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18 <h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES
19 Programming HOWTO</a></h1>
21 <h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep
24 <div class="AFFILIATION">
26 <p class="ADDRESS"><code class="EMAIL"><<a href=
27 "mailto:ppadala@gmail.com">ppadala@gmail.com</a>></code></p>
31 <p class="PUBDATE">v1.9, 2005-06-20<br></p>
33 <div class="REVHISTORY">
34 <table width="100%" border="0">
36 <th align="left" valign="top" colspan="3"><b>Revision
41 <td align="left">Revision 1.9</td>
43 <td align="left">2005-06-20</td>
45 <td align="left">Revised by: ppadala</td>
49 <td align="left" colspan="3">The license has been
50 changed to the MIT-style license used by NCURSES. Note
51 that the programs are also re-licensed under this.</td>
55 <td align="left">Revision 1.8</td>
57 <td align="left">2005-06-17</td>
59 <td align="left">Revised by: ppadala</td>
63 <td align="left" colspan="3">Lots of updates. Added
64 references and perl examples. Changes to examples. Many
65 grammatical and stylistic changes to the content.
66 Changes to NCURSES history.</td>
70 <td align="left">Revision 1.7.1</td>
72 <td align="left">2002-06-25</td>
74 <td align="left">Revised by: ppadala</td>
78 <td align="left" colspan="3">Added a README file for
79 building and instructions for building from
84 <td align="left">Revision 1.7</td>
86 <td align="left">2002-06-25</td>
88 <td align="left">Revised by: ppadala</td>
92 <td align="left" colspan="3">Added "Other formats"
93 section and made a lot of fancy changes to the
94 programs. Inlining of programs is gone.</td>
98 <td align="left">Revision 1.6.1</td>
100 <td align="left">2002-02-24</td>
102 <td align="left">Revised by: ppadala</td>
106 <td align="left" colspan="3">Removed the old Changelog
107 section, cleaned the makefiles</td>
111 <td align="left">Revision 1.6</td>
113 <td align="left">2002-02-16</td>
115 <td align="left">Revised by: ppadala</td>
119 <td align="left" colspan="3">Corrected a lot of
120 spelling mistakes, added ACS variables section</td>
124 <td align="left">Revision 1.5</td>
126 <td align="left">2002-01-05</td>
128 <td align="left">Revised by: ppadala</td>
132 <td align="left" colspan="3">Changed structure to
133 present proper TOC</td>
137 <td align="left">Revision 1.3.1</td>
139 <td align="left">2001-07-26</td>
141 <td align="left">Revised by: ppadala</td>
145 <td align="left" colspan="3">Corrected maintainers
146 paragraph, Corrected stable release number</td>
150 <td align="left">Revision 1.3</td>
152 <td align="left">2001-07-24</td>
154 <td align="left">Revised by: ppadala</td>
158 <td align="left" colspan="3">Added copyright notices to
159 main document (LDP license) and programs (GPL),
160 Corrected printw_example.</td>
164 <td align="left">Revision 1.2</td>
166 <td align="left">2001-06-05</td>
168 <td align="left">Revised by: ppadala</td>
172 <td align="left" colspan="3">Incorporated ravi's
173 changes. Mainly to introduction, menu, form, justforfun
178 <td align="left">Revision 1.1</td>
180 <td align="left">2001-05-22</td>
182 <td align="left">Revised by: ppadala</td>
186 <td align="left" colspan="3">Added "a word about
187 window" section, Added scanw_example.</td>
193 <div class="ABSTRACT">
194 <a name="AEN67" id="AEN67"></a>
196 <p><span class="emphasis"><i class="EMPHASIS">This
197 document is intended to be an "All in One" guide for
198 programming with ncurses and its sister libraries. We
199 graduate from a simple "Hello World" program to more
200 complex form manipulation. No prior experience in ncurses
201 is assumed. Send comments to <a href=
202 "mailto:ppadala@gmail.com" target="_top">this
203 address</a></i></span></p>
211 <dt><b>Table of Contents</b></dt>
213 <dt>1. <a href="#INTRO">Introduction</a></dt>
217 <dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt>
219 <dt>1.2. <a href="#WHATCANWEDO">What we can do with
222 <dt>1.3. <a href="#WHERETOGETIT">Where to get
225 <dt>1.4. <a href="#PURPOSE">Purpose/Scope of the
228 <dt>1.5. <a href="#ABOUTPROGRAMS">About the
231 <dt>1.6. <a href="#OTHERFORMATS">Other Formats of the
236 <dt>1.6.1. <a href="#LISTFORMATS">Readily available
237 formats from tldp.org</a></dt>
239 <dt>1.6.2. <a href="#BUILDSOURCE">Building from
244 <dt>1.7. <a href="#CREDITS">Credits</a></dt>
246 <dt>1.8. <a href="#WISHLIST">Wish List</a></dt>
248 <dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt>
252 <dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt>
256 <dt>2.1. <a href="#COMPILECURSES">Compiling With the
257 NCURSES Library</a></dt>
259 <dt>2.2. <a href="#DISSECTION">Dissection</a></dt>
263 <dt>2.2.1. <a href="#ABOUT-INITSCR">About
266 <dt>2.2.2. <a href="#MYST-REFRESH">The mysterious
269 <dt>2.2.3. <a href="#ABOUT-ENDWIN">About
276 <dt>3. <a href="#GORY">The Gory Details</a></dt>
278 <dt>4. <a href="#INIT">Initialization</a></dt>
282 <dt>4.1. <a href="#ABOUTINIT">Initialization
285 <dt>4.2. <a href="#RAWCBREAK">raw() and
288 <dt>4.3. <a href="#ECHONOECHO">echo() and
291 <dt>4.4. <a href="#KEYPAD">keypad()</a></dt>
293 <dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt>
295 <dt>4.6. <a href="#MISCINIT">Miscellaneous
296 Initialization functions</a></dt>
298 <dt>4.7. <a href="#INITEX">An Example</a></dt>
302 <dt>5. <a href="#AWORDWINDOWS">A Word about
305 <dt>6. <a href="#PRINTW">Output functions</a></dt>
309 <dt>6.1. <a href="#ADDCHCLASS">addch() class of
312 <dt>6.2. <a href="#AEN298">mvaddch(), waddch() and
315 <dt>6.3. <a href="#PRINTWCLASS">printw() class of
320 <dt>6.3.1. <a href="#PRINTWMVPRINTW">printw() and
323 <dt>6.3.2. <a href="#WPRINTWMVWPRINTW">wprintw()
324 and mvwprintw</a></dt>
326 <dt>6.3.3. <a href="#VWPRINTW">vwprintw()</a></dt>
328 <dt>6.3.4. <a href="#SIMPLEPRINTWEX">A Simple
329 printw example</a></dt>
333 <dt>6.4. <a href="#ADDSTRCLASS">addstr() class of
336 <dt>6.5. <a href="#ACAUTION">A word of caution</a></dt>
340 <dt>7. <a href="#SCANW">Input functions</a></dt>
344 <dt>7.1. <a href="#GETCHCLASS">getch() class of
347 <dt>7.2. <a href="#SCANWCLASS">scanw() class of
352 <dt>7.2.1. <a href="#SCANWMVSCANW">scanw() and
355 <dt>7.2.2. <a href="#WSCANWMVWSCANW">wscanw() and
358 <dt>7.2.3. <a href="#VWSCANW">vwscanw()</a></dt>
362 <dt>7.3. <a href="#GETSTRCLASS">getstr() class of
365 <dt>7.4. <a href="#GETSTREX">Some examples</a></dt>
369 <dt>8. <a href="#ATTRIB">Attributes</a></dt>
373 <dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt>
375 <dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs
378 <dt>8.3. <a href="#ATTRGET">attr_get()</a></dt>
380 <dt>8.4. <a href="#ATTRFUNCS">attr_ functions</a></dt>
382 <dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt>
384 <dt>8.6. <a href="#CHGAT">chgat() functions</a></dt>
388 <dt>9. <a href="#WINDOWS">Windows</a></dt>
392 <dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt>
394 <dt>9.2. <a href="#LETBEWINDOW">Let there be a Window
397 <dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt>
399 <dt>9.4. <a href="#OTHERSTUFF">The other stuff in the
402 <dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border
407 <dt>10. <a href="#COLOR">Colors</a></dt>
411 <dt>10.1. <a href="#COLORBASICS">The basics</a></dt>
413 <dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color
416 <dt>10.3. <a href="#COLORCONTENT">Color
421 <dt>11. <a href="#KEYS">Interfacing with the key
426 <dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt>
428 <dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage
433 <dt>12. <a href="#MOUSE">Interfacing with the
438 <dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt>
440 <dt>12.2. <a href="#GETTINGEVENTS">Getting the
443 <dt>12.3. <a href="#MOUSETOGETHER">Putting it all
446 <dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous
451 <dt>13. <a href="#SCREEN">Screen Manipulation</a></dt>
455 <dt>13.1. <a href="#GETYX">getyx() functions</a></dt>
457 <dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt>
459 <dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt>
463 <dt>14. <a href="#MISC">Miscellaneous features</a></dt>
467 <dt>14.1. <a href="#CURSSET">curs_set()</a></dt>
469 <dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving
472 <dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt>
476 <dt>15. <a href="#OTHERLIB">Other libraries</a></dt>
478 <dt>16. <a href="#PANELS">Panel Library</a></dt>
482 <dt>16.1. <a href="#PANELBASICS">The Basics</a></dt>
484 <dt>16.2. <a href="#COMPILEPANELS">Compiling With the
485 Panels Library</a></dt>
487 <dt>16.3. <a href="#PANELBROWSING">Panel Window
490 <dt>16.4. <a href="#USERPTRUSING">Using User
493 <dt>16.5. <a href="#PANELMOVERESIZE">Moving and
494 Resizing Panels</a></dt>
496 <dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing
499 <dt>16.7. <a href="#PANELABOVE">panel_above() and
500 panel_below() Functions</a></dt>
504 <dt>17. <a href="#MENUS">Menus Library</a></dt>
508 <dt>17.1. <a href="#MENUBASICS">The Basics</a></dt>
510 <dt>17.2. <a href="#COMPILEMENUS">Compiling With the
511 Menu Library</a></dt>
513 <dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work
514 horse of the menu system</a></dt>
516 <dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt>
518 <dt>17.5. <a href="#SCROLLMENUS">Scrolling
521 <dt>17.6. <a href="#MULTICOLUMN">Multi Columnar
524 <dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued
527 <dt>17.8. <a href="#MENUOPT">Menu Options</a></dt>
529 <dt>17.9. <a href="#MENUUSERPTR">The useful User
534 <dt>18. <a href="#FORMS">Forms Library</a></dt>
538 <dt>18.1. <a href="#FORMBASICS">The Basics</a></dt>
540 <dt>18.2. <a href="#COMPILEFORMS">Compiling With the
541 Forms Library</a></dt>
543 <dt>18.3. <a href="#PLAYFIELDS">Playing with
548 <dt>18.3.1. <a href="#FETCHINFO">Fetching Size and
549 Location of Field</a></dt>
551 <dt>18.3.2. <a href="#MOVEFIELD">Moving the
554 <dt>18.3.3. <a href="#JUSTIFYFIELD">Field
555 Justification</a></dt>
557 <dt>18.3.4. <a href="#FIELDDISPATTRIB">Field
558 Display Attributes</a></dt>
560 <dt>18.3.5. <a href="#FIELDOPTIONBITS">Field Option
563 <dt>18.3.6. <a href="#FIELDSTATUS">Field
566 <dt>18.3.7. <a href="#FIELDUSERPTR">Field User
570 "#VARIABLESIZEFIELDS">Variable-Sized
575 <dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt>
577 <dt>18.5. <a href="#FILEDVALIDATE">Field
580 <dt>18.6. <a href="#FORMDRIVER">Form Driver: The work
581 horse of the forms system</a></dt>
585 <dt>18.6.1. <a href="#PAGENAVREQ">Page Navigation
588 <dt>18.6.2. <a href="#INTERFIELDNAVREQ">Inter-Field
589 Navigation Requests</a></dt>
591 <dt>18.6.3. <a href="#INTRAFIELDNAVREQ">Intra-Field
592 Navigation Requests</a></dt>
594 <dt>18.6.4. <a href="#SCROLLREQ">Scrolling
597 <dt>18.6.5. <a href="#EDITREQ">Editing
600 <dt>18.6.6. <a href="#ORDERREQ">Order
603 <dt>18.6.7. <a href="#APPLICCOMMANDS">Application
610 <dt>19. <a href="#TOOLS">Tools and Widget
615 <dt>19.1. <a href="#CDK">CDK (Curses Development
620 <dt>19.1.1. <a href="#WIDGETLIST">Widget
623 <dt>19.1.2. <a href="#CDKATTRACT">Some Attractive
627 "#CDKCONCLUSION">Conclusion</a></dt>
631 <dt>19.2. <a href="#DIALOG">The dialog</a></dt>
633 <dt>19.3. <a href="#PERLCURSES">Perl Curses Modules
634 CURSES::FORM and CURSES::WIDGETS</a></dt>
638 <dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt>
642 <dt>20.1. <a href="#GAMEOFLIFE">The Game of
645 <dt>20.2. <a href="#MAGIC">Magic Square</a></dt>
647 <dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt>
649 <dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt>
651 <dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt>
653 <dt>20.6. <a href="#TT">Typing Tutor</a></dt>
657 <dt>21. <a href="#REF">References</a></dt>
662 <h2 class="SECT1"><a name="INTRO" id="INTRO">1.
663 Introduction</a></h2>
665 <p>In the olden days of teletype terminals, terminals were
666 away from computers and were connected to them through serial
667 cables. The terminals could be configured by sending a series
668 of bytes. All the capabilities (such as moving the cursor to
669 a new location, erasing part of the screen, scrolling the
670 screen, changing modes etc.) of terminals could be accessed
671 through these series of bytes. These control seeuqnces are
672 usually called escape sequences, because they start with an
673 escape(0x1B) character. Even today, with proper emulation, we
674 can send escape sequences to the emulator and achieve the
675 same effect on a terminal window.</p>
677 <p>Suppose you wanted to print a line in color. Try typing
678 this on your console.</p>
679 <pre class="PROGRAMLISTING">
680 echo "^[[0;31;40mIn Color"
683 <p>The first character is an escape character, which looks
684 like two characters ^ and [. To be able to print it, you have
685 to press CTRL+V and then the ESC key. All the others are
686 normal printable characters. You should be able to see the
687 string "In Color" in red. It stays that way and to revert
688 back to the original mode type this.</p>
689 <pre class="PROGRAMLISTING">
693 <p>Now, what do these magic characters mean? Difficult to
694 comprehend? They might even be different for different
695 terminals. So the designers of UNIX invented a mechanism
696 named <tt class="LITERAL">termcap</tt>. It is a file that
697 lists all the capabilities of a particular terminal, along
698 with the escape sequences needed to achieve a particular
699 effect. In the later years, this was replaced by <tt class=
700 "LITERAL">terminfo</tt>. Without delving too much into
701 details, this mechanism allows application programs to query
702 the terminfo database and obtain the control characters to be
703 sent to a terminal or terminal emulator.</p>
708 <h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is
711 <p>You might be wondering, what the import of all this
712 technical gibberish is. In the above scenario, every
713 application program is supposed to query the terminfo and
714 perform the necessary stuff (sending control characters
715 etc.). It soon became difficult to manage this complexity
716 and this gave birth to 'CURSES'. Curses is a pun on the
717 name "cursor optimization". The Curses library forms a
718 wrapper over working with raw terminal codes, and provides
719 highly flexible and efficient API (Application Programming
720 Interface). It provides functions to move the cursor,
721 create windows, produce colors, play with mouse etc. The
722 application programs need not worry about the underlying
723 terminal capabilities.</p>
725 <p>So what is NCURSES? NCURSES is a clone of the original
726 System V Release 4.0 (SVr4) curses. It is a freely
727 distributable library, fully compatible with older version
728 of curses. In short, it is a library of functions that
729 manages an application's display on character-cell
730 terminals. In the remainder of the document, the terms
731 curses and ncurses are used interchangeably.</p>
733 <p>A detailed history of NCURSES can be found in the NEWS
734 file from the source distribution. The current package is
735 maintained by <a href="mailto:dickey@his.com" target=
736 "_top">Thomas Dickey</a>. You can contact the maintainers
737 at <a href="mailto:bug-ncurses@gnu.org" target=
738 "_top">bug-ncurses@gnu.org</a>.</p>
744 <h3 class="SECT2"><a name="WHATCANWEDO" id=
745 "WHATCANWEDO">1.2. What we can do with NCURSES</a></h3>
747 <p>NCURSES not only creates a wrapper over terminal
748 capabilities, but also gives a robust framework to create
749 nice looking UI (User Interface)s in text mode. It provides
750 functions to create windows etc. Its sister libraries
751 panel, menu and form provide an extension to the basic
752 curses library. These libraries usually come along with
753 curses. One can create applications that contain multiple
754 windows, menus, panels and forms. Windows can be managed
755 independently, can provide 'scrollability' and even can be
758 <p>Menus provide the user with an easy command selection
759 option. Forms allow the creation of easy-to-use data entry
760 and display windows. Panels extend the capabilities of
761 ncurses to deal with overlapping and stacked windows.</p>
763 <p>These are just some of the basic things we can do with
764 ncurses. As we move along, We will see all the capabilities
765 of these libraries.</p>
771 <h3 class="SECT2"><a name="WHERETOGETIT" id=
772 "WHERETOGETIT">1.3. Where to get it</a></h3>
774 <p>All right, now that you know what you can do with
775 ncurses, you must be rearing to get started. NCURSES is
776 usually shipped with your installation. In case you don't
777 have the library or want to compile it on your own, read
780 <p><span class="emphasis"><i class="EMPHASIS">Compiling the
781 package</i></span></p>
783 <p>NCURSES can be obtained from <a href=
784 "ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target=
785 "_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a>
786 or any of the ftp sites mentioned in <a href=
787 "http://www.gnu.org/order/ftp.html" target=
788 "_top">http://www.gnu.org/order/ftp.html</a>.</p>
790 <p>Read the README and INSTALL files for details on to how
791 to install it. It usually involves the following
793 <pre class="PROGRAMLISTING">
794 tar zxvf ncurses<version>.tar.gz # unzip and untar the archive
795 cd ncurses<version> # cd to the directory
796 ./configure # configure the build according to your
799 su root # become root
800 make install # install it
803 <p><span class="emphasis"><i class="EMPHASIS">Using the
806 <p>NCURSES RPM can be found and downloaded from <a href=
807 "http://rpmfind.net" target="_top">http://rpmfind.net</a> .
808 The RPM can be installed with the following command after
810 <pre class="PROGRAMLISTING">
811 rpm -i <downloaded rpm>
818 <h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4.
819 Purpose/Scope of the document</a></h3>
821 <p>This document is intended to be a "All in One" guide for
822 programming with ncurses and its sister libraries. We
823 graduate from a simple "Hello World" program to more
824 complex form manipulation. No prior experience in ncurses
825 is assumed. The writing is informal, but a lot of detail is
826 provided for each of the examples.</p>
832 <h3 class="SECT2"><a name="ABOUTPROGRAMS" id=
833 "ABOUTPROGRAMS">1.5. About the Programs</a></h3>
835 <p>All the programs in the document are available in zipped
837 "http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz"
838 target="_top">here</a>. Unzip and untar it. The directory
839 structure looks like this.</p>
840 <pre class="PROGRAMLISTING">
843 |----> JustForFun -- just for fun programs
844 |----> basics -- basic programs
845 |----> demo -- output files go into this directory after make
847 | |----> exe -- exe files of all example programs
848 |----> forms -- programs related to form library
849 |----> menus -- programs related to menus library
850 |----> panels -- programs related to panels library
851 |----> perl -- perl equivalents of the examples (contributed
852 | by Anuradha Ratnaweera)
853 |----> Makefile -- the top level Makefile
854 |----> README -- the top level README file. contains instructions
855 |----> COPYING -- copyright notice
858 <p>The individual directories contain the following
860 <pre class="PROGRAMLISTING">
861 Description of files in each directory
862 --------------------------------------
865 |----> hanoi.c -- The Towers of Hanoi Solver
866 |----> life.c -- The Game of Life demo
867 |----> magic.c -- An Odd Order Magic Square builder
868 |----> queens.c -- The famous N-Queens Solver
869 |----> shuffle.c -- A fun game, if you have time to kill
870 |----> tt.c -- A very trivial typing tutor
874 |----> acs_vars.c -- ACS_ variables example
875 |----> hello_world.c -- Simple "Hello World" Program
876 |----> init_func_example.c -- Initialization functions example
877 |----> key_code.c -- Shows the scan code of the key pressed
878 |----> mouse_menu.c -- A menu accessible by mouse
879 |----> other_border.c -- Shows usage of other border functions apa
881 |----> printw_example.c -- A very simple printw() example
882 |----> scanw_example.c -- A very simple getstr() example
883 |----> simple_attr.c -- A program that can print a c file with
884 | -- comments in attribute
885 |----> simple_color.c -- A simple example demonstrating colors
886 |----> simple_key.c -- A menu accessible with keyboard UP, DOWN
888 |----> temp_leave.c -- Demonstrates temporarily leaving curses mode
889 |----> win_border.c -- Shows Creation of windows and borders
890 |----> with_chgat.c -- chgat() usage example
894 |----> form_attrib.c -- Usage of field attributes
895 |----> form_options.c -- Usage of field options
896 |----> form_simple.c -- A simple form example
897 |----> form_win.c -- Demo of windows associated with forms
901 |----> menu_attrib.c -- Usage of menu attributes
902 |----> menu_item_data.c -- Usage of item_name() etc.. functions
903 |----> menu_multi_column.c -- Creates multi columnar menus
904 |----> menu_scroll.c -- Demonstrates scrolling capability of menus
905 |----> menu_simple.c -- A simple menu accessed by arrow keys
906 |----> menu_toggle.c -- Creates multi valued menus and explains
908 |----> menu_userptr.c -- Usage of user pointer
909 |----> menu_win.c -- Demo of windows associated with menus
913 |----> panel_browse.c -- Panel browsing through tab. Usage of user
915 |----> panel_hide.c -- Hiding and Un hiding of panels
916 |----> panel_resize.c -- Moving and resizing of panels
917 |----> panel_simple.c -- A simple panel example
920 |----> 01-10.pl -- Perl equivalents of first ten example programs
923 <p>There is a top level Makefile included in the main
924 directory. It builds all the files and puts the
925 ready-to-use exes in demo/exe directory. You can also do
926 selective make by going into the corresponding directory.
927 Each directory contains a README file explaining the
928 purpose of each c file in the directory.</p>
930 <p>For every example, I have included path name for the
931 file relative to the examples directory.</p>
933 <p>If you prefer browsing individual programs, point your
935 "http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/"
937 "_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p>
939 <p>All the programs are released under the same license
940 that is used by ncurses (MIT-style). This gives you the
941 ability to do pretty much anything other than claiming them
942 as yours. Feel free to use them in your programs as
949 <h3 class="SECT2"><a name="OTHERFORMATS" id=
950 "OTHERFORMATS">1.6. Other Formats of the document</a></h3>
952 <p>This howto is also availabe in various other formats on
953 the tldp.org site. Here are the links to other formats of
959 <h4 class="SECT3"><a name="LISTFORMATS" id=
960 "LISTFORMATS">1.6.1. Readily available formats from
966 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf"
967 target="_top">Acrobat PDF Format</a></p>
972 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz"
973 target="_top">PostScript Format</a></p>
978 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz"
979 target="_top">In Multiple HTML pages</a></p>
984 "http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html"
985 target="_top">In One big HTML format</a></p>
993 <h4 class="SECT3"><a name="BUILDSOURCE" id=
994 "BUILDSOURCE">1.6.2. Building from source</a></h4>
996 <p>If above links are broken or if you want to experiment
997 with sgml read on.</p>
998 <pre class="PROGRAMLISTING">
999 Get both the source and the tar,gzipped programs, available at
1000 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
1001 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml
1002 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
1003 NCURSES-HOWTO/ncurses_programs.tar.gz
1005 Unzip ncurses_programs.tar.gz with
1006 tar zxvf ncurses_programs.tar.gz
1008 Use jade to create various formats. For example if you just want to create
1009 the multiple html files, you would use
1010 jade -t sgml -i html -d <path to docbook html stylesheet>
1011 NCURSES-Programming-HOWTO.sgml
1012 to get pdf, first create a single html file of the HOWTO with
1013 jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks
1014 NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html
1015 then use htmldoc to get pdf file with
1016 htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf>
1017 NCURSES-ONE-BIG-FILE.html
1018 for ps, you would use
1019 htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps>
1020 NCURSES-ONE-BIG-FILE.html
1024 "http://www.tldp.org/LDP/LDP-Author-Guide/" target=
1025 "_top">LDP Author guide</a> for more details. If all else
1026 failes, mail me at <a href="ppadala@gmail.com" target=
1027 "_top">ppadala@gmail.com</a></p>
1034 <h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7.
1037 <p>I thank <a href="mailto:sharath_1@usa.net" target=
1038 "_top">Sharath</a> and Emre Akbas for helping me with few
1039 sections. The introduction was initially written by
1040 sharath. I rewrote it with few excerpts taken from his
1041 initial work. Emre helped in writing printw and scanw
1044 <p>Perl equivalents of the example programs are contributed
1045 by <a href="mailto:Aratnaweera@virtusa.com" target=
1046 "_top">Anuradha Ratnaweera</a>.</p>
1048 <p>Then comes <a href="mailto:parimi@ece.arizona.edu"
1049 target="_top">Ravi Parimi</a>, my dearest friend, who has
1050 been on this project before even one line was written. He
1051 constantly bombarded me with suggestions and patiently
1052 reviewed the whole text. He also checked each program on
1053 Linux and Solaris.</p>
1059 <h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8.
1062 <p>This is the wish list, in the order of priority. If you
1063 have a wish or you want to work on completing the wish,
1064 mail <a href="mailto:ppadala@gmail.com" target=
1069 <p>Add examples to last parts of forms section.</p>
1073 <p>Prepare a Demo showing all the programs and allow
1074 the user to browse through description of each program.
1075 Let the user compile and see the program in action. A
1076 dialog based interface is preferred.</p>
1080 <p>Add debug info. _tracef, _tracemouse stuff.</p>
1084 <p>Accessing termcap, terminfo using functions provided
1085 by ncurses package.</p>
1089 <p>Working on two terminals simultaneously.</p>
1093 <p>Add more stuff to miscellaneous section.</p>
1101 <h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9.
1104 <p>Copyright © 2001 by Pradeep Padala.</p>
1106 <p>Permission is hereby granted, free of charge, to any
1107 person obtaining a copy of this software and associated
1108 documentation files (the "Software"), to deal in the
1109 Software without restriction, including without limitation
1110 the rights to use, copy, modify, merge, publish,
1111 distribute, distribute with modifications, sublicense,
1112 and/or sell copies of the Software, and to permit persons
1113 to whom the Software is furnished to do so, subject to the
1114 following conditions:</p>
1116 <p>The above copyright notice and this permission notice
1117 shall be included in all copies or substantial portions of
1120 <p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
1121 ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
1122 THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
1123 PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE
1124 COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
1125 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
1126 OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
1127 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</p>
1129 <p>Except as contained in this notice, the name(s) of the
1130 above copyright holders shall not be used in advertising or
1131 otherwise to promote the sale, use or other dealings in
1132 this Software without prior written authorization.</p>
1139 <h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2.
1140 Hello World !!!</a></h2>
1142 <p>Welcome to the world of curses. Before we plunge into the
1143 library and look into its various features, let's write a
1144 simple program and say hello to the world.</p>
1149 <h3 class="SECT2"><a name="COMPILECURSES" id=
1150 "COMPILECURSES">2.1. Compiling With the NCURSES
1153 <p>To use ncurses library functions, you have to include
1154 ncurses.h in your programs. To link the program with
1155 ncurses the flag -lncurses should be added.</p>
1156 <pre class="PROGRAMLISTING">
1157 #include <ncurses.h>
1162 compile and link: gcc <program file> -lncurses
1165 <div class="EXAMPLE">
1166 <a name="BHW" id="BHW"></a>
1168 <p><b>Example 1. The Hello World !!! Program</b></p>
1169 <pre class="PROGRAMLISTING">
1170 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
1174 initscr(); /* Start curses mode */
1175 printw("Hello World !!!"); /* Print Hello World */
1176 refresh(); /* Print it on to the real screen */
1177 getch(); /* Wait for user input */
1178 endwin(); /* End curses mode */
1189 <h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2.
1192 <p>The above program prints "Hello World !!!" to the screen
1193 and exits. This program shows how to initialize curses and
1194 do screen manipulation and end curses mode. Let's dissect
1195 it line by line.</p>
1200 <h4 class="SECT3"><a name="ABOUT-INITSCR" id=
1201 "ABOUT-INITSCR">2.2.1. About initscr()</a></h4>
1203 <p>The function initscr() initializes the terminal in
1204 curses mode. In some implementations, it clears the
1205 screen and presents a blank screen. To do any screen
1206 manipulation using curses package this has to be called
1207 first. This function initializes the curses system and
1208 allocates memory for our present window (called
1209 <tt class="LITERAL">stdscr</tt>) and some other
1210 data-structures. Under extreme cases this function might
1211 fail due to insufficient memory to allocate memory for
1212 curses library's data structures.</p>
1214 <p>After this is done, we can do a variety of
1215 initializations to customize our curses settings. These
1216 details will be explained <a href="#INIT">later</a> .</p>
1222 <h4 class="SECT3"><a name="MYST-REFRESH" id=
1223 "MYST-REFRESH">2.2.2. The mysterious refresh()</a></h4>
1225 <p>The next line printw prints the string "Hello World
1226 !!!" on to the screen. This function is analogous to
1227 normal printf in all respects except that it prints the
1228 data on a window called stdscr at the current (y,x)
1229 co-ordinates. Since our present co-ordinates are at 0,0
1230 the string is printed at the left hand corner of the
1233 <p>This brings us to that mysterious refresh(). Well,
1234 when we called printw the data is actually written to an
1235 imaginary window, which is not updated on the screen yet.
1236 The job of printw is to update a few flags and data
1237 structures and write the data to a buffer corresponding
1238 to stdscr. In order to show it on the screen, we need to
1239 call refresh() and tell the curses system to dump the
1240 contents on the screen.</p>
1242 <p>The philosophy behind all this is to allow the
1243 programmer to do multiple updates on the imaginary screen
1244 or windows and do a refresh once all his screen update is
1245 done. refresh() checks the window and updates only the
1246 portion which has been changed. This improves performance
1247 and offers greater flexibility too. But, it is sometimes
1248 frustrating to beginners. A common mistake committed by
1249 beginners is to forget to call refresh() after they did
1250 some update through printw() class of functions. I still
1251 forget to add it sometimes :-)</p>
1257 <h4 class="SECT3"><a name="ABOUT-ENDWIN" id=
1258 "ABOUT-ENDWIN">2.2.3. About endwin()</a></h4>
1260 <p>And finally don't forget to end the curses mode.
1261 Otherwise your terminal might behave strangely after the
1262 program quits. endwin() frees the memory taken by curses
1263 sub-system and its data structures and puts the terminal
1264 in normal mode. This function must be called after you
1265 are done with the curses mode.</p>
1273 <h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory
1276 <p>Now that we have seen how to write a simple curses program
1277 let's get into the details. There are many functions that
1278 help customize what you see on screen and many features which
1279 can be put to full use.</p>
1281 <p>Here we go...</p>
1287 <h2 class="SECT1"><a name="INIT" id="INIT">4.
1288 Initialization</a></h2>
1290 <p>We now know that to initialize curses system the function
1291 initscr() has to be called. There are functions which can be
1292 called after this initialization to customize our curses
1293 session. We may ask the curses system to set the terminal in
1294 raw mode or initialize color or initialize the mouse etc..
1295 Let's discuss some of the functions that are normally called
1296 immediately after initscr();</p>
1301 <h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1.
1302 Initialization functions</a></h3>
1308 <h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2.
1309 raw() and cbreak()</a></h3>
1311 <p>Normally the terminal driver buffers the characters a
1312 user types until a new line or carriage return is
1313 encountered. But most programs require that the characters
1314 be available as soon as the user types them. The above two
1315 functions are used to disable line buffering. The
1316 difference between these two functions is in the way
1317 control characters like suspend (CTRL-Z), interrupt and
1318 quit (CTRL-C) are passed to the program. In the raw() mode
1319 these characters are directly passed to the program without
1320 generating a signal. In the <tt class=
1321 "LITERAL">cbreak()</tt> mode these control characters are
1322 interpreted as any other character by the terminal driver.
1323 I personally prefer to use raw() as I can exercise greater
1324 control over what the user does.</p>
1330 <h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3.
1331 echo() and noecho()</a></h3>
1333 <p>These functions control the echoing of characters typed
1334 by the user to the terminal. <tt class=
1335 "LITERAL">noecho()</tt> switches off echoing. The reason
1336 you might want to do this is to gain more control over
1337 echoing or to suppress unnecessary echoing while taking
1338 input from the user through the getch() etc. functions.
1339 Most of the interactive programs call <tt class=
1340 "LITERAL">noecho()</tt> at initialization and do the
1341 echoing of characters in a controlled manner. It gives the
1342 programmer the flexibility of echoing characters at any
1343 place in the window without updating current (y,x)
1350 <h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4.
1353 <p>This is my favorite initialization function. It enables
1354 the reading of function keys like F1, F2, arrow keys etc.
1355 Almost every interactive program enables this, as arrow
1356 keys are a major part of any User Interface. Do <tt class=
1357 "LITERAL">keypad(stdscr, TRUE)</tt> to enable this feature
1358 for the regular screen (stdscr). You will learn more about
1359 key management in later sections of this document.</p>
1365 <h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5.
1366 halfdelay()</a></h3>
1368 <p>This function, though not used very often, is a useful
1369 one at times. halfdelay()is called to enable the half-delay
1370 mode, which is similar to the cbreak() mode in that
1371 characters typed are immediately available to program.
1372 However, it waits for 'X' tenths of a second for input and
1373 then returns ERR, if no input is available. 'X' is the
1374 timeout value passed to the function halfdelay(). This
1375 function is useful when you want to ask the user for input,
1376 and if he doesn't respond with in certain time, we can do
1377 some thing else. One possible example is a timeout at the
1378 password prompt.</p>
1384 <h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6.
1385 Miscellaneous Initialization functions</a></h3>
1387 <p>There are few more functions which are called at
1388 initialization to customize curses behavior. They are not
1389 used as extensively as those mentioned above. Some of them
1390 are explained where appropriate.</p>
1396 <h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An
1399 <p>Let's write a program which will clarify the usage of
1400 these functions.</p>
1402 <div class="EXAMPLE">
1403 <a name="BINFU" id="BINFU"></a>
1405 <p><b>Example 2. Initialization Function Usage
1407 <pre class="PROGRAMLISTING">
1408 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
1413 initscr(); /* Start curses mode */
1414 raw(); /* Line buffering disabled */
1415 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
1416 noecho(); /* Don't echo() while we do getch */
1418 printw("Type any character to see it in bold\n");
1419 ch = getch(); /* If raw() hadn't been called
1420 * we have to press enter before it
1421 * gets to the program */
1422 if(ch == KEY_F(1)) /* Without keypad enabled this will */
1423 printw("F1 Key pressed");/* not get to us either */
1424 /* Without noecho() some ugly escape
1425 * charachters might have been printed
1428 { printw("The pressed key is ");
1433 refresh(); /* Print it on to the real screen */
1434 getch(); /* Wait for user input */
1435 endwin(); /* End curses mode */
1442 <p>This program is self-explanatory. But I used functions
1443 which aren't explained yet. The function <tt class=
1444 "LITERAL">getch()</tt> is used to get a character from
1445 user. It is equivalent to normal <tt class=
1446 "LITERAL">getchar()</tt> except that we can disable the
1447 line buffering to avoid <enter> after input. Look for
1448 more about <tt class="LITERAL">getch()</tt>and reading keys
1449 in the <a href="#KEYS">key management section</a> . The
1450 functions attron and attroff are used to switch some
1451 attributes on and off respectively. In the example I used
1452 them to print the character in bold. These functions are
1453 explained in detail later.</p>
1460 <h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5.
1461 A Word about Windows</a></h2>
1463 <p>Before we plunge into the myriad ncurses functions, let me
1464 clear few things about windows. Windows are explained in
1465 detail in following <a href="#WINDOWS">sections</a></p>
1467 <p>A Window is an imaginary screen defined by curses system.
1468 A window does not mean a bordered window which you usually
1469 see on Win9X platforms. When curses is initialized, it
1470 creates a default window named <tt class=
1471 "LITERAL">stdscr</tt> which represents your 80x25 (or the
1472 size of window in which you are running) screen. If you are
1473 doing simple tasks like printing few strings, reading input
1474 etc., you can safely use this single window for all of your
1475 purposes. You can also create windows and call functions
1476 which explicitly work on the specified window.</p>
1478 <p>For example, if you call</p>
1479 <pre class="PROGRAMLISTING">
1480 printw("Hi There !!!");
1484 <p>It prints the string on stdscr at the present cursor
1485 position. Similarly the call to refresh(), works on stdscr
1488 <p>Say you have created <a href="#WINDOWS">windows</a> then
1489 you have to call a function with a 'w' added to the usual
1491 <pre class="PROGRAMLISTING">
1492 wprintw(win, "Hi There !!!");
1496 <p>As you will see in the rest of the document, naming of
1497 functions follow the same convention. For each function there
1498 usually are three more functions.</p>
1499 <pre class="PROGRAMLISTING">
1500 printw(string); /* Print on stdscr at present cursor position */
1501 mvprintw(y, x, string);/* Move to (y, x) then print string */
1502 wprintw(win, string); /* Print on window win at present cursor position */
1504 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */
1505 /* co-ordinates and then print */
1508 <p>Usually the w-less functions are macros which expand to
1509 corresponding w-function with stdscr as the window
1516 <h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
1519 <p>I guess you can't wait any more to see some action. Back
1520 to our odyssey of curses functions. Now that curses is
1521 initialized, let's interact with world.</p>
1523 <p>There are three classes of functions which you can use to
1524 do output on screen.</p>
1528 <p>addch() class: Print single character with
1533 <p>printw() class: Print formatted output similar to
1538 <p>addstr() class: Print strings</p>
1542 <p>These functions can be used interchangeably and it's a
1543 matter of style as to which class is used. Let's see each one
1549 <h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1.
1550 addch() class of functions</a></h3>
1552 <p>These functions put a single character into the current
1553 cursor location and advance the position of the cursor. You
1554 can give the character to be printed but they usually are
1555 used to print a character with some attributes. Attributes
1556 are explained in detail in later <a href=
1557 "#ATTRIB">sections</a> of the document. If a character is
1558 associated with an attribute(bold, reverse video etc.),
1559 when curses prints the character, it is printed in that
1562 <p>In order to combine a character with some attributes,
1563 you have two options:</p>
1567 <p>By OR'ing a single character with the desired
1568 attribute macros. These attribute macros could be found
1569 in the header file <tt class="LITERAL">ncurses.h</tt>.
1570 For example, you want to print a character ch(of type
1571 char) bold and underlined, you would call addch() as
1573 <pre class="PROGRAMLISTING">
1574 addch(ch | A_BOLD | A_UNDERLINE);
1579 <p>By using functions like <tt class=
1580 "LITERAL">attrset(),attron(),attroff()</tt>. These
1581 functions are explained in the <a href=
1582 "#ATTRIB">Attributes</a> section. Briefly, they
1583 manipulate the current attributes of the given window.
1584 Once set, the character printed in the window are
1585 associated with the attributes until it is turned
1590 <p>Additionally, <tt class="LITERAL">curses</tt> provides
1591 some special characters for character-based graphics. You
1592 can draw tables, horizontal or vertical lines, etc. You can
1593 find all avaliable characters in the header file <tt class=
1594 "LITERAL">ncurses.h</tt>. Try looking for macros beginning
1595 with <tt class="LITERAL">ACS_</tt> in this file.</p>
1601 <h3 class="SECT2"><a name="AEN298" id="AEN298">6.2.
1602 mvaddch(), waddch() and mvwaddch()</a></h3>
1604 <p><tt class="LITERAL">mvaddch()</tt> is used to move the
1605 cursor to a given point, and then print. Thus, the
1607 <pre class="PROGRAMLISTING">
1608 move(row,col); /* moves the cursor to row<span class=
1609 "emphasis"><i class=
1610 "EMPHASIS">th</i></span> row and col<span class="emphasis"><i class="EMPHASIS">th</i></span> column */
1612 </pre>can be replaced by
1613 <pre class="PROGRAMLISTING">
1614 mvaddch(row,col,ch);
1617 <p><tt class="LITERAL">waddch()</tt> is similar to
1618 <tt class="LITERAL">addch()</tt>, except that it adds a
1619 character into the given window. (Note that <tt class=
1620 "LITERAL">addch()</tt> adds a character into the window
1621 <tt class="LITERAL">stdscr</tt>.)</p>
1623 <p>In a similar fashion <tt class="LITERAL">mvwaddch()</tt>
1624 function is used to add a character into the given window
1625 at the given coordinates.</p>
1627 <p>Now, we are familiar with the basic output function
1628 <tt class="LITERAL">addch()</tt>. But, if we want to print
1629 a string, it would be very annoying to print it character
1630 by character. Fortunately, <tt class="LITERAL">ncurses</tt>
1631 provides <tt class="LITERAL">printf</tt><span class=
1632 "emphasis"><i class="EMPHASIS">-like</i></span> or
1633 <tt class="LITERAL">puts</tt><span class=
1634 "emphasis"><i class="EMPHASIS">-like</i></span>
1641 <h3 class="SECT2"><a name="PRINTWCLASS" id=
1642 "PRINTWCLASS">6.3. printw() class of functions</a></h3>
1644 <p>These functions are similar to <tt class=
1645 "LITERAL">printf()</tt> with the added capability of
1646 printing at any position on the screen.</p>
1651 <h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
1652 "PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
1654 <p>These two functions work much like <tt class=
1655 "LITERAL">printf()</tt>. <tt class=
1656 "LITERAL">mvprintw()</tt> can be used to move the cursor
1657 to a position and then print. If you want to move the
1658 cursor first and then print using <tt class=
1659 "LITERAL">printw()</tt> function, use <tt class=
1660 "LITERAL">move()</tt> first and then use <tt class=
1661 "LITERAL">printw()</tt> though I see no point why one
1662 should avoid using <tt class="LITERAL">mvprintw()</tt>,
1663 you have the flexibility to manipulate.</p>
1669 <h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
1670 "WPRINTWMVWPRINTW">6.3.2. wprintw() and
1673 <p>These two functions are similar to above two except
1674 that they print in the corresponding window given as
1681 <h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
1684 <p>This function is similar to <tt class=
1685 "LITERAL">vprintf()</tt>. This can be used when variable
1686 number of arguments are to be printed.</p>
1692 <h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
1693 "SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
1695 <div class="EXAMPLE">
1696 <a name="BPREX" id="BPREX"></a>
1698 <p><b>Example 3. A Simple printw example</b></p>
1699 <pre class="PROGRAMLISTING">
1701 "INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1702 #include <string.h>
1706 char mesg[]="Just a string"; /* message to be appeared on the screen */
1707 int row,col; /* to store the number of rows and *
1708 * the number of colums of the screen */
1709 initscr(); /* start the curses mode */
1710 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1711 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1712 /* print the message at the center of the screen */
1713 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
1714 printw("Try resizing your window(if possible) and then run this program again");
1724 <p>Above program demonstrates how easy it is to use
1725 <tt class="LITERAL">printw</tt>. You just feed the
1726 coordinates and the message to be appeared on the screen,
1727 then it does what you want.</p>
1729 <p>The above program introduces us to a new function
1730 <tt class="LITERAL">getmaxyx()</tt>, a macro defined in
1731 <tt class="LITERAL">ncurses.h</tt>. It gives the number
1732 of columns and the number of rows in a given window.
1733 <tt class="LITERAL">getmaxyx()</tt> does this by updating
1734 the variables given to it. Since <tt class=
1735 "LITERAL">getmaxyx()</tt> is not a function we don't pass
1736 pointers to it, we just give two integer variables.</p>
1743 <h3 class="SECT2"><a name="ADDSTRCLASS" id=
1744 "ADDSTRCLASS">6.4. addstr() class of functions</a></h3>
1746 <p><tt class="LITERAL">addstr()</tt> is used to put a
1747 character string into a given window. This function is
1748 similar to calling <tt class="LITERAL">addch()</tt> once
1749 for each character in a given string. This is true for all
1750 output functions. There are other functions from this
1751 family such as <tt class=
1752 "LITERAL">mvaddstr(),mvwaddstr()</tt> and <tt class=
1753 "LITERAL">waddstr()</tt>, which obey the naming convention
1754 of curses.(e.g. mvaddstr() is similar to the respective
1755 calls move() and then addstr().) Another function of this
1756 family is addnstr(), which takes an integer parameter(say
1757 n) additionally. This function puts at most n characters
1758 into the screen. If n is negative, then the entire string
1765 <h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A
1766 word of caution</a></h3>
1768 <p>All these functions take y co-ordinate first and then x
1769 in their arguments. A common mistake by beginners is to
1770 pass x,y in that order. If you are doing too many
1771 manipulations of (y,x) co-ordinates, think of dividing the
1772 screen into windows and manipulate each one separately.
1773 Windows are explained in the <a href="#WINDOWS">windows</a>
1781 <h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
1784 <p>Well, printing without taking input, is boring. Let's see
1785 functions which allow us to get input from user. These
1786 functions also can be divided into three categories.</p>
1790 <p>getch() class: Get a character</p>
1794 <p>scanw() class: Get formatted input</p>
1798 <p>getstr() class: Get strings</p>
1805 <h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1.
1806 getch() class of functions</a></h3>
1808 <p>These functions read a single character from the
1809 terminal. But there are several subtle facts to consider.
1810 For example if you don't use the function cbreak(), curses
1811 will not read your input characters contiguously but will
1812 begin read them only after a new line or an EOF is
1813 encountered. In order to avoid this, the cbreak() function
1814 must used so that characters are immediately available to
1815 your program. Another widely used function is noecho(). As
1816 the name suggests, when this function is set (used), the
1817 characters that are keyed in by the user will not show up
1818 on the screen. The two functions cbreak() and noecho() are
1819 typical examples of key management. Functions of this genre
1820 are explained in the <a href="#KEYS">key management
1827 <h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2.
1828 scanw() class of functions</a></h3>
1830 <p>These functions are similar to <tt class=
1831 "LITERAL">scanf()</tt> with the added capability of getting
1832 the input from any location on the screen.</p>
1837 <h4 class="SECT3"><a name="SCANWMVSCANW" id=
1838 "SCANWMVSCANW">7.2.1. scanw() and mvscanw</a></h4>
1840 <p>The usage of these functions is similar to that of
1841 <tt class="LITERAL">sscanf()</tt>, where the line to be
1842 scanned is provided by <tt class="LITERAL">wgetstr()</tt>
1843 function. That is, these functions call to <tt class=
1844 "LITERAL">wgetstr()</tt> function(explained below) and
1845 uses the resulting line for a scan.</p>
1851 <h4 class="SECT3"><a name="WSCANWMVWSCANW" id=
1852 "WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4>
1854 <p>These are similar to above two functions except that
1855 they read from a window, which is supplied as one of the
1856 arguments to these functions.</p>
1862 <h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3.
1865 <p>This function is similar to <tt class=
1866 "LITERAL">vscanf()</tt>. This can be used when a variable
1867 number of arguments are to be scanned.</p>
1874 <h3 class="SECT2"><a name="GETSTRCLASS" id=
1875 "GETSTRCLASS">7.3. getstr() class of functions</a></h3>
1877 <p>These functions are used to get strings from the
1878 terminal. In essence, this function performs the same task
1879 as would be achieved by a series of calls to <tt class=
1880 "LITERAL">getch()</tt> until a newline, carriage return, or
1881 end-of-file is received. The resulting string of characters
1882 are pointed to by <tt class="LITERAL">str</tt>, which is a
1883 character pointer provided by the user.</p>
1889 <h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4.
1890 Some examples</a></h3>
1892 <div class="EXAMPLE">
1893 <a name="BSCEX" id="BSCEX"></a>
1895 <p><b>Example 4. A Simple scanw example</b></p>
1896 <pre class="PROGRAMLISTING">
1898 "INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */
1899 #include <string.h>
1903 char mesg[]="Enter a string: "; /* message to be appeared on the screen */
1905 int row,col; /* to store the number of rows and *
1906 * the number of colums of the screen */
1907 initscr(); /* start the curses mode */
1908 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1909 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1910 /* print the message at the center of the screen */
1912 mvprintw(LINES - 2, 0, "You Entered: %s", str);
1926 <h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8.
1929 <p>We have seen an example of how attributes can be used to
1930 print characters with some special effects. Attributes, when
1931 set prudently, can present information in an easy,
1932 understandable manner. The following program takes a C file
1933 as input and prints the file with comments in bold. Scan
1934 through the code.</p>
1936 <div class="EXAMPLE">
1937 <a name="BSIAT" id="BSIAT"></a>
1939 <p><b>Example 5. A Simple Attributes example</b></p>
1940 <pre class="PROGRAMLISTING">
1942 "INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */
1943 #include <ncurses.h>
1944 #include <stdlib.h>
1946 int main(int argc, char *argv[])
1948 int ch, prev, row, col;
1955 printf("Usage: %s <a c file name>\n", argv[0]);
1958 fp = fopen(argv[1], "r");
1961 perror("Cannot open input file");
1964 initscr(); /* Start curses mode */
1965 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */
1966 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */
1968 getyx(stdscr, y, x); /* get the current curser position */
1969 if(y == (row - 1)) /* are we are at the end of the screen */
1971 printw("<-Press Any Key->"); /* tell the user to press a key */
1973 clear(); /* clear the screen */
1974 move(0, 0); /* start at the beginning of the screen */
1976 if(prev == '/' && ch == '*') /* If it is / and * then only
1979 attron(A_BOLD); /* cut bold on */
1980 getyx(stdscr, y, x); /* get the current curser position */
1981 move(y, x - 1); /* back up one space */
1982 printw("%c%c", '/', ch); /* The actual printing is done here */
1987 if(prev == '*' && ch == '/')
1988 attroff(A_BOLD); /* Switch it off once we got *
1992 endwin(); /* End curses mode */
1999 <p>Don't worry about all those initialization and other crap.
2000 Concentrate on the while loop. It reads each character in the
2001 file and searches for the pattern /*. Once it spots the
2002 pattern, it switches the BOLD attribute on with <tt class=
2003 "LITERAL">attron()</tt> . When we get the pattern */ it is
2004 switched off by <tt class="LITERAL">attroff()</tt> .</p>
2006 <p>The above program also introduces us to two useful
2007 functions <tt class="LITERAL">getyx()</tt> and <tt class=
2008 "LITERAL">move()</tt>. The first function gets the
2009 co-ordinates of the present cursor into the variables y, x.
2010 Since getyx() is a macro we don't have to pass pointers to
2011 variables. The function <tt class="LITERAL">move()</tt> moves
2012 the cursor to the co-ordinates given to it.</p>
2014 <p>The above program is really a simple one which doesn't do
2015 much. On these lines one could write a more useful program
2016 which reads a C file, parses it and prints it in different
2017 colors. One could even extend it to other languages as
2023 <h3 class="SECT2"><a name="ATTRIBDETAILS" id=
2024 "ATTRIBDETAILS">8.1. The details</a></h3>
2026 <p>Let's get into more details of attributes. The functions
2027 <tt class="LITERAL">attron(), attroff(), attrset()</tt> ,
2028 and their sister functions <tt class=
2029 "LITERAL">attr_get()</tt> etc.. can be used to switch
2030 attributes on/off , get attributes and produce a colorful
2033 <p>The functions attron and attroff take a bit-mask of
2034 attributes and switch them on or off, respectively. The
2035 following video attributes, which are defined in
2036 <curses.h> can be passed to these functions.</p>
2037 <pre class="PROGRAMLISTING">
2039 A_NORMAL Normal display (no highlight)
2040 A_STANDOUT Best highlighting mode of the terminal.
2041 A_UNDERLINE Underlining
2042 A_REVERSE Reverse video
2045 A_BOLD Extra bright or bold
2046 A_PROTECT Protected mode
2047 A_INVIS Invisible or blank mode
2048 A_ALTCHARSET Alternate character set
2049 A_CHARTEXT Bit-mask to extract a character
2050 COLOR_PAIR(n) Color-pair number n
2054 <p>The last one is the most colorful one :-) Colors are
2055 explained in the <a href="#color" target="_top">next
2058 <p>We can OR(|) any number of above attributes to get a
2059 combined effect. If you wanted reverse video with blinking
2060 characters you can use</p>
2061 <pre class="PROGRAMLISTING">
2062 attron(A_REVERSE | A_BLINK);
2069 <h3 class="SECT2"><a name="ATTRONVSATTRSET" id=
2070 "ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3>
2072 <p>Then what is the difference between attron() and
2073 attrset()? attrset sets the attributes of window whereas
2074 attron just switches on the attribute given to it. So
2075 attrset() fully overrides whatever attributes the window
2076 previously had and sets it to the new attribute(s).
2077 Similarly attroff() just switches off the attribute(s)
2078 given to it as an argument. This gives us the flexibility
2079 of managing attributes easily.But if you use them
2080 carelessly you may loose track of what attributes the
2081 window has and garble the display. This is especially true
2082 while managing menus with colors and highlighting. So
2083 decide on a consistent policy and stick to it. You can
2084 always use <tt class="LITERAL">standend()</tt> which is
2085 equivalent to <tt class="LITERAL">attrset(A_NORMAL)</tt>
2086 which turns off all attributes and brings you to normal
2093 <h3 class="SECT2"><a name="ATTRGET" id="ATTRGET">8.3.
2096 <p>The function attr_get() gets the current attributes and
2097 color pair of the window. Though we might not use this as
2098 often as the above functions, this is useful in scanning
2099 areas of screen. Say we wanted to do some complex update on
2100 screen and we are not sure what attribute each character is
2101 associated with. Then this function can be used with either
2102 attrset or attron to produce the desired effect.</p>
2108 <h3 class="SECT2"><a name="ATTRFUNCS" id="ATTRFUNCS">8.4.
2109 attr_ functions</a></h3>
2111 <p>There are series of functions like attr_set(), attr_on
2112 etc.. These are similar to above functions except that they
2113 take parameters of type <tt class=
2114 "LITERAL">attr_t</tt>.</p>
2120 <h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5.
2121 wattr functions</a></h3>
2123 <p>For each of the above functions we have a corresponding
2124 function with 'w' which operates on a particular window.
2125 The above functions operate on stdscr.</p>
2131 <h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat()
2134 <p>The function chgat() is listed in the end of the man
2135 page curs_attr. It actually is a useful one. This function
2136 can be used to set attributes for a group of characters
2137 without moving. I mean it !!! without moving the cursor :-)
2138 It changes the attributes of a given number of characters
2139 starting at the current cursor location.</p>
2141 <p>We can give -1 as the character count to update till end
2142 of line. If you want to change attributes of characters
2143 from current position to end of line, just use this.</p>
2144 <pre class="PROGRAMLISTING">
2145 chgat(-1, A_REVERSE, 0, NULL);
2148 <p>This function is useful when changing attributes for
2149 characters that are already on the screen. Move to the
2150 character from which you want to change and change the
2153 <p>Other functions wchgat(), mvchgat(), wchgat() behave
2154 similarly except that the w functions operate on the
2155 particular window. The mv functions first move the cursor
2156 then perform the work given to them. Actually chgat is a
2157 macro which is replaced by a wchgat() with stdscr as the
2158 window. Most of the "w-less" functions are macros.</p>
2160 <div class="EXAMPLE">
2161 <a name="BWICH" id="BWICH"></a>
2163 <p><b>Example 6. Chgat() Usage example</b></p>
2164 <pre class="PROGRAMLISTING">
2165 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2167 int main(int argc, char *argv[])
2168 { initscr(); /* Start curses mode */
2169 start_color(); /* Start color functionality */
2171 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2172 printw("A Big string which i didn't care to type fully ");
2173 mvchgat(0, 0, -1, A_BLINK, 1, NULL);
2175 * First two parameters specify the position at which to start
2176 * Third parameter number of characters to update. -1 means till
2178 * Forth parameter is the normal attribute you wanted to give
2180 * Fifth is the color index. It is the index given during init_pair()
2181 * use 0 if you didn't want color
2182 * Sixth one is always NULL
2186 endwin(); /* End curses mode */
2192 <p>This example also introduces us to the color world of
2193 curses. Colors will be explained in detail later. Use 0 for
2201 <h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9.
2204 <p>Windows form the most important concept in curses. You
2205 have seen the standard window stdscr above where all the
2206 functions implicitly operated on this window. Now to make
2207 design even a simplest GUI, you need to resort to windows.
2208 The main reason you may want to use windows is to manipulate
2209 parts of the screen separately, for better efficiency, by
2210 updating only the windows that need to be changed and for a
2211 better design. I would say the last reason is the most
2212 important in going for windows. You should always strive for
2213 a better and easy-to-manage design in your programs. If you
2214 are writing big, complex GUIs this is of pivotal importance
2215 before you start doing anything.</p>
2220 <h3 class="SECT2"><a name="WINDOWBASICS" id=
2221 "WINDOWBASICS">9.1. The basics</a></h3>
2223 <p>A Window can be created by calling the function
2224 <tt class="LITERAL">newwin()</tt>. It doesn't create any
2225 thing on the screen actually. It allocates memory for a
2226 structure to manipulate the window and updates the
2227 structure with data regarding the window like it's size,
2228 beginy, beginx etc.. Hence in curses, a window is just an
2229 abstraction of an imaginary window, which can be
2230 manipulated independent of other parts of screen. The
2231 function newwin() returns a pointer to structure WINDOW,
2232 which can be passed to window related functions like
2233 wprintw() etc.. Finally the window can be destroyed with
2234 delwin(). It will deallocate the memory associated with the
2235 window structure.</p>
2241 <h3 class="SECT2"><a name="LETBEWINDOW" id=
2242 "LETBEWINDOW">9.2. Let there be a Window !!!</a></h3>
2244 <p>What fun is it, if a window is created and we can't see
2245 it. So the fun part begins by displaying the window. The
2246 function <tt class="LITERAL">box()</tt> can be used to draw
2247 a border around the window. Let's explore these functions
2248 in more detail in this example.</p>
2250 <div class="EXAMPLE">
2251 <a name="BWIBO" id="BWIBO"></a>
2253 <p><b>Example 7. Window Border example</b></p>
2254 <pre class="PROGRAMLISTING">
2255 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2258 WINDOW *create_newwin(int height, int width, int starty, int startx);
2259 void destroy_win(WINDOW *local_win);
2261 int main(int argc, char *argv[])
2263 int startx, starty, width, height;
2266 initscr(); /* Start curses mode */
2267 cbreak(); /* Line buffering disabled, Pass on
2268 * everty thing to me */
2269 keypad(stdscr, TRUE); /* I need that nifty F1 */
2273 starty = (LINES - height) / 2; /* Calculating for a center placement */
2274 startx = (COLS - width) / 2; /* of the window */
2275 printw("Press F1 to exit");
2277 my_win = create_newwin(height, width, starty, startx);
2279 while((ch = getch()) != KEY_F(1))
2282 destroy_win(my_win);
2283 my_win = create_newwin(height, width, starty,--startx);
2286 destroy_win(my_win);
2287 my_win = create_newwin(height, width, starty,++startx);
2290 destroy_win(my_win);
2291 my_win = create_newwin(height, width, --starty,startx);
2294 destroy_win(my_win);
2295 my_win = create_newwin(height, width, ++starty,startx);
2300 endwin(); /* End curses mode */
2304 WINDOW *create_newwin(int height, int width, int starty, int startx)
2305 { WINDOW *local_win;
2307 local_win = newwin(height, width, starty, startx);
2308 box(local_win, 0 , 0); /* 0, 0 gives default characters
2309 * for the vertical and horizontal
2311 wrefresh(local_win); /* Show that box */
2316 void destroy_win(WINDOW *local_win)
2318 /* box(local_win, ' ', ' '); : This won't produce the desired
2319 * result of erasing the window. It will leave it's four corners
2320 * and so an ugly remnant of window.
2322 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' ');
2323 /* The parameters taken are
2324 * 1. win: the window on which to operate
2325 * 2. ls: character to be used for the left side of the window
2326 * 3. rs: character to be used for the right side of the window
2327 * 4. ts: character to be used for the top side of the window
2328 * 5. bs: character to be used for the bottom side of the window
2329 * 6. tl: character to be used for the top left corner of the window
2330 * 7. tr: character to be used for the top right corner of the window
2331 * 8. bl: character to be used for the bottom left corner of the window
2332 * 9. br: character to be used for the bottom right corner of the window
2334 wrefresh(local_win);
2344 <h3 class="SECT2"><a name="BORDEREXEXPL" id=
2345 "BORDEREXEXPL">9.3. Explanation</a></h3>
2347 <p>Don't scream. I know it's a big example. But I have to
2348 explain some important things here :-). This program
2349 creates a rectangular window that can be moved with left,
2350 right, up, down arrow keys. It repeatedly creates and
2351 destroys windows as user press a key. Don't go beyond the
2352 screen limits. Checking for those limits is left as an
2353 exercise for the reader. Let's dissect it by line by
2356 <p>The <tt class="LITERAL">create_newwin()</tt> function
2357 creates a window with <tt class="LITERAL">newwin()</tt> and
2358 displays a border around it with box. The function
2359 <tt class="LITERAL">destroy_win()</tt> first erases the
2360 window from screen by painting a border with ' ' character
2361 and then calling <tt class="LITERAL">delwin()</tt> to
2362 deallocate memory related to it. Depending on the key the
2363 user presses, starty or startx is changed and a new window
2366 <p>In the destroy_win, as you can see, I used wborder
2367 instead of box. The reason is written in the comments (You
2368 missed it. I know. Read the code :-)). wborder draws a
2369 border around the window with the characters given to it as
2370 the 4 corner points and the 4 lines. To put it clearly, if
2371 you have called wborder as below:</p>
2372 <pre class="PROGRAMLISTING">
2373 wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');
2376 <p>it produces some thing like</p>
2377 <pre class="PROGRAMLISTING">
2392 <h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4.
2393 The other stuff in the example</a></h3>
2395 <p>You can also see in the above examples, that I have used
2396 the variables COLS, LINES which are initialized to the
2397 screen sizes after initscr(). They can be useful in finding
2398 screen dimensions and finding the center co-ordinate of the
2399 screen as above. The function <tt class=
2400 "LITERAL">getch()</tt> as usual gets the key from keyboard
2401 and according to the key it does the corresponding work.
2402 This type of switch- case is very common in any GUI based
2409 <h3 class="SECT2"><a name="OTHERBORDERFUNCS" id=
2410 "OTHERBORDERFUNCS">9.5. Other Border functions</a></h3>
2412 <p>Above program is grossly inefficient in that with each
2413 press of a key, a window is destroyed and another is
2414 created. So let's write a more efficient program which uses
2415 other border related functions.</p>
2417 <p>The following program uses <tt class=
2418 "LITERAL">mvhline()</tt> and <tt class=
2419 "LITERAL">mvvline()</tt> to achieve similar effect. These
2420 two functions are simple. They create a horizontal or
2421 vertical line of the specified length at the specified
2424 <div class="EXAMPLE">
2425 <a name="BOTBO" id="BOTBO"></a>
2427 <p><b>Example 8. More border functions</b></p>
2428 <pre class="PROGRAMLISTING">
2429 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2431 typedef struct _win_border_struct {
2432 chtype ls, rs, ts, bs,
2436 typedef struct _WIN_struct {
2443 void init_win_params(WIN *p_win);
2444 void print_win_params(WIN *p_win);
2445 void create_box(WIN *win, bool flag);
2447 int main(int argc, char *argv[])
2451 initscr(); /* Start curses mode */
2452 start_color(); /* Start the color functionality */
2453 cbreak(); /* Line buffering disabled, Pass on
2454 * everty thing to me */
2455 keypad(stdscr, TRUE); /* I need that nifty F1 */
2457 init_pair(1, COLOR_CYAN, COLOR_BLACK);
2459 /* Initialize the window parameters */
2460 init_win_params(&win);
2461 print_win_params(&win);
2463 attron(COLOR_PAIR(1));
2464 printw("Press F1 to exit");
2466 attroff(COLOR_PAIR(1));
2468 create_box(&win, TRUE);
2469 while((ch = getch()) != KEY_F(1))
2472 create_box(&win, FALSE);
2474 create_box(&win, TRUE);
2477 create_box(&win, FALSE);
2479 create_box(&win, TRUE);
2482 create_box(&win, FALSE);
2484 create_box(&win, TRUE);
2487 create_box(&win, FALSE);
2489 create_box(&win, TRUE);
2493 endwin(); /* End curses mode */
2496 void init_win_params(WIN *p_win)
2498 p_win->height = 3;
2499 p_win->width = 10;
2500 p_win->starty = (LINES - p_win->height)/2;
2501 p_win->startx = (COLS - p_win->width)/2;
2503 p_win->border.ls = '|';
2504 p_win->border.rs = '|';
2505 p_win->border.ts = '-';
2506 p_win->border.bs = '-';
2507 p_win->border.tl = '+';
2508 p_win->border.tr = '+';
2509 p_win->border.bl = '+';
2510 p_win->border.br = '+';
2513 void print_win_params(WIN *p_win)
2516 mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty,
2517 p_win->width, p_win->height);
2521 void create_box(WIN *p_win, bool flag)
2525 x = p_win->startx;
2526 y = p_win->starty;
2527 w = p_win->width;
2528 h = p_win->height;
2531 { mvaddch(y, x, p_win->border.tl);
2532 mvaddch(y, x + w, p_win->border.tr);
2533 mvaddch(y + h, x, p_win->border.bl);
2534 mvaddch(y + h, x + w, p_win->border.br);
2535 mvhline(y, x + 1, p_win->border.ts, w - 1);
2536 mvhline(y + h, x + 1, p_win->border.bs, w - 1);
2537 mvvline(y + 1, x, p_win->border.ls, h - 1);
2538 mvvline(y + 1, x + w, p_win->border.rs, h - 1);
2542 for(j = y; j <= y + h; ++j)
2543 for(i = x; i <= x + w; ++i)
2557 <h2 class="SECT1"><a name="COLOR" id="COLOR">10.
2561 <h3 class="SECT2"><a name="COLORBASICS" id=
2562 "COLORBASICS">10.1. The basics</a></h3>
2564 <p>Life seems dull with no colors. Curses has a nice
2565 mechanism to handle colors. Let's get into the thick of the
2566 things with a small program.</p>
2568 <div class="EXAMPLE">
2569 <a name="BSICO" id="BSICO"></a>
2571 <p><b>Example 9. A Simple Color example</b></p>
2572 <pre class="PROGRAMLISTING">
2573 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2575 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string);
2576 int main(int argc, char *argv[])
2577 { initscr(); /* Start curses mode */
2578 if(has_colors() == FALSE)
2580 printf("Your terminal does not support color\n");
2583 start_color(); /* Start color */
2584 init_pair(1, COLOR_RED, COLOR_BLACK);
2586 attron(COLOR_PAIR(1));
2587 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ...");
2588 attroff(COLOR_PAIR(1));
2592 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string)
2606 length = strlen(string);
2607 temp = (width - length)/ 2;
2608 x = startx + (int)temp;
2609 mvwprintw(win, y, x, "%s", string);
2616 <p>As you can see, to start using color, you should first
2617 call the function <tt class="LITERAL">start_color()</tt>.
2618 After that, you can use color capabilities of your
2619 terminals using various functions. To find out whether a
2620 terminal has color capabilities or not, you can use
2621 <tt class="LITERAL">has_colors()</tt> function, which
2622 returns FALSE if the terminal does not support color.</p>
2624 <p>Curses initializes all the colors supported by terminal
2625 when start_color() is called. These can be accessed by the
2626 define constants like <tt class="LITERAL">COLOR_BLACK</tt>
2627 etc. Now to actually start using colors, you have to define
2628 pairs. Colors are always used in pairs. That means you have
2629 to use the function <tt class="LITERAL">init_pair()</tt> to
2630 define the foreground and background for the pair number
2631 you give. After that that pair number can be used as a
2632 normal attribute with <tt class=
2633 "LITERAL">COLOR_PAIR()</tt>function. This may seem to be
2634 cumbersome at first. But this elegant solution allows us to
2635 manage color pairs very easily. To appreciate it, you have
2636 to look into the the source code of "dialog", a utility for
2637 displaying dialog boxes from shell scripts. The developers
2638 have defined foreground and background combinations for all
2639 the colors they might need and initialized at the
2640 beginning. This makes it very easy to set attributes just
2641 by accessing a pair which we already have defined as a
2644 <p>The following colors are defined in <tt class=
2645 "LITERAL">curses.h</tt>. You can use these as parameters
2646 for various color functions.</p>
2647 <pre class="PROGRAMLISTING">
2662 <h3 class="SECT2"><a name="CHANGECOLORDEFS" id=
2663 "CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3>
2665 <p>The function <tt class="LITERAL">init_color()</tt>can be
2666 used to change the rgb values for the colors defined by
2667 curses initially. Say you wanted to lighten the intensity
2668 of red color by a minuscule. Then you can use this function
2670 <pre class="PROGRAMLISTING">
2671 init_color(COLOR_RED, 700, 0, 0);
2672 /* param 1 : color name
2673 * param 2, 3, 4 : rgb content min = 0, max = 1000 */
2676 <p>If your terminal cannot change the color definitions,
2677 the function returns ERR. The function <tt class=
2678 "LITERAL">can_change_color()</tt> can be used to find out
2679 whether the terminal has the capability of changing color
2680 content or not. The rgb content is scaled from 0 to 1000.
2681 Initially RED color is defined with content 1000(r), 0(g),
2688 <h3 class="SECT2"><a name="COLORCONTENT" id=
2689 "COLORCONTENT">10.3. Color Content</a></h3>
2691 <p>The functions <tt class="LITERAL">color_content()</tt>
2692 and <tt class="LITERAL">pair_content()</tt> can be used to
2693 find the color content and foreground, background
2694 combination for the pair.</p>
2701 <h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing
2702 with the key board</a></h2>
2705 <h3 class="SECT2"><a name="KEYSBASICS" id=
2706 "KEYSBASICS">11.1. The Basics</a></h3>
2708 <p>No GUI is complete without a strong user interface and
2709 to interact with the user, a curses program should be
2710 sensitive to key presses or the mouse actions done by the
2711 user. Let's deal with the keys first.</p>
2713 <p>As you have seen in almost all of the above examples,
2714 it's very easy to get key input from the user. A simple way
2715 of getting key presses is to use <tt class=
2716 "LITERAL">getch()</tt> function. The cbreak mode should be
2717 enabled to read keys when you are interested in reading
2718 individual key hits rather than complete lines of text
2719 (which usually end with a carriage return). keypad should
2720 be enabled to get the Functions keys, arrow keys etc. See
2721 the initialization section for details.</p>
2723 <p><tt class="LITERAL">getch()</tt> returns an integer
2724 corresponding to the key pressed. If it is a normal
2725 character, the integer value will be equivalent to the
2726 character. Otherwise it returns a number which can be
2727 matched with the constants defined in <tt class=
2728 "LITERAL">curses.h</tt>. For example if the user presses
2729 F1, the integer returned is 265. This can be checked using
2730 the macro KEY_F() defined in curses.h. This makes reading
2731 keys portable and easy to manage.</p>
2733 <p>For example, if you call getch() like this</p>
2734 <pre class="PROGRAMLISTING">
2740 <p>getch() will wait for the user to press a key, (unless
2741 you specified a timeout) and when user presses a key, the
2742 corresponding integer is returned. Then you can check the
2743 value returned with the constants defined in curses.h to
2744 match against the keys you want.</p>
2746 <p>The following code piece will do that job.</p>
2747 <pre class="PROGRAMLISTING">
2749 printw("Left arrow is pressed\n");
2752 <p>Let's write a small program which creates a menu which
2753 can be navigated by up and down arrows.</p>
2759 <h3 class="SECT2"><a name="SIMPLEKEYEX" id=
2760 "SIMPLEKEYEX">11.2. A Simple Key Usage example</a></h3>
2762 <div class="EXAMPLE">
2763 <a name="BSIKE" id="BSIKE"></a>
2765 <p><b>Example 10. A Simple Key Usage example</b></p>
2766 <pre class="PROGRAMLISTING">
2767 <span class="INLINEMEDIAOBJECT">#include <stdio.h>
2768 #include <ncurses.h>
2783 int n_choices = sizeof(choices) / sizeof(char *);
2784 void print_menu(WINDOW *menu_win, int highlight);
2795 cbreak(); /* Line buffering disabled. pass on everything */
2796 startx = (80 - WIDTH) / 2;
2797 starty = (24 - HEIGHT) / 2;
2799 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2800 keypad(menu_win, TRUE);
2801 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice");
2803 print_menu(menu_win, highlight);
2805 { c = wgetch(menu_win);
2809 highlight = n_choices;
2814 if(highlight == n_choices)
2823 mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c);
2827 print_menu(menu_win, highlight);
2828 if(choice != 0) /* User did a choice come out of the infinite loop */
2831 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]);
2839 void print_menu(WINDOW *menu_win, int highlight)
2845 box(menu_win, 0, 0);
2846 for(i = 0; i < n_choices; ++i)
2847 { if(highlight == i + 1) /* High light the present choice */
2848 { wattron(menu_win, A_REVERSE);
2849 mvwprintw(menu_win, y, x, "%s", choices[i]);
2850 wattroff(menu_win, A_REVERSE);
2853 mvwprintw(menu_win, y, x, "%s", choices[i]);
2867 <h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing
2868 with the mouse</a></h2>
2870 <p>Now that you have seen how to get keys, lets do the same
2871 thing from mouse. Usually each UI allows the user to interact
2872 with both keyboard and mouse.</p>
2877 <h3 class="SECT2"><a name="MOUSEBASICS" id=
2878 "MOUSEBASICS">12.1. The Basics</a></h3>
2880 <p>Before you do any thing else, the events you want to
2881 receive have to be enabled with <tt class=
2882 "LITERAL">mousemask()</tt>.</p>
2883 <pre class="PROGRAMLISTING">
2884 mousemask( mmask_t newmask, /* The events you want to listen to */
2885 mmask_t *oldmask) /* The old events mask */
2888 <p>The first parameter to above function is a bit mask of
2889 events you would like to listen. By default, all the events
2890 are turned off. The bit mask <tt class=
2891 "LITERAL">ALL_MOUSE_EVENTS</tt> can be used to get all the
2894 <p>The following are all the event masks:</p>
2895 <pre class="PROGRAMLISTING">
2897 ---------------------------------------------------------------------
2898 BUTTON1_PRESSED mouse button 1 down
2899 BUTTON1_RELEASED mouse button 1 up
2900 BUTTON1_CLICKED mouse button 1 clicked
2901 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
2902 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
2903 BUTTON2_PRESSED mouse button 2 down
2904 BUTTON2_RELEASED mouse button 2 up
2905 BUTTON2_CLICKED mouse button 2 clicked
2906 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
2907 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
2908 BUTTON3_PRESSED mouse button 3 down
2909 BUTTON3_RELEASED mouse button 3 up
2910 BUTTON3_CLICKED mouse button 3 clicked
2911 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
2912 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
2913 BUTTON4_PRESSED mouse button 4 down
2914 BUTTON4_RELEASED mouse button 4 up
2915 BUTTON4_CLICKED mouse button 4 clicked
2916 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
2917 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
2918 BUTTON_SHIFT shift was down during button state change
2919 BUTTON_CTRL control was down during button state change
2920 BUTTON_ALT alt was down during button state change
2921 ALL_MOUSE_EVENTS report all button state changes
2922 REPORT_MOUSE_POSITION report mouse movement
2929 <h3 class="SECT2"><a name="GETTINGEVENTS" id=
2930 "GETTINGEVENTS">12.2. Getting the events</a></h3>
2932 <p>Once a class of mouse events have been enabled, getch()
2933 class of functions return KEY_MOUSE every time some mouse
2934 event happens. Then the mouse event can be retrieved with
2935 <tt class="LITERAL">getmouse()</tt>.</p>
2937 <p>The code approximately looks like this:</p>
2938 <pre class="PROGRAMLISTING">
2943 if(getmouse(&event) == OK)
2944 . /* Do some thing with the event */
2949 <p>getmouse() returns the event into the pointer given to
2950 it. It's a structure which contains</p>
2951 <pre class="PROGRAMLISTING">
2954 short id; /* ID to distinguish multiple devices */
2955 int x, y, z; /* event coordinates */
2956 mmask_t bstate; /* button state bits */
2960 <p>The <tt class="LITERAL">bstate</tt> is the main variable
2961 we are interested in. It tells the button state of the
2964 <p>Then with a code snippet like the following, we can find
2965 out what happened.</p>
2966 <pre class="PROGRAMLISTING">
2967 if(event.bstate & BUTTON1_PRESSED)
2968 printw("Left Button Pressed");
2975 <h3 class="SECT2"><a name="MOUSETOGETHER" id=
2976 "MOUSETOGETHER">12.3. Putting it all Together</a></h3>
2978 <p>That's pretty much interfacing with mouse. Let's create
2979 the same menu and enable mouse interaction. To make things
2980 simpler, key handling is removed.</p>
2982 <div class="EXAMPLE">
2983 <a name="BMOME" id="BMOME"></a>
2985 <p><b>Example 11. Access the menu with mouse !!!</b></p>
2986 <pre class="PROGRAMLISTING">
2987 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
2995 char *choices[] = { "Choice 1",
3002 int n_choices = sizeof(choices) / sizeof(char *);
3004 void print_menu(WINDOW *menu_win, int highlight);
3005 void report_choice(int mouse_x, int mouse_y, int *p_choice);
3008 { int c, choice = 0;
3012 /* Initialize curses */
3016 cbreak(); //Line buffering disabled. pass on everything
3018 /* Try to put the window in the middle of screen */
3019 startx = (80 - WIDTH) / 2;
3020 starty = (24 - HEIGHT) / 2;
3023 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
3027 /* Print the menu for the first time */
3028 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
3029 print_menu(menu_win, 1);
3030 /* Get all the mouse events */
3031 mousemask(ALL_MOUSE_EVENTS, NULL);
3034 { c = wgetch(menu_win);
3037 if(getmouse(&event) == OK)
3038 { /* When the user clicks left mouse button */
3039 if(event.bstate & BUTTON1_PRESSED)
3040 { report_choice(event.x + 1, event.y + 1, &choice);
3041 if(choice == -1) //Exit chosen
3043 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
3047 print_menu(menu_win, choice);
3057 void print_menu(WINDOW *menu_win, int highlight)
3063 box(menu_win, 0, 0);
3064 for(i = 0; i < n_choices; ++i)
3065 { if(highlight == i + 1)
3066 { wattron(menu_win, A_REVERSE);
3067 mvwprintw(menu_win, y, x, "%s", choices[i]);
3068 wattroff(menu_win, A_REVERSE);
3071 mvwprintw(menu_win, y, x, "%s", choices[i]);
3077 /* Report the choice according to mouse position */
3078 void report_choice(int mouse_x, int mouse_y, int *p_choice)
3084 for(choice = 0; choice < n_choices; ++choice)
3085 if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice]))
3086 { if(choice == n_choices - 1)
3089 *p_choice = choice + 1;
3100 <h3 class="SECT2"><a name="MISCMOUSEFUNCS" id=
3101 "MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3>
3103 <p>The functions mouse_trafo() and wmouse_trafo() can be
3104 used to convert to mouse co-ordinates to screen relative
3105 co-ordinates. See curs_mouse(3X) man page for details.</p>
3107 <p>The mouseinterval function sets the maximum time (in
3108 thousands of a second) that can elapse between press and
3109 release events in order for them to be recognized as a
3110 click. This function returns the previous interval value.
3111 The default is one fifth of a second.</p>
3118 <h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen
3119 Manipulation</a></h2>
3121 <p>In this section, we will look into some functions, which
3122 allow us to manage the screen efficiently and to write some
3123 fancy programs. This is especially important in writing
3129 <h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx()
3132 <p>The function <tt class="LITERAL">getyx()</tt> can be
3133 used to find out the present cursor co-ordinates. It will
3134 fill the values of x and y co-ordinates in the arguments
3135 given to it. Since getyx() is a macro you don't have to
3136 pass the address of the variables. It can be called as</p>
3137 <pre class="PROGRAMLISTING">
3139 /* win: window pointer
3140 * y, x: y, x co-ordinates will be put into this variables
3144 <p>The function getparyx() gets the beginning co-ordinates
3145 of the sub window relative to the main window. This is some
3146 times useful to update a sub window. When designing fancy
3147 stuff like writing multiple menus, it becomes difficult to
3148 store the menu positions, their first option co-ordinates
3149 etc. A simple solution to this problem, is to create menus
3150 in sub windows and later find the starting co-ordinates of
3151 the menus by using getparyx().</p>
3153 <p>The functions getbegyx() and getmaxyx() store current
3154 window's beginning and maximum co-ordinates. These
3155 functions are useful in the same way as above in managing
3156 the windows and sub windows effectively.</p>
3162 <h3 class="SECT2"><a name="SCREENDUMP" id=
3163 "SCREENDUMP">13.2. Screen Dumping</a></h3>
3165 <p>While writing games, some times it becomes necessary to
3166 store the state of the screen and restore it back to the
3167 same state. The function scr_dump() can be used to dump the
3168 screen contents to a file given as an argument. Later it
3169 can be restored by scr_restore function. These two simple
3170 functions can be used effectively to maintain a fast moving
3171 game with changing scenarios.</p>
3177 <h3 class="SECT2"><a name="WINDOWDUMP" id=
3178 "WINDOWDUMP">13.3. Window Dumping</a></h3>
3180 <p>To store and restore windows, the functions <tt class=
3181 "LITERAL">putwin()</tt> and <tt class=
3182 "LITERAL">getwin()</tt> can be used. <tt class=
3183 "LITERAL">putwin()</tt> puts the present window state into
3184 a file, which can be later restored by <tt class=
3185 "LITERAL">getwin()</tt>.</p>
3187 <p>The function <tt class="LITERAL">copywin()</tt> can be
3188 used to copy a window completely onto another window. It
3189 takes the source and destination windows as parameters and
3190 according to the rectangle specified, it copies the
3191 rectangular region from source to destination window. It's
3192 last parameter specifies whether to overwrite or just
3193 overlay the contents on to the destination window. If this
3194 argument is true, then the copying is non-destructive.</p>
3201 <h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous
3204 <p>Now you know enough features to write a good curses
3205 program, with all bells and whistles. There are some
3206 miscellaneous functions which are useful in various cases.
3207 Let's go headlong into some of those.</p>
3212 <h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1.
3215 <p>This function can be used to make the cursor invisible.
3216 The parameter to this function should be</p>
3217 <pre class="PROGRAMLISTING">
3227 <h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2.
3228 Temporarily Leaving Curses mode</a></h3>
3230 <p>Some times you may want to get back to cooked mode
3231 (normal line buffering mode) temporarily. In such a case
3232 you will first need to save the tty modes with a call to
3233 <tt class="LITERAL">def_prog_mode()</tt> and then call
3234 <tt class="LITERAL">endwin()</tt> to end the curses mode.
3235 This will leave you in the original tty mode. To get back
3236 to curses once you are done, call <tt class=
3237 "LITERAL">reset_prog_mode()</tt> . This function returns
3238 the tty to the state stored by <tt class=
3239 "LITERAL">def_prog_mode()</tt>. Then do refresh(), and you
3240 are back to the curses mode. Here is an example showing the
3241 sequence of things to be done.</p>
3243 <div class="EXAMPLE">
3244 <a name="BTELE" id="BTELE"></a>
3246 <p><b>Example 12. Temporarily Leaving Curses Mode</b></p>
3247 <pre class="PROGRAMLISTING">
3248 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
3252 initscr(); /* Start curses mode */
3253 printw("Hello World !!!\n"); /* Print Hello World */
3254 refresh(); /* Print it on to the real screen */
3255 def_prog_mode(); /* Save the tty modes */
3256 endwin(); /* End curses mode temporarily */
3257 system("/bin/sh"); /* Do whatever you like in cooked mode */
3258 reset_prog_mode(); /* Return to the previous tty mode*/
3259 /* stored by def_prog_mode() */
3260 refresh(); /* Do refresh() to restore the */
3261 /* Screen contents */
3262 printw("Another String\n"); /* Back to curses use the full */
3263 refresh(); /* capabilities of curses */
3264 endwin(); /* End curses mode */
3275 <h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_
3278 <p>If you have ever programmed in DOS, you know about those
3279 nifty characters in extended character set. They are
3280 printable only on some terminals. NCURSES functions like
3281 <tt class="LITERAL">box()</tt> use these characters. All
3282 these variables start with ACS meaning alternative
3283 character set. You might have noticed me using these
3284 characters in some of the programs above. Here's an example
3285 showing all the characters.</p>
3287 <div class="EXAMPLE">
3288 <a name="BACSVARS" id="BACSVARS"></a>
3290 <p><b>Example 13. ACS Variables Example</b></p>
3291 <pre class="PROGRAMLISTING">
3292 <span class="INLINEMEDIAOBJECT">#include <ncurses.h>
3298 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n");
3299 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n");
3300 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n");
3301 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n");
3302 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n");
3303 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n");
3304 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n");
3305 printw("Horizontal line "); addch(ACS_HLINE); printw("\n");
3306 printw("Vertical line "); addch(ACS_VLINE); printw("\n");
3307 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n");
3308 printw("Scan Line 1 "); addch(ACS_S1); printw("\n");
3309 printw("Scan Line 3 "); addch(ACS_S3); printw("\n");
3310 printw("Scan Line 7 "); addch(ACS_S7); printw("\n");
3311 printw("Scan Line 9 "); addch(ACS_S9); printw("\n");
3312 printw("Diamond "); addch(ACS_DIAMOND); printw("\n");
3313 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n");
3314 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n");
3315 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n");
3316 printw("Bullet "); addch(ACS_BULLET); printw("\n");
3317 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n");
3318 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n");
3319 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n");
3320 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n");
3321 printw("Board of squares "); addch(ACS_BOARD); printw("\n");
3322 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n");
3323 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n");
3324 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n");
3325 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n");
3326 printw("Pi "); addch(ACS_PI); printw("\n");
3327 printw("Not equal "); addch(ACS_NEQUAL); printw("\n");
3328 printw("UK pound sign "); addch(ACS_STERLING); printw("\n");
3344 <h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other
3347 <p>Apart from the curses library, there are few text mode
3348 libraries, which provide more functionality and a lot of
3349 features. The following sections explain three standard
3350 libraries which are usually distributed along with
3357 <h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel
3360 <p>Now that you are proficient in curses, you wanted to do
3361 some thing big. You created a lot of overlapping windows to
3362 give a professional windows-type look. Unfortunately, it soon
3363 becomes difficult to manage these. The multiple refreshes,
3364 updates plunge you into a nightmare. The overlapping windows
3365 create blotches, whenever you forget to refresh the windows
3366 in the proper order.</p>
3368 <p>Don't despair. There's an elegant solution provided in
3369 panels library. In the words of developers of ncurses</p>
3371 <p><span class="emphasis"><i class="EMPHASIS">When your
3372 interface design is such that windows may dive deeper into
3373 the visibility stack or pop to the top at runtime, the
3374 resulting book-keeping can be tedious and difficult to get
3375 right. Hence the panels library.</i></span></p>
3377 <p>If you have lot of overlapping windows, then panels
3378 library is the way to go. It obviates the need of doing
3379 series of wnoutrefresh(), doupdate() and relieves the burden
3380 of doing it correctly(bottom up). The library maintains
3381 information about the order of windows, their overlapping and
3382 update the screen properly. So why wait? Let's take a close
3383 peek into panels.</p>
3388 <h3 class="SECT2"><a name="PANELBASICS" id=
3389 "PANELBASICS">16.1. The Basics</a></h3>
3391 <p>Panel object is a window that is implicitly treated as
3392 part of a deck including all other panel objects. The deck
3393 is treated as a stack with the top panel being completely
3394 visible and the other panels may or may not be obscured
3395 according to their positions. So the basic idea is to
3396 create a stack of overlapping panels and use panels library
3397 to display them correctly. There is a function similar to
3398 refresh() which, when called , displays panels in the
3399 correct order. Functions are provided to hide or show
3400 panels, move panels, change its size etc.. The overlapping
3401 problem is managed by the panels library during all the
3402 calls to these functions.</p>
3404 <p>The general flow of a panel program goes like this:</p>
3408 <p>Create the windows (with newwin()) to be attached to
3413 <p>Create panels with the chosen visibility order.
3414 Stack them up according to the desired visibility. The
3415 function new_panel() is used to created panels.</p>
3419 <p>Call update_panels() to write the panels to the
3420 virtual screen in correct visibility order. Do a
3421 doupdate() to show it on the screen.</p>
3425 <p>Mainpulate the panels with show_panel(),
3426 hide_panel(), move_panel() etc. Make use of helper
3427 functions like panel_hidden() and panel_window(). Make
3428 use of user pointer to store custom data for a panel.
3429 Use the functions set_panel_userptr() and
3430 panel_userptr() to set and get the user pointer for a
3435 <p>When you are done with the panel use del_panel() to
3436 delete the panel.</p>
3440 <p>Let's make the concepts clear, with some programs. The
3441 following is a simple program which creates 3 overlapping
3442 panels and shows them on the screen.</p>
3448 <h3 class="SECT2"><a name="COMPILEPANELS" id=
3449 "COMPILEPANELS">16.2. Compiling With the Panels
3452 <p>To use panels library functions, you have to include
3453 panel.h and to link the program with panels library the
3454 flag -lpanel should be added along with -lncurses in that
3456 <pre class="PROGRAMLISTING">
3457 #include <panel.h>
3462 compile and link: gcc <program file> -lpanel -lncurses
3465 <div class="EXAMPLE">
3466 <a name="PPASI" id="PPASI"></a>
3468 <p><b>Example 14. Panel basics</b></p>
3469 <pre class="PROGRAMLISTING">
3470 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3473 { WINDOW *my_wins[3];
3474 PANEL *my_panels[3];
3475 int lines = 10, cols = 40, y = 2, x = 4, i;
3481 /* Create windows for the panels */
3482 my_wins[0] = newwin(lines, cols, y, x);
3483 my_wins[1] = newwin(lines, cols, y + 1, x + 5);
3484 my_wins[2] = newwin(lines, cols, y + 2, x + 10);
3487 * Create borders around the windows so that you can see the effect
3490 for(i = 0; i < 3; ++i)
3491 box(my_wins[i], 0, 0);
3493 /* Attach a panel to each window */ /* Order is bottom up */
3494 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3495 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3496 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3498 /* Update the stacking order. 2nd panel will be on top */
3501 /* Show it on the screen */
3511 <p>As you can see, above program follows a simple flow as
3512 explained. The windows are created with newwin() and then
3513 they are attached to panels with new_panel(). As we attach
3514 one panel after another, the stack of panels gets updated.
3515 To put them on screen update_panels() and doupdate() are
3522 <h3 class="SECT2"><a name="PANELBROWSING" id=
3523 "PANELBROWSING">16.3. Panel Window Browsing</a></h3>
3525 <p>A slightly complicated example is given below. This
3526 program creates 3 windows which can be cycled through using
3527 tab. Have a look at the code.</p>
3529 <div class="EXAMPLE">
3530 <a name="PPABR" id="PPABR"></a>
3532 <p><b>Example 15. Panel Window Browsing Example</b></p>
3533 <pre class="PROGRAMLISTING">
3534 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3539 void init_wins(WINDOW **wins, int n);
3540 void win_show(WINDOW *win, char *label, int label_color);
3541 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3544 { WINDOW *my_wins[3];
3545 PANEL *my_panels[3];
3549 /* Initialize curses */
3554 keypad(stdscr, TRUE);
3556 /* Initialize all the colors */
3557 init_pair(1, COLOR_RED, COLOR_BLACK);
3558 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3559 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3560 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3562 init_wins(my_wins, 3);
3564 /* Attach a panel to each window */ /* Order is bottom up */
3565 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3566 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3567 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3569 /* Set up the user pointers to the next panel */
3570 set_panel_userptr(my_panels[0], my_panels[1]);
3571 set_panel_userptr(my_panels[1], my_panels[2]);
3572 set_panel_userptr(my_panels[2], my_panels[0]);
3574 /* Update the stacking order. 2nd panel will be on top */
3577 /* Show it on the screen */
3578 attron(COLOR_PAIR(4));
3579 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3580 attroff(COLOR_PAIR(4));
3584 while((ch = getch()) != KEY_F(1))
3587 top = (PANEL *)panel_userptr(top);
3598 /* Put all the windows */
3599 void init_wins(WINDOW **wins, int n)
3605 for(i = 0; i < n; ++i)
3606 { wins[i] = newwin(NLINES, NCOLS, y, x);
3607 sprintf(label, "Window Number %d", i + 1);
3608 win_show(wins[i], label, i + 1);
3614 /* Show the window with a border and a label */
3615 void win_show(WINDOW *win, char *label, int label_color)
3616 { int startx, starty, height, width;
3618 getbegyx(win, starty, startx);
3619 getmaxyx(win, height, width);
3622 mvwaddch(win, 2, 0, ACS_LTEE);
3623 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3624 mvwaddch(win, 2, width - 1, ACS_RTEE);
3626 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3629 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3643 length = strlen(string);
3644 temp = (width - length)/ 2;
3645 x = startx + (int)temp;
3646 wattron(win, color);
3647 mvwprintw(win, y, x, "%s", string);
3648 wattroff(win, color);
3658 <h3 class="SECT2"><a name="USERPTRUSING" id=
3659 "USERPTRUSING">16.4. Using User Pointers</a></h3>
3661 <p>In the above example I used user pointers to find out
3662 the next window in the cycle. We can attach custom
3663 information to the panel by specifying a user pointer,
3664 which can point to any information you want to store. In
3665 this case I stored the pointer to the next panel in the
3666 cycle. User pointer for a panel can be set with the
3667 function <tt class="LITERAL">set_panel_userptr()</tt>. It
3668 can be accessed using the function <tt class=
3669 "LITERAL">panel_userptr()</tt> which will return the user
3670 pointer for the panel given as argument. After finding the
3671 next panel in the cycle It's brought to the top by the
3672 function top_panel(). This function brings the panel given
3673 as argument to the top of the panel stack.</p>
3679 <h3 class="SECT2"><a name="PANELMOVERESIZE" id=
3680 "PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3>
3682 <p>The function <tt class="LITERAL">move_panel()</tt> can
3683 be used to move a panel to the desired location. It does
3684 not change the position of the panel in the stack. Make
3685 sure that you use move_panel() instead mvwin() on the
3686 window associated with the panel.</p>
3688 <p>Resizing a panel is slightly complex. There is no
3689 straight forward function just to resize the window
3690 associated with a panel. A solution to resize a panel is to
3691 create a new window with the desired sizes, change the
3692 window associated with the panel using replace_panel().
3693 Don't forget to delete the old window. The window
3694 associated with a panel can be found by using the function
3697 <p>The following program shows these concepts, in
3698 supposedly simple program. You can cycle through the window
3699 with <TAB> as usual. To resize or move the active
3700 panel press 'r' for resize 'm' for moving. Then use arrow
3701 keys to resize or move it to the desired way and press
3702 enter to end your resizing or moving. This example makes
3703 use of user data to get the required data to do the
3706 <div class="EXAMPLE">
3707 <a name="PPARE" id="PPARE"></a>
3709 <p><b>Example 16. Panel Moving and Resizing
3711 <pre class="PROGRAMLISTING">
3712 <span class="INLINEMEDIAOBJECT">#include <panel.h>
3714 typedef struct _PANEL_DATA {
3724 void init_wins(WINDOW **wins, int n);
3725 void win_show(WINDOW *win, char *label, int label_color);
3726 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3727 void set_user_ptrs(PANEL **panels, int n);
3730 { WINDOW *my_wins[3];
3731 PANEL *my_panels[3];
3734 WINDOW *temp_win, *old_win;
3736 int newx, newy, neww, newh;
3737 int size = FALSE, move = FALSE;
3739 /* Initialize curses */
3744 keypad(stdscr, TRUE);
3746 /* Initialize all the colors */
3747 init_pair(1, COLOR_RED, COLOR_BLACK);
3748 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3749 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3750 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3752 init_wins(my_wins, 3);
3754 /* Attach a panel to each window */ /* Order is bottom up */
3755 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3756 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3757 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3759 set_user_ptrs(my_panels, 3);
3760 /* Update the stacking order. 2nd panel will be on top */
3763 /* Show it on the screen */
3764 attron(COLOR_PAIR(4));
3765 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3766 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3767 attroff(COLOR_PAIR(4));
3770 stack_top = my_panels[2];
3771 top = (PANEL_DATA *)panel_userptr(stack_top);
3776 while((ch = getch()) != KEY_F(1))
3779 top = (PANEL_DATA *)panel_userptr(stack_top);
3780 top_panel(top->next);
3781 stack_top = top->next;
3782 top = (PANEL_DATA *)panel_userptr(stack_top);
3788 case 'r': /* Re-Size*/
3790 attron(COLOR_PAIR(4));
3791 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing");
3793 attroff(COLOR_PAIR(4));
3795 case 'm': /* Move */
3796 attron(COLOR_PAIR(4));
3797 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving");
3799 attroff(COLOR_PAIR(4));
3834 case 10: /* Enter */
3839 { old_win = panel_window(stack_top);
3840 temp_win = newwin(newh, neww, newy, newx);
3841 replace_panel(stack_top, temp_win);
3842 win_show(temp_win, top->label, top->label_color);
3847 { move_panel(stack_top, newy, newx);
3853 attron(COLOR_PAIR(4));
3854 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3855 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3856 attroff(COLOR_PAIR(4));
3865 /* Put all the windows */
3866 void init_wins(WINDOW **wins, int n)
3872 for(i = 0; i < n; ++i)
3873 { wins[i] = newwin(NLINES, NCOLS, y, x);
3874 sprintf(label, "Window Number %d", i + 1);
3875 win_show(wins[i], label, i + 1);
3881 /* Set the PANEL_DATA structures for individual panels */
3882 void set_user_ptrs(PANEL **panels, int n)
3888 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA));
3890 for(i = 0;i < n; ++i)
3891 { win = panel_window(panels[i]);
3892 getbegyx(win, y, x);
3893 getmaxyx(win, h, w);
3898 sprintf(temp, "Window Number %d", i + 1);
3899 strcpy(ptrs[i].label, temp);
3900 ptrs[i].label_color = i + 1;
3902 ptrs[i].next = panels[0];
3904 ptrs[i].next = panels[i + 1];
3905 set_panel_userptr(panels[i], &ptrs[i]);
3909 /* Show the window with a border and a label */
3910 void win_show(WINDOW *win, char *label, int label_color)
3911 { int startx, starty, height, width;
3913 getbegyx(win, starty, startx);
3914 getmaxyx(win, height, width);
3917 mvwaddch(win, 2, 0, ACS_LTEE);
3918 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3919 mvwaddch(win, 2, width - 1, ACS_RTEE);
3921 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3924 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3938 length = strlen(string);
3939 temp = (width - length)/ 2;
3940 x = startx + (int)temp;
3941 wattron(win, color);
3942 mvwprintw(win, y, x, "%s", string);
3943 wattroff(win, color);
3949 <p>Concentrate on the main while loop. Once it finds out
3950 the type of key pressed, it takes appropriate action. If
3951 'r' is pressed resizing mode is started. After this the new
3952 sizes are updated as the user presses the arrow keys. When
3953 the user presses <ENTER> present selection ends and
3954 panel is resized by using the concept explained. While in
3955 resizing mode the program doesn't show how the window is
3956 getting resized. It's left as an exercise to the reader to
3957 print a dotted border while it gets resized to a new
3960 <p>When the user presses 'm' the move mode starts. This is
3961 a bit simpler than resizing. As the arrow keys are pressed
3962 the new position is updated and pressing of <ENTER>
3963 causes the panel to be moved by calling the function
3966 <p>In this program the user data which is represented as
3967 PANEL_DATA, plays very important role in finding the
3968 associated information with a panel. As written in the
3969 comments, the PANEL_DATA stores the panel sizes, label,
3970 label color and a pointer to the next panel in the
3977 <h3 class="SECT2"><a name="PANELSHOWHIDE" id=
3978 "PANELSHOWHIDE">16.6. Hiding and Showing Panels</a></h3>
3980 <p>A Panel can be hidden by using the function
3981 hide_panel(). This function merely removes it form the
3982 stack of panels, thus hiding it on the screen once you do
3983 update_panels() and doupdate(). It doesn't destroy the
3984 PANEL structure associated with the hidden panel. It can be
3985 shown again by using the show_panel() function.</p>
3987 <p>The following program shows the hiding of panels. Press
3988 'a' or 'b' or 'c' to show or hide first, second and third
3989 windows respectively. It uses a user data with a small
3990 variable hide, which keeps track of whether the window is
3991 hidden or not. For some reason the function <tt class=
3992 "LITERAL">panel_hidden()</tt> which tells whether a panel
3993 is hidden or not is not working. A bug report was also
3994 presented by Michael Andres <a href=
3995 "http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/"
3996 target="_top">here</a></p>
3998 <div class="EXAMPLE">
3999 <a name="PPAHI" id="PPAHI"></a>
4001 <p><b>Example 17. Panel Hiding and Showing
4003 <pre class="PROGRAMLISTING">
4004 <span class="INLINEMEDIAOBJECT">#include <panel.h>
4006 typedef struct _PANEL_DATA {
4007 int hide; /* TRUE if panel is hidden */
4013 void init_wins(WINDOW **wins, int n);
4014 void win_show(WINDOW *win, char *label, int label_color);
4015 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4018 { WINDOW *my_wins[3];
4019 PANEL *my_panels[3];
4020 PANEL_DATA panel_datas[3];
4024 /* Initialize curses */
4029 keypad(stdscr, TRUE);
4031 /* Initialize all the colors */
4032 init_pair(1, COLOR_RED, COLOR_BLACK);
4033 init_pair(2, COLOR_GREEN, COLOR_BLACK);
4034 init_pair(3, COLOR_BLUE, COLOR_BLACK);
4035 init_pair(4, COLOR_CYAN, COLOR_BLACK);
4037 init_wins(my_wins, 3);
4039 /* Attach a panel to each window */ /* Order is bottom up */
4040 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
4041 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
4042 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
4044 /* Initialize panel datas saying that nothing is hidden */
4045 panel_datas[0].hide = FALSE;
4046 panel_datas[1].hide = FALSE;
4047 panel_datas[2].hide = FALSE;
4049 set_panel_userptr(my_panels[0], &panel_datas[0]);
4050 set_panel_userptr(my_panels[1], &panel_datas[1]);
4051 set_panel_userptr(my_panels[2], &panel_datas[2]);
4053 /* Update the stacking order. 2nd panel will be on top */
4056 /* Show it on the screen */
4057 attron(COLOR_PAIR(4));
4058 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)");
4059 mvprintw(LINES - 2, 0, "F1 to Exit");
4061 attroff(COLOR_PAIR(4));
4064 while((ch = getch()) != KEY_F(1))
4067 temp = (PANEL_DATA *)panel_userptr(my_panels[0]);
4068 if(temp->hide == FALSE)
4069 { hide_panel(my_panels[0]);
4070 temp->hide = TRUE;
4073 { show_panel(my_panels[0]);
4074 temp->hide = FALSE;
4078 temp = (PANEL_DATA *)panel_userptr(my_panels[1]);
4079 if(temp->hide == FALSE)
4080 { hide_panel(my_panels[1]);
4081 temp->hide = TRUE;
4084 { show_panel(my_panels[1]);
4085 temp->hide = FALSE;
4089 temp = (PANEL_DATA *)panel_userptr(my_panels[2]);
4090 if(temp->hide == FALSE)
4091 { hide_panel(my_panels[2]);
4092 temp->hide = TRUE;
4095 { show_panel(my_panels[2]);
4096 temp->hide = FALSE;
4107 /* Put all the windows */
4108 void init_wins(WINDOW **wins, int n)
4114 for(i = 0; i < n; ++i)
4115 { wins[i] = newwin(NLINES, NCOLS, y, x);
4116 sprintf(label, "Window Number %d", i + 1);
4117 win_show(wins[i], label, i + 1);
4123 /* Show the window with a border and a label */
4124 void win_show(WINDOW *win, char *label, int label_color)
4125 { int startx, starty, height, width;
4127 getbegyx(win, starty, startx);
4128 getmaxyx(win, height, width);
4131 mvwaddch(win, 2, 0, ACS_LTEE);
4132 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
4133 mvwaddch(win, 2, width - 1, ACS_RTEE);
4135 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
4138 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4152 length = strlen(string);
4153 temp = (width - length)/ 2;
4154 x = startx + (int)temp;
4155 wattron(win, color);
4156 mvwprintw(win, y, x, "%s", string);
4157 wattroff(win, color);
4167 <h3 class="SECT2"><a name="PANELABOVE" id=
4168 "PANELABOVE">16.7. panel_above() and panel_below()
4171 <p>The functions <tt class="LITERAL">panel_above()</tt> and
4172 <tt class="LITERAL">panel_below()</tt> can be used to find
4173 out the panel above and below a panel. If the argument to
4174 these functions is NULL, then they return a pointer to
4175 bottom panel and top panel respectively.</p>
4182 <h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus
4185 <p>The menus library provides a nice extension to basic
4186 curses, through which you can create menus. It provides a set
4187 of functions to create menus. But they have to be customized
4188 to give a nicer look, with colors etc. Let's get into the
4191 <p>A menu is a screen display that assists the user to choose
4192 some subset of a given set of items. To put it simple, a menu
4193 is a collection of items from which one or more items can be
4194 chosen. Some readers might not be aware of multiple item
4195 selection capability. Menu library provides functionality to
4196 write menus from which the user can chose more than one item
4197 as the preferred choice. This is dealt with in a later
4198 section. Now it is time for some rudiments.</p>
4203 <h3 class="SECT2"><a name="MENUBASICS" id=
4204 "MENUBASICS">17.1. The Basics</a></h3>
4206 <p>To create menus, you first create items, and then post
4207 the menu to the display. After that, all the processing of
4208 user responses is done in an elegant function menu_driver()
4209 which is the work horse of any menu program.</p>
4211 <p>The general flow of control of a menu program looks like
4216 <p>Initialize curses</p>
4220 <p>Create items using new_item(). You can specify a
4221 name and description for the items.</p>
4225 <p>Create the menu with new_menu() by specifying the
4226 items to be attached with.</p>
4230 <p>Post the menu with menu_post() and refresh the
4235 <p>Process the user requests with a loop and do
4236 necessary updates to menu with menu_driver.</p>
4240 <p>Unpost the menu with menu_unpost()</p>
4244 <p>Free the memory allocated to menu by free_menu()</p>
4248 <p>Free the memory allocated to the items with
4257 <p>Let's see a program which prints a simple menu and
4258 updates the current selection with up, down arrows.</p>
4264 <h3 class="SECT2"><a name="COMPILEMENUS" id=
4265 "COMPILEMENUS">17.2. Compiling With the Menu
4268 <p>To use menu library functions, you have to include
4269 menu.h and to link the program with menu library the flag
4270 -lmenu should be added along with -lncurses in that
4272 <pre class="PROGRAMLISTING">
4273 #include <menu.h>
4278 compile and link: gcc <program file> -lmenu -lncurses
4281 <div class="EXAMPLE">
4282 <a name="MMESI" id="MMESI"></a>
4284 <p><b>Example 18. Menu Basics</b></p>
4285 <pre class="PROGRAMLISTING">
4286 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4287 #include <menu.h>
4289 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4311 keypad(stdscr, TRUE);
4313 n_choices = ARRAY_SIZE(choices);
4314 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4316 for(i = 0; i < n_choices; ++i)
4317 my_items[i] = new_item(choices[i], choices[i]);
4318 my_items[n_choices] = (ITEM *)NULL;
4320 my_menu = new_menu((ITEM **)my_items);
4321 mvprintw(LINES - 2, 0, "F1 to Exit");
4325 while((c = getch()) != KEY_F(1))
4328 menu_driver(my_menu, REQ_DOWN_ITEM);
4331 menu_driver(my_menu, REQ_UP_ITEM);
4336 free_item(my_items[0]);
4337 free_item(my_items[1]);
4345 <p>This program demonstrates the basic concepts involved in
4346 creating a menu using menus library. First we create the
4347 items using new_item() and then attach them to the menu
4348 with new_menu() function. After posting the menu and
4349 refreshing the screen, the main processing loop starts. It
4350 reads user input and takes corresponding action. The
4351 function menu_driver() is the main work horse of the menu
4352 system. The second parameter to this function tells what's
4353 to be done with the menu. According to the parameter,
4354 menu_driver() does the corresponding task. The value can be
4355 either a menu navigational request, an ascii character, or
4356 a KEY_MOUSE special key associated with a mouse event.</p>
4358 <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.
4380 <p>Don't get overwhelmed by the number of options. We will
4381 see them slowly one after another. The options of interest
4382 in this example are REQ_UP_ITEM and REQ_DOWN_ITEM. These
4383 two options when passed to menu_driver, menu driver updates
4384 the current item to one item up or down respectively.</p>
4390 <h3 class="SECT2"><a name="MENUDRIVER" id=
4391 "MENUDRIVER">17.3. Menu Driver: The work horse of the menu
4394 <p>As you have seen in the above example, menu_driver plays
4395 an important role in updating the menu. It is very
4396 important to understand various options it takes and what
4397 they do. As explained above, the second parameter to
4398 menu_driver() can be either a navigational request, a
4399 printable character or a KEY_MOUSE key. Let's dissect the
4400 different navigational requests.</p>
4404 <p><span class="emphasis"><i class=
4405 "EMPHASIS">REQ_LEFT_ITEM and
4406 REQ_RIGHT_ITEM</i></span></p>
4408 <p>A Menu can be displayed with multiple columns for
4409 more than one item. This can be done by using the
4410 <tt class="LITERAL">menu_format()</tt>function. When a
4411 multi columnar menu is displayed these requests cause
4412 the menu driver to move the current selection to left
4417 <p><span class="emphasis"><i class=
4418 "EMPHASIS">REQ_UP_ITEM and REQ_DOWN_ITEM</i></span></p>
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_*
4428 options</i></span></p>
4430 <p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE,
4431 REQ_SCR_DPAGE, REQ_SCR_UPAGE are related to scrolling.
4432 If all the items in the menu cannot be displayed in the
4433 menu sub window, then the menu is scrollable. These
4434 requests can be given to the menu_driver to do the
4435 scrolling either one line up, down or one page down or
4436 up respectively.</p>
4440 <p><span class="emphasis"><i class=
4441 "EMPHASIS">REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM
4442 and REQ_PREV_ITEM</i></span></p>
4444 <p>These requests are self explanatory.</p>
4448 <p><span class="emphasis"><i class=
4449 "EMPHASIS">REQ_TOGGLE_ITEM</i></span></p>
4451 <p>This request when given, toggles the present
4452 selection. This option is to be used only in a multi
4453 valued menu. So to use this request the option
4454 O_ONEVALUE must be off. This option can be made off or
4455 on with set_menu_opts().</p>
4459 <p><span class="emphasis"><i class="EMPHASIS">Pattern
4460 Requests</i></span></p>
4462 <p>Every menu has an associated pattern buffer, which
4463 is used to find the nearest match to the ascii
4464 characters entered by the user. Whenever ascii
4465 characters are given to menu_driver, it puts in to the
4466 pattern buffer. It also tries to find the nearest match
4467 to the pattern in the items list and moves current
4468 selection to that item. The request REQ_CLEAR_PATTERN
4469 clears the pattern buffer. The request REQ_BACK_PATTERN
4470 deletes the previous character in the pattern buffer.
4471 In case the pattern matches more than one item then the
4472 matched items can be cycled through REQ_NEXT_MATCH and
4473 REQ_PREV_MATCH which move the current selection to the
4474 next and previous matches respectively.</p>
4478 <p><span class="emphasis"><i class="EMPHASIS">Mouse
4479 Requests</i></span></p>
4481 <p>In case of KEY_MOUSE requests, according to the
4482 mouse position an action is taken accordingly. The
4483 action to be taken is explained in the man page as,</p>
4484 <pre class="PROGRAMLISTING">
4485 <span class="emphasis"><i class=
4486 "EMPHASIS"> If the second argument is the KEY_MOUSE special key, the
4487 associated mouse event is translated into one of the above
4488 pre-defined requests. Currently only clicks in the user
4489 window (e.g. inside the menu display area or the decora­
4490 tion window) are handled. If you click above the display
4491 region of the menu, a REQ_SCR_ULINE is generated, if you
4492 doubleclick a REQ_SCR_UPAGE is generated and if you
4493 tripleclick a REQ_FIRST_ITEM is generated. If you click
4494 below the display region of the menu, a REQ_SCR_DLINE is
4495 generated, if you doubleclick a REQ_SCR_DPAGE is generated
4496 and if you tripleclick a REQ_LAST_ITEM is generated. If
4497 you click at an item inside the display area of the menu,
4498 the menu cursor is positioned to that item.</i></span>
4503 <p>Each of the above requests will be explained in the
4504 following lines with several examples whenever
4511 <h3 class="SECT2"><a name="MENUWINDOWS" id=
4512 "MENUWINDOWS">17.4. Menu Windows</a></h3>
4514 <p>Every menu created is associated with a window and a sub
4515 window. The menu window displays any title or border
4516 associated with the menu. The menu sub window displays the
4517 menu items currently available for selection. But we didn't
4518 specify any window or sub window in the simple example.
4519 When a window is not specified, stdscr is taken as the main
4520 window, and then menu system calculates the sub window size
4521 required for the display of items. Then items are displayed
4522 in the calculated sub window. So let's play with these
4523 windows and display a menu with a border and a title.</p>
4525 <div class="EXAMPLE">
4526 <a name="MMEWI" id="MMEWI"></a>
4528 <p><b>Example 19. Menu Windows Usage example</b></p>
4529 <pre class="PROGRAMLISTING">
4530 <span class="INLINEMEDIAOBJECT">#include <menu.h>
4532 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4543 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4549 WINDOW *my_menu_win;
4552 /* Initialize curses */
4557 keypad(stdscr, TRUE);
4558 init_pair(1, COLOR_RED, COLOR_BLACK);
4561 n_choices = ARRAY_SIZE(choices);
4562 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4563 for(i = 0; i < n_choices; ++i)
4564 my_items[i] = new_item(choices[i], choices[i]);
4567 my_menu = new_menu((ITEM **)my_items);
4569 /* Create the window to be associated with the menu */
4570 my_menu_win = newwin(10, 40, 4, 4);
4571 keypad(my_menu_win, TRUE);
4573 /* Set main window and sub window */
4574 set_menu_win(my_menu, my_menu_win);
4575 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4577 /* Set menu mark to the string " * " */
4578 set_menu_mark(my_menu, " * ");
4580 /* Print a border around the main window and print a title */
4581 box(my_menu_win, 0, 0);
4582 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4583 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4584 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4585 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4586 mvprintw(LINES - 2, 0, "F1 to exit");
4591 wrefresh(my_menu_win);
4593 while((c = wgetch(my_menu_win)) != KEY_F(1))
4596 menu_driver(my_menu, REQ_DOWN_ITEM);
4599 menu_driver(my_menu, REQ_UP_ITEM);
4602 wrefresh(my_menu_win);
4605 /* Unpost and free all the memory taken up */
4606 unpost_menu(my_menu);
4608 for(i = 0; i < n_choices; ++i)
4609 free_item(my_items[i]);
4613 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4627 length = strlen(string);
4628 temp = (width - length)/ 2;
4629 x = startx + (int)temp;
4630 wattron(win, color);
4631 mvwprintw(win, y, x, "%s", string);
4632 wattroff(win, color);
4638 <p>This example creates a menu with a title, border, a
4639 fancy line separating title and the items. As you can see,
4640 in order to attach a window to a menu the function
4641 set_menu_win() has to be used. Then we attach the sub
4642 window also. This displays the items in the sub window. You
4643 can also set the mark string which gets displayed to the
4644 left of the selected item with set_menu_mark().</p>
4650 <h3 class="SECT2"><a name="SCROLLMENUS" id=
4651 "SCROLLMENUS">17.5. Scrolling Menus</a></h3>
4653 <p>If the sub window given for a window is not big enough
4654 to show all the items, then the menu will be scrollable.
4655 When you are on the last item in the present list, if you
4656 send REQ_DOWN_ITEM, it gets translated into REQ_SCR_DLINE
4657 and the menu scrolls by one item. You can manually give
4658 REQ_SCR_ operations to do scrolling. Let's see how it can
4661 <div class="EXAMPLE">
4662 <a name="MMESC" id="MMESC"></a>
4664 <p><b>Example 20. Scrolling Menus example</b></p>
4665 <pre class="PROGRAMLISTING">
4666 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4667 #include <menu.h>
4669 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4686 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4692 WINDOW *my_menu_win;
4695 /* Initialize curses */
4700 keypad(stdscr, TRUE);
4701 init_pair(1, COLOR_RED, COLOR_BLACK);
4702 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4705 n_choices = ARRAY_SIZE(choices);
4706 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4707 for(i = 0; i < n_choices; ++i)
4708 my_items[i] = new_item(choices[i], choices[i]);
4711 my_menu = new_menu((ITEM **)my_items);
4713 /* Create the window to be associated with the menu */
4714 my_menu_win = newwin(10, 40, 4, 4);
4715 keypad(my_menu_win, TRUE);
4717 /* Set main window and sub window */
4718 set_menu_win(my_menu, my_menu_win);
4719 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4720 set_menu_format(my_menu, 5, 1);
4722 /* Set menu mark to the string " * " */
4723 set_menu_mark(my_menu, " * ");
4725 /* Print a border around the main window and print a title */
4726 box(my_menu_win, 0, 0);
4727 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4728 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4729 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4730 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4734 wrefresh(my_menu_win);
4736 attron(COLOR_PAIR(2));
4737 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items");
4738 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)");
4739 attroff(COLOR_PAIR(2));
4742 while((c = wgetch(my_menu_win)) != KEY_F(1))
4745 menu_driver(my_menu, REQ_DOWN_ITEM);
4748 menu_driver(my_menu, REQ_UP_ITEM);
4751 menu_driver(my_menu, REQ_SCR_DPAGE);
4754 menu_driver(my_menu, REQ_SCR_UPAGE);
4757 wrefresh(my_menu_win);
4760 /* Unpost and free all the memory taken up */
4761 unpost_menu(my_menu);
4763 for(i = 0; i < n_choices; ++i)
4764 free_item(my_items[i]);
4768 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4782 length = strlen(string);
4783 temp = (width - length)/ 2;
4784 x = startx + (int)temp;
4785 wattron(win, color);
4786 mvwprintw(win, y, x, "%s", string);
4787 wattroff(win, color);
4793 <p>This program is self-explanatory. In this example the
4794 number of choices has been increased to ten, which is
4795 larger than our sub window size which can hold 6 items.
4796 This message has to be explicitly conveyed to the menu
4797 system with the function set_menu_format(). In here we
4798 specify the number of rows and columns we want to be
4799 displayed for a single page. We can specify any number of
4800 items to be shown, in the rows variables, if it is less
4801 than the height of the sub window. If the key pressed by
4802 the user is a PAGE UP or PAGE DOWN, the menu is scrolled a
4803 page due to the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE)
4804 given to menu_driver().</p>
4810 <h3 class="SECT2"><a name="MULTICOLUMN" id=
4811 "MULTICOLUMN">17.6. Multi Columnar Menus</a></h3>
4813 <p>In the above example you have seen how to use the
4814 function set_menu_format(). I didn't mention what the cols
4815 variable (third parameter) does. Well, If your sub window
4816 is wide enough, you can opt to display more than one item
4817 per row. This can be specified in the cols variable. To
4818 make things simpler, the following example doesn't show
4819 descriptions for the items.</p>
4821 <div class="EXAMPLE">
4822 <a name="MMEMUCO" id="MMEMUCO"></a>
4824 <p><b>Example 21. Milt Columnar Menus Example</b></p>
4825 <pre class="PROGRAMLISTING">
4826 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4827 #include <menu.h>
4829 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4833 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5",
4834 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10",
4835 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15",
4836 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20",
4845 WINDOW *my_menu_win;
4848 /* Initialize curses */
4853 keypad(stdscr, TRUE);
4854 init_pair(1, COLOR_RED, COLOR_BLACK);
4855 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4858 n_choices = ARRAY_SIZE(choices);
4859 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4860 for(i = 0; i < n_choices; ++i)
4861 my_items[i] = new_item(choices[i], choices[i]);
4864 my_menu = new_menu((ITEM **)my_items);
4866 /* Set menu option not to show the description */
4867 menu_opts_off(my_menu, O_SHOWDESC);
4869 /* Create the window to be associated with the menu */
4870 my_menu_win = newwin(10, 70, 4, 4);
4871 keypad(my_menu_win, TRUE);
4873 /* Set main window and sub window */
4874 set_menu_win(my_menu, my_menu_win);
4875 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1));
4876 set_menu_format(my_menu, 5, 3);
4877 set_menu_mark(my_menu, " * ");
4879 /* Print a border around the main window and print a title */
4880 box(my_menu_win, 0, 0);
4882 attron(COLOR_PAIR(2));
4883 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll");
4884 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)");
4885 attroff(COLOR_PAIR(2));
4890 wrefresh(my_menu_win);
4892 while((c = wgetch(my_menu_win)) != KEY_F(1))
4895 menu_driver(my_menu, REQ_DOWN_ITEM);
4898 menu_driver(my_menu, REQ_UP_ITEM);
4901 menu_driver(my_menu, REQ_LEFT_ITEM);
4904 menu_driver(my_menu, REQ_RIGHT_ITEM);
4907 menu_driver(my_menu, REQ_SCR_DPAGE);
4910 menu_driver(my_menu, REQ_SCR_UPAGE);
4913 wrefresh(my_menu_win);
4916 /* Unpost and free all the memory taken up */
4917 unpost_menu(my_menu);
4919 for(i = 0; i < n_choices; ++i)
4920 free_item(my_items[i]);
4926 <p>Watch the function call to set_menu_format(). It
4927 specifies the number of columns to be 3, thus displaying 3
4928 items per row. We have also switched off the showing
4929 descriptions with the function menu_opts_off(). There are
4930 couple of functions set_menu_opts(), menu_opts_on() and
4931 menu_opts() which can be used to manipulate menu options.
4932 The following menu options can be specified.</p>
4933 <pre class="PROGRAMLISTING">
4935 Only one item can be selected for this menu.
4938 Display the item descriptions when the menu is
4942 Display the menu in row-major order.
4945 Ignore the case when pattern-matching.
4948 Move the cursor to within the item name while pat­
4952 Don't wrap around next-item and previous-item,
4953 requests to the other end of the menu.
4956 <p>All options are on by default. You can switch specific
4957 attributes on or off with menu_opts_on() and
4958 menu_opts_off() functions. You can also use set_menu_opts()
4959 to directly specify the options. The argument to this
4960 function should be a OR ed value of some of those above
4961 constants. The function menu_opts() can be used to find out
4962 a menu's present options.</p>
4968 <h3 class="SECT2"><a name="MULTIVALUEMENUS" id=
4969 "MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3>
4971 <p>You might be wondering what if you switch off the option
4972 O_ONEVALUE. Then the menu becomes multi-valued. That means
4973 you can select more than one item. This brings us to the
4974 request REQ_TOGGLE_ITEM. Let's see it in action.</p>
4976 <div class="EXAMPLE">
4977 <a name="MMETO" id="MMETO"></a>
4979 <p><b>Example 22. Multi Valued Menus example</b></p>
4980 <pre class="PROGRAMLISTING">
4981 <span class="INLINEMEDIAOBJECT">#include <curses.h>
4982 #include <menu.h>
4984 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5005 /* Initialize curses */
5009 keypad(stdscr, TRUE);
5011 /* Initialize items */
5012 n_choices = ARRAY_SIZE(choices);
5013 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5014 for(i = 0; i < n_choices; ++i)
5015 my_items[i] = new_item(choices[i], choices[i]);
5016 my_items[n_choices] = (ITEM *)NULL;
5018 my_menu = new_menu((ITEM **)my_items);
5020 /* Make the menu multi valued */
5021 menu_opts_off(my_menu, O_ONEVALUE);
5023 mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item.");
5024 mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)");
5028 while((c = getch()) != KEY_F(1))
5031 menu_driver(my_menu, REQ_DOWN_ITEM);
5034 menu_driver(my_menu, REQ_UP_ITEM);
5037 menu_driver(my_menu, REQ_TOGGLE_ITEM);
5039 case 10: /* Enter */
5043 items = menu_items(my_menu);
5045 for(i = 0; i < item_count(my_menu); ++i)
5046 if(item_value(items[i]) == TRUE)
5047 { strcat(temp, item_name(items[i]));
5052 mvprintw(20, 0, temp);
5059 free_item(my_items[0]);
5060 free_item(my_items[1]);
5068 <p>Whew, A lot of new functions. Let's take them one after
5069 another. Firstly, the REQ_TOGGLE_ITEM. In a multi-valued
5070 menu, the user should be allowed to select or un select
5071 more than one item. The request REQ_TOGGLE_ITEM toggles the
5072 present selection. In this case when space is pressed
5073 REQ_TOGGLE_ITEM request is sent to menu_driver to achieve
5076 <p>Now when the user presses <ENTER> we show the
5077 items he presently selected. First we find out the items
5078 associated with the menu using the function menu_items().
5079 Then we loop through the items to find out if the item is
5080 selected or not. The function item_value() returns TRUE if
5081 an item is selected. The function item_count() returns the
5082 number of items in the menu. The item name can be found
5083 with item_name(). You can also find the description
5084 associated with an item using item_description().</p>
5090 <h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu
5093 <p>Well, by this time you must be itching for some
5094 difference in your menu, with lots of functionality. I
5095 know. You want Colors !!!. You want to create nice menus
5096 similar to those text mode <a href=
5097 "http://www.jersey.net/~debinjoe/games/" target="_top">dos
5098 games</a>. The functions set_menu_fore() and
5099 set_menu_back() can be used to change the attribute of the
5100 selected item and unselected item. The names are
5101 misleading. They don't change menu's foreground or
5102 background which would have been useless.</p>
5104 <p>The function set_menu_grey() can be used to set the
5105 display attribute for the non-selectable items in the menu.
5106 This brings us to the interesting option for an item the
5107 one and only O_SELECTABLE. We can turn it off by the
5108 function item_opts_off() and after that that item is not
5109 selectable. It's like a grayed item in those fancy windows
5110 menus. Let's put these concepts in practice with this
5113 <div class="EXAMPLE">
5114 <a name="MMEAT" id="MMEAT"></a>
5116 <p><b>Example 23. Menu Options example</b></p>
5117 <pre class="PROGRAMLISTING">
5118 <span class="INLINEMEDIAOBJECT">#include <menu.h>
5120 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5141 /* Initialize curses */
5146 keypad(stdscr, TRUE);
5147 init_pair(1, COLOR_RED, COLOR_BLACK);
5148 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5149 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5151 /* Initialize items */
5152 n_choices = ARRAY_SIZE(choices);
5153 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5154 for(i = 0; i < n_choices; ++i)
5155 my_items[i] = new_item(choices[i], choices[i]);
5156 my_items[n_choices] = (ITEM *)NULL;
5157 item_opts_off(my_items[3], O_SELECTABLE);
5158 item_opts_off(my_items[6], O_SELECTABLE);
5161 my_menu = new_menu((ITEM **)my_items);
5163 /* Set fore ground and back ground of the menu */
5164 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE);
5165 set_menu_back(my_menu, COLOR_PAIR(2));
5166 set_menu_grey(my_menu, COLOR_PAIR(3));
5169 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5170 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5174 while((c = getch()) != KEY_F(1))
5177 menu_driver(my_menu, REQ_DOWN_ITEM);
5180 menu_driver(my_menu, REQ_UP_ITEM);
5182 case 10: /* Enter */
5185 mvprintw(20, 0, "Item selected is : %s",
5186 item_name(current_item(my_menu)));
5187 pos_menu_cursor(my_menu);
5191 unpost_menu(my_menu);
5192 for(i = 0; i < n_choices; ++i)
5193 free_item(my_items[i]);
5205 <h3 class="SECT2"><a name="MENUUSERPTR" id=
5206 "MENUUSERPTR">17.9. The useful User Pointer</a></h3>
5208 <p>We can associate a user pointer with each item in the
5209 menu. It works the same way as user pointer in panels. It's
5210 not touched by menu system. You can store any thing you
5211 like in that. I usually use it to store the function to be
5212 executed when the menu option is chosen (It's selected and
5213 may be the user pressed <ENTER>);</p>
5215 <div class="EXAMPLE">
5216 <a name="MMEUS" id="MMEUS"></a>
5218 <p><b>Example 24. Menu User Pointer Usage</b></p>
5219 <pre class="PROGRAMLISTING">
5220 <span class="INLINEMEDIAOBJECT">#include <curses.h>
5221 #include <menu.h>
5223 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
5236 void func(char *name);
5245 /* Initialize curses */
5250 keypad(stdscr, TRUE);
5251 init_pair(1, COLOR_RED, COLOR_BLACK);
5252 init_pair(2, COLOR_GREEN, COLOR_BLACK);
5253 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
5255 /* Initialize items */
5256 n_choices = ARRAY_SIZE(choices);
5257 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
5258 for(i = 0; i < n_choices; ++i)
5259 { my_items[i] = new_item(choices[i], choices[i]);
5260 /* Set the user pointer */
5261 set_item_userptr(my_items[i], func);
5263 my_items[n_choices] = (ITEM *)NULL;
5266 my_menu = new_menu((ITEM **)my_items);
5269 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected");
5270 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
5274 while((c = getch()) != KEY_F(1))
5277 menu_driver(my_menu, REQ_DOWN_ITEM);
5280 menu_driver(my_menu, REQ_UP_ITEM);
5282 case 10: /* Enter */
5286 cur = current_item(my_menu);
5287 p = item_userptr(cur);
5288 p((char *)item_name(cur));
5289 pos_menu_cursor(my_menu);
5295 unpost_menu(my_menu);
5296 for(i = 0; i < n_choices; ++i)
5297 free_item(my_items[i]);
5302 void func(char *name)
5305 mvprintw(20, 0, "Item selected is : %s", name);
5315 <h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms
5318 <p>Well. If you have seen those forms on web pages which take
5319 input from users and do various kinds of things, you might be
5320 wondering how would any one create such forms in text mode
5321 display. It's quite difficult to write those nifty forms in
5322 plain ncurses. Forms library tries to provide a basic frame
5323 work to build and maintain forms with ease. It has lot of
5324 features(functions) which manage validation, dynamic
5325 expansion of fields etc.. Let's see it in full flow.</p>
5327 <p>A form is a collection of fields; each field can be either
5328 a label(static text) or a data-entry location. The forms also
5329 library provides functions to divide forms into multiple
5335 <h3 class="SECT2"><a name="FORMBASICS" id=
5336 "FORMBASICS">18.1. The Basics</a></h3>
5338 <p>Forms are created in much the same way as menus. First
5339 the fields related to the form are created with
5340 new_field(). You can set options for the fields, so that
5341 they can be displayed with some fancy attributes, validated
5342 before the field looses focus etc.. Then the fields are
5343 attached to form. After this, the form can be posted to
5344 display and is ready to receive inputs. On the similar
5345 lines to menu_driver(), the form is manipulated with
5346 form_driver(). We can send requests to form_driver to move
5347 focus to a certain field, move cursor to end of the field
5348 etc.. After the user enters values in the fields and
5349 validation done, form can be unposted and memory allocated
5352 <p>The general flow of control of a forms program looks
5357 <p>Initialize curses</p>
5361 <p>Create fields using new_field(). You can specify the
5362 height and width of the field, and its position on the
5367 <p>Create the forms with new_form() by specifying the
5368 fields to be attached with.</p>
5372 <p>Post the form with form_post() and refresh the
5377 <p>Process the user requests with a loop and do
5378 necessary updates to form with form_driver.</p>
5382 <p>Unpost the menu with form_unpost()</p>
5386 <p>Free the memory allocated to menu by free_form()</p>
5390 <p>Free the memory allocated to the items with
5399 <p>As you can see, working with forms library is much
5400 similar to handling menu library. The following examples
5401 will explore various aspects of form processing. Let's
5402 start the journey with a simple example. first.</p>
5408 <h3 class="SECT2"><a name="COMPILEFORMS" id=
5409 "COMPILEFORMS">18.2. Compiling With the Forms
5412 <p>To use forms library functions, you have to include
5413 form.h and to link the program with forms library the flag
5414 -lform should be added along with -lncurses in that
5416 <pre class="PROGRAMLISTING">
5417 #include <form.h>
5422 compile and link: gcc <program file> -lform -lncurses
5425 <div class="EXAMPLE">
5426 <a name="FFOSI" id="FFOSI"></a>
5428 <p><b>Example 25. Forms Basics</b></p>
5429 <pre class="PROGRAMLISTING">
5430 <span class="INLINEMEDIAOBJECT">#include <form.h>
5437 /* Initialize curses */
5441 keypad(stdscr, TRUE);
5443 /* Initialize the fields */
5444 field[0] = new_field(1, 10, 4, 18, 0, 0);
5445 field[1] = new_field(1, 10, 6, 18, 0, 0);
5448 /* Set field options */
5449 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */
5450 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5451 /* Field is filled up */
5452 set_field_back(field[1], A_UNDERLINE);
5453 field_opts_off(field[1], O_AUTOSKIP);
5455 /* Create the form and post it */
5456 my_form = new_form(field);
5460 mvprintw(4, 10, "Value 1:");
5461 mvprintw(6, 10, "Value 2:");
5464 /* Loop through to get user requests */
5465 while((ch = getch()) != KEY_F(1))
5468 /* Go to next field */
5469 form_driver(my_form, REQ_NEXT_FIELD);
5470 /* Go to the end of the present buffer */
5471 /* Leaves nicely at the last character */
5472 form_driver(my_form, REQ_END_LINE);
5475 /* Go to previous field */
5476 form_driver(my_form, REQ_PREV_FIELD);
5477 form_driver(my_form, REQ_END_LINE);
5480 /* If this is a normal character, it gets */
5482 form_driver(my_form, ch);
5487 /* Un post form and free the memory */
5488 unpost_form(my_form);
5490 free_field(field[0]);
5491 free_field(field[1]);
5499 <p>Above example is pretty straight forward. It creates two
5500 fields with <tt class="LITERAL">new_field()</tt>.
5501 new_field() takes height, width, starty, startx, number of
5502 offscreen rows and number of additional working buffers.
5503 The fifth argument number of offscreen rows specifies how
5504 much of the field to be shown. If it is zero, the entire
5505 field is always displayed otherwise the form will be
5506 scrollable when the user accesses not displayed parts of
5507 the field. The forms library allocates one buffer per field
5508 to store the data user enters. Using the last parameter to
5509 new_field() we can specify it to allocate some additional
5510 buffers. These can be used for any purpose you like.</p>
5512 <p>After creating the fields, back ground attribute of both
5513 of them is set to an underscore with set_field_back(). The
5514 AUTOSKIP option is turned off using field_opts_off(). If
5515 this option is turned on, focus will move to the next field
5516 in the form once the active field is filled up
5519 <p>After attaching the fields to the form, it is posted.
5520 Here on, user inputs are processed in the while loop, by
5521 making corresponding requests to form_driver. The details
5522 of all the requests to the form_driver() are explained
5529 <h3 class="SECT2"><a name="PLAYFIELDS" id=
5530 "PLAYFIELDS">18.3. Playing with Fields</a></h3>
5532 <p>Each form field is associated with a lot of attributes.
5533 They can be manipulated to get the required effect and to
5534 have fun !!!. So why wait?</p>
5539 <h4 class="SECT3"><a name="FETCHINFO" id=
5540 "FETCHINFO">18.3.1. Fetching Size and Location of
5543 <p>The parameters we have given at the time of creation
5544 of a field can be retrieved with field_info(). It returns
5545 height, width, starty, startx, number of offscreen rows,
5546 and number of additional buffers into the parameters
5547 given to it. It is a sort of inverse of new_field().</p>
5548 <pre class="PROGRAMLISTING">
5549 int field_info( FIELD *field, /* field from which to fetch */
5550 int *height, *int width, /* field size */
5551 int *top, int *left, /* upper left corner */
5552 int *offscreen, /* number of offscreen rows */
5553 int *nbuf); /* number of working buffers */
5560 <h4 class="SECT3"><a name="MOVEFIELD" id=
5561 "MOVEFIELD">18.3.2. Moving the field</a></h4>
5563 <p>The location of the field can be moved to a different
5564 position with move_field().</p>
5565 <pre class="PROGRAMLISTING">
5566 int move_field( FIELD *field, /* field to alter */
5567 int top, int left); /* new upper-left corner */
5570 <p>As usual, the changed position can be queried with
5577 <h4 class="SECT3"><a name="JUSTIFYFIELD" id=
5578 "JUSTIFYFIELD">18.3.3. Field Justification</a></h4>
5580 <p>The justification to be done for the field can be
5581 fixed using the function set_field_just().</p>
5582 <pre class="PROGRAMLISTING">
5583 int set_field_just(FIELD *field, /* field to alter */
5584 int justmode); /* mode to set */
5585 int field_just(FIELD *field); /* fetch justify mode of field */
5588 <p>The justification mode valued accepted and returned by
5589 these functions are NO_JUSTIFICATION, JUSTIFY_RIGHT,
5590 JUSTIFY_LEFT, or JUSTIFY_CENTER.</p>
5596 <h4 class="SECT3"><a name="FIELDDISPATTRIB" id=
5597 "FIELDDISPATTRIB">18.3.4. Field Display
5600 <p>As you have seen, in the above example, display
5601 attribute for the fields can be set with set_field_fore()
5602 and setfield_back(). These functions set foreground and
5603 background attribute of the fields. You can also specify
5604 a pad character which will be filled in the unfilled
5605 portion of the field. The pad character is set with a
5606 call to set_field_pad(). Default pad value is a space.
5607 The functions field_fore(), field_back, field_pad() can
5608 be used to query the present foreground, background
5609 attributes and pad character for the field. The following
5610 list gives the usage of functions.</p>
5611 <pre class="PROGRAMLISTING">
5612 int set_field_fore(FIELD *field, /* field to alter */
5613 chtype attr); /* attribute to set */
5615 chtype field_fore(FIELD *field); /* field to query */
5616 /* returns foreground attribute */
5618 int set_field_back(FIELD *field, /* field to alter */
5619 chtype attr); /* attribute to set */
5621 chtype field_back(FIELD *field); /* field to query */
5622 /* returns background attribute */
5624 int set_field_pad(FIELD *field, /* field to alter */
5625 int pad); /* pad character to set */
5627 chtype field_pad(FIELD *field); /* field to query */
5628 /* returns present pad character */
5631 <p>Though above functions seem quite simple, using colors
5632 with set_field_fore() may be frustrating in the
5633 beginning. Let me first explain about foreground and
5634 background attributes of a field. The foreground
5635 attribute is associated with the character. That means a
5636 character in the field is printed with the attribute you
5637 have set with set_field_fore(). Background attribute is
5638 the attribute used to fill background of field, whether
5639 any character is there or not. So what about colors?
5640 Since colors are always defined in pairs, what is the
5641 right way to display colored fields? Here's an example
5642 clarifying color attributes.</p>
5644 <div class="EXAMPLE">
5645 <a name="FFOAT" id="FFOAT"></a>
5647 <p><b>Example 26. Form Attributes example</b></p>
5648 <pre class="PROGRAMLISTING">
5649 <span class="INLINEMEDIAOBJECT">#include <form.h>
5656 /* Initialize curses */
5661 keypad(stdscr, TRUE);
5663 /* Initialize few color pairs */
5664 init_pair(1, COLOR_WHITE, COLOR_BLUE);
5665 init_pair(2, COLOR_WHITE, COLOR_BLUE);
5667 /* Initialize the fields */
5668 field[0] = new_field(1, 10, 4, 18, 0, 0);
5669 field[1] = new_field(1, 10, 6, 18, 0, 0);
5672 /* Set field options */
5673 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */
5674 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */
5675 /* are printed in white */
5676 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5677 /* Field is filled up */
5678 set_field_back(field[1], A_UNDERLINE);
5679 field_opts_off(field[1], O_AUTOSKIP);
5681 /* Create the form and post it */
5682 my_form = new_form(field);
5686 set_current_field(my_form, field[0]); /* Set focus to the colored field */
5687 mvprintw(4, 10, "Value 1:");
5688 mvprintw(6, 10, "Value 2:");
5689 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5692 /* Loop through to get user requests */
5693 while((ch = getch()) != KEY_F(1))
5696 /* Go to next field */
5697 form_driver(my_form, REQ_NEXT_FIELD);
5698 /* Go to the end of the present buffer */
5699 /* Leaves nicely at the last character */
5700 form_driver(my_form, REQ_END_LINE);
5703 /* Go to previous field */
5704 form_driver(my_form, REQ_PREV_FIELD);
5705 form_driver(my_form, REQ_END_LINE);
5708 /* If this is a normal character, it gets */
5710 form_driver(my_form, ch);
5715 /* Un post form and free the memory */
5716 unpost_form(my_form);
5718 free_field(field[0]);
5719 free_field(field[1]);
5727 <p>Play with the color pairs and try to understand the
5728 foreground and background attributes. In my programs
5729 using color attributes, I usually set only the background
5730 with set_field_back(). Curses simply doesn't allow
5731 defining individual color attributes.</p>
5737 <h4 class="SECT3"><a name="FIELDOPTIONBITS" id=
5738 "FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4>
5740 <p>There is also a large collection of field option bits
5741 you can set to control various aspects of forms
5742 processing. You can manipulate them with these
5744 <pre class="PROGRAMLISTING">
5745 int set_field_opts(FIELD *field, /* field to alter */
5746 int attr); /* attribute to set */
5748 int field_opts_on(FIELD *field, /* field to alter */
5749 int attr); /* attributes to turn on */
5751 int field_opts_off(FIELD *field, /* field to alter */
5752 int attr); /* attributes to turn off */
5754 int field_opts(FIELD *field); /* field to query */
5757 <p>The function set_field_opts() can be used to directly
5758 set attributes of a field or you can choose to switch a
5759 few attributes on and off with field_opts_on() and
5760 field_opts_off() selectively. Anytime you can query the
5761 attributes of a field with field_opts(). The following is
5762 the list of available options. By default, all options
5765 <div class="VARIABLELIST">
5770 <p>Controls whether the field is visible on the
5771 screen. Can be used during form processing to hide
5772 or pop up fields depending on the value of parent
5779 <p>Controls whether the field is active during
5780 forms processing (i.e. visited by form navigation
5781 keys). Can be used to make labels or derived fields
5782 with buffer values alterable by the forms
5783 application, not the user.</p>
5789 <p>Controls whether data is displayed during field
5790 entry. If this option is turned off on a field, the
5791 library will accept and edit data in that field,
5792 but it will not be displayed and the visible field
5793 cursor will not move. You can turn off the O_PUBLIC
5794 bit to define password fields.</p>
5800 <p>Controls whether the field's data can be
5801 modified. When this option is off, all editing
5802 requests except <tt class=
5803 "LITERAL">REQ_PREV_CHOICE</tt> and <tt class=
5804 "LITERAL">REQ_NEXT_CHOICE</tt>will fail. Such
5805 read-only fields may be useful for help
5812 <p>Controls word-wrapping in multi-line fields.
5813 Normally, when any character of a (blank-separated)
5814 word reaches the end of the current line, the
5815 entire word is wrapped to the next line (assuming
5816 there is one). When this option is off, the word
5817 will be split across the line break.</p>
5823 <p>Controls field blanking. When this option is on,
5824 entering a character at the first field position
5825 erases the entire field (except for the
5826 just-entered character).</p>
5832 <p>Controls automatic skip to next field when this
5833 one fills. Normally, when the forms user tries to
5834 type more data into a field than will fit, the
5835 editing location jumps to next field. When this
5836 option is off, the user's cursor will hang at the
5837 end of the field. This option is ignored in dynamic
5838 fields that have not reached their size limit.</p>
5844 <p>Controls whether validation is applied to blank
5845 fields. Normally, it is not; the user can leave a
5846 field blank without invoking the usual validation
5847 check on exit. If this option is off on a field,
5848 exit from it will invoke a validation check.</p>
5854 <p>Controls whether validation occurs on every
5855 exit, or only after the field is modified. Normally
5856 the latter is true. Setting O_PASSOK may be useful
5857 if your field's validation function may change
5858 during forms processing.</p>
5864 <p>Controls whether the field is fixed to its
5865 initial dimensions. If you turn this off, the field
5866 becomes dynamic and will stretch to fit entered
5872 <p>A field's options cannot be changed while the field is
5873 currently selected. However, options may be changed on
5874 posted fields that are not current.</p>
5876 <p>The option values are bit-masks and can be composed
5877 with logical-or in the obvious way. You have seen the
5878 usage of switching off O_AUTOSKIP option. The following
5879 example clarifies usage of some more options. Other
5880 options are explained where appropriate.</p>
5882 <div class="EXAMPLE">
5883 <a name="FFOOP" id="FFOOP"></a>
5885 <p><b>Example 27. Field Options Usage example</b></p>
5886 <pre class="PROGRAMLISTING">
5887 <span class="INLINEMEDIAOBJECT">#include <form.h>
5896 { FIELD *field[N_FIELDS];
5900 /* Initialize curses */
5904 keypad(stdscr, TRUE);
5906 /* Initialize the fields */
5907 for(i = 0; i < N_FIELDS - 1; ++i)
5908 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0);
5909 field[N_FIELDS - 1] = NULL;
5911 /* Set field options */
5912 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */
5914 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */
5915 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/
5916 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */
5917 /* after last character is entered */
5919 /* Create the form and post it */
5920 my_form = new_form(field);
5924 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */
5925 set_field_buffer(field[0], 0, "This is a static Field");
5926 /* Initialize the field */
5927 mvprintw(STARTY, STARTX - 10, "Field 1:");
5928 mvprintw(STARTY + 2, STARTX - 10, "Field 2:");
5931 /* Loop through to get user requests */
5932 while((ch = getch()) != KEY_F(1))
5935 /* Go to next field */
5936 form_driver(my_form, REQ_NEXT_FIELD);
5937 /* Go to the end of the present buffer */
5938 /* Leaves nicely at the last character */
5939 form_driver(my_form, REQ_END_LINE);
5942 /* Go to previous field */
5943 form_driver(my_form, REQ_PREV_FIELD);
5944 form_driver(my_form, REQ_END_LINE);
5947 /* If this is a normal character, it gets */
5949 form_driver(my_form, ch);
5954 /* Un post form and free the memory */
5955 unpost_form(my_form);
5957 free_field(field[0]);
5958 free_field(field[1]);
5966 <p>This example, though useless, shows the usage of
5967 options. If used properly, they can present information
5968 very effectively in a form. The second field being not
5969 O_PUBLIC, does not show the characters you are
5976 <h4 class="SECT3"><a name="FIELDSTATUS" id=
5977 "FIELDSTATUS">18.3.6. Field Status</a></h4>
5979 <p>The field status specifies whether the field has got
5980 edited or not. It is initially set to FALSE and when user
5981 enters something and the data buffer gets modified it
5982 becomes TRUE. So a field's status can be queried to find
5983 out whether it has been modified or not. The following
5984 functions can assist in those operations.</p>
5985 <pre class="PROGRAMLISTING">
5986 int set_field_status(FIELD *field, /* field to alter */
5987 int status); /* status to set */
5989 int field_status(FIELD *field); /* fetch status of field */
5992 <p>It's better to check the field's status only after
5993 after leaving the field, as data buffer might not have
5994 been updated yet as the validation is still due. To
5995 guarantee that right status is returned, call
5996 field_status() either (1) in the field's exit validation
5997 check routine, (2) from the field's or form's
5998 initialization or termination hooks, or (3) just after a
5999 REQ_VALIDATION request has been processed by the forms
6006 <h4 class="SECT3"><a name="FIELDUSERPTR" id=
6007 "FIELDUSERPTR">18.3.7. Field User Pointer</a></h4>
6009 <p>Every field structure contains one pointer that can be
6010 used by the user for various purposes. It is not touched
6011 by forms library and can be used for any purpose by the
6012 user. The following functions set and fetch user
6014 <pre class="PROGRAMLISTING">
6015 int set_field_userptr(FIELD *field,
6016 char *userptr); /* the user pointer you wish to associate */
6017 /* with the field */
6019 char *field_userptr(FIELD *field); /* fetch user pointer of the field */
6026 <h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id=
6027 "VARIABLESIZEFIELDS">18.3.8. Variable-Sized
6030 <p>If you want a dynamically changing field with variable
6031 width, this is the feature you want to put to full use.
6032 This will allow the user to enter more data than the
6033 original size of the field and let the field grow.
6034 According to the field orientation it will scroll
6035 horizontally or vertically to incorporate the new
6038 <p>To make a field dynamically growable, the option
6039 O_STATIC should be turned off. This can be done with
6041 <pre class="PROGRAMLISTING">
6042 field_opts_off(field_pointer, O_STATIC);
6045 <p>But it's usually not advisable to allow a field to
6046 grow infinitely. You can set a maximum limit to the
6047 growth of the field with</p>
6048 <pre class="PROGRAMLISTING">
6049 int set_max_field(FIELD *field, /* Field on which to operate */
6050 int max_growth); /* maximum growth allowed for the field */
6053 <p>The field info for a dynamically growable field can be
6055 <pre class="PROGRAMLISTING">
6056 int dynamic_field_info( FIELD *field, /* Field on which to operate */
6057 int *prows, /* number of rows will be filled in this */
6058 int *pcols, /* number of columns will be filled in this*/
6059 int *pmax) /* maximum allowable growth will be filled */
6061 </pre>Though field_info work as usual, it is advisable to use this
6062 function to get the proper attributes of a dynamically growable
6065 <p>Recall the library routine new_field; a new field
6066 created with height set to one will be defined to be a
6067 one line field. A new field created with height greater
6068 than one will be defined to be a multi line field.</p>
6070 <p>A one line field with O_STATIC turned off (dynamically
6071 growable field) will contain a single fixed row, but the
6072 number of columns can increase if the user enters more
6073 data than the initial field will hold. The number of
6074 columns displayed will remain fixed and the additional
6075 data will scroll horizontally.</p>
6077 <p>A multi line field with O_STATIC turned off
6078 (dynamically growable field) will contain a fixed number
6079 of columns, but the number of rows can increase if the
6080 user enters more data than the initial field will hold.
6081 The number of rows displayed will remain fixed and the
6082 additional data will scroll vertically.</p>
6084 <p>The above two paragraphs pretty much describe a
6085 dynamically growable field's behavior. The way other
6086 parts of forms library behaves is described below:</p>
6090 <p>The field option O_AUTOSKIP will be ignored if the
6091 option O_STATIC is off and there is no maximum growth
6092 specified for the field. Currently, O_AUTOSKIP
6093 generates an automatic REQ_NEXT_FIELD form driver
6094 request when the user types in the last character
6095 position of a field. On a growable field with no
6096 maximum growth specified, there is no last character
6097 position. If a maximum growth is specified, the
6098 O_AUTOSKIP option will work as normal if the field
6099 has grown to its maximum size.</p>
6103 <p>The field justification will be ignored if the
6104 option O_STATIC is off. Currently, set_field_just can
6105 be used to JUSTIFY_LEFT, JUSTIFY_RIGHT,
6106 JUSTIFY_CENTER the contents of a one line field. A
6107 growable one line field will, by definition, grow and
6108 scroll horizontally and may contain more data than
6109 can be justified. The return from field_just will be
6114 <p>The overloaded form driver request REQ_NEW_LINE
6115 will operate the same way regardless of the
6116 O_NL_OVERLOAD form option if the field option
6117 O_STATIC is off and there is no maximum growth
6118 specified for the field. Currently, if the form
6119 option O_NL_OVERLOAD is on, REQ_NEW_LINE implicitly
6120 generates a REQ_NEXT_FIELD if called from the last
6121 line of a field. If a field can grow without bound,
6122 there is no last line, so REQ_NEW_LINE will never
6123 implicitly generate a REQ_NEXT_FIELD. If a maximum
6124 growth limit is specified and the O_NL_OVERLOAD form
6125 option is on, REQ_NEW_LINE will only implicitly
6126 generate REQ_NEXT_FIELD if the field has grown to its
6127 maximum size and the user is on the last line.</p>
6131 <p>The library call dup_field will work as usual; it
6132 will duplicate the field, including the current
6133 buffer size and contents of the field being
6134 duplicated. Any specified maximum growth will also be
6139 <p>The library call link_field will work as usual; it
6140 will duplicate all field attributes and share buffers
6141 with the field being linked. If the O_STATIC field
6142 option is subsequently changed by a field sharing
6143 buffers, how the system reacts to an attempt to enter
6144 more data into the field than the buffer will
6145 currently hold will depend on the setting of the
6146 option in the current field.</p>
6150 <p>The library call field_info will work as usual;
6151 the variable nrow will contain the value of the
6152 original call to new_field. The user should use
6153 dynamic_field_info, described above, to query the
6154 current size of the buffer.</p>
6158 <p>Some of the above points make sense only after
6159 explaining form driver. We will be looking into that in
6160 next few sections.</p>
6167 <h3 class="SECT2"><a name="FORMWINDOWS" id=
6168 "FORMWINDOWS">18.4. Form Windows</a></h3>
6170 <p>The form windows concept is pretty much similar to menu
6171 windows. Every form is associated with a main window and a
6172 sub window. The form main window displays any title or
6173 border associated or whatever the user wishes. Then the sub
6174 window contains all the fields and displays them according
6175 to their position. This gives the flexibility of
6176 manipulating fancy form displaying very easily.</p>
6178 <p>Since this is pretty much similar to menu windows, I am
6179 providing an example with out much explanation. The
6180 functions are similar and they work the same way.</p>
6182 <div class="EXAMPLE">
6183 <a name="FFOWI" id="FFOWI"></a>
6185 <p><b>Example 28. Form Windows Example</b></p>
6186 <pre class="PROGRAMLISTING">
6187 <span class="INLINEMEDIAOBJECT">#include <form.h>
6189 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
6195 WINDOW *my_form_win;
6198 /* Initialize curses */
6203 keypad(stdscr, TRUE);
6205 /* Initialize few color pairs */
6206 init_pair(1, COLOR_RED, COLOR_BLACK);
6208 /* Initialize the fields */
6209 field[0] = new_field(1, 10, 6, 1, 0, 0);
6210 field[1] = new_field(1, 10, 8, 1, 0, 0);
6213 /* Set field options */
6214 set_field_back(field[0], A_UNDERLINE);
6215 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
6216 /* Field is filled up */
6217 set_field_back(field[1], A_UNDERLINE);
6218 field_opts_off(field[1], O_AUTOSKIP);
6220 /* Create the form and post it */
6221 my_form = new_form(field);
6223 /* Calculate the area required for the form */
6224 scale_form(my_form, &rows, &cols);
6226 /* Create the window to be associated with the form */
6227 my_form_win = newwin(rows + 4, cols + 4, 4, 4);
6228 keypad(my_form_win, TRUE);
6230 /* Set main window and sub window */
6231 set_form_win(my_form, my_form_win);
6232 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2));
6234 /* Print a border around the main window and print a title */
6235 box(my_form_win, 0, 0);
6236 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1));
6239 wrefresh(my_form_win);
6241 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
6244 /* Loop through to get user requests */
6245 while((ch = wgetch(my_form_win)) != KEY_F(1))
6248 /* Go to next field */
6249 form_driver(my_form, REQ_NEXT_FIELD);
6250 /* Go to the end of the present buffer */
6251 /* Leaves nicely at the last character */
6252 form_driver(my_form, REQ_END_LINE);
6255 /* Go to previous field */
6256 form_driver(my_form, REQ_PREV_FIELD);
6257 form_driver(my_form, REQ_END_LINE);
6260 /* If this is a normal character, it gets */
6262 form_driver(my_form, ch);
6267 /* Un post form and free the memory */
6268 unpost_form(my_form);
6270 free_field(field[0]);
6271 free_field(field[1]);
6277 void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
6291 length = strlen(string);
6292 temp = (width - length)/ 2;
6293 x = startx + (int)temp;
6294 wattron(win, color);
6295 mvwprintw(win, y, x, "%s", string);
6296 wattroff(win, color);
6306 <h3 class="SECT2"><a name="FILEDVALIDATE" id=
6307 "FILEDVALIDATE">18.5. Field Validation</a></h3>
6309 <p>By default, a field will accept any data input by the
6310 user. It is possible to attach validation to the field.
6311 Then any attempt by the user to leave the field, while it
6312 contains data that doesn't match the validation type will
6313 fail. Some validation types also have a character-validity
6314 check for each time a character is entered in the
6317 <p>Validation can be attached to a field with the following
6319 <pre class="PROGRAMLISTING">
6320 int set_field_type(FIELD *field, /* field to alter */
6321 FIELDTYPE *ftype, /* type to associate */
6322 ...); /* additional arguments*/
6323 </pre>Once set, the validation type for a field can be queried with
6324 <pre class="PROGRAMLISTING">
6325 FIELDTYPE *field_type(FIELD *field); /* field to query */
6328 <p>The form driver validates the data in a field only when
6329 data is entered by the end-user. Validation does not occur
6334 <p>the application program changes the field value by
6335 calling set_field_buffer.</p>
6339 <p>linked field values are changed indirectly -- by
6340 changing the field to which they are linked</p>
6344 <p>The following are the pre-defined validation types. You
6345 can also specify custom validation, though it's a bit
6346 tricky and cumbersome.</p>
6348 <h1 class="BRIDGEHEAD"><a name="AEN1069" id=
6349 "AEN1069"></a>TYPE_ALPHA</h1>
6351 <p>This field type accepts alphabetic data; no blanks, no
6352 digits, no special characters (this is checked at
6353 character-entry time). It is set up with:</p>
6354 <pre class="PROGRAMLISTING">
6355 int set_field_type(FIELD *field, /* field to alter */
6356 TYPE_ALPHA, /* type to associate */
6357 int width); /* minimum width of field */
6360 <p>The width argument sets a minimum width of data. The
6361 user has to enter at-least width number of characters
6362 before he can leave the field. Typically you'll want to set
6363 this to the field width; if it's greater than the field
6364 width, the validation check will always fail. A minimum
6365 width of zero makes field completion optional.</p>
6367 <h1 class="BRIDGEHEAD"><a name="AEN1073" id=
6368 "AEN1073"></a>TYPE_ALNUM</h1>
6370 <p>This field type accepts alphabetic data and digits; no
6371 blanks, no special characters (this is checked at
6372 character-entry time). It is set up with:</p>
6373 <pre class="PROGRAMLISTING">
6374 int set_field_type(FIELD *field, /* field to alter */
6375 TYPE_ALNUM, /* type to associate */
6376 int width); /* minimum width of field */
6379 <p>The width argument sets a minimum width of data. As with
6380 TYPE_ALPHA, typically you'll want to set this to the field
6381 width; if it's greater than the field width, the validation
6382 check will always fail. A minimum width of zero makes field
6383 completion optional.</p>
6385 <h1 class="BRIDGEHEAD"><a name="AEN1077" id=
6386 "AEN1077"></a>TYPE_ENUM</h1>
6388 <p>This type allows you to restrict a field's values to be
6389 among a specified set of string values (for example, the
6390 two-letter postal codes for U.S. states). It is set up
6392 <pre class="PROGRAMLISTING">
6393 int set_field_type(FIELD *field, /* field to alter */
6394 TYPE_ENUM, /* type to associate */
6395 char **valuelist; /* list of possible values */
6396 int checkcase; /* case-sensitive? */
6397 int checkunique); /* must specify uniquely? */
6400 <p>The valuelist parameter must point at a NULL-terminated
6401 list of valid strings. The checkcase argument, if true,
6402 makes comparison with the string case-sensitive.</p>
6404 <p>When the user exits a TYPE_ENUM field, the validation
6405 procedure tries to complete the data in the buffer to a
6406 valid entry. If a complete choice string has been entered,
6407 it is of course valid. But it is also possible to enter a
6408 prefix of a valid string and have it completed for you.</p>
6410 <p>By default, if you enter such a prefix and it matches
6411 more than one value in the string list, the prefix will be
6412 completed to the first matching value. But the checkunique
6413 argument, if true, requires prefix matches to be unique in
6414 order to be valid.</p>
6416 <p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests
6417 can be particularly useful with these fields.</p>
6419 <h1 class="BRIDGEHEAD"><a name="AEN1084" id=
6420 "AEN1084"></a>TYPE_INTEGER</h1>
6422 <p>This field type accepts an integer. It is set up as
6424 <pre class="PROGRAMLISTING">
6425 int set_field_type(FIELD *field, /* field to alter */
6426 TYPE_INTEGER, /* type to associate */
6427 int padding, /* # places to zero-pad to */
6428 int vmin, int vmax); /* valid range */
6431 <p>Valid characters consist of an optional leading minus
6432 and digits. The range check is performed on exit. If the
6433 range maximum is less than or equal to the minimum, the
6434 range is ignored.</p>
6436 <p>If the value passes its range check, it is padded with
6437 as many leading zero digits as necessary to meet the
6438 padding argument.</p>
6440 <p>A TYPE_INTEGER value buffer can conveniently be
6441 interpreted with the C library function atoi(3).</p>
6443 <h1 class="BRIDGEHEAD"><a name="AEN1090" id=
6444 "AEN1090"></a>TYPE_NUMERIC</h1>
6446 <p>This field type accepts a decimal number. It is set up
6448 <pre class="PROGRAMLISTING">
6449 int set_field_type(FIELD *field, /* field to alter */
6450 TYPE_NUMERIC, /* type to associate */
6451 int padding, /* # places of precision */
6452 int vmin, int vmax); /* valid range */
6455 <p>Valid characters consist of an optional leading minus
6456 and digits. possibly including a decimal point. The range
6457 check is performed on exit. If the range maximum is less
6458 than or equal to the minimum, the range is ignored.</p>
6460 <p>If the value passes its range check, it is padded with
6461 as many trailing zero digits as necessary to meet the
6462 padding argument.</p>
6464 <p>A TYPE_NUMERIC value buffer can conveniently be
6465 interpreted with the C library function atof(3).</p>
6467 <h1 class="BRIDGEHEAD"><a name="AEN1096" id=
6468 "AEN1096"></a>TYPE_REGEXP</h1>
6470 <p>This field type accepts data matching a regular
6471 expression. It is set up as follows:</p>
6472 <pre class="PROGRAMLISTING">
6473 int set_field_type(FIELD *field, /* field to alter */
6474 TYPE_REGEXP, /* type to associate */
6475 char *regexp); /* expression to match */
6478 <p>The syntax for regular expressions is that of
6479 regcomp(3). The check for regular-expression match is
6480 performed on exit.</p>
6486 <h3 class="SECT2"><a name="FORMDRIVER" id=
6487 "FORMDRIVER">18.6. Form Driver: The work horse of the forms
6490 <p>As in the menu system, form_driver() plays a very
6491 important role in forms system. All types of requests to
6492 forms system should be funneled through form_driver().</p>
6493 <pre class="PROGRAMLISTING">
6494 int form_driver(FORM *form, /* form on which to operate */
6495 int request) /* form request code */
6498 <p>As you have seen some of the examples above, you have to
6499 be in a loop looking for user input and then decide whether
6500 it's a field data or a form request. The form requests are
6501 then passed to form_driver() to do the work.</p>
6503 <p>The requests roughly can be divided into following
6504 categories. Different requests and their usage is explained
6510 <h4 class="SECT3"><a name="PAGENAVREQ" id=
6511 "PAGENAVREQ">18.6.1. Page Navigation Requests</a></h4>
6513 <p>These requests cause page-level moves through the
6514 form, triggering display of a new form screen. A form can
6515 be made of multiple pages. If you have a big form with
6516 lot of fields and logical sections, then you can divide
6517 the form into pages. The function set_new_page() to set a
6518 new page at the field specified.</p>
6519 <pre class="PROGRAMLISTING">
6520 int set_new_page(FIELD *field,/* Field at which page break to be set or unset */
6521 bool new_page_flag); /* should be TRUE to put a break */
6524 <p>The following requests allow you to move to different
6529 <p><span class="emphasis"><i class=
6530 "EMPHASIS">REQ_NEXT_PAGE</i></span> Move to the next
6535 <p><span class="emphasis"><i class=
6536 "EMPHASIS">REQ_PREV_PAGE</i></span> Move to the
6537 previous form page.</p>
6541 <p><span class="emphasis"><i class=
6542 "EMPHASIS">REQ_FIRST_PAGE</i></span> Move to the
6543 first form page.</p>
6547 <p><span class="emphasis"><i class=
6548 "EMPHASIS">REQ_LAST_PAGE</i></span> Move to the last
6553 <p>These requests treat the list as cyclic; that is,
6554 REQ_NEXT_PAGE from the last page goes to the first, and
6555 REQ_PREV_PAGE from the first page goes to the last.</p>
6561 <h4 class="SECT3"><a name="INTERFIELDNAVREQ" id=
6562 "INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation
6565 <p>These requests handle navigation between fields on the
6570 <p><span class="emphasis"><i class=
6571 "EMPHASIS">REQ_NEXT_FIELD</i></span> Move to next
6576 <p><span class="emphasis"><i class=
6577 "EMPHASIS">REQ_PREV_FIELD</i></span> Move to previous
6582 <p><span class="emphasis"><i class=
6583 "EMPHASIS">REQ_FIRST_FIELD</i></span> Move to the
6588 <p><span class="emphasis"><i class=
6589 "EMPHASIS">REQ_LAST_FIELD</i></span> Move to the last
6594 <p><span class="emphasis"><i class=
6595 "EMPHASIS">REQ_SNEXT_FIELD</i></span> Move to sorted
6600 <p><span class="emphasis"><i class=
6601 "EMPHASIS">REQ_SPREV_FIELD</i></span> Move to sorted
6606 <p><span class="emphasis"><i class=
6607 "EMPHASIS">REQ_SFIRST_FIELD</i></span> Move to the
6608 sorted first field.</p>
6612 <p><span class="emphasis"><i class=
6613 "EMPHASIS">REQ_SLAST_FIELD</i></span> Move to the
6614 sorted last field.</p>
6618 <p><span class="emphasis"><i class=
6619 "EMPHASIS">REQ_LEFT_FIELD</i></span> Move left to
6624 <p><span class="emphasis"><i class=
6625 "EMPHASIS">REQ_RIGHT_FIELD</i></span> Move right to
6630 <p><span class="emphasis"><i class=
6631 "EMPHASIS">REQ_UP_FIELD</i></span> Move up to
6636 <p><span class="emphasis"><i class=
6637 "EMPHASIS">REQ_DOWN_FIELD</i></span> Move down to
6642 <p>These requests treat the list of fields on a page as
6643 cyclic; that is, REQ_NEXT_FIELD from the last field goes
6644 to the first, and REQ_PREV_FIELD from the first field
6645 goes to the last. The order of the fields for these (and
6646 the REQ_FIRST_FIELD and REQ_LAST_FIELD requests) is
6647 simply the order of the field pointers in the form array
6648 (as set up by new_form() or set_form_fields()</p>
6650 <p>It is also possible to traverse the fields as if they
6651 had been sorted in screen-position order, so the sequence
6652 goes left-to-right and top-to-bottom. To do this, use the
6653 second group of four sorted-movement requests.</p>
6655 <p>Finally, it is possible to move between fields using
6656 visual directions up, down, right, and left. To
6657 accomplish this, use the third group of four requests.
6658 Note, however, that the position of a form for purposes
6659 of these requests is its upper-left corner.</p>
6661 <p>For example, suppose you have a multi-line field B,
6662 and two single-line fields A and C on the same line with
6663 B, with A to the left of B and C to the right of B. A
6664 REQ_MOVE_RIGHT from A will go to B only if A, B, and C
6665 all share the same first line; otherwise it will skip
6672 <h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id=
6673 "INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation
6676 <p>These requests drive movement of the edit cursor
6677 within the currently selected field.</p>
6681 <p><span class="emphasis"><i class=
6682 "EMPHASIS">REQ_NEXT_CHAR</i></span> Move to next
6687 <p><span class="emphasis"><i class=
6688 "EMPHASIS">REQ_PREV_CHAR</i></span> Move to previous
6693 <p><span class="emphasis"><i class=
6694 "EMPHASIS">REQ_NEXT_LINE</i></span> Move to next
6699 <p><span class="emphasis"><i class=
6700 "EMPHASIS">REQ_PREV_LINE</i></span> Move to previous
6705 <p><span class="emphasis"><i class=
6706 "EMPHASIS">REQ_NEXT_WORD</i></span> Move to next
6711 <p><span class="emphasis"><i class=
6712 "EMPHASIS">REQ_PREV_WORD</i></span> Move to previous
6717 <p><span class="emphasis"><i class=
6718 "EMPHASIS">REQ_BEG_FIELD</i></span> Move to beginning
6723 <p><span class="emphasis"><i class=
6724 "EMPHASIS">REQ_END_FIELD</i></span> Move to end of
6729 <p><span class="emphasis"><i class=
6730 "EMPHASIS">REQ_BEG_LINE</i></span> Move to beginning
6735 <p><span class="emphasis"><i class=
6736 "EMPHASIS">REQ_END_LINE</i></span> Move to end of
6741 <p><span class="emphasis"><i class=
6742 "EMPHASIS">REQ_LEFT_CHAR</i></span> Move left in
6747 <p><span class="emphasis"><i class=
6748 "EMPHASIS">REQ_RIGHT_CHAR</i></span> Move right in
6753 <p><span class="emphasis"><i class=
6754 "EMPHASIS">REQ_UP_CHAR</i></span> Move up in
6759 <p><span class="emphasis"><i class=
6760 "EMPHASIS">REQ_DOWN_CHAR</i></span> Move down in
6765 <p>Each word is separated from the previous and next
6766 characters by whitespace. The commands to move to
6767 beginning and end of line or field look for the first or
6768 last non-pad character in their ranges.</p>
6774 <h4 class="SECT3"><a name="SCROLLREQ" id=
6775 "SCROLLREQ">18.6.4. Scrolling Requests</a></h4>
6777 <p>Fields that are dynamic and have grown and fields
6778 explicitly created with offscreen rows are scrollable.
6779 One-line fields scroll horizontally; multi-line fields
6780 scroll vertically. Most scrolling is triggered by editing
6781 and intra-field movement (the library scrolls the field
6782 to keep the cursor visible). It is possible to explicitly
6783 request scrolling with the following requests:</p>
6787 <p><span class="emphasis"><i class=
6788 "EMPHASIS">REQ_SCR_FLINE</i></span> Scroll vertically
6793 <p><span class="emphasis"><i class=
6794 "EMPHASIS">REQ_SCR_BLINE</i></span> Scroll vertically
6795 backward a line.</p>
6799 <p><span class="emphasis"><i class=
6800 "EMPHASIS">REQ_SCR_FPAGE</i></span> Scroll vertically
6805 <p><span class="emphasis"><i class=
6806 "EMPHASIS">REQ_SCR_BPAGE</i></span> Scroll vertically
6807 backward a page.</p>
6811 <p><span class="emphasis"><i class=
6812 "EMPHASIS">REQ_SCR_FHPAGE</i></span> Scroll
6813 vertically forward half a page.</p>
6817 <p><span class="emphasis"><i class=
6818 "EMPHASIS">REQ_SCR_BHPAGE</i></span> Scroll
6819 vertically backward half a page.</p>
6823 <p><span class="emphasis"><i class=
6824 "EMPHASIS">REQ_SCR_FCHAR</i></span> Scroll
6825 horizontally forward a character.</p>
6829 <p><span class="emphasis"><i class=
6830 "EMPHASIS">REQ_SCR_BCHAR</i></span> Scroll
6831 horizontally backward a character.</p>
6835 <p><span class="emphasis"><i class=
6836 "EMPHASIS">REQ_SCR_HFLINE</i></span> Scroll
6837 horizontally one field width forward.</p>
6841 <p><span class="emphasis"><i class=
6842 "EMPHASIS">REQ_SCR_HBLINE</i></span> Scroll
6843 horizontally one field width backward.</p>
6847 <p><span class="emphasis"><i class=
6848 "EMPHASIS">REQ_SCR_HFHALF</i></span> Scroll
6849 horizontally one half field width forward.</p>
6853 <p><span class="emphasis"><i class=
6854 "EMPHASIS">REQ_SCR_HBHALF</i></span> Scroll
6855 horizontally one half field width backward.</p>
6859 <p>For scrolling purposes, a page of a field is the
6860 height of its visible part.</p>
6866 <h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5.
6867 Editing Requests</a></h4>
6869 <p>When you pass the forms driver an ASCII character, it
6870 is treated as a request to add the character to the
6871 field's data buffer. Whether this is an insertion or a
6872 replacement depends on the field's edit mode (insertion
6875 <p>The following requests support editing the field and
6876 changing the edit mode:</p>
6880 <p><span class="emphasis"><i class=
6881 "EMPHASIS">REQ_INS_MODE</i></span> Set insertion
6886 <p><span class="emphasis"><i class=
6887 "EMPHASIS">REQ_OVL_MODE</i></span> Set overlay
6892 <p><span class="emphasis"><i class=
6893 "EMPHASIS">REQ_NEW_LINE</i></span> New line request
6894 (see below for explanation).</p>
6898 <p><span class="emphasis"><i class=
6899 "EMPHASIS">REQ_INS_CHAR</i></span> Insert space at
6900 character location.</p>
6904 <p><span class="emphasis"><i class=
6905 "EMPHASIS">REQ_INS_LINE</i></span> Insert blank line
6906 at character location.</p>
6910 <p><span class="emphasis"><i class=
6911 "EMPHASIS">REQ_DEL_CHAR</i></span> Delete character
6916 <p><span class="emphasis"><i class=
6917 "EMPHASIS">REQ_DEL_PREV</i></span> Delete previous
6922 <p><span class="emphasis"><i class=
6923 "EMPHASIS">REQ_DEL_LINE</i></span> Delete line at
6928 <p><span class="emphasis"><i class=
6929 "EMPHASIS">REQ_DEL_WORD</i></span> Delete word at
6934 <p><span class="emphasis"><i class=
6935 "EMPHASIS">REQ_CLR_EOL</i></span> Clear to end of
6940 <p><span class="emphasis"><i class=
6941 "EMPHASIS">REQ_CLR_EOF</i></span> Clear to end of
6946 <p><span class="emphasis"><i class=
6947 "EMPHASIS">REQ_CLR_FIELD</i></span> Clear entire
6952 <p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV
6953 requests is complicated and partly controlled by a pair
6954 of forms options. The special cases are triggered when
6955 the cursor is at the beginning of a field, or on the last
6956 line of the field.</p>
6958 <p>First, we consider REQ_NEW_LINE:</p>
6960 <p>The normal behavior of REQ_NEW_LINE in insert mode is
6961 to break the current line at the position of the edit
6962 cursor, inserting the portion of the current line after
6963 the cursor as a new line following the current and moving
6964 the cursor to the beginning of that new line (you may
6965 think of this as inserting a newline in the field
6968 <p>The normal behavior of REQ_NEW_LINE in overlay mode is
6969 to clear the current line from the position of the edit
6970 cursor to end of line. The cursor is then moved to the
6971 beginning of the next line.</p>
6973 <p>However, REQ_NEW_LINE at the beginning of a field, or
6974 on the last line of a field, instead does a
6975 REQ_NEXT_FIELD. O_NL_OVERLOAD option is off, this special
6976 action is disabled.</p>
6978 <p>Now, let us consider REQ_DEL_PREV:</p>
6980 <p>The normal behavior of REQ_DEL_PREV is to delete the
6981 previous character. If insert mode is on, and the cursor
6982 is at the start of a line, and the text on that line will
6983 fit on the previous one, it instead appends the contents
6984 of the current line to the previous one and deletes the
6985 current line (you may think of this as deleting a newline
6986 from the field buffer).</p>
6988 <p>However, REQ_DEL_PREV at the beginning of a field is
6989 instead treated as a REQ_PREV_FIELD.</p>
6991 <p>If the O_BS_OVERLOAD option is off, this special
6992 action is disabled and the forms driver just returns
6993 E_REQUEST_DENIED.</p>
6999 <h4 class="SECT3"><a name="ORDERREQ" id=
7000 "ORDERREQ">18.6.6. Order Requests</a></h4>
7002 <p>If the type of your field is ordered, and has
7003 associated functions for getting the next and previous
7004 values of the type from a given value, there are requests
7005 that can fetch that value into the field buffer:</p>
7009 <p><span class="emphasis"><i class=
7010 "EMPHASIS">REQ_NEXT_CHOICE</i></span> Place the
7011 successor value of the current value in the
7016 <p><span class="emphasis"><i class=
7017 "EMPHASIS">REQ_PREV_CHOICE</i></span> Place the
7018 predecessor value of the current value in the
7023 <p>Of the built-in field types, only TYPE_ENUM has
7024 built-in successor and predecessor functions. When you
7025 define a field type of your own (see Custom Validation
7026 Types), you can associate our own ordering functions.</p>
7032 <h4 class="SECT3"><a name="APPLICCOMMANDS" id=
7033 "APPLICCOMMANDS">18.6.7. Application Commands</a></h4>
7035 <p>Form requests are represented as integers above the
7036 curses value greater than KEY_MAX and less than or equal
7037 to the constant MAX_COMMAND. A value within this range
7038 gets ignored by form_driver(). So this can be used for
7039 any purpose by the application. It can be treated as an
7040 application specific action and take corresponding
7049 <h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and
7050 Widget Libraries</a></h2>
7052 <p>Now that you have seen the capabilities of ncurses and its
7053 sister libraries, you are rolling your sleeves up and gearing
7054 for a project that heavily manipulates screen. But wait.. It
7055 can be pretty difficult to write and maintain complex GUI
7056 widgets in plain ncurses or even with the additional
7057 libraries. There are some ready-to-use tools and widget
7058 libraries that can be used instead of writing your own
7059 widgets. You can use some of them, get ideas from the code,
7060 or even extend them.</p>
7065 <h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses
7066 Development Kit)</a></h3>
7068 <p>In the author's words</p>
7070 <p><span class="emphasis"><i class="EMPHASIS">CDK stands
7071 for 'Curses Development Kit' and it currently contains 21
7072 ready to use widgets which facilitate the speedy
7073 development of full screen curses programs.</i></span></p>
7075 <p>The kit provides some useful widgets, which can be used
7076 in your programs directly. It's pretty well written and the
7077 documentation is very good. The examples in the examples
7078 directory can be a good place to start for beginners. The
7079 CDK can be downloaded from <a href=
7080 "http://invisible-island.net/cdk/" target=
7081 "_top">http://invisible-island.net/cdk/</a> . Follow the
7082 instructions in README file to install it.</p>
7087 <h4 class="SECT3"><a name="WIDGETLIST" id=
7088 "WIDGETLIST">19.1.1. Widget List</a></h4>
7090 <p>The following is the list of widgets provided with cdk
7091 and their description.</p>
7092 <pre class="PROGRAMLISTING">
7093 Widget Type Quick Description
7094 ===========================================================================
7095 Alphalist Allows a user to select from a list of words, with
7096 the ability to narrow the search list by typing in a
7097 few characters of the desired word.
7098 Buttonbox This creates a multiple button widget.
7099 Calendar Creates a little simple calendar widget.
7100 Dialog Prompts the user with a message, and the user
7101 can pick an answer from the buttons provided.
7102 Entry Allows the user to enter various types of information.
7103 File Selector A file selector built from Cdk base widgets. This
7104 example shows how to create more complicated widgets
7105 using the Cdk widget library.
7106 Graph Draws a graph.
7107 Histogram Draws a histogram.
7108 Item List Creates a pop up field which allows the user to select
7109 one of several choices in a small field. Very useful
7110 for things like days of the week or month names.
7111 Label Displays messages in a pop up box, or the label can be
7112 considered part of the screen.
7113 Marquee Displays a message in a scrolling marquee.
7114 Matrix Creates a complex matrix with lots of options.
7115 Menu Creates a pull-down menu interface.
7116 Multiple Line Entry A multiple line entry field. Very useful
7117 for long fields. (like a description
7119 Radio List Creates a radio button list.
7120 Scale Creates a numeric scale. Used for allowing a user to
7121 pick a numeric value and restrict them to a range of
7123 Scrolling List Creates a scrolling list/menu list.
7124 Scrolling Window Creates a scrolling log file viewer. Can add
7125 information into the window while its running.
7126 A good widget for displaying the progress of
7127 something. (akin to a console window)
7128 Selection List Creates a multiple option selection list.
7129 Slider Akin to the scale widget, this widget provides a
7130 visual slide bar to represent the numeric value.
7131 Template Creates a entry field with character sensitive
7132 positions. Used for pre-formatted fields like
7133 dates and phone numbers.
7134 Viewer This is a file/information viewer. Very useful
7135 when you need to display loads of information.
7136 ===========================================================================
7139 <p>A few of the widgets are modified by Thomas Dickey in
7140 recent versions.</p>
7146 <h4 class="SECT3"><a name="CDKATTRACT" id=
7147 "CDKATTRACT">19.1.2. Some Attractive Features</a></h4>
7149 <p>Apart from making our life easier with readily usable
7150 widgets, cdk solves one frustrating problem with printing
7151 multi colored strings, justified strings elegantly.
7152 Special formatting tags can be embedded in the strings
7153 which are passed to CDK functions. For Example</p>
7155 <p>If the string</p>
7156 <pre class="PROGRAMLISTING">
7157 "</B/1>This line should have a yellow foreground and a blue
7158 background.<!1>"
7161 <p>given as a parameter to newCDKLabel(), it prints the
7162 line with yellow foreground and blue background. There
7163 are other tags available for justifying string, embedding
7164 special drawing characters etc.. Please refer to the man
7165 page cdk_display(3X) for details. The man page explains
7166 the usage with nice examples.</p>
7172 <h4 class="SECT3"><a name="CDKCONCLUSION" id=
7173 "CDKCONCLUSION">19.1.3. Conclusion</a></h4>
7175 <p>All in all, CDK is a well-written package of widgets,
7176 which if used properly can form a strong frame work for
7177 developing complex GUI.</p>
7184 <h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The
7187 <p>Long long ago, in September 1994, when few people knew
7188 linux, Jeff Tranter wrote an <a href=
7189 "http://www2.linuxjournal.com/lj-issues/issue5/2807.html"
7190 target="_top">article</a> on dialog in Linux Journal. He
7191 starts the article with these words..</p>
7193 <p><span class="emphasis"><i class="EMPHASIS">Linux is
7194 based on the Unix operating system, but also features a
7195 number of unique and useful kernel features and application
7196 programs that often go beyond what is available under Unix.
7197 One little-known gem is "dialog", a utility for creating
7198 professional-looking dialog boxes from within shell
7199 scripts. This article presents a tutorial introduction to
7200 the dialog utility, and shows examples of how and where it
7201 can be used</i></span></p>
7203 <p>As he explains, dialog is a real gem in making
7204 professional-looking dialog boxes with ease. It creates a
7205 variety of dialog boxes, menus, check lists etc.. It is
7206 usually installed by default. If not, you can download it
7207 from <a href="http://invisible-island.net/dialog/" target=
7208 "_top">Thomas Dickey</a>'s site.</p>
7210 <p>The above-mentioned article gives a very good overview
7211 of its uses and capabilites. The man page has more details.
7212 It can be used in variety of situations. One good example
7213 is building of linux kernel in text mode. Linux kernel uses
7214 a modified version of dialog tailored for its needs.</p>
7216 <p>dialog was initially designed to be used with shell
7217 scripts. If you want to use its functionality in a c
7218 program, then you can use libdialog. The documentation
7219 regarding this is sparse. Definitive reference is the
7220 dialog.h header file which comes with the library. You may
7221 need to hack here and there to get the required output. The
7222 source is easily customizable. I have used it on a number
7223 of occasions by modifying the code.</p>
7229 <h3 class="SECT2"><a name="PERLCURSES" id=
7230 "PERLCURSES">19.3. Perl Curses Modules CURSES::FORM and
7231 CURSES::WIDGETS</a></h3>
7233 <p>The perl module Curses, Curses::Form and Curses::Widgets
7234 give access to curses from perl. If you have curses and
7235 basic perl is installed, you can get these modules from
7236 <a href="http://www.cpan.org/modules/01modules.index.html"
7237 target="_top">CPAN All Modules page</a>. Get the three
7238 zipped modules in the Curses category. Once installed you
7239 can use these modules from perl scripts like any other
7240 module. For more information on perl modules see perlmod
7241 man page. The above modules come with good documentation
7242 and they have some demo scripts to test the functionality.
7243 Though the widgets provided are very rudimentary, these
7244 modules provide good access to curses library from
7247 <p>Some of my code examples are converted to perl by
7248 Anuradha Ratnaweera and they are available in the
7249 <tt class="LITERAL">perl</tt> directory.</p>
7251 <p>For more information see man pages Curses(3) ,
7252 Curses::Form(3) and Curses::Widgets(3). These pages are
7253 installed only when the above modules are acquired and
7261 <h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20.
7262 Just For Fun !!!</a></h2>
7264 <p>This section contains few programs written by me just for
7265 fun. They don't signify a better programming practice or the
7266 best way of using ncurses. They are provided here so as to
7267 allow beginners to get ideas and add more programs to this
7268 section. If you have written a couple of nice, simple
7269 programs in curses and want them to included here, contact
7270 <a href="mailto:ppadala@gmail.com" target="_top">me</a>.</p>
7275 <h3 class="SECT2"><a name="GAMEOFLIFE" id=
7276 "GAMEOFLIFE">20.1. The Game of Life</a></h3>
7278 <p>Game of life is a wonder of math. In <a href=
7279 "http://www.math.com/students/wonders/life/life.html"
7280 target="_top">Paul Callahan</a>'s words</p>
7281 <pre class="PROGRAMLISTING">
7282 <span class="emphasis"><i class=
7283 "EMPHASIS">The Game of Life (or simply Life) is not a game in the conventional sense. There
7284 are no players, and no winning or losing. Once the "pieces" are placed in the
7285 starting position, the rules determine everything that happens later.
7286 Nevertheless, Life is full of surprises! In most cases, it is impossible to look
7287 at a starting position (or pattern) and see what will happen in the future. The
7288 only way to find out is to follow the rules of the game.</i></span>
7291 <p>This program starts with a simple inverted U pattern and
7292 shows how wonderful life works. There is a lot of room for
7293 improvement in the program. You can let the user enter
7294 pattern of his choice or even take input from a file. You
7295 can also change rules and play with a lot of variations.
7296 Search on <a href="http://www.google.com" target=
7297 "_top">google</a> for interesting information on game of
7300 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7301 JustForFun/life.c</i></span></p>
7307 <h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic
7310 <p>Magic Square, another wonder of math, is very simple to
7311 understand but very difficult to make. In a magic square
7312 sum of the numbers in each row, each column is equal. Even
7313 diagnol sum can be equal. There are many variations which
7314 have special properties.</p>
7316 <p>This program creates a simple magic square of odd
7319 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7320 JustForFun/magic.c</i></span></p>
7326 <h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers
7329 <p>The famous towers of hanoi solver. The aim of the game
7330 is to move the disks on the first peg to last peg, using
7331 middle peg as a temporary stay. The catch is not to place a
7332 larger disk over a small disk at any time.</p>
7334 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7335 JustForFun/hanoi.c</i></span></p>
7341 <h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens
7344 <p>The objective of the famous N-Queen puzzle is to put N
7345 queens on a N X N chess board without attacking each
7348 <p>This program solves it with a simple backtracking
7351 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7352 JustForFun/queens.c</i></span></p>
7358 <h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5.
7361 <p>A fun game, if you have time to kill.</p>
7363 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7364 JustForFun/shuffle.c</i></span></p>
7370 <h3 class="SECT2"><a name="TT" id="TT">20.6. Typing
7373 <p>A simple typing tutor, I created more out of need than
7374 for ease of use. If you know how to put your fingers
7375 correctly on the keyboard, but lack practice, this can be
7378 <p><span class="emphasis"><i class="EMPHASIS">File Path:
7379 JustForFun/tt.c</i></span></p>
7386 <h2 class="SECT1"><a name="REF" id="REF">21.
7391 <p>NCURSES man pages</p>
7395 <p>NCURSES FAQ at <a href=
7396 "http://invisible-island.net/ncurses/ncurses.faq.html"
7398 "_top">http://invisible-island.net/ncurses/ncurses.faq.html</a></p>
7402 <p>Writing programs with NCURSES by Eric Raymond and Zeyd
7403 M. Ben-Halim at <a href=
7404 "http://invisible-island.net/ncurses/ncurses-intro.html"
7406 "_top">http://invisible-island.net/ncurses/ncurses-intro.html</a>
7407 - somewhat obsolete. I was inspired by this document and
7408 the structure of this HOWTO follows from the original
projects / ncurses.git / blob