.</p>
3417 <p>Call update_panels() to write the panels to the
3418 virtual screen in correct visibility order. Do a
3419 doupdate() to show it on the screen.</p>
3423 <p>Mainpulate the panels with show_panel(),
3424 hide_panel(), move_panel() etc. Make use of helper
3425 functions like panel_hidden() and panel_window(). Make
3426 use of user pointer to store custom data for a panel.
3427 Use the functions set_panel_userptr() and
3428 panel_userptr() to set and get the user pointer for a
3433 <p>When you are done with the panel use del_panel() to
3434 delete the panel.</p>
3438 <p>Let's make the concepts clear, with some programs. The
3439 following is a simple program which creates 3 overlapping
3440 panels and shows them on the screen.</p>
3446 <h3 class="SECT2"><a name="COMPILEPANELS" id=
3447 "COMPILEPANELS">16.2. Compiling With the Panels Library</a></h3>
3449 <p>To use panels library functions, you have to include
3450 panel.h and to link the program with panels library the
3451 flag -lpanel should be added along with -lncurses in that
3454 <pre class="PROGRAMLISTING">
3455 #include <panel.h>
3460 compile and link: gcc <program file> -lpanel -lncurses
3462 <div class="EXAMPLE">
3463 <a name="PPASI" id="PPASI"></a>
3464 <p><b>Example 14. Panel basics</b>
3467 <pre class="PROGRAMLISTING">
3468 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3471 { WINDOW *my_wins[3];
3472 PANEL *my_panels[3];
3473 int lines = 10, cols = 40, y = 2, x = 4, i;
3479 /* Create windows for the panels */
3480 my_wins[0] = newwin(lines, cols, y, x);
3481 my_wins[1] = newwin(lines, cols, y + 1, x + 5);
3482 my_wins[2] = newwin(lines, cols, y + 2, x + 10);
3485 * Create borders around the windows so that you can see the effect
3488 for(i = 0; i < 3; ++i)
3489 box(my_wins[i], 0, 0);
3491 /* Attach a panel to each window */ /* Order is bottom up */
3492 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3493 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3494 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3496 /* Update the stacking order. 2nd panel will be on top */
3499 /* Show it on the screen */
3509 <p>As you can see, above program follows a simple flow as
3510 explained. The windows are created with newwin() and then
3511 they are attached to panels with new_panel(). As we attach
3512 one panel after another, the stack of panels gets updated.
3513 To put them on screen update_panels() and doupdate() are
3520 <h3 class="SECT2"><a name="PANELBROWSING" id=
3521 "PANELBROWSING">16.3. Panel Window Browsing</a></h3>
3523 <p>A slightly complicated example is given below. This
3524 program creates 3 windows which can be cycled through using
3525 tab. Have a look at the code.</p>
3527 <div class="EXAMPLE">
3528 <a name="PPABR" id="PPABR"></a>
3529 <p><b>Example 15. Panel Window Browsing Example</b>
3532 <pre class="PROGRAMLISTING">
3533 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3538 void init_wins(WINDOW **wins, int n);
3539 void win_show(WINDOW *win, char *label, int label_color);
3540 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3543 { WINDOW *my_wins[3];
3544 PANEL *my_panels[3];
3548 /* Initialize curses */
3553 keypad(stdscr, TRUE);
3555 /* Initialize all the colors */
3556 init_pair(1, COLOR_RED, COLOR_BLACK);
3557 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3558 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3559 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3561 init_wins(my_wins, 3);
3563 /* Attach a panel to each window */ /* Order is bottom up */
3564 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3565 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3566 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3568 /* Set up the user pointers to the next panel */
3569 set_panel_userptr(my_panels[0], my_panels[1]);
3570 set_panel_userptr(my_panels[1], my_panels[2]);
3571 set_panel_userptr(my_panels[2], my_panels[0]);
3573 /* Update the stacking order. 2nd panel will be on top */
3576 /* Show it on the screen */
3577 attron(COLOR_PAIR(4));
3578 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3579 attroff(COLOR_PAIR(4));
3583 while((ch = getch()) != KEY_F(1))
3586 top = (PANEL *)panel_userptr(top);
3597 /* Put all the windows */
3598 void init_wins(WINDOW **wins, int n)
3604 for(i = 0; i < n; ++i)
3605 { wins[i] = newwin(NLINES, NCOLS, y, x);
3606 sprintf(label, "Window Number %d", i + 1);
3607 win_show(wins[i], label, i + 1);
3613 /* Show the window with a border and a label */
3614 void win_show(WINDOW *win, char *label, int label_color)
3615 { int startx, starty, height, width;
3617 getbegyx(win, starty, startx);
3618 getmaxyx(win, height, width);
3621 mvwaddch(win, 2, 0, ACS_LTEE);
3622 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3623 mvwaddch(win, 2, width - 1, ACS_RTEE);
3625 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3628 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3642 length = strlen(string);
3643 temp = (width - length)/ 2;
3644 x = startx + (int)temp;
3645 wattron(win, color);
3646 mvwprintw(win, y, x, "%s", string);
3647 wattroff(win, color);
3657 <h3 class="SECT2"><a name="USERPTRUSING" id=
3658 "USERPTRUSING">16.4. Using User Pointers</a></h3>
3660 <p>In the above example I used user pointers to find out
3661 the next window in the cycle. We can attach custom
3662 information to the panel by specifying a user pointer,
3663 which can point to any information you want to store. In
3664 this case I stored the pointer to the next panel in the
3665 cycle. User pointer for a panel can be set with the
3666 function <tt class="LITERAL">set_panel_userptr()</tt>. It
3667 can be accessed using the function <tt class=
3668 "LITERAL">panel_userptr()</tt> which will return the user
3669 pointer for the panel given as argument. After finding the
3670 next panel in the cycle It is brought to the top by the
3671 function top_panel(). This function brings the panel given
3672 as argument to the top of the panel stack.</p>
3678 <h3 class="SECT2"><a name="PANELMOVERESIZE" id=
3679 "PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3>
3681 <p>The function <tt class="LITERAL">move_panel()</tt> can
3682 be used to move a panel to the desired location. It does
3683 not change the position of the panel in the stack. Make
3684 sure that you use move_panel() instead mvwin() on the
3685 window associated with the panel.</p>
3687 <p>Resizing a panel is slightly complex. There is no
3688 straight forward function just to resize the window
3689 associated with a panel. A solution to resize a panel is to
3690 create a new window with the desired sizes, change the
3691 window associated with the panel using replace_panel().
3692 Don't forget to delete the old window. The window
3693 associated with a panel can be found by using the function
3696 <p>The following program shows these concepts, in
3697 supposedly simple program. You can cycle through the window
3698 with <TAB> as usual. To resize or move the active
3699 panel press 'r' for resize 'm' for moving. Then use arrow
3700 keys to resize or move it to the desired way and press
3701 enter to end your resizing or moving. This example makes
3702 use of user data to get the required data to do the
3705 <div class="EXAMPLE">
3706 <a name="PPARE" id="PPARE"></a>
3707 <p><b>Example 16. Panel Moving and Resizing example</b>
3710 <pre class="PROGRAMLISTING">
3711 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3713 typedef struct _PANEL_DATA {
3723 void init_wins(WINDOW **wins, int n);
3724 void win_show(WINDOW *win, char *label, int label_color);
3725 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3726 void set_user_ptrs(PANEL **panels, int n);
3729 { WINDOW *my_wins[3];
3730 PANEL *my_panels[3];
3733 WINDOW *temp_win, *old_win;
3735 int newx, newy, neww, newh;
3736 int size = FALSE, move = FALSE;
3738 /* Initialize curses */
3743 keypad(stdscr, TRUE);
3745 /* Initialize all the colors */
3746 init_pair(1, COLOR_RED, COLOR_BLACK);
3747 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3748 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3749 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3751 init_wins(my_wins, 3);
3753 /* Attach a panel to each window */ /* Order is bottom up */
3754 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3755 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3756 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3758 set_user_ptrs(my_panels, 3);
3759 /* Update the stacking order. 2nd panel will be on top */
3762 /* Show it on the screen */
3763 attron(COLOR_PAIR(4));
3764 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3765 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3766 attroff(COLOR_PAIR(4));
3769 stack_top = my_panels[2];
3770 top = (PANEL_DATA *)panel_userptr(stack_top);
3775 while((ch = getch()) != KEY_F(1))
3778 top = (PANEL_DATA *)panel_userptr(stack_top);
3779 top_panel(top->next);
3780 stack_top = top->next;
3781 top = (PANEL_DATA *)panel_userptr(stack_top);
3787 case 'r': /* Re-Size*/
3789 attron(COLOR_PAIR(4));
3790 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing");
3792 attroff(COLOR_PAIR(4));
3794 case 'm': /* Move */
3795 attron(COLOR_PAIR(4));
3796 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving");
3798 attroff(COLOR_PAIR(4));
3833 case 10: /* Enter */
3838 { old_win = panel_window(stack_top);
3839 temp_win = newwin(newh, neww, newy, newx);
3840 replace_panel(stack_top, temp_win);
3841 win_show(temp_win, top->label, top->label_color);
3846 { move_panel(stack_top, newy, newx);
3852 attron(COLOR_PAIR(4));
3853 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3854 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3855 attroff(COLOR_PAIR(4));
3864 /* Put all the windows */
3865 void init_wins(WINDOW **wins, int n)
3871 for(i = 0; i < n; ++i)
3872 { wins[i] = newwin(NLINES, NCOLS, y, x);
3873 sprintf(label, "Window Number %d", i + 1);
3874 win_show(wins[i], label, i + 1);
3880 /* Set the PANEL_DATA structures for individual panels */
3881 void set_user_ptrs(PANEL **panels, int n)
3887 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA));
3889 for(i = 0;i < n; ++i)
3890 { win = panel_window(panels[i]);
3891 getbegyx(win, y, x);
3892 getmaxyx(win, h, w);
3897 sprintf(temp, "Window Number %d", i + 1);
3898 strcpy(ptrs[i].label, temp);
3899 ptrs[i].label_color = i + 1;
3901 ptrs[i].next = panels[0];
3903 ptrs[i].next = panels[i + 1];
3904 set_panel_userptr(panels[i], &ptrs[i]);
3908 /* Show the window with a border and a label */
3909 void win_show(WINDOW *win, char *label, int label_color)
3910 { int startx, starty, height, width;
3912 getbegyx(win, starty, startx);
3913 getmaxyx(win, height, width);
3916 mvwaddch(win, 2, 0, ACS_LTEE);
3917 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3918 mvwaddch(win, 2, width - 1, ACS_RTEE);
3920 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3923 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3937 length = strlen(string);
3938 temp = (width - length)/ 2;
3939 x = startx + (int)temp;
3940 wattron(win, color);
3941 mvwprintw(win, y, x, "%s", string);
3942 wattroff(win, color);
3948 <p>Concentrate on the main while loop. Once it finds out
3949 the type of key pressed, it takes appropriate action. If
3950 'r' is pressed resizing mode is started. After this the new
3951 sizes are updated as the user presses the arrow keys. When
3952 the user presses <ENTER> present selection ends and
3953 panel is resized by using the concept explained. While in
3954 resizing mode the program doesn't show how the window is
3955 getting resized. It is left as an exercise to the reader to
3956 print a dotted border while it gets resized to a new
3959 <p>When the user presses 'm' the move mode starts. This is
3960 a bit simpler than resizing. As the arrow keys are pressed
3961 the new position is updated and pressing of <ENTER>
3962 causes the panel to be moved by calling the function
3965 <p>In this program the user data which is represented as
3966 PANEL_DATA, plays very important role in finding the
3967 associated information with a panel. As written in the
3968 comments, the PANEL_DATA stores the panel sizes, label,
3969 label color and a pointer to the next panel in the
3976 <h3 class="SECT2"><a name="PANELSHOWHIDE" id=
3977 "PANELSHOWHIDE">16.6. Hiding and Showing Panels</a></h3>
3979 <p>A Panel can be hidden by using the function
3980 hide_panel(). This function merely removes it form the
3981 stack of panels, thus hiding it on the screen once you do
3982 update_panels() and doupdate(). It doesn't destroy the
3983 PANEL structure associated with the hidden panel. It can be
3984 shown again by using the show_panel() function.</p>
3986 <p>The following program shows the hiding of panels. Press
3987 'a' or 'b' or 'c' to show or hide first, second and third
3988 windows respectively. It uses a user data with a small
3989 variable hide, which keeps track of whether the window is
3990 hidden or not. For some reason the function <tt class=
3991 "LITERAL">panel_hidden()</tt> which tells whether a panel
3992 is hidden or not is not working. A bug report was also
3993 presented by Michael Andres <a href=
3994 "http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/"
3995 target="_top">here</a></p>
3997 <div class="EXAMPLE">
3998 <a name="PPAHI" id="PPAHI"></a>
3999 <p><b>Example 17. Panel Hiding and Showing example</b>
4002 <pre class="PROGRAMLISTING">
4003 <span class="INLINEMEDIAOBJECT">#include <panel.h>
4005 typedef struct _PANEL_DATA {
4006 int hide; /* TRUE if panel is hidden */
4012 void init_wins(WINDOW **wins, int n);
4013 void win_show(WINDOW *win, char *label, int label_color);
4014 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4017 { WINDOW *my_wins[3];
4018 PANEL *my_panels[3];
4019 PANEL_DATA panel_datas[3];
4023 /* Initialize curses */
4028 keypad(stdscr, TRUE);
4030 /* Initialize all the colors */
4031 init_pair(1, COLOR_RED, COLOR_BLACK);
4032 init_pair(2, COLOR_GREEN, COLOR_BLACK);
4033 init_pair(3, COLOR_BLUE, COLOR_BLACK);
4034 init_pair(4, COLOR_CYAN, COLOR_BLACK);
4036 init_wins(my_wins, 3);
4038 /* Attach a panel to each window */ /* Order is bottom up */
4039 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
4040 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
4041 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
4043 /* Initialize panel datas saying that nothing is hidden */
4044 panel_datas[0].hide = FALSE;
4045 panel_datas[1].hide = FALSE;
4046 panel_datas[2].hide = FALSE;
4048 set_panel_userptr(my_panels[0], &panel_datas[0]);
4049 set_panel_userptr(my_panels[1], &panel_datas[1]);
4050 set_panel_userptr(my_panels[2], &panel_datas[2]);
4052 /* Update the stacking order. 2nd panel will be on top */
4055 /* Show it on the screen */
4056 attron(COLOR_PAIR(4));
4057 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)");
4058 mvprintw(LINES - 2, 0, "F1 to Exit");
4060 attroff(COLOR_PAIR(4));
4063 while((ch = getch()) != KEY_F(1))
4066 temp = (PANEL_DATA *)panel_userptr(my_panels[0]);
4067 if(temp->hide == FALSE)
4068 { hide_panel(my_panels[0]);
4069 temp->hide = TRUE;
4072 { show_panel(my_panels[0]);
4073 temp->hide = FALSE;
4077 temp = (PANEL_DATA *)panel_userptr(my_panels[1]);
4078 if(temp->hide == FALSE)
4079 { hide_panel(my_panels[1]);
4080 temp->hide = TRUE;
4083 { show_panel(my_panels[1]);
4084 temp->hide = FALSE;
4088 temp = (PANEL_DATA *)panel_userptr(my_panels[2]);
4089 if(temp->hide == FALSE)
4090 { hide_panel(my_panels[2]);
4091 temp->hide = TRUE;
4094 { show_panel(my_panels[2]);
4095 temp->hide = FALSE;
4106 /* Put all the windows */
4107 void init_wins(WINDOW **wins, int n)
4113 for(i = 0; i < n; ++i)
4114 { wins[i] = newwin(NLINES, NCOLS, y, x);
4115 sprintf(label, "Window Number %d", i + 1);
4116 win_show(wins[i], label, i + 1);
4122 /* Show the window with a border and a label */
4123 void win_show(WINDOW *win, char *label, int label_color)
4124 { int startx, starty, height, width;
4126 getbegyx(win, starty, startx);
4127 getmaxyx(win, height, width);
4130 mvwaddch(win, 2, 0, ACS_LTEE);
4131 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
4132 mvwaddch(win, 2, width - 1, ACS_RTEE);
4134 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
4137 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4151 length = strlen(string);
4152 temp = (width - length)/ 2;
4153 x = startx + (int)temp;
4154 wattron(win, color);
4155 mvwprintw(win, y, x, "%s", string);
4156 wattroff(win, color);
4166 <h3 class="SECT2"><a name="PANELABOVE" id=
4167 "PANELABOVE">16.7. panel_above() and panel_below()
4170 <p>The functions <tt class="LITERAL">panel_above()</tt> and
4171 <tt class="LITERAL">panel_below()</tt> can be used to find
4172 out the panel above and below a panel. If the argument to
4173 these functions is NULL, then they return a pointer to
4174 bottom panel and top panel respectively.</p>
4181 <h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus
4184 <p>The menus library provides a nice extension to basic
4185 curses, through which you can create menus. It provides a set
4186 of functions to create menus. But they have to be customized
4187 to give a nicer look, with colors etc. Let's get into the
4190 <p>A menu is a screen display that assists the user to choose
4191 some subset of a given set of items. To put it simple, a menu
4192 is a collection of items from which one or more items can be
4193 chosen. Some readers might not be aware of multiple item
4194 selection capability. Menu library provides functionality to
4195 write menus from which the user can chose more than one item
4196 as the preferred choice. This is dealt with in a later
4197 section. Now it is time for some rudiments.</p>
4202 <h3 class="SECT2"><a name="MENUBASICS" id=
4203 "MENUBASICS">17.1. The Basics</a></h3>
4205 <p>To create menus, you first create items, and then post
4206 the menu to the display. After that, all the processing of
4207 user responses is done in an elegant function menu_driver()
4208 which is the work horse of any menu program.</p>
4210 <p>The general flow of control of a menu program looks like
4215 <p>Initialize curses</p>
4219 <p>Create items using new_item(). You can specify a
4220 name and description for the items.</p>
4224 <p>Create the menu with new_menu() by specifying the
4225 items to be attached with.</p>
4229 <p>Post the menu with menu_post() and refresh the
4234 <p>Process the user requests with a loop and do
4235 necessary updates to menu with menu_driver.</p>
4239 <p>Unpost the menu with menu_unpost()</p>
4243 <p>Free the memory allocated to menu by free_menu()</p>
4247 <p>Free the memory allocated to the items with
4256 <p>Let's see a program which prints a simple menu and
4257 updates the current selection with up, down arrows.</p>
4263 <h3 class="SECT2"><a name="COMPILEMENUS" id=
4264 "COMPILEMENUS">17.2. Compiling With the Menu Library</a></h3>
4266 <p>To use menu library functions, you have to include
4267 menu.h and to link the program with menu library the flag
4268 -lmenu should be added along with -lncurses in that
4271 <pre class="PROGRAMLISTING">
4272 #include <menu.h>
4277 compile and link: gcc <program file> -lmenu -lncurses
4279 <div class="EXAMPLE">
4280 <a name="MMESI" id="MMESI"></a>
4281 <p><b>Example 18. Menu Basics</b>
4284 <pre class="PROGRAMLISTING">
4285 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4286 #include <menu.h>
4288 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4310 keypad(stdscr, TRUE);
4312 n_choices = ARRAY_SIZE(choices);
4313 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4315 for(i = 0; i < n_choices; ++i)
4316 my_items[i] = new_item(choices[i], choices[i]);
4317 my_items[n_choices] = (ITEM *)NULL;
4319 my_menu = new_menu((ITEM **)my_items);
4320 mvprintw(LINES - 2, 0, "F1 to Exit");
4324 while((c = getch()) != KEY_F(1))
4327 menu_driver(my_menu, REQ_DOWN_ITEM);
4330 menu_driver(my_menu, REQ_UP_ITEM);
4335 free_item(my_items[0]);
4336 free_item(my_items[1]);
4344 <p>This program demonstrates the basic concepts involved in
4345 creating a menu using menus library. First we create the
4346 items using new_item() and then attach them to the menu
4347 with new_menu() function. After posting the menu and
4348 refreshing the screen, the main processing loop starts. It
4349 reads user input and takes corresponding action. The
4350 function menu_driver() is the main work horse of the menu
4351 system. The second parameter to this function tells what's
4352 to be done with the menu. According to the parameter,
4353 menu_driver() does the corresponding task. The value can be
4354 either a menu navigational request, an ascii character, or
4355 a KEY_MOUSE special key associated with a mouse event.</p>
4357 <p>The menu_driver accepts following navigational
4360 <pre class="PROGRAMLISTING">
4361 REQ_LEFT_ITEM Move left to an item.
4362 REQ_RIGHT_ITEM Move right to an item.
4363 REQ_UP_ITEM Move up to an item.
4364 REQ_DOWN_ITEM Move down to an item.
4365 REQ_SCR_ULINE Scroll up a line.
4366 REQ_SCR_DLINE Scroll down a line.
4367 REQ_SCR_DPAGE Scroll down a page.
4368 REQ_SCR_UPAGE Scroll up a page.
4369 REQ_FIRST_ITEM Move to the first item.
4370 REQ_LAST_ITEM Move to the last item.
4371 REQ_NEXT_ITEM Move to the next item.
4372 REQ_PREV_ITEM Move to the previous item.
4373 REQ_TOGGLE_ITEM Select/deselect an item.
4374 REQ_CLEAR_PATTERN Clear the menu pattern buffer.
4375 REQ_BACK_PATTERN Delete the previous character from the pattern buffer.
4376 REQ_NEXT_MATCH Move to the next item matching the pattern match.
4377 REQ_PREV_MATCH Move to the previous item matching the pattern match.
4379 <p>Don't get overwhelmed by the number of options. We will
4380 see them slowly one after another. The options of interest
4381 in this example are REQ_UP_ITEM and REQ_DOWN_ITEM. These
4382 two options when passed to menu_driver, menu driver updates
4383 the current item to one item up or down respectively.</p>
4389 <h3 class="SECT2"><a name="MENUDRIVER" id=
4390 "MENUDRIVER">17.3. Menu Driver: The work horse of the menu
4393 <p>As you have seen in the above example, menu_driver plays
4394 an important role in updating the menu. It is very
4395 important to understand various options it takes and what
4396 they do. As explained above, the second parameter to
4397 menu_driver() can be either a navigational request, a
4398 printable character or a KEY_MOUSE key. Let's dissect the
4399 different navigational requests.</p>
4403 <p><span class="emphasis"><i class=
4404 "EMPHASIS">REQ_LEFT_ITEM and REQ_RIGHT_ITEM</i></span>
4407 <p>A Menu can be displayed with multiple columns for
4408 more than one item. This can be done by using the
4409 <tt class="LITERAL">menu_format()</tt>function. When a
4410 multi columnar menu is displayed these requests cause
4411 the menu driver to move the current selection to left
4416 <p><span class="emphasis"><i class=
4417 "EMPHASIS">REQ_UP_ITEM and REQ_DOWN_ITEM</i></span>
4420 <p>These two options you have seen in the above
4421 example. These options when given, makes the
4422 menu_driver to move the current selection to an item up
4427 <p><span class="emphasis"><i class="EMPHASIS">REQ_SCR_*
4431 <p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE,
4432 REQ_SCR_DPAGE, REQ_SCR_UPAGE are related to scrolling.
4433 If all the items in the menu cannot be displayed in the
4434 menu sub window, then the menu is scrollable. These
4435 requests can be given to the menu_driver to do the
4436 scrolling either one line up, down or one page down or
4437 up respectively.</p>
4441 <p><span class="emphasis"><i class=
4442 "EMPHASIS">REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM
4443 and REQ_PREV_ITEM</i></span>
4446 <p>These requests are self explanatory.</p>
4450 <p><span class="emphasis"><i class=
4451 "EMPHASIS">REQ_TOGGLE_ITEM</i></span>
4454 <p>This request when given, toggles the present
4455 selection. This option is to be used only in a multi
4456 valued menu. So to use this request the option
4457 O_ONEVALUE must be off. This option can be made off or
4458 on with set_menu_opts().</p>
4462 <p><span class="emphasis"><i class="EMPHASIS">Pattern
4466 <p>Every menu has an associated pattern buffer, which
4467 is used to find the nearest match to the ascii
4468 characters entered by the user. Whenever ascii
4469 characters are given to menu_driver, it puts in to the
4470 pattern buffer. It also tries to find the nearest match
4471 to the pattern in the items list and moves current
4472 selection to that item. The request REQ_CLEAR_PATTERN
4473 clears the pattern buffer. The request REQ_BACK_PATTERN
4474 deletes the previous character in the pattern buffer.
4475 In case the pattern matches more than one item then the
4476 matched items can be cycled through REQ_NEXT_MATCH and
4477 REQ_PREV_MATCH which move the current selection to the
4478 next and previous matches respectively.</p>
4482 <p><span class="emphasis"><i class="EMPHASIS">Mouse
4486 <p>In case of KEY_MOUSE requests, according to the
4487 mouse position an action is taken accordingly. The
4488 action to be taken is explained in the man page as,</p>
4490 <pre class="PROGRAMLISTING">
4491 <span class="emphasis"><i class=
4492 "EMPHASIS"> If the second argument is the KEY_MOUSE special key, the
4493 associated mouse event is translated into one of the above
4494 pre-defined requests. Currently only clicks in the user
4495 window (e.g. inside the menu display area or the decora­
4496 tion window) are handled. If you click above the display
4497 region of the menu, a REQ_SCR_ULINE is generated, if you
4498 doubleclick a REQ_SCR_UPAGE is generated and if you
4499 tripleclick a REQ_FIRST_ITEM is generated. If you click
4500 below the display region of the menu, a REQ_SCR_DLINE is
4501 generated, if you doubleclick a REQ_SCR_DPAGE is generated
4502 and if you tripleclick a REQ_LAST_ITEM is generated. If
4503 you click at an item inside the display area of the menu,
4504 the menu cursor is positioned to that item.</i></span>
4509 <p>Each of the above requests will be explained in the
4510 following lines with several examples whenever
4517 <h3 class="SECT2"><a name="MENUWINDOWS" id=
4518 "MENUWINDOWS">17.4. Menu Windows</a></h3>
4520 <p>Every menu created is associated with a window and a sub
4521 window. The menu window displays any title or border
4522 associated with the menu. The menu sub window displays the
4523 menu items currently available for selection. But we didn't
4524 specify any window or sub window in the simple example.
4525 When a window is not specified, stdscr is taken as the main
4526 window, and then menu system calculates the sub window size
4527 required for the display of items. Then items are displayed
4528 in the calculated sub window. So let's play with these
4529 windows and display a menu with a border and a title.</p>
4531 <div class="EXAMPLE">
4532 <a name="MMEWI" id="MMEWI"></a>
4533 <p><b>Example 19. Menu Windows Usage example</b>
4536 <pre class="PROGRAMLISTING">
4537 <span class="INLINEMEDIAOBJECT">#include <menu.h>
4539 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4550 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4556 WINDOW *my_menu_win;
4559 /* Initialize curses */
4564 keypad(stdscr, TRUE);
4565 init_pair(1, COLOR_RED, COLOR_BLACK);
4568 n_choices = ARRAY_SIZE(choices);
4569 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4570 for(i = 0; i < n_choices; ++i)
4571 my_items[i] = new_item(choices[i], choices[i]);
4574 my_menu = new_menu((ITEM **)my_items);
4576 /* Create the window to be associated with the menu */
4577 my_menu_win = newwin(10, 40, 4, 4);
4578 keypad(my_menu_win, TRUE);
4580 /* Set main window and sub window */
4581 set_menu_win(my_menu, my_menu_win);
4582 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4584 /* Set menu mark to the string " * " */
4585 set_menu_mark(my_menu, " * ");
4587 /* Print a border around the main window and print a title */
4588 box(my_menu_win, 0, 0);
4589 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4590 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4591 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4592 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4593 mvprintw(LINES - 2, 0, "F1 to exit");
4598 wrefresh(my_menu_win);
4600 while((c = wgetch(my_menu_win)) != KEY_F(1))
4603 menu_driver(my_menu, REQ_DOWN_ITEM);
4606 menu_driver(my_menu, REQ_UP_ITEM);
4609 wrefresh(my_menu_win);
4612 /* Unpost and free all the memory taken up */
4613 unpost_menu(my_menu);
4615 for(i = 0; i < n_choices; ++i)
4616 free_item(my_items[i]);
4620 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4634 length = strlen(string);
4635 temp = (width - length)/ 2;
4636 x = startx + (int)temp;
4637 wattron(win, color);
4638 mvwprintw(win, y, x, "%s", string);
4639 wattroff(win, color);
4645 <p>This example creates a menu with a title, border, a
4646 fancy line separating title and the items. As you can see,
4647 in order to attach a window to a menu the function
4648 set_menu_win() has to be used. Then we attach the sub
4649 window also. This displays the items in the sub window. You
4650 can also set the mark string which gets displayed to the
4651 left of the selected item with set_menu_mark().</p>
4657 <h3 class="SECT2"><a name="SCROLLMENUS" id=
4658 "SCROLLMENUS">17.5. Scrolling Menus</a></h3>
4660 <p>If the sub window given for a window is not big enough
4661 to show all the items, then the menu will be scrollable.
4662 When you are on the last item in the present list, if you
4663 send REQ_DOWN_ITEM, it gets translated into REQ_SCR_DLINE
4664 and the menu scrolls by one item. You can manually give
4665 REQ_SCR_ operations to do scrolling. Let's see how it can
4668 <div class="EXAMPLE">
4669 <a name="MMESC" id="MMESC"></a>
4670 <p><b>Example 20. Scrolling Menus example</b>
4673 <pre class="PROGRAMLISTING">
4674 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4675 #include <menu.h>
4677 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4694 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4700 WINDOW *my_menu_win;
4703 /* Initialize curses */
4708 keypad(stdscr, TRUE);
4709 init_pair(1, COLOR_RED, COLOR_BLACK);
4710 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4713 n_choices = ARRAY_SIZE(choices);
4714 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4715 for(i = 0; i < n_choices; ++i)
4716 my_items[i] = new_item(choices[i], choices[i]);
4719 my_menu = new_menu((ITEM **)my_items);
4721 /* Create the window to be associated with the menu */
4722 my_menu_win = newwin(10, 40, 4, 4);
4723 keypad(my_menu_win, TRUE);
4725 /* Set main window and sub window */
4726 set_menu_win(my_menu, my_menu_win);
4727 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4728 set_menu_format(my_menu, 5, 1);
4730 /* Set menu mark to the string " * " */
4731 set_menu_mark(my_menu, " * ");
4733 /* Print a border around the main window and print a title */
4734 box(my_menu_win, 0, 0);
4735 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4736 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4737 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4738 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4742 wrefresh(my_menu_win);
4744 attron(COLOR_PAIR(2));
4745 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items");
4746 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)");
4747 attroff(COLOR_PAIR(2));
4750 while((c = wgetch(my_menu_win)) != KEY_F(1))
4753 menu_driver(my_menu, REQ_DOWN_ITEM);
4756 menu_driver(my_menu, REQ_UP_ITEM);
4759 menu_driver(my_menu, REQ_SCR_DPAGE);
4762 menu_driver(my_menu, REQ_SCR_UPAGE);
4765 wrefresh(my_menu_win);
4768 /* Unpost and free all the memory taken up */
4769 unpost_menu(my_menu);
4771 for(i = 0; i < n_choices; ++i)
4772 free_item(my_items[i]);
4776 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4790 length = strlen(string);
4791 temp = (width - length)/ 2;
4792 x = startx + (int)temp;
4793 wattron(win, color);
4794 mvwprintw(win, y, x, "%s", string);
4795 wattroff(win, color);
4801 <p>This program is self-explanatory. In this example the
4802 number of choices has been increased to ten, which is
4803 larger than our sub window size which can hold 6 items.
4804 This message has to be explicitly conveyed to the menu
4805 system with the function set_menu_format(). In here we
4806 specify the number of rows and columns we want to be
4807 displayed for a single page. We can specify any number of
4808 items to be shown, in the rows variables, if it is less
4809 than the height of the sub window. If the key pressed by
4810 the user is a PAGE UP or PAGE DOWN, the menu is scrolled a
4811 page due to the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE)
4812 given to menu_driver().</p>
4818 <h3 class="SECT2"><a name="MULTICOLUMN" id=
4819 "MULTICOLUMN">17.6. Multi Columnar Menus</a></h3>
4821 <p>In the above example you have seen how to use the
4822 function set_menu_format(). I didn't mention what the cols
4823 variable (third parameter) does. Well, If your sub window
4824 is wide enough, you can opt to display more than one item
4825 per row. This can be specified in the cols variable. To
4826 make things simpler, the following example doesn't show
4827 descriptions for the items.</p>
4829 <div class="EXAMPLE">
4830 <a name="MMEMUCO" id="MMEMUCO"></a>
4831 <p><b>Example 21. Milt Columnar Menus Example</b>
4834 <pre class="PROGRAMLISTING">
4835 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4836 #include <menu.h>
4838 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4842 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5",
4843 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10",
4844 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15",
4845 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20",
4854 WINDOW *my_menu_win;
4857 /* Initialize curses */
4862 keypad(stdscr, TRUE);
4863 init_pair(1, COLOR_RED, COLOR_BLACK);
4864 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4867 n_choices = ARRAY_SIZE(choices);
4868 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4869 for(i = 0; i < n_choices; ++i)
4870 my_items[i] = new_item(choices[i], choices[i]);
4873 my_menu = new_menu((ITEM **)my_items);
4875 /* Set menu option not to show the description */
4876 menu_opts_off(my_menu, O_SHOWDESC);
4878 /* Create the window to be associated with the menu */
4879 my_menu_win = newwin(10, 70, 4, 4);
4880 keypad(my_menu_win, TRUE);
4882 /* Set main window and sub window */
4883 set_menu_win(my_menu, my_menu_win);
4884 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1));
4885 set_menu_format(my_menu, 5, 3);
4886 set_menu_mark(my_menu, " * ");
4888 /* Print a border around the main window and print a title */
4889 box(my_menu_win, 0, 0);
4891 attron(COLOR_PAIR(2));
4892 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll");
4893 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)");
4894 attroff(COLOR_PAIR(2));
4899 wrefresh(my_menu_win);
4901 while((c = wgetch(my_menu_win)) != KEY_F(1))
4904 menu_driver(my_menu, REQ_DOWN_ITEM);
4907 menu_driver(my_menu, REQ_UP_ITEM);
4910 menu_driver(my_menu, REQ_LEFT_ITEM);
4913 menu_driver(my_menu, REQ_RIGHT_ITEM);
4916 menu_driver(my_menu, REQ_SCR_DPAGE);
4919 menu_driver(my_menu, REQ_SCR_UPAGE);
4922 wrefresh(my_menu_win);
4925 /* Unpost and free all the memory taken up */
4926 unpost_menu(my_menu);
4928 for(i = 0; i < n_choices; ++i)
4929 free_item(my_items[i]);
4935 <p>Watch the function call to set_menu_format(). It
4936 specifies the number of columns to be 3, thus displaying 3
4937 items per row. We have also switched off the showing
4938 descriptions with the function menu_opts_off(). There are
4939 couple of functions set_menu_opts(), menu_opts_on() and
4940 menu_opts() which can be used to manipulate menu options.
4941 The following menu options can be specified.</p>
4943 <pre class="PROGRAMLISTING">
4945 Only one item can be selected for this menu.
4948 Display the item descriptions when the menu is
4952 Display the menu in row-major order.
4955 Ignore the case when pattern-matching.
4958 Move the cursor to within the item name while pat­
4962 Don't wrap around next-item and previous-item,
4963 requests to the other end of the menu.
4965 <p>All options are on by default. You can switch specific
4966 attributes on or off with menu_opts_on() and
4967 menu_opts_off() functions. You can also use set_menu_opts()
4968 to directly specify the options. The argument to this
4969 function should be a OR ed value of some of those above
4970 constants. The function menu_opts() can be used to find out
4971 a menu's present options.</p>
4977 <h3 class="SECT2"><a name="MULTIVALUEMENUS" id=
4978 "MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3>
4980 <p>You might be wondering what if you switch off the option
4981 O_ONEVALUE. Then the menu becomes multi-valued. That means
4982 you can select more than one item. This brings us to the
4983 request REQ_TOGGLE_ITEM. Let's see it in action.</p>
4985 <div class="EXAMPLE">
4986 <a name="MMETO" id="MMETO"></a>
4987 <p><b>Example 22. Multi Valued Menus example</b>
4990 <pre class="PROGRAMLISTING">
4991 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4992 #include <menu.h>
4994 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5015 /* Initialize curses */
5019 keypad(stdscr, TRUE);
5021 /* Initialize items */
5022 n_choices = ARRAY_SIZE(choices);
5023 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5024 for(i = 0; i < n_choices; ++i)
5025 my_items[i] = new_item(choices[i], choices[i]);
5026 my_items[n_choices] = (ITEM *)NULL;
5028 my_menu = new_menu((ITEM **)my_items);
5030 /* Make the menu multi valued */
5031 menu_opts_off(my_menu, O_ONEVALUE);
5033 mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item.");
5034 mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)");
5038 while((c = getch()) != KEY_F(1))
5041 menu_driver(my_menu, REQ_DOWN_ITEM);
5044 menu_driver(my_menu, REQ_UP_ITEM);
5047 menu_driver(my_menu, REQ_TOGGLE_ITEM);
5049 case 10: /* Enter */
5053 items = menu_items(my_menu);
5055 for(i = 0; i < item_count(my_menu); ++i)
5056 if(item_value(items[i]) == TRUE)
5057 { strcat(temp, item_name(items[i]));
5062 mvprintw(20, 0, temp);
5069 free_item(my_items[0]);
5070 free_item(my_items[1]);
5078 <p>Whew, A lot of new functions. Let's take them one after
5079 another. Firstly, the REQ_TOGGLE_ITEM. In a multi-valued
5080 menu, the user should be allowed to select or un select
5081 more than one item. The request REQ_TOGGLE_ITEM toggles the
5082 present selection. In this case when space is pressed
5083 REQ_TOGGLE_ITEM request is sent to menu_driver to achieve
5086 <p>Now when the user presses <ENTER> we show the
5087 items he presently selected. First we find out the items
5088 associated with the menu using the function menu_items().
5089 Then we loop through the items to find out if the item is
5090 selected or not. The function item_value() returns TRUE if
5091 an item is selected. The function item_count() returns the
5092 number of items in the menu. The item name can be found
5093 with item_name(). You can also find the description
5094 associated with an item using item_description().</p>
5100 <h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu
5103 <p>Well, by this time you must be itching for some
5104 difference in your menu, with lots of functionality. I
5105 know. You want Colors !!!. You want to create nice menus
5106 similar to those text mode <a href=
5107 "http://www.jersey.net/~debinjoe/games/" target="_top">dos
5108 games</a>. The functions set_menu_fore() and
5109 set_menu_back() can be used to change the attribute of the
5110 selected item and unselected item. The names are
5111 misleading. They don't change menu's foreground or
5112 background which would have been useless.</p>
5114 <p>The function set_menu_grey() can be used to set the
5115 display attribute for the non-selectable items in the menu.
5116 This brings us to the interesting option for an item the
5117 one and only O_SELECTABLE. We can turn it off by the
5118 function item_opts_off() and after that that item is not
5119 selectable. It is like a grayed item in those fancy windows
5120 menus. Let's put these concepts in practice with this
5123 <div class="EXAMPLE">
5124 <a name="MMEAT" id="MMEAT"></a>
5125 <p><b>Example 23. Menu Options example</b>
5128 <pre class="PROGRAMLISTING">
5129 <span class="INLINEMEDIAOBJECT">#include <menu.h>
5131 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5152 /* Initialize curses */
5157 keypad(stdscr, TRUE);
5158 init_pair(1, COLOR_RED, COLOR_BLACK);
5159 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5160 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5162 /* Initialize items */
5163 n_choices = ARRAY_SIZE(choices);
5164 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5165 for(i = 0; i < n_choices; ++i)
5166 my_items[i] = new_item(choices[i], choices[i]);
5167 my_items[n_choices] = (ITEM *)NULL;
5168 item_opts_off(my_items[3], O_SELECTABLE);
5169 item_opts_off(my_items[6], O_SELECTABLE);
5172 my_menu = new_menu((ITEM **)my_items);
5174 /* Set fore ground and back ground of the menu */
5175 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE);
5176 set_menu_back(my_menu, COLOR_PAIR(2));
5177 set_menu_grey(my_menu, COLOR_PAIR(3));
5180 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5181 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5185 while((c = getch()) != KEY_F(1))
5188 menu_driver(my_menu, REQ_DOWN_ITEM);
5191 menu_driver(my_menu, REQ_UP_ITEM);
5193 case 10: /* Enter */
5196 mvprintw(20, 0, "Item selected is : %s",
5197 item_name(current_item(my_menu)));
5198 pos_menu_cursor(my_menu);
5202 unpost_menu(my_menu);
5203 for(i = 0; i < n_choices; ++i)
5204 free_item(my_items[i]);
5216 <h3 class="SECT2"><a name="MENUUSERPTR" id=
5217 "MENUUSERPTR">17.9. The useful User Pointer</a></h3>
5219 <p>We can associate a user pointer with each item in the
5220 menu. It works the same way as user pointer in panels. It
5221 is not touched by menu system. You can store any thing you
5222 like in that. I usually use it to store the function to be
5223 executed when the menu option is chosen (It is selected and
5224 may be the user pressed <ENTER>);</p>
5226 <div class="EXAMPLE">
5227 <a name="MMEUS" id="MMEUS"></a>
5228 <p><b>Example 24. Menu User Pointer Usage</b>
5231 <pre class="PROGRAMLISTING">
5232 <span class="INLINEMEDIAOBJECT">#include <curses.h>
5233 #include <menu.h>
5235 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5248 void func(char *name);
5257 /* Initialize curses */
5262 keypad(stdscr, TRUE);
5263 init_pair(1, COLOR_RED, COLOR_BLACK);
5264 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5265 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5267 /* Initialize items */
5268 n_choices = ARRAY_SIZE(choices);
5269 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5270 for(i = 0; i < n_choices; ++i)
5271 { my_items[i] = new_item(choices[i], choices[i]);
5272 /* Set the user pointer */
5273 set_item_userptr(my_items[i], func);
5275 my_items[n_choices] = (ITEM *)NULL;
5278 my_menu = new_menu((ITEM **)my_items);
5281 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5282 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5286 while((c = getch()) != KEY_F(1))
5289 menu_driver(my_menu, REQ_DOWN_ITEM);
5292 menu_driver(my_menu, REQ_UP_ITEM);
5294 case 10: /* Enter */
5298 cur = current_item(my_menu);
5299 p = item_userptr(cur);
5300 p((char *)item_name(cur));
5301 pos_menu_cursor(my_menu);
5307 unpost_menu(my_menu);
5308 for(i = 0; i < n_choices; ++i)
5309 free_item(my_items[i]);
5314 void func(char *name)
5317 mvprintw(20, 0, "Item selected is : %s", name);
5327 <h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms
5330 <p>Well. If you have seen those forms on web pages which take
5331 input from users and do various kinds of things, you might be
5332 wondering how would any one create such forms in text mode
5333 display. It is quite difficult to write those nifty forms in
5334 plain ncurses. Forms library tries to provide a basic frame
5335 work to build and maintain forms with ease. It has lot of
5336 features(functions) which manage validation, dynamic
5337 expansion of fields etc.. Let's see it in full flow.</p>
5339 <p>A form is a collection of fields; each field can be either
5340 a label(static text) or a data-entry location. The forms also
5341 library provides functions to divide forms into multiple
5347 <h3 class="SECT2"><a name="FORMBASICS" id=
5348 "FORMBASICS">18.1. The Basics</a></h3>
5350 <p>Forms are created in much the same way as menus. First
5351 the fields related to the form are created with
5352 new_field(). You can set options for the fields, so that
5353 they can be displayed with some fancy attributes, validated
5354 before the field looses focus etc.. Then the fields are
5355 attached to form. After this, the form can be posted to
5356 display and is ready to receive inputs. On the similar
5357 lines to menu_driver(), the form is manipulated with
5358 form_driver(). We can send requests to form_driver to move
5359 focus to a certain field, move cursor to end of the field
5360 etc.. After the user enters values in the fields and
5361 validation done, form can be unposted and memory allocated
5364 <p>The general flow of control of a forms program looks
5369 <p>Initialize curses</p>
5373 <p>Create fields using new_field(). You can specify the
5374 height and width of the field, and its position on the
5379 <p>Create the forms with new_form() by specifying the
5380 fields to be attached with.</p>
5384 <p>Post the form with form_post() and refresh the
5389 <p>Process the user requests with a loop and do
5390 necessary updates to form with form_driver.</p>
5394 <p>Unpost the menu with form_unpost()</p>
5398 <p>Free the memory allocated to menu by free_form()</p>
5402 <p>Free the memory allocated to the items with
5411 <p>As you can see, working with forms library is much
5412 similar to handling menu library. The following examples
5413 will explore various aspects of form processing. Let's
5414 start the journey with a simple example. first.</p>
5420 <h3 class="SECT2"><a name="COMPILEFORMS" id=
5421 "COMPILEFORMS">18.2. Compiling With the Forms Library</a></h3>
5423 <p>To use forms library functions, you have to include
5424 form.h and to link the program with forms library the flag
5425 -lform should be added along with -lncurses in that
5428 <pre class="PROGRAMLISTING">
5429 #include <form.h>
5434 compile and link: gcc <program file> -lform -lncurses
5436 <div class="EXAMPLE">
5437 <a name="FFOSI" id="FFOSI"></a>
5438 <p><b>Example 25. Forms Basics</b>
5441 <pre class="PROGRAMLISTING">
5442 <span class="INLINEMEDIAOBJECT">#include <form.h>
5449 /* Initialize curses */
5453 keypad(stdscr, TRUE);
5455 /* Initialize the fields */
5456 field[0] = new_field(1, 10, 4, 18, 0, 0);
5457 field[1] = new_field(1, 10, 6, 18, 0, 0);
5460 /* Set field options */
5461 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */
5462 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5463 /* Field is filled up */
5464 set_field_back(field[1], A_UNDERLINE);
5465 field_opts_off(field[1], O_AUTOSKIP);
5467 /* Create the form and post it */
5468 my_form = new_form(field);
5472 mvprintw(4, 10, "Value 1:");
5473 mvprintw(6, 10, "Value 2:");
5476 /* Loop through to get user requests */
5477 while((ch = getch()) != KEY_F(1))
5480 /* Go to next field */
5481 form_driver(my_form, REQ_NEXT_FIELD);
5482 /* Go to the end of the present buffer */
5483 /* Leaves nicely at the last character */
5484 form_driver(my_form, REQ_END_LINE);
5487 /* Go to previous field */
5488 form_driver(my_form, REQ_PREV_FIELD);
5489 form_driver(my_form, REQ_END_LINE);
5492 /* If this is a normal character, it gets */
5494 form_driver(my_form, ch);
5499 /* Un post form and free the memory */
5500 unpost_form(my_form);
5502 free_field(field[0]);
5503 free_field(field[1]);
5511 <p>Above example is pretty straight forward. It creates two
5512 fields with <tt class="LITERAL">new_field()</tt>.
5513 new_field() takes height, width, starty, startx, number of
5514 offscreen rows and number of additional working buffers.
5515 The fifth argument number of offscreen rows specifies how
5516 much of the field to be shown. If it is zero, the entire
5517 field is always displayed otherwise the form will be
5518 scrollable when the user accesses not displayed parts of
5519 the field. The forms library allocates one buffer per field
5520 to store the data user enters. Using the last parameter to
5521 new_field() we can specify it to allocate some additional
5522 buffers. These can be used for any purpose you like.</p>
5524 <p>After creating the fields, back ground attribute of both
5525 of them is set to an underscore with set_field_back(). The
5526 AUTOSKIP option is turned off using field_opts_off(). If
5527 this option is turned on, focus will move to the next field
5528 in the form once the active field is filled up
5531 <p>After attaching the fields to the form, it is posted.
5532 Here on, user inputs are processed in the while loop, by
5533 making corresponding requests to form_driver. The details
5534 of all the requests to the form_driver() are explained
5541 <h3 class="SECT2"><a name="PLAYFIELDS" id=
5542 "PLAYFIELDS">18.3. Playing with Fields</a></h3>
5544 <p>Each form field is associated with a lot of attributes.
5545 They can be manipulated to get the required effect and to
5546 have fun !!!. So why wait?</p>
5551 <h4 class="SECT3"><a name="FETCHINFO" id=
5552 "FETCHINFO">18.3.1. Fetching Size and Location of
5555 <p>The parameters we have given at the time of creation
5556 of a field can be retrieved with field_info(). It returns
5557 height, width, starty, startx, number of offscreen rows,
5558 and number of additional buffers into the parameters
5559 given to it. It is a sort of inverse of new_field().</p>
5561 <pre class="PROGRAMLISTING">
5562 int field_info( FIELD *field, /* field from which to fetch */
5563 int *height, *int width, /* field size */
5564 int *top, int *left, /* upper left corner */
5565 int *offscreen, /* number of offscreen rows */
5566 int *nbuf); /* number of working buffers */
5573 <h4 class="SECT3"><a name="MOVEFIELD" id=
5574 "MOVEFIELD">18.3.2. Moving the field</a></h4>
5576 <p>The location of the field can be moved to a different
5577 position with move_field().</p>
5579 <pre class="PROGRAMLISTING">
5580 int move_field( FIELD *field, /* field to alter */
5581 int top, int left); /* new upper-left corner */
5583 <p>As usual, the changed position can be queried with
5590 <h4 class="SECT3"><a name="JUSTIFYFIELD" id=
5591 "JUSTIFYFIELD">18.3.3. Field Justification</a></h4>
5593 <p>The justification to be done for the field can be
5594 fixed using the function set_field_just().</p>
5596 <pre class="PROGRAMLISTING">
5597 int set_field_just(FIELD *field, /* field to alter */
5598 int justmode); /* mode to set */
5599 int field_just(FIELD *field); /* fetch justify mode of field */
5601 <p>The justification mode valued accepted and returned by
5602 these functions are NO_JUSTIFICATION, JUSTIFY_RIGHT,
5603 JUSTIFY_LEFT, or JUSTIFY_CENTER.</p>
5609 <h4 class="SECT3"><a name="FIELDDISPATTRIB" id=
5610 "FIELDDISPATTRIB">18.3.4. Field Display Attributes</a></h4>
5612 <p>As you have seen, in the above example, display
5613 attribute for the fields can be set with set_field_fore()
5614 and setfield_back(). These functions set foreground and
5615 background attribute of the fields. You can also specify
5616 a pad character which will be filled in the unfilled
5617 portion of the field. The pad character is set with a
5618 call to set_field_pad(). Default pad value is a space.
5619 The functions field_fore(), field_back, field_pad() can
5620 be used to query the present foreground, background
5621 attributes and pad character for the field. The following
5622 list gives the usage of functions.</p>
5624 <pre class="PROGRAMLISTING">
5625 int set_field_fore(FIELD *field, /* field to alter */
5626 chtype attr); /* attribute to set */
5628 chtype field_fore(FIELD *field); /* field to query */
5629 /* returns foreground attribute */
5631 int set_field_back(FIELD *field, /* field to alter */
5632 chtype attr); /* attribute to set */
5634 chtype field_back(FIELD *field); /* field to query */
5635 /* returns background attribute */
5637 int set_field_pad(FIELD *field, /* field to alter */
5638 int pad); /* pad character to set */
5640 chtype field_pad(FIELD *field); /* field to query */
5641 /* returns present pad character */
5643 <p>Though above functions seem quite simple, using colors
5644 with set_field_fore() may be frustrating in the
5645 beginning. Let me first explain about foreground and
5646 background attributes of a field. The foreground
5647 attribute is associated with the character. That means a
5648 character in the field is printed with the attribute you
5649 have set with set_field_fore(). Background attribute is
5650 the attribute used to fill background of field, whether
5651 any character is there or not. So what about colors?
5652 Since colors are always defined in pairs, what is the
5653 right way to display colored fields? Here's an example
5654 clarifying color attributes.</p>
5656 <div class="EXAMPLE">
5657 <a name="FFOAT" id="FFOAT"></a>
5658 <p><b>Example 26. Form Attributes example</b>
5661 <pre class="PROGRAMLISTING">
5662 <span class="INLINEMEDIAOBJECT">#include <form.h>
5669 /* Initialize curses */
5674 keypad(stdscr, TRUE);
5676 /* Initialize few color pairs */
5677 init_pair(1, COLOR_WHITE, COLOR_BLUE);
5678 init_pair(2, COLOR_WHITE, COLOR_BLUE);
5680 /* Initialize the fields */
5681 field[0] = new_field(1, 10, 4, 18, 0, 0);
5682 field[1] = new_field(1, 10, 6, 18, 0, 0);
5685 /* Set field options */
5686 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */
5687 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */
5688 /* are printed in white */
5689 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5690 /* Field is filled up */
5691 set_field_back(field[1], A_UNDERLINE);
5692 field_opts_off(field[1], O_AUTOSKIP);
5694 /* Create the form and post it */
5695 my_form = new_form(field);
5699 set_current_field(my_form, field[0]); /* Set focus to the colored field */
5700 mvprintw(4, 10, "Value 1:");
5701 mvprintw(6, 10, "Value 2:");
5702 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5705 /* Loop through to get user requests */
5706 while((ch = getch()) != KEY_F(1))
5709 /* Go to next field */
5710 form_driver(my_form, REQ_NEXT_FIELD);
5711 /* Go to the end of the present buffer */
5712 /* Leaves nicely at the last character */
5713 form_driver(my_form, REQ_END_LINE);
5716 /* Go to previous field */
5717 form_driver(my_form, REQ_PREV_FIELD);
5718 form_driver(my_form, REQ_END_LINE);
5721 /* If this is a normal character, it gets */
5723 form_driver(my_form, ch);
5728 /* Un post form and free the memory */
5729 unpost_form(my_form);
5731 free_field(field[0]);
5732 free_field(field[1]);
5740 <p>Play with the color pairs and try to understand the
5741 foreground and background attributes. In my programs
5742 using color attributes, I usually set only the background
5743 with set_field_back(). Curses simply doesn't allow
5744 defining individual color attributes.</p>
5750 <h4 class="SECT3"><a name="FIELDOPTIONBITS" id=
5751 "FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4>
5753 <p>There is also a large collection of field option bits
5754 you can set to control various aspects of forms
5755 processing. You can manipulate them with these
5758 <pre class="PROGRAMLISTING">
5759 int set_field_opts(FIELD *field, /* field to alter */
5760 int attr); /* attribute to set */
5762 int field_opts_on(FIELD *field, /* field to alter */
5763 int attr); /* attributes to turn on */
5765 int field_opts_off(FIELD *field, /* field to alter */
5766 int attr); /* attributes to turn off */
5768 int field_opts(FIELD *field); /* field to query */
5770 <p>The function set_field_opts() can be used to directly
5771 set attributes of a field or you can choose to switch a
5772 few attributes on and off with field_opts_on() and
5773 field_opts_off() selectively. Anytime you can query the
5774 attributes of a field with field_opts(). The following is
5775 the list of available options. By default, all options
5778 <div class="VARIABLELIST">
5783 <p>Controls whether the field is visible on the
5784 screen. Can be used during form processing to hide
5785 or pop up fields depending on the value of parent
5792 <p>Controls whether the field is active during
5793 forms processing (i.e. visited by form navigation
5794 keys). Can be used to make labels or derived fields
5795 with buffer values alterable by the forms
5796 application, not the user.</p>
5802 <p>Controls whether data is displayed during field
5803 entry. If this option is turned off on a field, the
5804 library will accept and edit data in that field,
5805 but it will not be displayed and the visible field
5806 cursor will not move. You can turn off the O_PUBLIC
5807 bit to define password fields.</p>
5813 <p>Controls whether the field's data can be
5814 modified. When this option is off, all editing
5815 requests except <tt class=
5816 "LITERAL">REQ_PREV_CHOICE</tt> and <tt class=
5817 "LITERAL">REQ_NEXT_CHOICE</tt>will fail. Such
5818 read-only fields may be useful for help
5825 <p>Controls word-wrapping in multi-line fields.
5826 Normally, when any character of a (blank-separated)
5827 word reaches the end of the current line, the
5828 entire word is wrapped to the next line (assuming
5829 there is one). When this option is off, the word
5830 will be split across the line break.</p>
5836 <p>Controls field blanking. When this option is on,
5837 entering a character at the first field position
5838 erases the entire field (except for the
5839 just-entered character).</p>
5845 <p>Controls automatic skip to next field when this
5846 one fills. Normally, when the forms user tries to
5847 type more data into a field than will fit, the
5848 editing location jumps to next field. When this
5849 option is off, the user's cursor will hang at the
5850 end of the field. This option is ignored in dynamic
5851 fields that have not reached their size limit.</p>
5857 <p>Controls whether validation is applied to blank
5858 fields. Normally, it is not; the user can leave a
5859 field blank without invoking the usual validation
5860 check on exit. If this option is off on a field,
5861 exit from it will invoke a validation check.</p>
5867 <p>Controls whether validation occurs on every
5868 exit, or only after the field is modified. Normally
5869 the latter is true. Setting O_PASSOK may be useful
5870 if your field's validation function may change
5871 during forms processing.</p>
5877 <p>Controls whether the field is fixed to its
5878 initial dimensions. If you turn this off, the field
5879 becomes dynamic and will stretch to fit entered
5885 <p>A field's options cannot be changed while the field is
5886 currently selected. However, options may be changed on
5887 posted fields that are not current.</p>
5889 <p>The option values are bit-masks and can be composed
5890 with logical-or in the obvious way. You have seen the
5891 usage of switching off O_AUTOSKIP option. The following
5892 example clarifies usage of some more options. Other
5893 options are explained where appropriate.</p>
5895 <div class="EXAMPLE">
5896 <a name="FFOOP" id="FFOOP"></a>
5897 <p><b>Example 27. Field Options Usage example</b>
5900 <pre class="PROGRAMLISTING">
5901 <span class="INLINEMEDIAOBJECT">#include <form.h>
5910 { FIELD *field[N_FIELDS];
5914 /* Initialize curses */
5918 keypad(stdscr, TRUE);
5920 /* Initialize the fields */
5921 for(i = 0; i < N_FIELDS - 1; ++i)
5922 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0);
5923 field[N_FIELDS - 1] = NULL;
5925 /* Set field options */
5926 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */
5928 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */
5929 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/
5930 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */
5931 /* after last character is entered */
5933 /* Create the form and post it */
5934 my_form = new_form(field);
5938 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */
5939 set_field_buffer(field[0], 0, "This is a static Field");
5940 /* Initialize the field */
5941 mvprintw(STARTY, STARTX - 10, "Field 1:");
5942 mvprintw(STARTY + 2, STARTX - 10, "Field 2:");
5945 /* Loop through to get user requests */
5946 while((ch = getch()) != KEY_F(1))
5949 /* Go to next field */
5950 form_driver(my_form, REQ_NEXT_FIELD);
5951 /* Go to the end of the present buffer */
5952 /* Leaves nicely at the last character */
5953 form_driver(my_form, REQ_END_LINE);
5956 /* Go to previous field */
5957 form_driver(my_form, REQ_PREV_FIELD);
5958 form_driver(my_form, REQ_END_LINE);
5961 /* If this is a normal character, it gets */
5963 form_driver(my_form, ch);
5968 /* Un post form and free the memory */
5969 unpost_form(my_form);
5971 free_field(field[0]);
5972 free_field(field[1]);
5980 <p>This example, though useless, shows the usage of
5981 options. If used properly, they can present information
5982 very effectively in a form. The second field being not
5983 O_PUBLIC, does not show the characters you are
5990 <h4 class="SECT3"><a name="FIELDSTATUS" id=
5991 "FIELDSTATUS">18.3.6. Field Status</a></h4>
5993 <p>The field status specifies whether the field has got
5994 edited or not. It is initially set to FALSE and when user
5995 enters something and the data buffer gets modified it
5996 becomes TRUE. So a field's status can be queried to find
5997 out whether it has been modified or not. The following
5998 functions can assist in those operations.</p>
6000 <pre class="PROGRAMLISTING">
6001 int set_field_status(FIELD *field, /* field to alter */
6002 int status); /* status to set */
6004 int field_status(FIELD *field); /* fetch status of field */
6006 <p>It is better to check the field's status only after
6007 after leaving the field, as data buffer might not have
6008 been updated yet as the validation is still due. To
6009 guarantee that right status is returned, call
6010 field_status() either (1) in the field's exit validation
6011 check routine, (2) from the field's or form's
6012 initialization or termination hooks, or (3) just after a
6013 REQ_VALIDATION request has been processed by the forms
6020 <h4 class="SECT3"><a name="FIELDUSERPTR" id=
6021 "FIELDUSERPTR">18.3.7. Field User Pointer</a></h4>
6023 <p>Every field structure contains one pointer that can be
6024 used by the user for various purposes. It is not touched
6025 by forms library and can be used for any purpose by the
6026 user. The following functions set and fetch user
6029 <pre class="PROGRAMLISTING">
6030 int set_field_userptr(FIELD *field,
6031 char *userptr); /* the user pointer you wish to associate */
6032 /* with the field */
6034 char *field_userptr(FIELD *field); /* fetch user pointer of the field */
6041 <h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id=
6042 "VARIABLESIZEFIELDS">18.3.8. Variable-Sized Fields</a></h4>
6044 <p>If you want a dynamically changing field with variable
6045 width, this is the feature you want to put to full use.
6046 This will allow the user to enter more data than the
6047 original size of the field and let the field grow.
6048 According to the field orientation it will scroll
6049 horizontally or vertically to incorporate the new
6052 <p>To make a field dynamically growable, the option
6053 O_STATIC should be turned off. This can be done with
6056 <pre class="PROGRAMLISTING">
6057 field_opts_off(field_pointer, O_STATIC);
6059 <p>But it is usually not advisable to allow a field to
6060 grow infinitely. You can set a maximum limit to the
6061 growth of the field with</p>
6063 <pre class="PROGRAMLISTING">
6064 int set_max_field(FIELD *field, /* Field on which to operate */
6065 int max_growth); /* maximum growth allowed for the field */
6067 <p>The field info for a dynamically growable field can be
6070 <pre class="PROGRAMLISTING">
6071 int dynamic_field_info( FIELD *field, /* Field on which to operate */
6072 int *prows, /* number of rows will be filled in this */
6073 int *pcols, /* number of columns will be filled in this*/
6074 int *pmax) /* maximum allowable growth will be filled */
6076 </pre>Though field_info work as usual, it is advisable to use this
6077 function to get the proper attributes of a dynamically growable
6079 <p>Recall the library routine new_field; a new field
6080 created with height set to one will be defined to be a
6081 one line field. A new field created with height greater
6082 than one will be defined to be a multi line field.</p>
6084 <p>A one line field with O_STATIC turned off (dynamically
6085 growable field) will contain a single fixed row, but the
6086 number of columns can increase if the user enters more
6087 data than the initial field will hold. The number of
6088 columns displayed will remain fixed and the additional
6089 data will scroll horizontally.</p>
6091 <p>A multi line field with O_STATIC turned off
6092 (dynamically growable field) will contain a fixed number
6093 of columns, but the number of rows can increase if the
6094 user enters more data than the initial field will hold.
6095 The number of rows displayed will remain fixed and the
6096 additional data will scroll vertically.</p>
6098 <p>The above two paragraphs pretty much describe a
6099 dynamically growable field's behavior. The way other
6100 parts of forms library behaves is described below:</p>
6104 <p>The field option O_AUTOSKIP will be ignored if the
6105 option O_STATIC is off and there is no maximum growth
6106 specified for the field. Currently, O_AUTOSKIP
6107 generates an automatic REQ_NEXT_FIELD form driver
6108 request when the user types in the last character
6109 position of a field. On a growable field with no
6110 maximum growth specified, there is no last character
6111 position. If a maximum growth is specified, the
6112 O_AUTOSKIP option will work as normal if the field
6113 has grown to its maximum size.</p>
6117 <p>The field justification will be ignored if the
6118 option O_STATIC is off. Currently, set_field_just can
6119 be used to JUSTIFY_LEFT, JUSTIFY_RIGHT,
6120 JUSTIFY_CENTER the contents of a one line field. A
6121 growable one line field will, by definition, grow and
6122 scroll horizontally and may contain more data than
6123 can be justified. The return from field_just will be
6128 <p>The overloaded form driver request REQ_NEW_LINE
6129 will operate the same way regardless of the
6130 O_NL_OVERLOAD form option if the field option
6131 O_STATIC is off and there is no maximum growth
6132 specified for the field. Currently, if the form
6133 option O_NL_OVERLOAD is on, REQ_NEW_LINE implicitly
6134 generates a REQ_NEXT_FIELD if called from the last
6135 line of a field. If a field can grow without bound,
6136 there is no last line, so REQ_NEW_LINE will never
6137 implicitly generate a REQ_NEXT_FIELD. If a maximum
6138 growth limit is specified and the O_NL_OVERLOAD form
6139 option is on, REQ_NEW_LINE will only implicitly
6140 generate REQ_NEXT_FIELD if the field has grown to its
6141 maximum size and the user is on the last line.</p>
6145 <p>The library call dup_field will work as usual; it
6146 will duplicate the field, including the current
6147 buffer size and contents of the field being
6148 duplicated. Any specified maximum growth will also be
6153 <p>The library call link_field will work as usual; it
6154 will duplicate all field attributes and share buffers
6155 with the field being linked. If the O_STATIC field
6156 option is subsequently changed by a field sharing
6157 buffers, how the system reacts to an attempt to enter
6158 more data into the field than the buffer will
6159 currently hold will depend on the setting of the
6160 option in the current field.</p>
6164 <p>The library call field_info will work as usual;
6165 the variable nrow will contain the value of the
6166 original call to new_field. The user should use
6167 dynamic_field_info, described above, to query the
6168 current size of the buffer.</p>
6172 <p>Some of the above points make sense only after
6173 explaining form driver. We will be looking into that in
6174 next few sections.</p>
6181 <h3 class="SECT2"><a name="FORMWINDOWS" id=
6182 "FORMWINDOWS">18.4. Form Windows</a></h3>
6184 <p>The form windows concept is pretty much similar to menu
6185 windows. Every form is associated with a main window and a
6186 sub window. The form main window displays any title or
6187 border associated or whatever the user wishes. Then the sub
6188 window contains all the fields and displays them according
6189 to their position. This gives the flexibility of
6190 manipulating fancy form displaying very easily.</p>
6192 <p>Since this is pretty much similar to menu windows, I am
6193 providing an example with out much explanation. The
6194 functions are similar and they work the same way.</p>
6196 <div class="EXAMPLE">
6197 <a name="FFOWI" id="FFOWI"></a>
6198 <p><b>Example 28. Form Windows Example</b>
6201 <pre class="PROGRAMLISTING">
6202 <span class="INLINEMEDIAOBJECT">#include <form.h>
6204 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
6210 WINDOW *my_form_win;
6213 /* Initialize curses */
6218 keypad(stdscr, TRUE);
6220 /* Initialize few color pairs */
6221 init_pair(1, COLOR_RED, COLOR_BLACK);
6223 /* Initialize the fields */
6224 field[0] = new_field(1, 10, 6, 1, 0, 0);
6225 field[1] = new_field(1, 10, 8, 1, 0, 0);
6228 /* Set field options */
6229 set_field_back(field[0], A_UNDERLINE);
6230 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
6231 /* Field is filled up */
6232 set_field_back(field[1], A_UNDERLINE);
6233 field_opts_off(field[1], O_AUTOSKIP);
6235 /* Create the form and post it */
6236 my_form = new_form(field);
6238 /* Calculate the area required for the form */
6239 scale_form(my_form, &rows, &cols);
6241 /* Create the window to be associated with the form */
6242 my_form_win = newwin(rows + 4, cols + 4, 4, 4);
6243 keypad(my_form_win, TRUE);
6245 /* Set main window and sub window */
6246 set_form_win(my_form, my_form_win);
6247 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2));
6249 /* Print a border around the main window and print a title */
6250 box(my_form_win, 0, 0);
6251 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1));
6254 wrefresh(my_form_win);
6256 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
6259 /* Loop through to get user requests */
6260 while((ch = wgetch(my_form_win)) != KEY_F(1))
6263 /* Go to next field */
6264 form_driver(my_form, REQ_NEXT_FIELD);
6265 /* Go to the end of the present buffer */
6266 /* Leaves nicely at the last character */
6267 form_driver(my_form, REQ_END_LINE);
6270 /* Go to previous field */
6271 form_driver(my_form, REQ_PREV_FIELD);
6272 form_driver(my_form, REQ_END_LINE);
6275 /* If this is a normal character, it gets */
6277 form_driver(my_form, ch);
6282 /* Un post form and free the memory */
6283 unpost_form(my_form);
6285 free_field(field[0]);
6286 free_field(field[1]);
6292 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
6306 length = strlen(string);
6307 temp = (width - length)/ 2;
6308 x = startx + (int)temp;
6309 wattron(win, color);
6310 mvwprintw(win, y, x, "%s", string);
6311 wattroff(win, color);
6321 <h3 class="SECT2"><a name="FILEDVALIDATE" id=
6322 "FILEDVALIDATE">18.5. Field Validation</a></h3>
6324 <p>By default, a field will accept any data input by the
6325 user. It is possible to attach validation to the field.
6326 Then any attempt by the user to leave the field, while it
6327 contains data that doesn't match the validation type will
6328 fail. Some validation types also have a character-validity
6329 check for each time a character is entered in the
6332 <p>Validation can be attached to a field with the following
6335 <pre class="PROGRAMLISTING">
6336 int set_field_type(FIELD *field, /* field to alter */
6337 FIELDTYPE *ftype, /* type to associate */
6338 ...); /* additional arguments*/
6339 </pre>Once set, the validation type for a field can be queried with
6341 <pre class="PROGRAMLISTING">
6342 FIELDTYPE *field_type(FIELD *field); /* field to query */
6344 <p>The form driver validates the data in a field only when
6345 data is entered by the end-user. Validation does not occur
6350 <p>the application program changes the field value by
6351 calling set_field_buffer.</p>
6355 <p>linked field values are changed indirectly -- by
6356 changing the field to which they are linked</p>
6360 <p>The following are the pre-defined validation types. You
6361 can also specify custom validation, though it is a bit
6362 tricky and cumbersome.</p>
6364 <h1 class="BRIDGEHEAD"><a name="AEN1069" id=
6365 "AEN1069"></a>TYPE_ALPHA</h1>
6367 <p>This field type accepts alphabetic data; no blanks, no
6368 digits, no special characters (this is checked at
6369 character-entry time). It is set up with:</p>
6371 <pre class="PROGRAMLISTING">
6372 int set_field_type(FIELD *field, /* field to alter */
6373 TYPE_ALPHA, /* type to associate */
6374 int width); /* minimum width of field */
6376 <p>The width argument sets a minimum width of data. The
6377 user has to enter at-least width number of characters
6378 before he can leave the field. Typically you'll want to set
6379 this to the field width; if it is greater than the field
6380 width, the validation check will always fail. A minimum
6381 width of zero makes field completion optional.</p>
6383 <h1 class="BRIDGEHEAD"><a name="AEN1073" id=
6384 "AEN1073"></a>TYPE_ALNUM</h1>
6386 <p>This field type accepts alphabetic data and digits; no
6387 blanks, no special characters (this is checked at
6388 character-entry time). It is set up with:</p>
6390 <pre class="PROGRAMLISTING">
6391 int set_field_type(FIELD *field, /* field to alter */
6392 TYPE_ALNUM, /* type to associate */
6393 int width); /* minimum width of field */
6395 <p>The width argument sets a minimum width of data. As with
6396 TYPE_ALPHA, typically you'll want to set this to the field
6397 width; if it is greater than the field width, the
6398 validation check will always fail. A minimum width of zero
6399 makes field completion optional.</p>
6401 <h1 class="BRIDGEHEAD"><a name="AEN1077" id=
6402 "AEN1077"></a>TYPE_ENUM</h1>
6404 <p>This type allows you to restrict a field's values to be
6405 among a specified set of string values (for example, the
6406 two-letter postal codes for U.S. states). It is set up
6409 <pre class="PROGRAMLISTING">
6410 int set_field_type(FIELD *field, /* field to alter */
6411 TYPE_ENUM, /* type to associate */
6412 char **valuelist; /* list of possible values */
6413 int checkcase; /* case-sensitive? */
6414 int checkunique); /* must specify uniquely? */
6416 <p>The valuelist parameter must point at a NULL-terminated
6417 list of valid strings. The checkcase argument, if true,
6418 makes comparison with the string case-sensitive.</p>
6420 <p>When the user exits a TYPE_ENUM field, the validation
6421 procedure tries to complete the data in the buffer to a
6422 valid entry. If a complete choice string has been entered,
6423 it is of course valid. But it is also possible to enter a
6424 prefix of a valid string and have it completed for you.</p>
6426 <p>By default, if you enter such a prefix and it matches
6427 more than one value in the string list, the prefix will be
6428 completed to the first matching value. But the checkunique
6429 argument, if true, requires prefix matches to be unique in
6430 order to be valid.</p>
6432 <p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests
6433 can be particularly useful with these fields.</p>
6435 <h1 class="BRIDGEHEAD"><a name="AEN1084" id=
6436 "AEN1084"></a>TYPE_INTEGER</h1>
6438 <p>This field type accepts an integer. It is set up as
6441 <pre class="PROGRAMLISTING">
6442 int set_field_type(FIELD *field, /* field to alter */
6443 TYPE_INTEGER, /* type to associate */
6444 int padding, /* # places to zero-pad to */
6445 int vmin, int vmax); /* valid range */
6447 <p>Valid characters consist of an optional leading minus
6448 and digits. The range check is performed on exit. If the
6449 range maximum is less than or equal to the minimum, the
6450 range is ignored.</p>
6452 <p>If the value passes its range check, it is padded with
6453 as many leading zero digits as necessary to meet the
6454 padding argument.</p>
6456 <p>A TYPE_INTEGER value buffer can conveniently be
6457 interpreted with the C library function atoi(3).</p>
6459 <h1 class="BRIDGEHEAD"><a name="AEN1090" id=
6460 "AEN1090"></a>TYPE_NUMERIC</h1>
6462 <p>This field type accepts a decimal number. It is set up
6465 <pre class="PROGRAMLISTING">
6466 int set_field_type(FIELD *field, /* field to alter */
6467 TYPE_NUMERIC, /* type to associate */
6468 int padding, /* # places of precision */
6469 int vmin, int vmax); /* valid range */
6471 <p>Valid characters consist of an optional leading minus
6472 and digits. possibly including a decimal point. The range
6473 check is performed on exit. If the range maximum is less
6474 than or equal to the minimum, the range is ignored.</p>
6476 <p>If the value passes its range check, it is padded with
6477 as many trailing zero digits as necessary to meet the
6478 padding argument.</p>
6480 <p>A TYPE_NUMERIC value buffer can conveniently be
6481 interpreted with the C library function atof(3).</p>
6483 <h1 class="BRIDGEHEAD"><a name="AEN1096" id=
6484 "AEN1096"></a>TYPE_REGEXP</h1>
6486 <p>This field type accepts data matching a regular
6487 expression. It is set up as follows:</p>
6489 <pre class="PROGRAMLISTING">
6490 int set_field_type(FIELD *field, /* field to alter */
6491 TYPE_REGEXP, /* type to associate */
6492 char *regexp); /* expression to match */
6494 <p>The syntax for regular expressions is that of
6495 regcomp(3). The check for regular-expression match is
6496 performed on exit.</p>
6502 <h3 class="SECT2"><a name="FORMDRIVER" id=
6503 "FORMDRIVER">18.6. Form Driver: The work horse of the forms
6506 <p>As in the menu system, form_driver() plays a very
6507 important role in forms system. All types of requests to
6508 forms system should be funneled through form_driver().</p>
6510 <pre class="PROGRAMLISTING">
6511 int form_driver(FORM *form, /* form on which to operate */
6512 int request) /* form request code */
6514 <p>As you have seen some of the examples above, you have to
6515 be in a loop looking for user input and then decide whether
6516 it is a field data or a form request. The form requests are
6517 then passed to form_driver() to do the work.</p>
6519 <p>The requests roughly can be divided into following
6520 categories. Different requests and their usage is explained
6526 <h4 class="SECT3"><a name="PAGENAVREQ" id=
6527 "PAGENAVREQ">18.6.1. Page Navigation Requests</a></h4>
6529 <p>These requests cause page-level moves through the
6530 form, triggering display of a new form screen. A form can
6531 be made of multiple pages. If you have a big form with
6532 lot of fields and logical sections, then you can divide
6533 the form into pages. The function set_new_page() to set a
6534 new page at the field specified.</p>
6536 <pre class="PROGRAMLISTING">
6537 int set_new_page(FIELD *field,/* Field at which page break to be set or unset */
6538 bool new_page_flag); /* should be TRUE to put a break */
6540 <p>The following requests allow you to move to different
6545 <p><span class="emphasis"><i class=
6546 "EMPHASIS">REQ_NEXT_PAGE</i></span> Move to the next
6551 <p><span class="emphasis"><i class=
6552 "EMPHASIS">REQ_PREV_PAGE</i></span> Move to the
6553 previous form page.</p>
6557 <p><span class="emphasis"><i class=
6558 "EMPHASIS">REQ_FIRST_PAGE</i></span> Move to the
6559 first form page.</p>
6563 <p><span class="emphasis"><i class=
6564 "EMPHASIS">REQ_LAST_PAGE</i></span> Move to the last
6569 <p>These requests treat the list as cyclic; that is,
6570 REQ_NEXT_PAGE from the last page goes to the first, and
6571 REQ_PREV_PAGE from the first page goes to the last.</p>
6577 <h4 class="SECT3"><a name="INTERFIELDNAVREQ" id=
6578 "INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation
6581 <p>These requests handle navigation between fields on the
6586 <p><span class="emphasis"><i class=
6587 "EMPHASIS">REQ_NEXT_FIELD</i></span> Move to next
6592 <p><span class="emphasis"><i class=
6593 "EMPHASIS">REQ_PREV_FIELD</i></span> Move to previous
6598 <p><span class="emphasis"><i class=
6599 "EMPHASIS">REQ_FIRST_FIELD</i></span> Move to the
6604 <p><span class="emphasis"><i class=
6605 "EMPHASIS">REQ_LAST_FIELD</i></span> Move to the last
6610 <p><span class="emphasis"><i class=
6611 "EMPHASIS">REQ_SNEXT_FIELD</i></span> Move to sorted
6616 <p><span class="emphasis"><i class=
6617 "EMPHASIS">REQ_SPREV_FIELD</i></span> Move to sorted
6622 <p><span class="emphasis"><i class=
6623 "EMPHASIS">REQ_SFIRST_FIELD</i></span> Move to the
6624 sorted first field.</p>
6628 <p><span class="emphasis"><i class=
6629 "EMPHASIS">REQ_SLAST_FIELD</i></span> Move to the
6630 sorted last field.</p>
6634 <p><span class="emphasis"><i class=
6635 "EMPHASIS">REQ_LEFT_FIELD</i></span> Move left to
6640 <p><span class="emphasis"><i class=
6641 "EMPHASIS">REQ_RIGHT_FIELD</i></span> Move right to
6646 <p><span class="emphasis"><i class=
6647 "EMPHASIS">REQ_UP_FIELD</i></span> Move up to
6652 <p><span class="emphasis"><i class=
6653 "EMPHASIS">REQ_DOWN_FIELD</i></span> Move down to
6658 <p>These requests treat the list of fields on a page as
6659 cyclic; that is, REQ_NEXT_FIELD from the last field goes
6660 to the first, and REQ_PREV_FIELD from the first field
6661 goes to the last. The order of the fields for these (and
6662 the REQ_FIRST_FIELD and REQ_LAST_FIELD requests) is
6663 simply the order of the field pointers in the form array
6664 (as set up by new_form() or set_form_fields()</p>
6666 <p>It is also possible to traverse the fields as if they
6667 had been sorted in screen-position order, so the sequence
6668 goes left-to-right and top-to-bottom. To do this, use the
6669 second group of four sorted-movement requests.</p>
6671 <p>Finally, it is possible to move between fields using
6672 visual directions up, down, right, and left. To
6673 accomplish this, use the third group of four requests.
6674 Note, however, that the position of a form for purposes
6675 of these requests is its upper-left corner.</p>
6677 <p>For example, suppose you have a multi-line field B,
6678 and two single-line fields A and C on the same line with
6679 B, with A to the left of B and C to the right of B. A
6680 REQ_MOVE_RIGHT from A will go to B only if A, B, and C
6681 all share the same first line; otherwise it will skip
6688 <h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id=
6689 "INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation
6692 <p>These requests drive movement of the edit cursor
6693 within the currently selected field.</p>
6697 <p><span class="emphasis"><i class=
6698 "EMPHASIS">REQ_NEXT_CHAR</i></span> Move to next
6703 <p><span class="emphasis"><i class=
6704 "EMPHASIS">REQ_PREV_CHAR</i></span> Move to previous
6709 <p><span class="emphasis"><i class=
6710 "EMPHASIS">REQ_NEXT_LINE</i></span> Move to next
6715 <p><span class="emphasis"><i class=
6716 "EMPHASIS">REQ_PREV_LINE</i></span> Move to previous
6721 <p><span class="emphasis"><i class=
6722 "EMPHASIS">REQ_NEXT_WORD</i></span> Move to next
6727 <p><span class="emphasis"><i class=
6728 "EMPHASIS">REQ_PREV_WORD</i></span> Move to previous
6733 <p><span class="emphasis"><i class=
6734 "EMPHASIS">REQ_BEG_FIELD</i></span> Move to beginning
6739 <p><span class="emphasis"><i class=
6740 "EMPHASIS">REQ_END_FIELD</i></span> Move to end of
6745 <p><span class="emphasis"><i class=
6746 "EMPHASIS">REQ_BEG_LINE</i></span> Move to beginning
6751 <p><span class="emphasis"><i class=
6752 "EMPHASIS">REQ_END_LINE</i></span> Move to end of
6757 <p><span class="emphasis"><i class=
6758 "EMPHASIS">REQ_LEFT_CHAR</i></span> Move left in
6763 <p><span class="emphasis"><i class=
6764 "EMPHASIS">REQ_RIGHT_CHAR</i></span> Move right in
6769 <p><span class="emphasis"><i class=
6770 "EMPHASIS">REQ_UP_CHAR</i></span> Move up in
6775 <p><span class="emphasis"><i class=
6776 "EMPHASIS">REQ_DOWN_CHAR</i></span> Move down in
6781 <p>Each word is separated from the previous and next
6782 characters by whitespace. The commands to move to
6783 beginning and end of line or field look for the first or
6784 last non-pad character in their ranges.</p>
6790 <h4 class="SECT3"><a name="SCROLLREQ" id=
6791 "SCROLLREQ">18.6.4. Scrolling Requests</a></h4>
6793 <p>Fields that are dynamic and have grown and fields
6794 explicitly created with offscreen rows are scrollable.
6795 One-line fields scroll horizontally; multi-line fields
6796 scroll vertically. Most scrolling is triggered by editing
6797 and intra-field movement (the library scrolls the field
6798 to keep the cursor visible). It is possible to explicitly
6799 request scrolling with the following requests:</p>
6803 <p><span class="emphasis"><i class=
6804 "EMPHASIS">REQ_SCR_FLINE</i></span> Scroll vertically
6809 <p><span class="emphasis"><i class=
6810 "EMPHASIS">REQ_SCR_BLINE</i></span> Scroll vertically
6811 backward a line.</p>
6815 <p><span class="emphasis"><i class=
6816 "EMPHASIS">REQ_SCR_FPAGE</i></span> Scroll vertically
6821 <p><span class="emphasis"><i class=
6822 "EMPHASIS">REQ_SCR_BPAGE</i></span> Scroll vertically
6823 backward a page.</p>
6827 <p><span class="emphasis"><i class=
6828 "EMPHASIS">REQ_SCR_FHPAGE</i></span> Scroll
6829 vertically forward half a page.</p>
6833 <p><span class="emphasis"><i class=
6834 "EMPHASIS">REQ_SCR_BHPAGE</i></span> Scroll
6835 vertically backward half a page.</p>
6839 <p><span class="emphasis"><i class=
6840 "EMPHASIS">REQ_SCR_FCHAR</i></span> Scroll
6841 horizontally forward a character.</p>
6845 <p><span class="emphasis"><i class=
6846 "EMPHASIS">REQ_SCR_BCHAR</i></span> Scroll
6847 horizontally backward a character.</p>
6851 <p><span class="emphasis"><i class=
6852 "EMPHASIS">REQ_SCR_HFLINE</i></span> Scroll
6853 horizontally one field width forward.</p>
6857 <p><span class="emphasis"><i class=
6858 "EMPHASIS">REQ_SCR_HBLINE</i></span> Scroll
6859 horizontally one field width backward.</p>
6863 <p><span class="emphasis"><i class=
6864 "EMPHASIS">REQ_SCR_HFHALF</i></span> Scroll
6865 horizontally one half field width forward.</p>
6869 <p><span class="emphasis"><i class=
6870 "EMPHASIS">REQ_SCR_HBHALF</i></span> Scroll
6871 horizontally one half field width backward.</p>
6875 <p>For scrolling purposes, a page of a field is the
6876 height of its visible part.</p>
6882 <h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5.
6883 Editing Requests</a></h4>
6885 <p>When you pass the forms driver an ASCII character, it
6886 is treated as a request to add the character to the
6887 field's data buffer. Whether this is an insertion or a
6888 replacement depends on the field's edit mode (insertion
6891 <p>The following requests support editing the field and
6892 changing the edit mode:</p>
6896 <p><span class="emphasis"><i class=
6897 "EMPHASIS">REQ_INS_MODE</i></span> Set insertion
6902 <p><span class="emphasis"><i class=
6903 "EMPHASIS">REQ_OVL_MODE</i></span> Set overlay
6908 <p><span class="emphasis"><i class=
6909 "EMPHASIS">REQ_NEW_LINE</i></span> New line request
6910 (see below for explanation).</p>
6914 <p><span class="emphasis"><i class=
6915 "EMPHASIS">REQ_INS_CHAR</i></span> Insert space at
6916 character location.</p>
6920 <p><span class="emphasis"><i class=
6921 "EMPHASIS">REQ_INS_LINE</i></span> Insert blank line
6922 at character location.</p>
6926 <p><span class="emphasis"><i class=
6927 "EMPHASIS">REQ_DEL_CHAR</i></span> Delete character
6932 <p><span class="emphasis"><i class=
6933 "EMPHASIS">REQ_DEL_PREV</i></span> Delete previous
6938 <p><span class="emphasis"><i class=
6939 "EMPHASIS">REQ_DEL_LINE</i></span> Delete line at
6944 <p><span class="emphasis"><i class=
6945 "EMPHASIS">REQ_DEL_WORD</i></span> Delete word at
6950 <p><span class="emphasis"><i class=
6951 "EMPHASIS">REQ_CLR_EOL</i></span> Clear to end of
6956 <p><span class="emphasis"><i class=
6957 "EMPHASIS">REQ_CLR_EOF</i></span> Clear to end of
6962 <p><span class="emphasis"><i class=
6963 "EMPHASIS">REQ_CLR_FIELD</i></span> Clear entire
6968 <p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV
6969 requests is complicated and partly controlled by a pair
6970 of forms options. The special cases are triggered when
6971 the cursor is at the beginning of a field, or on the last
6972 line of the field.</p>
6974 <p>First, we consider REQ_NEW_LINE:</p>
6976 <p>The normal behavior of REQ_NEW_LINE in insert mode is
6977 to break the current line at the position of the edit
6978 cursor, inserting the portion of the current line after
6979 the cursor as a new line following the current and moving
6980 the cursor to the beginning of that new line (you may
6981 think of this as inserting a newline in the field
6984 <p>The normal behavior of REQ_NEW_LINE in overlay mode is
6985 to clear the current line from the position of the edit
6986 cursor to end of line. The cursor is then moved to the
6987 beginning of the next line.</p>
6989 <p>However, REQ_NEW_LINE at the beginning of a field, or
6990 on the last line of a field, instead does a
6991 REQ_NEXT_FIELD. O_NL_OVERLOAD option is off, this special
6992 action is disabled.</p>
6994 <p>Now, let us consider REQ_DEL_PREV:</p>
6996 <p>The normal behavior of REQ_DEL_PREV is to delete the
6997 previous character. If insert mode is on, and the cursor
6998 is at the start of a line, and the text on that line will
6999 fit on the previous one, it instead appends the contents
7000 of the current line to the previous one and deletes the
7001 current line (you may think of this as deleting a newline
7002 from the field buffer).</p>
7004 <p>However, REQ_DEL_PREV at the beginning of a field is
7005 instead treated as a REQ_PREV_FIELD.</p>
7007 <p>If the O_BS_OVERLOAD option is off, this special
7008 action is disabled and the forms driver just returns
7009 E_REQUEST_DENIED.</p>
7015 <h4 class="SECT3"><a name="ORDERREQ" id=
7016 "ORDERREQ">18.6.6. Order Requests</a></h4>
7018 <p>If the type of your field is ordered, and has
7019 associated functions for getting the next and previous
7020 values of the type from a given value, there are requests
7021 that can fetch that value into the field buffer:</p>
7025 <p><span class="emphasis"><i class=
7026 "EMPHASIS">REQ_NEXT_CHOICE</i></span> Place the
7027 successor value of the current value in the
7032 <p><span class="emphasis"><i class=
7033 "EMPHASIS">REQ_PREV_CHOICE</i></span> Place the
7034 predecessor value of the current value in the
7039 <p>Of the built-in field types, only TYPE_ENUM has
7040 built-in successor and predecessor functions. When you
7041 define a field type of your own (see Custom Validation
7042 Types), you can associate our own ordering functions.</p>
7048 <h4 class="SECT3"><a name="APPLICCOMMANDS" id=
7049 "APPLICCOMMANDS">18.6.7. Application Commands</a></h4>
7051 <p>Form requests are represented as integers above the
7052 curses value greater than KEY_MAX and less than or equal
7053 to the constant MAX_COMMAND. A value within this range
7054 gets ignored by form_driver(). So this can be used for
7055 any purpose by the application. It can be treated as an
7056 application specific action and take corresponding
7065 <h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and
7066 Widget Libraries</a></h2>
7068 <p>Now that you have seen the capabilities of ncurses and its
7069 sister libraries, you are rolling your sleeves up and gearing
7070 for a project that heavily manipulates screen. But wait.. It
7071 can be pretty difficult to write and maintain complex GUI
7072 widgets in plain ncurses or even with the additional
7073 libraries. There are some ready-to-use tools and widget
7074 libraries that can be used instead of writing your own
7075 widgets. You can use some of them, get ideas from the code,
7076 or even extend them.</p>
7081 <h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses
7082 Development Kit)</a></h3>
7084 <p>In the author's words</p>
7086 <p><span class="emphasis"><i class="EMPHASIS">CDK stands
7087 for 'Curses Development Kit' and it currently contains 21
7088 ready to use widgets which facilitate the speedy
7089 development of full screen curses programs.</i></span>
7092 <p>The kit provides some useful widgets, which can be used
7093 in your programs directly. It is pretty well written and
7094 the documentation is very good. The examples in the
7095 examples directory can be a good place to start for
7096 beginners. The CDK can be downloaded from <a href=
7097 "https://invisible-island.net/cdk/" target=
7098 "_top">https://invisible-island.net/cdk/</a> . Follow the
7099 instructions in README file to install it.</p>
7104 <h4 class="SECT3"><a name="WIDGETLIST" id=
7105 "WIDGETLIST">19.1.1. Widget List</a></h4>
7107 <p>The following is the list of widgets provided with cdk
7108 and their description.</p>
7110 <pre class="PROGRAMLISTING">
7111 Widget Type Quick Description
7112 ===========================================================================
7113 Alphalist Allows a user to select from a list of words, with
7114 the ability to narrow the search list by typing in a
7115 few characters of the desired word.
7116 Buttonbox This creates a multiple button widget.
7117 Calendar Creates a little simple calendar widget.
7118 Dialog Prompts the user with a message, and the user
7119 can pick an answer from the buttons provided.
7120 Entry Allows the user to enter various types of information.
7121 File Selector A file selector built from Cdk base widgets. This
7122 example shows how to create more complicated widgets
7123 using the Cdk widget library.
7124 Graph Draws a graph.
7125 Histogram Draws a histogram.
7126 Item List Creates a pop up field which allows the user to select
7127 one of several choices in a small field. Very useful
7128 for things like days of the week or month names.
7129 Label Displays messages in a pop up box, or the label can be
7130 considered part of the screen.
7131 Marquee Displays a message in a scrolling marquee.
7132 Matrix Creates a complex matrix with lots of options.
7133 Menu Creates a pull-down menu interface.
7134 Multiple Line Entry A multiple line entry field. Very useful
7135 for long fields. (like a description
7137 Radio List Creates a radio button list.
7138 Scale Creates a numeric scale. Used for allowing a user to
7139 pick a numeric value and restrict them to a range of
7141 Scrolling List Creates a scrolling list/menu list.
7142 Scrolling Window Creates a scrolling log file viewer. Can add
7143 information into the window while its running.
7144 A good widget for displaying the progress of
7145 something. (akin to a console window)
7146 Selection List Creates a multiple option selection list.
7147 Slider Akin to the scale widget, this widget provides a
7148 visual slide bar to represent the numeric value.
7149 Template Creates a entry field with character sensitive
7150 positions. Used for pre-formatted fields like
7151 dates and phone numbers.
7152 Viewer This is a file/information viewer. Very useful
7153 when you need to display loads of information.
7154 ===========================================================================
7156 <p>A few of the widgets are modified by Thomas Dickey in
7157 recent versions.</p>
7163 <h4 class="SECT3"><a name="CDKATTRACT" id=
7164 "CDKATTRACT">19.1.2. Some Attractive Features</a></h4>
7166 <p>Apart from making our life easier with readily usable
7167 widgets, cdk solves one frustrating problem with printing
7168 multi colored strings, justified strings elegantly.
7169 Special formatting tags can be embedded in the strings
7170 which are passed to CDK functions. For Example</p>
7172 <p>If the string</p>
7174 <pre class="PROGRAMLISTING">
7175 "</B/1>This line should have a yellow foreground and a blue
7176 background.<!1>"
7178 <p>given as a parameter to newCDKLabel(), it prints the
7179 line with yellow foreground and blue background. There
7180 are other tags available for justifying string, embedding
7181 special drawing characters etc.. Please refer to the man
7182 page cdk_display(3X) for details. The man page explains
7183 the usage with nice examples.</p>
7189 <h4 class="SECT3"><a name="CDKCONCLUSION" id=
7190 "CDKCONCLUSION">19.1.3. Conclusion</a></h4>
7192 <p>All in all, CDK is a well-written package of widgets,
7193 which if used properly can form a strong frame work for
7194 developing complex GUI.</p>
7201 <h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The
7204 <p>Long long ago, in September 1994, when few people knew
7205 linux, Jeff Tranter wrote an <a href=
7206 "http://www2.linuxjournal.com/lj-issues/issue5/2807.html"
7207 target="_top">article</a> on dialog in Linux Journal. He
7208 starts the article with these words..</p>
7210 <p><span class="emphasis"><i class="EMPHASIS">Linux is
7211 based on the Unix operating system, but also features a
7212 number of unique and useful kernel features and application
7213 programs that often go beyond what is available under Unix.
7214 One little-known gem is "dialog", a utility for creating
7215 professional-looking dialog boxes from within shell
7216 scripts. This article presents a tutorial introduction to
7217 the dialog utility, and shows examples of how and where it
7218 can be used</i></span>
7221 <p>As he explains, dialog is a real gem in making
7222 professional-looking dialog boxes with ease. It creates a
7223 variety of dialog boxes, menus, check lists etc.. It is
7224 usually installed by default. If not, you can download it
7225 from <a href="https://invisible-island.net/dialog/" target=
7226 "_top">Thomas Dickey</a>'s site.</p>
7228 <p>The above-mentioned article gives a very good overview
7229 of its uses and capabilites. The man page has more details.
7230 It can be used in variety of situations. One good example
7231 is building of linux kernel in text mode. Linux kernel uses
7232 a modified version of dialog tailored for its needs.</p>
7234 <p>dialog was initially designed to be used with shell
7235 scripts. If you want to use its functionality in a c
7236 program, then you can use libdialog. The documentation
7237 regarding this is sparse. Definitive reference is the
7238 dialog.h header file which comes with the library. You may
7239 need to hack here and there to get the required output. The
7240 source is easily customizable. I have used it on a number
7241 of occasions by modifying the code.</p>
7247 <h3 class="SECT2"><a name="PERLCURSES" id=
7248 "PERLCURSES">19.3. Perl Curses Modules CURSES::FORM and
7249 CURSES::WIDGETS</a></h3>
7251 <p>The perl module Curses, Curses::Form and Curses::Widgets
7252 give access to curses from perl. If you have curses and
7253 basic perl is installed, you can get these modules from
7254 <a href="http://www.cpan.org/modules/01modules.index.html"
7255 target="_top">CPAN All Modules page</a>. Get the three
7256 zipped modules in the Curses category. Once installed you
7257 can use these modules from perl scripts like any other
7258 module. For more information on perl modules see perlmod
7259 man page. The above modules come with good documentation
7260 and they have some demo scripts to test the functionality.
7261 Though the widgets provided are very rudimentary, these
7262 modules provide good access to curses library from
7265 <p>Some of my code examples are converted to perl by
7266 Anuradha Ratnaweera and they are available in the
7267 <tt class="LITERAL">perl</tt> directory.</p>
7269 <p>For more information see man pages Curses(3) ,
7270 Curses::Form(3) and Curses::Widgets(3). These pages are
7271 installed only when the above modules are acquired and
7279 <h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20.
7280 Just For Fun !!!</a></h2>
7282 <p>This section contains few programs written by me just for
7283 fun. They don't signify a better programming practice or the
7284 best way of using ncurses. They are provided here so as to
7285 allow beginners to get ideas and add more programs to this
7286 section. If you have written a couple of nice, simple
7287 programs in curses and want them to included here, contact
7288 <a href="mailto:ppadala@gmail.com" target="_top">me</a>.</p>
7293 <h3 class="SECT2"><a name="GAMEOFLIFE" id=
7294 "GAMEOFLIFE">20.1. The Game of Life</a></h3>
7296 <p>Game of life is a wonder of math. In <a href=
7297 "http://www.math.com/students/wonders/life/life.html"
7298 target="_top">Paul Callahan</a>'s words</p>
7300 <pre class="PROGRAMLISTING">
7301 <span class="emphasis"><i class=
7302 "EMPHASIS">The Game of Life (or simply Life) is not a game in the conventional sense. There
7303 are no players, and no winning or losing. Once the "pieces" are placed in the
7304 starting position, the rules determine everything that happens later.
7305 Nevertheless, Life is full of surprises! In most cases, it is impossible to look
7306 at a starting position (or pattern) and see what will happen in the future. The
7307 only way to find out is to follow the rules of the game.</i></span>
7309 <p>This program starts with a simple inverted U pattern and
7310 shows how wonderful life works. There is a lot of room for
7311 improvement in the program. You can let the user enter
7312 pattern of his choice or even take input from a file. You
7313 can also change rules and play with a lot of variations.
7314 Search on <a href="http://www.google.com" target=
7315 "_top">google</a> for interesting information on game of
7318 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7319 JustForFun/life.c</i></span>
7326 <h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic
7329 <p>Magic Square, another wonder of math, is very simple to
7330 understand but very difficult to make. In a magic square
7331 sum of the numbers in each row, each column is equal. Even
7332 diagnol sum can be equal. There are many variations which
7333 have special properties.</p>
7335 <p>This program creates a simple magic square of odd
7338 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7339 JustForFun/magic.c</i></span>
7346 <h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers
7349 <p>The famous towers of hanoi solver. The aim of the game
7350 is to move the disks on the first peg to last peg, using
7351 middle peg as a temporary stay. The catch is not to place a
7352 larger disk over a small disk at any time.</p>
7354 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7355 JustForFun/hanoi.c</i></span>
7362 <h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens
7365 <p>The objective of the famous N-Queen puzzle is to put N
7366 queens on a N X N chess board without attacking each
7369 <p>This program solves it with a simple backtracking
7372 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7373 JustForFun/queens.c</i></span>
7380 <h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5.
7383 <p>A fun game, if you have time to kill.</p>
7385 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7386 JustForFun/shuffle.c</i></span>
7393 <h3 class="SECT2"><a name="TT" id="TT">20.6. Typing
7396 <p>A simple typing tutor, I created more out of need than
7397 for ease of use. If you know how to put your fingers
7398 correctly on the keyboard, but lack practice, this can be
7401 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7402 JustForFun/tt.c</i></span>
7410 <h2 class="SECT1"><a name="REF" id="REF">21. References</a></h2>
7414 <p>NCURSES man pages</p>
7418 <p>NCURSES FAQ at <a href=
7419 "https://invisible-island.net/ncurses/ncurses.faq.html"
7421 "_top">https://invisible-island.net/ncurses/ncurses.faq.html</a></p>
7425 <p>Writing programs with NCURSES by Eric Raymond and Zeyd
7426 M. Ben-Halim at <a href=
7427 "https://invisible-island.net/ncurses/ncurses-intro.html"
7429 "_top">https://invisible-island.net/ncurses/ncurses-intro.html</a>
7430 - somewhat obsolete. I was inspired by this document and
7431 the structure of this HOWTO follows from the original
projects / ncurses.git / blob