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7 <TITLE>Writing Programs with NCURSES</TITLE>
8 <link rev="made" href="mailto:bugs-ncurses@gnu.org">
12 <H1>Writing Programs with NCURSES</H1>
15 by Eric S. Raymond and Zeyd M. Ben-Halim<BR>
16 updates since release 1.9.9e by Thomas Dickey
21 <LI><A HREF="#introduction">Introduction</A>
23 <LI><A HREF="#history">A Brief History of Curses</A>
24 <LI><A HREF="#scope">Scope of This Document</A>
25 <LI><A HREF="#terminology">Terminology</A>
27 <LI><A HREF="#curses">The Curses Library</A>
29 <LI><A HREF="#overview">An Overview of Curses</A>
31 <LI><A HREF="#compiling">Compiling Programs using Curses</A>
32 <LI><A HREF="#updating">Updating the Screen</A>
33 <LI><A HREF="#stdscr">Standard Windows and Function Naming Conventions</A>
34 <LI><A HREF="#variables">Variables</A>
36 <LI><A HREF="#using">Using the Library</A>
38 <LI><A HREF="#starting">Starting up</A>
39 <LI><A HREF="#output">Output</A>
40 <LI><A HREF="#input">Input</A>
41 <LI><A HREF="#formschars">Using Forms Characters</A>
42 <LI><A HREF="#attributes">Character Attributes and Color</A>
43 <LI><A HREF="#mouse">Mouse Interfacing</A>
44 <LI><A HREF="#finishing">Finishing Up</A>
46 <LI><A HREF="#functions">Function Descriptions</A>
48 <LI><A HREF="#init">Initialization and Wrapup</A>
49 <LI><A HREF="#flush">Causing Output to the Terminal</A>
50 <LI><A HREF="#lowlevel">Low-Level Capability Access</A>
51 <LI><A HREF="#debugging">Debugging</A>
53 <LI><A HREF="#hints">Hints, Tips, and Tricks</A>
55 <LI><A HREF="#caution">Some Notes of Caution</A>
56 <LI><A HREF="#leaving">Temporarily Leaving ncurses Mode</A>
57 <LI><A HREF="#xterm">Using <CODE>ncurses</CODE> under <CODE>xterm</CODE></A>
58 <LI><A HREF="#screens">Handling Multiple Terminal Screens</A>
59 <LI><A HREF="#testing">Testing for Terminal Capabilities</A>
60 <LI><A HREF="#tuning">Tuning for Speed</A>
61 <LI><A HREF="#special">Special Features of <CODE>ncurses</CODE></A>
63 <LI><A HREF="#compat">Compatibility with Older Versions</A>
65 <LI><A HREF="#refbug">Refresh of Overlapping Windows</A>
66 <LI><A HREF="#backbug">Background Erase</A>
68 <LI><A HREF="#xsifuncs">XSI Curses Conformance</A>
70 <LI><A HREF="#panels">The Panels Library</A>
72 <LI><A HREF="#pcompile">Compiling With the Panels Library</A>
73 <LI><A HREF="#poverview">Overview of Panels</A>
74 <LI><A HREF="#pstdscr">Panels, Input, and the Standard Screen</A>
75 <LI><A HREF="#hiding">Hiding Panels</A>
76 <LI><A HREF="#pmisc">Miscellaneous Other Facilities</A>
78 <LI><A HREF="#menu">The Menu Library</A>
80 <LI><A HREF="#mcompile">Compiling with the menu Library</A>
81 <LI><A HREF="#moverview">Overview of Menus</A>
82 <LI><A HREF="#mselect">Selecting items</A>
83 <LI><A HREF="#mdisplay">Menu Display</A>
84 <LI><A HREF="#mwindows">Menu Windows</A>
85 <LI><A HREF="#minput">Processing Menu Input</A>
86 <LI><A HREF="#mmisc">Miscellaneous Other Features</A>
88 <LI><A HREF="#form">The Forms Library</A>
90 <LI><A HREF="#fcompile">Compiling with the forms Library</A>
91 <LI><A HREF="#foverview">Overview of Forms</A>
92 <LI><A HREF="#fcreate">Creating and Freeing Fields and Forms</A>
93 <LI><A HREF="#fattributes">Fetching and Changing Field Attributes</A>
95 <LI><A HREF="#fsizes">Fetching Size and Location Data</A>
96 <LI><A HREF="#flocation">Changing the Field Location</A>
97 <LI><A HREF="#fjust">The Justification Attribute</A>
98 <LI><A HREF="#fdispatts">Field Display Attributes</A>
99 <LI><A HREF="#foptions">Field Option Bits</A>
100 <LI><A HREF="#fstatus">Field Status</A>
101 <LI><A HREF="#fuser">Field User Pointer</A>
103 <LI><A HREF="#fdynamic">Variable-Sized Fields</A>
104 <LI><A HREF="#fvalidation">Field Validation</A>
106 <LI><A HREF="#ftype_alpha">TYPE_ALPHA</A>
107 <LI><A HREF="#ftype_alnum">TYPE_ALNUM</A>
108 <LI><A HREF="#ftype_enum">TYPE_ENUM</A>
109 <LI><A HREF="#ftype_integer">TYPE_INTEGER</A>
110 <LI><A HREF="#ftype_numeric">TYPE_NUMERIC</A>
111 <LI><A HREF="#ftype_regexp">TYPE_REGEXP</A>
113 <LI><A HREF="#fbuffer">Direct Field Buffer Manipulation</A>
114 <LI><A HREF="#formattrs">Attributes of Forms</A>
115 <LI><A HREF="#fdisplay">Control of Form Display</A>
116 <LI><A HREF="#fdriver">Input Processing in the Forms Driver</A>
118 <LI><A HREF="#fpage">Page Navigation Requests</A>
119 <LI><A HREF="#ffield">Inter-Field Navigation Requests</A>
120 <LI><A HREF="#fifield">Intra-Field Navigation Requests</A>
121 <LI><A HREF="#fscroll">Scrolling Requests</A>
122 <LI><A HREF="#fedit">Field Editing Requests</A>
123 <LI><A HREF="#forder">Order Requests</A>
124 <LI><A HREF="#fappcmds">Application Commands</A>
126 <LI><A HREF="#fhooks">Field Change Hooks</A>
127 <LI><A HREF="#ffocus">Field Change Commands</A>
128 <LI><A HREF="#frmoptions">Form Options</A>
129 <LI><A HREF="#fcustom">Custom Validation Types</A>
131 <LI><A HREF="#flinktypes">Union Types</A>
132 <LI><A HREF="#fnewtypes">New Field Types</A>
133 <LI><A HREF="#fcheckargs">Validation Function Arguments</A>
134 <LI><A HREF="#fcustorder">Order Functions For Custom Types</A>
135 <LI><A HREF="#fcustprobs">Avoiding Problems</A>
141 <H1><A NAME="introduction">Introduction</A></H1>
143 This document is an introduction to programming with <CODE>curses</CODE>. It is
144 not an exhaustive reference for the curses Application Programming Interface
145 (API); that role is filled by the <CODE>curses</CODE> manual pages. Rather, it
146 is intended to help C programmers ease into using the package. <P>
148 This document is aimed at C applications programmers not yet specifically
149 familiar with ncurses. If you are already an experienced <CODE>curses</CODE>
150 programmer, you should nevertheless read the sections on
151 <A HREF="#mouse">Mouse Interfacing</A>, <A HREF="#debugging">Debugging</A>,
152 <A HREF="#compat">Compatibility with Older Versions</A>,
153 and <A HREF="#hints">Hints, Tips, and Tricks</A>. These will bring you up
154 to speed on the special features and quirks of the <CODE>ncurses</CODE>
155 implementation. If you are not so experienced, keep reading. <P>
157 The <CODE>curses</CODE> package is a subroutine library for
158 terminal-independent screen-painting and input-event handling which
159 presents a high level screen model to the programmer, hiding differences
160 between terminal types and doing automatic optimization of output to change
161 one screen full of text into another. <CODE>Curses</CODE> uses terminfo, which
162 is a database format that can describe the capabilities of thousands of
163 different terminals. <P>
165 The <CODE>curses</CODE> API may seem something of an archaism on UNIX desktops
166 increasingly dominated by X, Motif, and Tcl/Tk. Nevertheless, UNIX still
167 supports tty lines and X supports <EM>xterm(1)</EM>; the <CODE>curses</CODE>
168 API has the advantage of (a) back-portability to character-cell terminals,
169 and (b) simplicity. For an application that does not require bit-mapped
170 graphics and multiple fonts, an interface implementation using <CODE>curses</CODE>
171 will typically be a great deal simpler and less expensive than one using an
174 <H2><A NAME="history">A Brief History of Curses</A></H2>
176 Historically, the first ancestor of <CODE>curses</CODE> was the routines written to
177 provide screen-handling for the game <CODE>rogue</CODE>; these used the
178 already-existing <CODE>termcap</CODE> database facility for describing terminal
179 capabilities. These routines were abstracted into a documented library and
180 first released with the early BSD UNIX versions. <P>
182 System III UNIX from Bell Labs featured a rewritten and much-improved
183 <CODE>curses</CODE> library. It introduced the terminfo format. Terminfo is based
184 on Berkeley's termcap database, but contains a number of improvements and
185 extensions. Parameterized capabilities strings were introduced, making it
186 possible to describe multiple video attributes, and colors and to handle far
187 more unusual terminals than possible with termcap. In the later AT&T
188 System V releases, <CODE>curses</CODE> evolved to use more facilities and offer
189 more capabilities, going far beyond BSD curses in power and flexibility.
191 <H2><A NAME="scope">Scope of This Document</A></H2>
193 This document describes <CODE>ncurses</CODE>, a free implementation of
194 the System V <CODE>curses</CODE> API with some clearly marked extensions.
195 It includes the following System V curses features:
197 <LI>Support for multiple screen highlights (BSD curses could only
198 handle one `standout' highlight, usually reverse-video).
199 <LI>Support for line- and box-drawing using forms characters.
200 <LI>Recognition of function keys on input.
202 <LI>Support for pads (windows of larger than screen size on which the
203 screen or a subwindow defines a viewport).
206 Also, this package makes use of the insert and delete line and character
207 features of terminals so equipped, and determines how to optimally use these
208 features with no help from the programmer. It allows arbitrary combinations of
209 video attributes to be displayed, even on terminals that leave ``magic
210 cookies'' on the screen to mark changes in attributes. <P>
212 The <CODE>ncurses</CODE> package can also capture and use event reports from a
213 mouse in some environments (notably, xterm under the X window system). This
214 document includes tips for using the mouse. <P>
216 The <CODE>ncurses</CODE> package was originated by Pavel Curtis. The original
217 maintainer of this package is
218 <A HREF="mailto:zmbenhal@netcom.com">Zeyd Ben-Halim</A>
219 <zmbenhal@netcom.com>.
220 <A HREF="mailto:esr@snark.thyrsus.com">Eric S. Raymond</A>
221 <esr@snark.thyrsus.com>
222 wrote many of the new features in versions after 1.8.1
223 and wrote most of this introduction.
224 <A HREF="mailto:juergen.pfeifer@gmx.net">Jürgen Pfeifer</A>
225 wrote all of the menu and forms code as well as the
226 <A HREF="http://www.adahome.com">Ada95</A> binding.
227 Ongoing work is being done by
228 <A HREF="mailto:dickey@herndon4.his.com">Thomas Dickey</A>
230 <A HREF="mailto:juergen.pfeifer@gmx.net">Jürgen Pfeifer</A>.
231 <A HREF="mailto:florian@gnu.org">Florian La Roche</A>
232 acts as the maintainer for the Free Software Foundation, which holds the
233 copyright on ncurses.
234 Contact the current maintainers at
235 <A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>.
238 This document also describes the <A HREF="#panels">panels</A> extension library,
239 similarly modeled on the SVr4 panels facility. This library allows you to
240 associate backing store with each of a stack or deck of overlapping windows,
241 and provides operations for moving windows around in the stack that change
242 their visibility in the natural way (handling window overlaps). <P>
244 Finally, this document describes in detail the <A HREF="#menu">menus</A> and <A
245 HREF="#form">forms</A> extension libraries, also cloned from System V,
246 which support easy construction and sequences of menus and fill-in
250 <H2><A NAME="terminology">Terminology</A></H2>
252 In this document, the following terminology is used with reasonable
258 A data structure describing a sub-rectangle of the screen (possibly the
259 entire screen). You can write to a window as though it were a miniature
260 screen, scrolling independently of other windows on the physical screen.
263 A subset of windows which are as large as the terminal screen, i.e., they start
264 at the upper left hand corner and encompass the lower right hand corner. One
265 of these, <CODE>stdscr</CODE>, is automatically provided for the programmer.
268 The package's idea of what the terminal display currently looks like, i.e.,
269 what the user sees now. This is a special screen.
272 <H1><A NAME="curses">The Curses Library</A></H1>
274 <H2><A NAME="overview">An Overview of Curses</A></H2>
276 <H3><A NAME="compiling">Compiling Programs using Curses</A></H3>
278 In order to use the library, it is necessary to have certain types and
279 variables defined. Therefore, the programmer must have a line:
282 #include <curses.h>
285 at the top of the program source. The screen package uses the Standard I/O
286 library, so <CODE><curses.h></CODE> includes
287 <CODE><stdio.h></CODE>. <CODE><curses.h></CODE> also includes
288 <CODE><termios.h></CODE>, <CODE><termio.h></CODE>, or
289 <CODE><sgtty.h></CODE> depending on your system. It is redundant (but
290 harmless) for the programmer to do these includes, too. In linking with
291 <CODE>curses</CODE> you need to have <CODE>-lncurses</CODE> in your LDFLAGS or on the
292 command line. There is no need for any other libraries.
294 <H3><A NAME="updating">Updating the Screen</A></H3>
296 In order to update the screen optimally, it is necessary for the routines to
297 know what the screen currently looks like and what the programmer wants it to
298 look like next. For this purpose, a data type (structure) named WINDOW is
299 defined which describes a window image to the routines, including its starting
300 position on the screen (the (y, x) coordinates of the upper left hand corner)
301 and its size. One of these (called <CODE>curscr</CODE>, for current screen) is a
302 screen image of what the terminal currently looks like. Another screen (called
303 <CODE>stdscr</CODE>, for standard screen) is provided by default to make changes
306 A window is a purely internal representation. It is used to build and store a
307 potential image of a portion of the terminal. It doesn't bear any necessary
308 relation to what is really on the terminal screen; it's more like a
309 scratchpad or write buffer. <P>
311 To make the section of physical screen corresponding to a window reflect the
312 contents of the window structure, the routine <CODE>refresh()</CODE> (or
313 <CODE>wrefresh()</CODE> if the window is not <CODE>stdscr</CODE>) is called. <P>
315 A given physical screen section may be within the scope of any number of
316 overlapping windows. Also, changes can be made to windows in any order,
317 without regard to motion efficiency. Then, at will, the programmer can
318 effectively say ``make it look like this,'' and let the package implementation
319 determine the most efficient way to repaint the screen.
321 <H3><A NAME="stdscr">Standard Windows and Function Naming Conventions</A></H3>
323 As hinted above, the routines can use several windows, but two are
324 automatically given: <CODE>curscr</CODE>, which knows what the terminal looks like,
325 and <CODE>stdscr</CODE>, which is what the programmer wants the terminal to look
326 like next. The user should never actually access <CODE>curscr</CODE> directly.
327 Changes should be made to through the API, and then the routine
328 <CODE>refresh()</CODE> (or <CODE>wrefresh()</CODE>) called. <P>
330 Many functions are defined to use <CODE>stdscr</CODE> as a default screen. For
331 example, to add a character to <CODE>stdscr</CODE>, one calls <CODE>addch()</CODE> with
332 the desired character as argument. To write to a different window. use the
333 routine <CODE>waddch()</CODE> (for `w'indow-specific addch()) is provided. This
334 convention of prepending function names with a `w' when they are to be
335 applied to specific windows is consistent. The only routines which do not
336 follow it are those for which a window must always be specified. <P>
338 In order to move the current (y, x) coordinates from one point to another, the
339 routines <CODE>move()</CODE> and <CODE>wmove()</CODE> are provided. However, it is
340 often desirable to first move and then perform some I/O operation. In order to
341 avoid clumsiness, most I/O routines can be preceded by the prefix 'mv' and
342 the desired (y, x) coordinates prepended to the arguments to the function. For
366 mvwaddch(win, y, x, ch);
369 Note that the window description pointer (win) comes before the added (y, x)
370 coordinates. If a function requires a window pointer, it is always the first
373 <H3><A NAME="variables">Variables</A></H3>
375 The <CODE>curses</CODE> library sets some variables describing the terminal
379 type name description
380 ------------------------------------------------------------------
381 int LINES number of lines on the terminal
382 int COLS number of columns on the terminal
385 The <CODE>curses.h</CODE> also introduces some <CODE>#define</CODE> constants and types
386 of general usefulness:
389 <DT> <CODE>bool</CODE>
390 <DD> boolean type, actually a `char' (e.g., <CODE>bool doneit;</CODE>)
391 <DT> <CODE>TRUE</CODE>
392 <DD> boolean `true' flag (1).
393 <DT> <CODE>FALSE</CODE>
394 <DD> boolean `false' flag (0).
395 <DT> <CODE>ERR</CODE>
396 <DD> error flag returned by routines on a failure (-1).
398 <DD> error flag returned by routines when things go right.
401 <H2><A NAME="using">Using the Library</A></H2>
403 Now we describe how to actually use the screen package. In it, we assume all
404 updating, reading, etc. is applied to <CODE>stdscr</CODE>. These instructions will
405 work on any window, providing you change the function names and parameters as
408 Here is a sample program to motivate the discussion:
411 #include <curses.h>
412 #include <signal.h>
414 static void finish(int sig);
417 main(int argc, char *argv[])
421 /* initialize your non-curses data structures here */
423 (void) signal(SIGINT, finish); /* arrange interrupts to terminate */
425 (void) initscr(); /* initialize the curses library */
426 keypad(stdscr, TRUE); /* enable keyboard mapping */
427 (void) nonl(); /* tell curses not to do NL->CR/NL on output */
428 (void) cbreak(); /* take input chars one at a time, no wait for \n */
429 (void) echo(); /* echo input - in color */
436 * Simple color assignment, often all we need. Color pair 0 cannot
437 * be redefined. This example uses the same value for the color
438 * pair as for the foreground color, though of course that is not
441 init_pair(1, COLOR_RED, COLOR_BLACK);
442 init_pair(2, COLOR_GREEN, COLOR_BLACK);
443 init_pair(3, COLOR_YELLOW, COLOR_BLACK);
444 init_pair(4, COLOR_BLUE, COLOR_BLACK);
445 init_pair(5, COLOR_CYAN, COLOR_BLACK);
446 init_pair(6, COLOR_MAGENTA, COLOR_BLACK);
447 init_pair(7, COLOR_WHITE, COLOR_BLACK);
452 int c = getch(); /* refresh, accept single keystroke of input */
453 attrset(COLOR_PAIR(num % 8));
456 /* process the command keystroke */
459 finish(0); /* we're done */
462 static void finish(int sig)
466 /* do your non-curses wrapup here */
472 <H3><A NAME="starting">Starting up</A></H3>
474 In order to use the screen package, the routines must know about terminal
475 characteristics, and the space for <CODE>curscr</CODE> and <CODE>stdscr</CODE> must be
476 allocated. These function <CODE>initscr()</CODE> does both these things. Since it
477 must allocate space for the windows, it can overflow memory when attempting to
478 do so. On the rare occasions this happens, <CODE>initscr()</CODE> will terminate
479 the program with an error message. <CODE>initscr()</CODE> must always be called
480 before any of the routines which affect windows are used. If it is not, the
481 program will core dump as soon as either <CODE>curscr</CODE> or <CODE>stdscr</CODE> are
482 referenced. However, it is usually best to wait to call it until after you are
483 sure you will need it, like after checking for startup errors. Terminal status
484 changing routines like <CODE>nl()</CODE> and <CODE>cbreak()</CODE> should be called
485 after <CODE>initscr()</CODE>. <P>
487 Once the screen windows have been allocated, you can set them up for
488 your program. If you want to, say, allow a screen to scroll, use
489 <CODE>scrollok()</CODE>. If you want the cursor to be left in place after
490 the last change, use <CODE>leaveok()</CODE>. If this isn't done,
491 <CODE>refresh()</CODE> will move the cursor to the window's current (y, x)
492 coordinates after updating it. <P>
494 You can create new windows of your own using the functions <CODE>newwin()</CODE>,
495 <CODE>derwin()</CODE>, and <CODE>subwin()</CODE>. The routine <CODE>delwin()</CODE> will
496 allow you to get rid of old windows. All the options described above can be
497 applied to any window.
499 <H3><A NAME="output">Output</A></H3>
501 Now that we have set things up, we will want to actually update the terminal.
502 The basic functions used to change what will go on a window are
503 <CODE>addch()</CODE> and <CODE>move()</CODE>. <CODE>addch()</CODE> adds a character at the
504 current (y, x) coordinates. <CODE>move()</CODE> changes the current (y, x)
505 coordinates to whatever you want them to be. It returns <CODE>ERR</CODE> if you
506 try to move off the window. As mentioned above, you can combine the two into
507 <CODE>mvaddch()</CODE> to do both things at once. <P>
509 The other output functions, such as <CODE>addstr()</CODE> and <CODE>printw()</CODE>,
510 all call <CODE>addch()</CODE> to add characters to the window. <P>
512 After you have put on the window what you want there, when you want the portion
513 of the terminal covered by the window to be made to look like it, you must call
514 <CODE>refresh()</CODE>. In order to optimize finding changes, <CODE>refresh()</CODE>
515 assumes that any part of the window not changed since the last
516 <CODE>refresh()</CODE> of that window has not been changed on the terminal, i.e.,
517 that you have not refreshed a portion of the terminal with an overlapping
518 window. If this is not the case, the routine <CODE>touchwin()</CODE> is provided
519 to make it look like the entire window has been changed, thus making
520 <CODE>refresh()</CODE> check the whole subsection of the terminal for changes. <P>
522 If you call <CODE>wrefresh()</CODE> with <CODE>curscr</CODE> as its argument, it will
523 make the screen look like <CODE>curscr</CODE> thinks it looks like. This is useful
524 for implementing a command which would redraw the screen in case it get messed
527 <H3><A NAME="input">Input</A></H3>
529 The complementary function to <CODE>addch()</CODE> is <CODE>getch()</CODE> which, if
530 echo is set, will call <CODE>addch()</CODE> to echo the character. Since the
531 screen package needs to know what is on the terminal at all times, if
532 characters are to be echoed, the tty must be in raw or cbreak mode. Since
533 initially the terminal has echoing enabled and is in ordinary ``cooked'' mode,
534 one or the other has to changed before calling <CODE>getch()</CODE>; otherwise,
535 the program's output will be unpredictable. <P>
537 When you need to accept line-oriented input in a window, the functions
538 <CODE>wgetstr()</CODE> and friends are available. There is even a <CODE>wscanw()</CODE>
539 function that can do <CODE>scanf()</CODE>(3)-style multi-field parsing on window
540 input. These pseudo-line-oriented functions turn on echoing while they
543 The example code above uses the call <CODE>keypad(stdscr, TRUE)</CODE> to enable
544 support for function-key mapping. With this feature, the <CODE>getch()</CODE> code
545 watches the input stream for character sequences that correspond to arrow and
546 function keys. These sequences are returned as pseudo-character values. The
547 <CODE>#define</CODE> values returned are listed in the <CODE>curses.h</CODE> The
548 mapping from sequences to <CODE>#define</CODE> values is determined by
549 <CODE>key_</CODE> capabilities in the terminal's terminfo entry.
551 <H3><A NAME="formschars">Using Forms Characters</A></H3>
553 The <CODE>addch()</CODE> function (and some others, including <CODE>box()</CODE> and
554 <CODE>border()</CODE>) can accept some pseudo-character arguments which are specially
555 defined by <CODE>ncurses</CODE>. These are <CODE>#define</CODE> values set up in
556 the <CODE>curses.h</CODE> header; see there for a complete list (look for
557 the prefix <CODE>ACS_</CODE>). <P>
559 The most useful of the ACS defines are the forms-drawing characters. You can
560 use these to draw boxes and simple graphs on the screen. If the terminal
561 does not have such characters, <CODE>curses.h</CODE> will map them to a
562 recognizable (though ugly) set of ASCII defaults.
564 <H3><A NAME="attributes">Character Attributes and Color</A></H3>
566 The <CODE>ncurses</CODE> package supports screen highlights including standout,
567 reverse-video, underline, and blink. It also supports color, which is treated
568 as another kind of highlight. <P>
570 Highlights are encoded, internally, as high bits of the pseudo-character type
571 (<CODE>chtype</CODE>) that <CODE>curses.h</CODE> uses to represent the contents of a
572 screen cell. See the <CODE>curses.h</CODE> header file for a complete list of
573 highlight mask values (look for the prefix <CODE>A_</CODE>).<P>
575 There are two ways to make highlights. One is to logical-or the value of the
576 highlights you want into the character argument of an <CODE>addch()</CODE> call,
577 or any other output call that takes a <CODE>chtype</CODE> argument. <P>
579 The other is to set the current-highlight value. This is logical-or'ed with
580 any highlight you specify the first way. You do this with the functions
581 <CODE>attron()</CODE>, <CODE>attroff()</CODE>, and <CODE>attrset()</CODE>; see the manual
584 Color is a special kind of highlight. The package actually thinks in terms
585 of color pairs, combinations of foreground and background colors. The sample
586 code above sets up eight color pairs, all of the guaranteed-available colors
587 on black. Note that each color pair is, in effect, given the name of its
588 foreground color. Any other range of eight non-conflicting values could
589 have been used as the first arguments of the <CODE>init_pair()</CODE> values. <P>
591 Once you've done an <CODE>init_pair()</CODE> that creates color-pair N, you can
592 use <CODE>COLOR_PAIR(N)</CODE> as a highlight that invokes that particular
593 color combination. Note that <CODE>COLOR_PAIR(N)</CODE>, for constant N,
594 is itself a compile-time constant and can be used in initializers.
596 <H3><A NAME="mouse">Mouse Interfacing</A></H3>
598 The <CODE>ncurses</CODE> library also provides a mouse interface.
599 <!-- The 'note' tag is not portable enough -->
601 <strong>NOTE:</strong> this facility is specific to <CODE>ncurses</CODE>, it is not part of either
602 the XSI Curses standard, nor of System V Release 4, nor BSD curses.
603 System V Release 4 curses contains code with similar interface definitions,
604 however it is not documented. Other than by disassembling the library, we
605 have no way to determine exactly how that mouse code works.
606 Thus, we recommend that you wrap mouse-related code in an #ifdef using the
607 feature macro NCURSES_MOUSE_VERSION so it will not be compiled and linked
608 on non-ncurses systems.
611 Presently, mouse event reporting works in the following environments:
613 <li>xterm and similar programs such as rxvt.
614 <li>Linux console, when configured with <CODE>gpm</CODE>(1), Alessandro
615 Rubini's mouse server.
619 The mouse interface is very simple. To activate it, you use the function
620 <CODE>mousemask()</CODE>, passing it as first argument a bit-mask that specifies
621 what kinds of events you want your program to be able to see. It will
622 return the bit-mask of events that actually become visible, which may differ
623 from the argument if the mouse device is not capable of reporting some of
624 the event types you specify. <P>
626 Once the mouse is active, your application's command loop should watch
627 for a return value of <CODE>KEY_MOUSE</CODE> from <CODE>wgetch()</CODE>. When
628 you see this, a mouse event report has been queued. To pick it off
629 the queue, use the function <CODE>getmouse()</CODE> (you must do this before
630 the next <CODE>wgetch()</CODE>, otherwise another mouse event might come
631 in and make the first one inaccessible). <P>
633 Each call to <CODE>getmouse()</CODE> fills a structure (the address of which you'll
634 pass it) with mouse event data. The event data includes zero-origin,
635 screen-relative character-cell coordinates of the mouse pointer. It also
636 includes an event mask. Bits in this mask will be set, corresponding
637 to the event type being reported. <P>
639 The mouse structure contains two additional fields which may be
640 significant in the future as ncurses interfaces to new kinds of
641 pointing device. In addition to x and y coordinates, there is a slot
642 for a z coordinate; this might be useful with touch-screens that can
643 return a pressure or duration parameter. There is also a device ID
644 field, which could be used to distinguish between multiple pointing
647 The class of visible events may be changed at any time via <CODE>mousemask()</CODE>.
648 Events that can be reported include presses, releases, single-, double- and
649 triple-clicks (you can set the maximum button-down time for clicks). If
650 you don't make clicks visible, they will be reported as press-release
651 pairs. In some environments, the event mask may include bits reporting
652 the state of shift, alt, and ctrl keys on the keyboard during the event. <P>
654 A function to check whether a mouse event fell within a given window is
655 also supplied. You can use this to see whether a given window should
656 consider a mouse event relevant to it. <P>
658 Because mouse event reporting will not be available in all
659 environments, it would be unwise to build <CODE>ncurses</CODE>
660 applications that <EM>require</EM> the use of a mouse. Rather, you should
661 use the mouse as a shortcut for point-and-shoot commands your application
662 would normally accept from the keyboard. Two of the test games in the
663 <CODE>ncurses</CODE> distribution (<CODE>bs</CODE> and <CODE>knight</CODE>) contain
664 code that illustrates how this can be done. <P>
666 See the manual page <CODE>curs_mouse(3X)</CODE> for full details of the
667 mouse-interface functions.
669 <H3><A NAME="finishing">Finishing Up</A></H3>
671 In order to clean up after the <CODE>ncurses</CODE> routines, the routine
672 <CODE>endwin()</CODE> is provided. It restores tty modes to what they were when
673 <CODE>initscr()</CODE> was first called, and moves the cursor down to the
674 lower-left corner. Thus, anytime after the call to initscr, <CODE>endwin()</CODE>
675 should be called before exiting.
677 <H2><A NAME="functions">Function Descriptions</A></H2>
679 We describe the detailed behavior of some important curses functions here, as a
680 supplement to the manual page descriptions.
682 <H3><A NAME="init">Initialization and Wrapup</A></H3>
685 <DT> <CODE>initscr()</CODE>
686 <DD> The first function called should almost always be <CODE>initscr()</CODE>.
687 This will determine the terminal type and
688 initialize curses data structures. <CODE>initscr()</CODE> also arranges that
689 the first call to <CODE>refresh()</CODE> will clear the screen. If an error
690 occurs a message is written to standard error and the program
691 exits. Otherwise it returns a pointer to stdscr. A few functions may be
692 called before initscr (<CODE>slk_init()</CODE>, <CODE>filter()</CODE>,
693 <CODE>ripofflines()</CODE>, <CODE>use_env()</CODE>, and, if you are using multiple
694 terminals, <CODE>newterm()</CODE>.)
695 <DT> <CODE>endwin()</CODE>
696 <DD> Your program should always call <CODE>endwin()</CODE> before exiting or
697 shelling out of the program. This function will restore tty modes,
698 move the cursor to the lower left corner of the screen, reset the
699 terminal into the proper non-visual mode. Calling <CODE>refresh()</CODE>
700 or <CODE>doupdate()</CODE> after a temporary escape from the program will
701 restore the ncurses screen from before the escape.
702 <DT> <CODE>newterm(type, ofp, ifp)</CODE>
703 <DD> A program which outputs to more than one terminal should use
704 <CODE>newterm()</CODE> instead of <CODE>initscr()</CODE>. <CODE>newterm()</CODE> should
705 be called once for each terminal. It returns a variable of type
706 <CODE>SCREEN *</CODE> which should be saved as a reference to that
707 terminal. The arguments are the type of the terminal (a string) and
708 <CODE>FILE</CODE> pointers for the output and input of the terminal. If
709 type is NULL then the environment variable <CODE>$TERM</CODE> is used.
710 <CODE>endwin()</CODE> should called once at wrapup time for each terminal
711 opened using this function.
712 <DT> <CODE>set_term(new)</CODE>
713 <DD> This function is used to switch to a different terminal previously
714 opened by <CODE>newterm()</CODE>. The screen reference for the new terminal
715 is passed as the parameter. The previous terminal is returned by the
716 function. All other calls affect only the current terminal.
717 <DT> <CODE>delscreen(sp)</CODE>
718 <DD> The inverse of <CODE>newterm()</CODE>; deallocates the data structures
719 associated with a given <CODE>SCREEN</CODE> reference.
722 <H3><A NAME="flush">Causing Output to the Terminal</A></H3>
725 <DT> <CODE>refresh()</CODE> and <CODE>wrefresh(win)</CODE>
726 <DD> These functions must be called to actually get any output on
727 the terminal, as other routines merely manipulate data
728 structures. <CODE>wrefresh()</CODE> copies the named window to the physical
729 terminal screen, taking into account what is already
730 there in order to do optimizations. <CODE>refresh()</CODE> does a
731 refresh of <CODE>stdscr()</CODE>. Unless <CODE>leaveok()</CODE> has been
732 enabled, the physical cursor of the terminal is left at the
733 location of the window's cursor.
734 <DT> <CODE>doupdate()</CODE> and <CODE>wnoutrefresh(win)</CODE>
735 <DD> These two functions allow multiple updates with more efficiency
736 than wrefresh. To use them, it is important to understand how curses
737 works. In addition to all the window structures, curses keeps two
738 data structures representing the terminal screen: a physical screen,
739 describing what is actually on the screen, and a virtual screen,
740 describing what the programmer wants to have on the screen. wrefresh
741 works by first copying the named window to the virtual screen
742 (<CODE>wnoutrefresh()</CODE>), and then calling the routine to update the
743 screen (<CODE>doupdate()</CODE>). If the programmer wishes to output
744 several windows at once, a series of calls to <CODE>wrefresh</CODE> will result
745 in alternating calls to <CODE>wnoutrefresh()</CODE> and <CODE>doupdate()</CODE>,
746 causing several bursts of output to the screen. By calling
747 <CODE>wnoutrefresh()</CODE> for each window, it is then possible to call
748 <CODE>doupdate()</CODE> once, resulting in only one burst of output, with
749 fewer total characters transmitted (this also avoids a visually annoying
750 flicker at each update).
753 <H3><A NAME="lowlevel">Low-Level Capability Access</A></H3>
756 <DT> <CODE>setupterm(term, filenum, errret)</CODE>
757 <DD> This routine is called to initialize a terminal's description, without setting
758 up the curses screen structures or changing the tty-driver mode bits.
759 <CODE>term</CODE> is the character string representing the name of the terminal
760 being used. <CODE>filenum</CODE> is the UNIX file descriptor of the terminal to
761 be used for output. <CODE>errret</CODE> is a pointer to an integer, in which a
762 success or failure indication is returned. The values returned can be 1 (all
763 is well), 0 (no such terminal), or -1 (some problem locating the terminfo
766 The value of <CODE>term</CODE> can be given as NULL, which will cause the value of
767 <CODE>TERM</CODE> in the environment to be used. The <CODE>errret</CODE> pointer can
768 also be given as NULL, meaning no error code is wanted. If <CODE>errret</CODE> is
769 defaulted, and something goes wrong, <CODE>setupterm()</CODE> will print an
770 appropriate error message and exit, rather than returning. Thus, a simple
771 program can call setupterm(0, 1, 0) and not worry about initialization
774 After the call to <CODE>setupterm()</CODE>, the global variable <CODE>cur_term</CODE> is
775 set to point to the current structure of terminal capabilities. By calling
776 <CODE>setupterm()</CODE> for each terminal, and saving and restoring
777 <CODE>cur_term</CODE>, it is possible for a program to use two or more terminals at
778 once. <CODE>Setupterm()</CODE> also stores the names section of the terminal
779 description in the global character array <CODE>ttytype[]</CODE>. Subsequent calls
780 to <CODE>setupterm()</CODE> will overwrite this array, so you'll have to save it
784 <H3><A NAME="debugging">Debugging</A></H3>
786 <!-- The 'note' tag is not portable enough -->
788 <strong>NOTE:</strong> These functions are not part of the standard curses API!
792 <DT> <CODE>trace()</CODE>
794 This function can be used to explicitly set a trace level. If the
795 trace level is nonzero, execution of your program will generate a file
796 called `trace' in the current working directory containing a report on
797 the library's actions. Higher trace levels enable more detailed (and
798 verbose) reporting -- see comments attached to <CODE>TRACE_</CODE> defines
799 in the <CODE>curses.h</CODE> file for details. (It is also possible to set
800 a trace level by assigning a trace level value to the environment variable
801 <CODE>NCURSES_TRACE</CODE>).
802 <DT> <CODE>_tracef()</CODE>
804 This function can be used to output your own debugging information. It is only
805 available only if you link with -lncurses_g. It can be used the same way as
806 <CODE>printf()</CODE>, only it outputs a newline after the end of arguments.
807 The output goes to a file called <CODE>trace</CODE> in the current directory.
810 Trace logs can be difficult to interpret due to the sheer volume of
811 data dumped in them. There is a script called <STRONG>tracemunch</STRONG>
812 included with the <CODE>ncurses</CODE> distribution that can alleviate
813 this problem somewhat; it compacts long sequences of similar operations into
814 more succinct single-line pseudo-operations. These pseudo-ops can be
815 distinguished by the fact that they are named in capital letters.
817 <H2><A NAME="hints">Hints, Tips, and Tricks</A></H2>
819 The <CODE>ncurses</CODE> manual pages are a complete reference for this library.
820 In the remainder of this document, we discuss various useful methods that
821 may not be obvious from the manual page descriptions.
823 <H3><A NAME="caution">Some Notes of Caution</A></H3>
825 If you find yourself thinking you need to use <CODE>noraw()</CODE> or
826 <CODE>nocbreak()</CODE>, think again and move carefully. It's probably
827 better design to use <CODE>getstr()</CODE> or one of its relatives to
828 simulate cooked mode. The <CODE>noraw()</CODE> and <CODE>nocbreak()</CODE>
829 functions try to restore cooked mode, but they may end up clobbering
830 some control bits set before you started your application. Also, they
831 have always been poorly documented, and are likely to hurt your
832 application's usability with other curses libraries. <P>
834 Bear in mind that <CODE>refresh()</CODE> is a synonym for <CODE>wrefresh(stdscr)</CODE>.
835 Don't try to mix use of <CODE>stdscr</CODE> with use of windows declared
836 by <CODE>newwin()</CODE>; a <CODE>refresh()</CODE> call will blow them off the
837 screen. The right way to handle this is to use <CODE>subwin()</CODE>, or
838 not touch <CODE>stdscr</CODE> at all and tile your screen with declared
839 windows which you then <CODE>wnoutrefresh()</CODE> somewhere in your program
840 event loop, with a single <CODE>doupdate()</CODE> call to trigger actual
843 You are much less likely to run into problems if you design your screen
844 layouts to use tiled rather than overlapping windows. Historically,
845 curses support for overlapping windows has been weak, fragile, and poorly
846 documented. The <CODE>ncurses</CODE> library is not yet an exception to this
849 There is a panels library included in the <CODE>ncurses</CODE>
850 distribution that does a pretty good job of strengthening the
851 overlapping-windows facilities. <P>
853 Try to avoid using the global variables LINES and COLS. Use
854 <CODE>getmaxyx()</CODE> on the <CODE>stdscr</CODE> context instead. Reason:
855 your code may be ported to run in an environment with window resizes,
856 in which case several screens could be open with different sizes.
858 <H3><A NAME="leaving">Temporarily Leaving NCURSES Mode</A></H3>
860 Sometimes you will want to write a program that spends most of its time in
861 screen mode, but occasionally returns to ordinary `cooked' mode. A common
862 reason for this is to support shell-out. This behavior is simple to arrange
863 in <CODE>ncurses</CODE>. <P>
865 To leave <CODE>ncurses</CODE> mode, call <CODE>endwin()</CODE> as you would if you
866 were intending to terminate the program. This will take the screen back to
867 cooked mode; you can do your shell-out. When you want to return to
868 <CODE>ncurses</CODE> mode, simply call <CODE>refresh()</CODE> or <CODE>doupdate()</CODE>.
869 This will repaint the screen. <P>
871 There is a boolean function, <CODE>isendwin()</CODE>, which code can use to
872 test whether <CODE>ncurses</CODE> screen mode is active. It returns <CODE>TRUE</CODE>
873 in the interval between an <CODE>endwin()</CODE> call and the following
874 <CODE>refresh()</CODE>, <CODE>FALSE</CODE> otherwise. <P>
876 Here is some sample code for shellout:
879 addstr("Shelling out...");
880 def_prog_mode(); /* save current tty modes */
881 endwin(); /* restore original tty modes */
882 system("sh"); /* run shell */
883 addstr("returned.\n"); /* prepare return message */
884 refresh(); /* restore save modes, repaint screen */
887 <H3><A NAME="xterm">Using NCURSES under XTERM</A></H3>
889 A resize operation in X sends SIGWINCH to the application running under xterm.
890 The <CODE>ncurses</CODE> library provides an experimental signal
891 handler, but in general does not catch this signal, because it cannot
892 know how you want the screen re-painted. You will usually have to write the
893 SIGWINCH handler yourself. Ncurses can give you some help. <P>
895 The easiest way to code your SIGWINCH handler is to have it do an
896 <CODE>endwin</CODE>, followed by an <CODE>refresh</CODE> and a screen repaint you code
897 yourself. The <CODE>refresh</CODE> will pick up the new screen size from the
898 xterm's environment. <P>
900 That is the standard way, of course (it even works with some vendor's curses
902 Its drawback is that it clears the screen to reinitialize the display, and does
903 not resize subwindows which must be shrunk.
904 <CODE>Ncurses</CODE> provides an extension which works better, the
905 <CODE>resizeterm</CODE> function. That function ensures that all windows
906 are limited to the new screen dimensions, and pads <CODE>stdscr</CODE>
907 with blanks if the screen is larger. <P>
909 Finally, ncurses can be configured to provide its own SIGWINCH handler,
910 based on <CODE>resizeterm</CODE>.
912 <H3><A NAME="screens">Handling Multiple Terminal Screens</A></H3>
914 The <CODE>initscr()</CODE> function actually calls a function named
915 <CODE>newterm()</CODE> to do most of its work. If you are writing a program that
916 opens multiple terminals, use <CODE>newterm()</CODE> directly. <P>
918 For each call, you will have to specify a terminal type and a pair of file
919 pointers; each call will return a screen reference, and <CODE>stdscr</CODE> will be
920 set to the last one allocated. You will switch between screens with the
921 <CODE>set_term</CODE> call. Note that you will also have to call
922 <CODE>def_shell_mode</CODE> and <CODE>def_prog_mode</CODE> on each tty yourself.
924 <H3><A NAME="testing">Testing for Terminal Capabilities</A></H3>
926 Sometimes you may want to write programs that test for the presence of various
927 capabilities before deciding whether to go into <CODE>ncurses</CODE> mode. An easy
928 way to do this is to call <CODE>setupterm()</CODE>, then use the functions
929 <CODE>tigetflag()</CODE>, <CODE>tigetnum()</CODE>, and <CODE>tigetstr()</CODE> to do your
932 A particularly useful case of this often comes up when you want to
933 test whether a given terminal type should be treated as `smart'
934 (cursor-addressable) or `stupid'. The right way to test this is to see
935 if the return value of <CODE>tigetstr("cup")</CODE> is non-NULL. Alternatively,
936 you can include the <CODE>term.h</CODE> file and test the value of the
937 macro <CODE>cursor_address</CODE>.
939 <H3><A NAME="tuning">Tuning for Speed</A></H3>
941 Use the <CODE>addchstr()</CODE> family of functions for fast
942 screen-painting of text when you know the text doesn't contain any
943 control characters. Try to make attribute changes infrequent on your
944 screens. Don't use the <CODE>immedok()</CODE> option!
946 <H3><A NAME="special">Special Features of NCURSES</A></H3>
948 The <CODE>wresize()</CODE> function allows you to resize a window in place.
949 The associated <CODE>resizeterm()</CODE> function simplifies the construction
950 of <a HREF="#xterm">SIGWINCH</a> handlers, for resizing all windows. <P>
952 The <CODE>define_key()</CODE> function allows you
953 to define at runtime function-key control sequences which are not in the
954 terminal description.
955 The <CODE>keyok()</CODE> function allows you to temporarily
956 enable or disable interpretation of any function-key control sequence. <P>
958 The <CODE>use_default_colors()</CODE> function allows you to construct
959 applications which can use the terminal's default foreground and
960 background colors as an additional "default" color.
961 Several terminal emulators support this feature, which is based on ISO 6429. <P>
963 Ncurses supports up 16 colors, unlike SVr4 curses which defines only 8.
964 While most terminals which provide color allow only 8 colors, about
965 a quarter (including XFree86 xterm) support 16 colors.
967 <H2><A NAME="compat">Compatibility with Older Versions</A></H2>
969 Despite our best efforts, there are some differences between <CODE>ncurses</CODE>
970 and the (undocumented!) behavior of older curses implementations. These arise
971 from ambiguities or omissions in the documentation of the API.
973 <H3><A NAME="refbug">Refresh of Overlapping Windows</A></H3>
975 If you define two windows A and B that overlap, and then alternately scribble
976 on and refresh them, the changes made to the overlapping region under historic
977 <CODE>curses</CODE> versions were often not documented precisely. <P>
979 To understand why this is a problem, remember that screen updates are
980 calculated between two representations of the <EM>entire</EM> display. The
981 documentation says that when you refresh a window, it is first copied to to the
982 virtual screen, and then changes are calculated to update the physical screen
983 (and applied to the terminal). But "copied to" is not very specific, and
984 subtle differences in how copying works can produce different behaviors in the
985 case where two overlapping windows are each being refreshed at unpredictable
988 What happens to the overlapping region depends on what <CODE>wnoutrefresh()</CODE>
989 does with its argument -- what portions of the argument window it copies to the
990 virtual screen. Some implementations do "change copy", copying down only
991 locations in the window that have changed (or been marked changed with
992 <CODE>wtouchln()</CODE> and friends). Some implementations do "entire copy",
993 copying <EM>all</EM> window locations to the virtual screen whether or not
994 they have changed. <P>
996 The <CODE>ncurses</CODE> library itself has not always been consistent on this
997 score. Due to a bug, versions 1.8.7 to 1.9.8a did entire copy. Versions
998 1.8.6 and older, and versions 1.9.9 and newer, do change copy. <P>
1000 For most commercial curses implementations, it is not documented and not known
1001 for sure (at least not to the <CODE>ncurses</CODE> maintainers) whether they do
1002 change copy or entire copy. We know that System V release 3 curses has logic
1003 in it that looks like an attempt to do change copy, but the surrounding logic
1004 and data representations are sufficiently complex, and our knowledge
1005 sufficiently indirect, that it's hard to know whether this is reliable.
1007 It is not clear what the SVr4 documentation and XSI standard intend. The XSI
1008 Curses standard barely mentions wnoutrefresh(); the SVr4 documents seem to be
1009 describing entire-copy, but it is possible with some effort and straining to
1010 read them the other way. <P>
1012 It might therefore be unwise to rely on either behavior in programs that might
1013 have to be linked with other curses implementations. Instead, you can do an
1014 explicit <CODE>touchwin()</CODE> before the <CODE>wnoutrefresh()</CODE> call to
1015 guarantee an entire-contents copy anywhere. <P>
1017 The really clean way to handle this is to use the panels library. If,
1018 when you want a screen update, you do <CODE>update_panels()</CODE>, it will
1019 do all the necessary <CODE>wnoutrfresh()</CODE> calls for whatever panel
1020 stacking order you have defined. Then you can do one <CODE>doupdate()</CODE>
1021 and there will be a <EM>single</EM> burst of physical I/O that will do
1024 <H3><A NAME="backbug">Background Erase</A></H3>
1026 If you have been using a very old versions of <CODE>ncurses</CODE> (1.8.7 or
1027 older) you may be surprised by the behavior of the erase functions. In older
1028 versions, erased areas of a window were filled with a blank modified by the
1029 window's current attribute (as set by <STRONG>wattrset()</STRONG>, <STRONG>wattron()</STRONG>,
1030 <STRONG>wattroff()</STRONG> and friends). <P>
1032 In newer versions, this is not so. Instead, the attribute of erased blanks
1033 is normal unless and until it is modified by the functions <CODE>bkgdset()</CODE>
1034 or <CODE>wbkgdset()</CODE>. <P>
1036 This change in behavior conforms <CODE>ncurses</CODE> to System V Release 4 and
1037 the XSI Curses standard.
1039 <H2><A NAME="xsifuncs">XSI Curses Conformance</A></H2>
1041 The <CODE>ncurses</CODE> library is intended to be base-level conformant with the
1042 XSI Curses standard from X/Open. Many extended-level features (in fact, almost
1043 all features not directly concerned with wide characters and
1044 internationalization) are also supported. <P>
1046 One effect of XSI conformance is the change in behavior described under
1047 <A HREF="#backbug">"Background Erase -- Compatibility with Old Versions"</A>. <P>
1049 Also, <CODE>ncurses</CODE> meets the XSI requirement that every macro
1050 entry point have a corresponding function which may be linked (and
1051 will be prototype-checked) if the macro definition is disabled with
1052 <CODE>#undef</CODE>.
1054 <H1><A NAME="panels">The Panels Library</A></H1>
1056 The <CODE>ncurses</CODE> library by itself provides good support for screen
1057 displays in which the windows are tiled (non-overlapping). In the more
1058 general case that windows may overlap, you have to use a series of
1059 <CODE>wnoutrefresh()</CODE> calls followed by a <CODE>doupdate()</CODE>, and be
1060 careful about the order you do the window refreshes in. It has to be
1061 bottom-upwards, otherwise parts of windows that should be obscured will
1064 When your interface design is such that windows may dive deeper into the
1065 visibility stack or pop to the top at runtime, the resulting book-keeping
1066 can be tedious and difficult to get right. Hence the panels library. <P>
1068 The <CODE>panel</CODE> library first appeared in AT&T System V. The
1069 version documented here is the <CODE>panel</CODE> code distributed
1070 with <CODE>ncurses</CODE>.
1072 <H2><A NAME="pcompile">Compiling With the Panels Library</A></H2>
1074 Your panels-using modules must import the panels library declarations with
1077 #include <panel.h>
1080 and must be linked explicitly with the panels library using an
1081 <CODE>-lpanel</CODE> argument. Note that they must also link the
1082 <CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers
1083 are two-pass and will accept either order, but it is still good practice
1084 to put <CODE>-lpanel</CODE> first and <CODE>-lncurses</CODE> second.
1086 <H2><A NAME="poverview">Overview of Panels</A></H2>
1088 A panel object is a window that is implicitly treated as part of a
1089 <DFN>deck</DFN> including all other panel objects. The deck has an implicit
1090 bottom-to-top visibility order. The panels library includes an update
1091 function (analogous to <CODE>refresh()</CODE>) that displays all panels in the
1092 deck in the proper order to resolve overlaps. The standard window,
1093 <CODE>stdscr</CODE>, is considered below all panels. <P>
1095 Details on the panels functions are available in the man pages. We'll just
1096 hit the highlights here. <P>
1098 You create a panel from a window by calling <CODE>new_panel()</CODE> on a
1099 window pointer. It then becomes the top of the deck. The panel's window
1100 is available as the value of <CODE>panel_window()</CODE> called with the
1101 panel pointer as argument.<P>
1103 You can delete a panel (removing it from the deck) with <CODE>del_panel</CODE>.
1104 This will not deallocate the associated window; you have to do that yourself.
1106 You can replace a panel's window with a different window by calling
1107 <CODE>replace_window</CODE>. The new window may be of different size;
1108 the panel code will re-compute all overlaps. This operation doesn't
1109 change the panel's position in the deck. <P>
1111 To move a panel's window, use <CODE>move_panel()</CODE>. The
1112 <CODE>mvwin()</CODE> function on the panel's window isn't sufficient because it
1113 doesn't update the panels library's representation of where the windows are.
1114 This operation leaves the panel's depth, contents, and size unchanged. <P>
1116 Two functions (<CODE>top_panel()</CODE>, <CODE>bottom_panel()</CODE>) are
1117 provided for rearranging the deck. The first pops its argument window to the
1118 top of the deck; the second sends it to the bottom. Either operation leaves
1119 the panel's screen location, contents, and size unchanged. <P>
1121 The function <CODE>update_panels()</CODE> does all the
1122 <CODE>wnoutrefresh()</CODE> calls needed to prepare for
1123 <CODE>doupdate()</CODE> (which you must call yourself, afterwards). <P>
1125 Typically, you will want to call <CODE>update_panels()</CODE> and
1126 <CODE>doupdate()</CODE> just before accepting command input, once in each cycle
1127 of interaction with the user. If you call <CODE>update_panels()</CODE> after
1128 each and every panel write, you'll generate a lot of unnecessary refresh
1129 activity and screen flicker.
1131 <H2><A NAME="pstdscr">Panels, Input, and the Standard Screen</A></H2>
1133 You shouldn't mix <CODE>wnoutrefresh()</CODE> or <CODE>wrefresh()</CODE>
1134 operations with panels code; this will work only if the argument window
1135 is either in the top panel or unobscured by any other panels. <P>
1137 The <CODE>stsdcr</CODE> window is a special case. It is considered below all
1138 panels. Because changes to panels may obscure parts of <CODE>stdscr</CODE>,
1139 though, you should call <CODE>update_panels()</CODE> before
1140 <CODE>doupdate()</CODE> even when you only change <CODE>stdscr</CODE>. <P>
1142 Note that <CODE>wgetch</CODE> automatically calls <CODE>wrefresh</CODE>.
1143 Therefore, before requesting input from a panel window, you need to be sure
1144 that the panel is totally unobscured. <P>
1146 There is presently no way to display changes to one obscured panel without
1147 repainting all panels.
1149 <H2><A NAME="hiding">Hiding Panels</A></H2>
1151 It's possible to remove a panel from the deck temporarily; use
1152 <CODE>hide_panel</CODE> for this. Use <CODE>show_panel()</CODE> to render it
1153 visible again. The predicate function <CODE>panel_hidden</CODE>
1154 tests whether or not a panel is hidden. <P>
1156 The <CODE>panel_update</CODE> code ignores hidden panels. You cannot do
1157 <CODE>top_panel()</CODE> or <CODE>bottom_panel</CODE> on a hidden panel().
1158 Other panels operations are applicable.
1160 <H2><A NAME="pmisc">Miscellaneous Other Facilities</A></H2>
1162 It's possible to navigate the deck using the functions
1163 <CODE>panel_above()</CODE> and <CODE>panel_below</CODE>. Handed a panel
1164 pointer, they return the panel above or below that panel. Handed
1165 <CODE>NULL</CODE>, they return the bottom-most or top-most panel. <P>
1167 Every panel has an associated user pointer, not used by the panel code, to
1168 which you can attach application data. See the man page documentation
1169 of <CODE>set_panel_userptr()</CODE> and <CODE>panel_userptr</CODE> for
1172 <H1><A NAME="menu">The Menu Library</A></H1>
1174 A menu is a screen display that assists the user to choose some subset
1175 of a given set of items. The <CODE>menu</CODE> library is a curses
1176 extension that supports easy programming of menu hierarchies with a
1177 uniform but flexible interface. <P>
1179 The <CODE>menu</CODE> library first appeared in AT&T System V. The
1180 version documented here is the <CODE>menu</CODE> code distributed
1181 with <CODE>ncurses</CODE>.
1183 <H2><A NAME="mcompile">Compiling With the menu Library</A></H2>
1185 Your menu-using modules must import the menu library declarations with
1188 #include <menu.h>
1191 and must be linked explicitly with the menus library using an
1192 <CODE>-lmenu</CODE> argument. Note that they must also link the
1193 <CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers
1194 are two-pass and will accept either order, but it is still good practice
1195 to put <CODE>-lmenu</CODE> first and <CODE>-lncurses</CODE> second.
1197 <H2><A NAME="moverview">Overview of Menus</A></H2>
1199 The menus created by this library consist of collections of
1200 <DFN>items</DFN> including a name string part and a description string
1201 part. To make menus, you create groups of these items and connect
1202 them with menu frame objects. <P>
1204 The menu can then by <DFN>posted</DFN>, that is written to an
1205 associated window. Actually, each menu has two associated windows; a
1206 containing window in which the programmer can scribble titles or
1207 borders, and a subwindow in which the menu items proper are displayed.
1208 If this subwindow is too small to display all the items, it will be a
1209 scrollable viewport on the collection of items. <P>
1211 A menu may also be <DFN>unposted</DFN> (that is, undisplayed), and finally
1212 freed to make the storage associated with it and its items available for
1215 The general flow of control of a menu program looks like this:
1218 <LI>Initialize <CODE>curses</CODE>.
1219 <LI>Create the menu items, using <CODE>new_item()</CODE>.
1220 <LI>Create the menu using <CODE>new_menu()</CODE>.
1221 <LI>Post the menu using <CODE>menu_post()</CODE>.
1222 <LI>Refresh the screen.
1223 <LI>Process user requests via an input loop.
1224 <LI>Unpost the menu using <CODE>menu_unpost()</CODE>.
1225 <LI>Free the menu, using <CODE>free_menu()</CODE>.
1226 <LI>Free the items using <CODE>free_item()</CODE>.
1227 <LI>Terminate <CODE>curses</CODE>.
1230 <H2><A NAME="mselect">Selecting items</A></H2>
1232 Menus may be multi-valued or (the default) single-valued (see the manual
1233 page <CODE>menu_opts(3x)</CODE> to see how to change the default).
1234 Both types always have a <DFN>current item</DFN>. <P>
1236 From a single-valued menu you can read the selected value simply by looking
1237 at the current item. From a multi-valued menu, you get the selected set
1238 by looping through the items applying the <CODE>item_value()</CODE>
1239 predicate function. Your menu-processing code can use the function
1240 <CODE>set_item_value()</CODE> to flag the items in the select set. <P>
1242 Menu items can be made unselectable using <CODE>set_item_opts()</CODE>
1243 or <CODE>item_opts_off()</CODE> with the <CODE>O_SELECTABLE</CODE>
1244 argument. This is the only option so far defined for menus, but it
1245 is good practice to code as though other option bits might be on.
1247 <H2><A NAME="mdisplay">Menu Display</A></H2>
1249 The menu library calculates a minimum display size for your window, based
1250 on the following variables:
1253 <LI>The number and maximum length of the menu items
1254 <LI>Whether the O_ROWMAJOR option is enabled
1255 <LI>Whether display of descriptions is enabled
1256 <LI>Whatever menu format may have been set by the programmer
1257 <LI>The length of the menu mark string used for highlighting selected items
1260 The function <CODE>set_menu_format()</CODE> allows you to set the
1261 maximum size of the viewport or <DFN>menu page</DFN> that will be used
1262 to display menu items. You can retrieve any format associated with a
1263 menu with <CODE>menu_format()</CODE>. The default format is rows=16,
1266 The actual menu page may be smaller than the format size. This depends
1267 on the item number and size and whether O_ROWMAJOR is on. This option
1268 (on by default) causes menu items to be displayed in a `raster-scan'
1269 pattern, so that if more than one item will fit horizontally the first
1270 couple of items are side-by-side in the top row. The alternative is
1271 column-major display, which tries to put the first several items in
1272 the first column. <P>
1274 As mentioned above, a menu format not large enough to allow all items to fit
1275 on-screen will result in a menu display that is vertically scrollable. <P>
1276 You can scroll it with requests to the menu driver, which will be described
1277 in the section on <A HREF="#minput">menu input handling</A>. <P>
1279 Each menu has a <DFN>mark string</DFN> used to visually tag selected items;
1280 see the <CODE>menu_mark(3x)</CODE> manual page for details. The mark
1281 string length also influences the menu page size. <P>
1283 The function <CODE>scale_menu()</CODE> returns the minimum display size
1284 that the menu code computes from all these factors.
1286 There are other menu display attributes including a select attribute,
1287 an attribute for selectable items, an attribute for unselectable items,
1288 and a pad character used to separate item name text from description
1289 text. These have reasonable defaults which the library allows you to
1290 change (see the <CODE>menu_attribs(3x)</CODE> manual page.
1292 <H2><A NAME="mwindows">Menu Windows</A></H2>
1294 Each menu has, as mentioned previously, a pair of associated windows.
1295 Both these windows are painted when the menu is posted and erased when
1296 the menu is unposted. <P>
1298 The outer or frame window is not otherwise touched by the menu
1299 routines. It exists so the programmer can associate a title, a
1300 border, or perhaps help text with the menu and have it properly
1301 refreshed or erased at post/unpost time. The inner window or
1302 <DFN>subwindow</DFN> is where the current menu page is displayed. <P>
1304 By default, both windows are <CODE>stdscr</CODE>. You can set them with the
1305 functions in <CODE>menu_win(3x)</CODE>. <P>
1307 When you call <CODE>menu_post()</CODE>, you write the menu to its
1308 subwindow. When you call <CODE>menu_unpost()</CODE>, you erase the
1309 subwindow, However, neither of these actually modifies the screen. To
1310 do that, call <CODE>wrefresh()</CODE> or some equivalent.
1312 <H2><A NAME="minput">Processing Menu Input</A></H2>
1314 The main loop of your menu-processing code should call
1315 <CODE>menu_driver()</CODE> repeatedly. The first argument of this routine
1316 is a menu pointer; the second is a menu command code. You should write an
1317 input-fetching routine that maps input characters to menu command codes, and
1318 pass its output to <CODE>menu_driver()</CODE>. The menu command codes are
1319 fully documented in <CODE>menu_driver(3x)</CODE>. <P>
1321 The simplest group of command codes is <CODE>REQ_NEXT_ITEM</CODE>,
1322 <CODE>REQ_PREV_ITEM</CODE>, <CODE>REQ_FIRST_ITEM</CODE>,
1323 <CODE>REQ_LAST_ITEM</CODE>, <CODE>REQ_UP_ITEM</CODE>,
1324 <CODE>REQ_DOWN_ITEM</CODE>, <CODE>REQ_LEFT_ITEM</CODE>,
1325 <CODE>REQ_RIGHT_ITEM</CODE>. These change the currently selected
1326 item. These requests may cause scrolling of the menu page if it only
1327 partially displayed. <P>
1329 There are explicit requests for scrolling which also change the
1330 current item (because the select location does not change, but the
1331 item there does). These are <CODE>REQ_SCR_DLINE</CODE>,
1332 <CODE>REQ_SCR_ULINE</CODE>, <CODE>REQ_SCR_DPAGE</CODE>, and
1333 <CODE>REQ_SCR_UPAGE</CODE>. <P>
1335 The <CODE>REQ_TOGGLE_ITEM</CODE> selects or deselects the current item.
1336 It is for use in multi-valued menus; if you use it with <CODE>O_ONEVALUE</CODE>
1337 on, you'll get an error return (<CODE>E_REQUEST_DENIED</CODE>). <P>
1339 Each menu has an associated pattern buffer. The
1340 <CODE>menu_driver()</CODE> logic tries to accumulate printable ASCII
1341 characters passed in in that buffer; when it matches a prefix of an
1342 item name, that item (or the next matching item) is selected. If
1343 appending a character yields no new match, that character is deleted
1344 from the pattern buffer, and <CODE>menu_driver()</CODE> returns
1345 <CODE>E_NO_MATCH</CODE>. <P>
1347 Some requests change the pattern buffer directly:
1348 <CODE>REQ_CLEAR_PATTERN</CODE>, <CODE>REQ_BACK_PATTERN</CODE>,
1349 <CODE>REQ_NEXT_MATCH</CODE>, <CODE>REQ_PREV_MATCH</CODE>. The latter
1350 two are useful when pattern buffer input matches more than one item
1351 in a multi-valued menu. <P>
1353 Each successful scroll or item navigation request clears the pattern
1354 buffer. It is also possible to set the pattern buffer explicitly
1355 with <CODE>set_menu_pattern()</CODE>. <P>
1357 Finally, menu driver requests above the constant <CODE>MAX_COMMAND</CODE>
1358 are considered application-specific commands. The <CODE>menu_driver()</CODE>
1359 code ignores them and returns <CODE>E_UNKNOWN_COMMAND</CODE>.
1361 <H2><A NAME="mmisc">Miscellaneous Other Features</A></H2>
1363 Various menu options can affect the processing and visual appearance
1364 and input processing of menus. See <CODE>menu_opts(3x) for
1367 It is possible to change the current item from application code; this
1368 is useful if you want to write your own navigation requests. It is
1369 also possible to explicitly set the top row of the menu display. See
1370 <CODE>mitem_current(3x)</CODE>.
1372 If your application needs to change the menu subwindow cursor for
1373 any reason, <CODE>pos_menu_cursor()</CODE> will restore it to the
1374 correct location for continuing menu driver processing. <P>
1376 It is possible to set hooks to be called at menu initialization and
1377 wrapup time, and whenever the selected item changes. See
1378 <CODE>menu_hook(3x)</CODE>. <P>
1380 Each item, and each menu, has an associated user pointer on which you
1381 can hang application data. See <CODE>mitem_userptr(3x)</CODE> and
1382 <CODE>menu_userptr(3x)</CODE>.
1384 <H1><A NAME="form">The Forms Library</A></H1>
1386 The <CODE>form</CODE> library is a curses extension that supports easy
1387 programming of on-screen forms for data entry and program control. <P>
1389 The <CODE>form</CODE> library first appeared in AT&T System V. The
1390 version documented here is the <CODE>form</CODE> code distributed
1391 with <CODE>ncurses</CODE>.
1393 <H2><A NAME="fcompile">Compiling With the form Library</A></H2>
1395 Your form-using modules must import the form library declarations with
1398 #include <form.h>
1401 and must be linked explicitly with the forms library using an
1402 <CODE>-lform</CODE> argument. Note that they must also link the
1403 <CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers
1404 are two-pass and will accept either order, but it is still good practice
1405 to put <CODE>-lform</CODE> first and <CODE>-lncurses</CODE> second.
1407 <H2><A NAME="foverview">Overview of Forms</A></H2>
1409 A form is a collection of fields; each field may be either a label
1410 (explanatory text) or a data-entry location. Long forms may be
1411 segmented into pages; each entry to a new page clears the screen. <P>
1412 To make forms, you create groups of fields and connect them with form
1413 frame objects; the form library makes this relatively simple. <P>
1415 Once defined, a form can be <DFN>posted</DFN>, that is written to an
1416 associated window. Actually, each form has two associated windows; a
1417 containing window in which the programmer can scribble titles or
1418 borders, and a subwindow in which the form fields proper are displayed. <P>
1420 As the form user fills out the posted form, navigation and editing
1421 keys support movement between fields, editing keys support modifying
1422 field, and plain text adds to or changes data in a current field. The
1423 form library allows you (the forms designer) to bind each navigation
1424 and editing key to any keystroke accepted by <CODE>curses</CODE>
1426 Fields may have validation conditions on them, so that they check input
1427 data for type and value. The form library supplies a rich set of
1428 pre-defined field types, and makes it relatively easy to define new ones. <P>
1430 Once its transaction is completed (or aborted), a form may be
1431 <DFN>unposted</DFN> (that is, undisplayed), and finally freed to make
1432 the storage associated with it and its items available for re-use. <P>
1434 The general flow of control of a form program looks like this:
1437 <LI>Initialize <CODE>curses</CODE>.
1438 <LI>Create the form fields, using <CODE>new_field()</CODE>.
1439 <LI>Create the form using <CODE>new_form()</CODE>.
1440 <LI>Post the form using <CODE>form_post()</CODE>.
1441 <LI>Refresh the screen.
1442 <LI>Process user requests via an input loop.
1443 <LI>Unpost the form using <CODE>form_unpost()</CODE>.
1444 <LI>Free the form, using <CODE>free_form()</CODE>.
1445 <LI>Free the fields using <CODE>free_field()</CODE>.
1446 <LI>Terminate <CODE>curses</CODE>.
1449 Note that this looks much like a menu program; the form library handles
1450 tasks which are in many ways similar, and its interface was obviously
1451 designed to resemble that of the <A HREF="#menu">menu library</A>
1452 wherever possible. <P>
1454 In forms programs, however, the `process user requests' is somewhat more
1455 complicated than for menus. Besides menu-like navigation operations,
1456 the menu driver loop has to support field editing and data validation.
1458 <H2><A NAME="fcreate">Creating and Freeing Fields and Forms</A></H2>
1460 The basic function for creating fields is <CODE>new_field()</CODE>:
1463 FIELD *new_field(int height, int width, /* new field size */
1464 int top, int left, /* upper left corner */
1465 int offscreen, /* number of offscreen rows */
1466 int nbuf); /* number of working buffers */
1469 Menu items always occupy a single row, but forms fields may have
1470 multiple rows. So <CODE>new_field()</CODE> requires you to specify a
1471 width and height (the first two arguments, which mist both be greater
1474 You must also specify the location of the field's upper left corner on
1475 the screen (the third and fourth arguments, which must be zero or
1476 greater). Note that these coordinates are relative to the form
1477 subwindow, which will coincide with <CODE>stdscr</CODE> by default but
1478 need not be <CODE>stdscr</CODE> if you've done an explicit
1479 <CODE>set_form_window()</CODE> call. <P>
1481 The fifth argument allows you to specify a number of off-screen rows. If
1482 this is zero, the entire field will always be displayed. If it is
1483 nonzero, the form will be scrollable, with only one screen-full (initially
1484 the top part) displayed at any given time. If you make a field dynamic
1485 and grow it so it will no longer fit on the screen, the form will become
1486 scrollable even if the <CODE>offscreen</CODE> argument was initially zero. <P>
1488 The forms library allocates one working buffer per field; the size of
1489 each buffer is <CODE>((height + offscreen)*width + 1</CODE>, one character
1490 for each position in the field plus a NUL terminator. The sixth
1491 argument is the number of additional data buffers to allocate for the
1492 field; your application can use them for its own purposes.
1495 FIELD *dup_field(FIELD *field, /* field to copy */
1496 int top, int left); /* location of new copy */
1499 The function <CODE>dup_field()</CODE> duplicates an existing field at a
1500 new location. Size and buffering information are copied; some
1501 attribute flags and status bits are not (see the
1502 <CODE>form_field_new(3X)</CODE> for details).
1505 FIELD *link_field(FIELD *field, /* field to copy */
1506 int top, int left); /* location of new copy */
1509 The function <CODE>link_field()</CODE> also duplicates an existing field
1510 at a new location. The difference from <CODE>dup_field()</CODE> is that
1511 it arranges for the new field's buffer to be shared with the old one. <P>
1513 Besides the obvious use in making a field editable from two different
1514 form pages, linked fields give you a way to hack in dynamic labels. If
1515 you declare several fields linked to an original, and then make them
1516 inactive, changes from the original will still be propagated to the
1519 As with duplicated fields, linked fields have attribute bits separate
1520 from the original. <P>
1522 As you might guess, all these field-allocations return <CODE>NULL</CODE> if
1523 the field allocation is not possible due to an out-of-memory error or
1524 out-of-bounds arguments. <P>
1526 To connect fields to a form, use
1529 FORM *new_form(FIELD **fields);
1532 This function expects to see a NULL-terminated array of field pointers.
1533 Said fields are connected to a newly-allocated form object; its address
1534 is returned (or else NULL if the allocation fails). <P>
1536 Note that <CODE>new_field()</CODE> does <EM>not</EM> copy the pointer array
1537 into private storage; if you modify the contents of the pointer array
1538 during forms processing, all manner of bizarre things might happen. Also
1539 note that any given field may only be connected to one form. <P>
1541 The functions <CODE>free_field()</CODE> and <CODE>free_form</CODE> are available
1542 to free field and form objects. It is an error to attempt to free a field
1543 connected to a form, but not vice-versa; thus, you will generally free
1544 your form objects first.
1546 <H2><A NAME="fattributes">Fetching and Changing Field Attributes</A></H2>
1548 Each form field has a number of location and size attributes
1549 associated with it. There are other field attributes used to control
1550 display and editing of the field. Some (for example, the <CODE>O_STATIC</CODE> bit)
1551 involve sufficient complications to be covered in sections of their own
1552 later on. We cover the functions used to get and set several basic
1553 attributes here. <P>
1555 When a field is created, the attributes not specified by the
1556 <CODE>new_field</CODE> function are copied from an invisible system
1557 default field. In attribute-setting and -fetching functions, the
1558 argument NULL is taken to mean this field. Changes to it persist
1559 as defaults until your forms application terminates.
1561 <H3><A NAME="fsizes">Fetching Size and Location Data</A></H3>
1563 You can retrieve field sizes and locations through:
1566 int field_info(FIELD *field, /* field from which to fetch */
1567 int *height, *int width, /* field size */
1568 int *top, int *left, /* upper left corner */
1569 int *offscreen, /* number of offscreen rows */
1570 int *nbuf); /* number of working buffers */
1573 This function is a sort of inverse of <CODE>new_field()</CODE>; instead of
1574 setting size and location attributes of a new field, it fetches them
1575 from an existing one.
1577 <H3><A NAME="flocation">Changing the Field Location</A></H3>
1579 It is possible to move a field's location on the screen:
1582 int move_field(FIELD *field, /* field to alter */
1583 int top, int left); /* new upper-left corner */
1586 You can, of course. query the current location through <CODE>field_info()</CODE>.
1588 <H3><A NAME="fjust">The Justification Attribute</A></H3>
1590 One-line fields may be unjustified, justified right, justified left,
1591 or centered. Here is how you manipulate this attribute:
1594 int set_field_just(FIELD *field, /* field to alter */
1595 int justmode); /* mode to set */
1597 int field_just(FIELD *field); /* fetch mode of field */
1600 The mode values accepted and returned by this functions are
1601 preprocessor macros <CODE>NO_JUSTIFICATION</CODE>, <CODE>JUSTIFY_RIGHT</CODE>,
1602 <CODE>JUSTIFY_LEFT</CODE>, or <CODE>JUSTIFY_CENTER</CODE>.
1604 <H3><A NAME="fdispatts">Field Display Attributes</A></H3>
1606 For each field, you can set a foreground attribute for entered
1607 characters, a background attribute for the entire field, and a pad
1608 character for the unfilled portion of the field. You can also
1609 control pagination of the form. <P>
1611 This group of four field attributes controls the visual appearance
1612 of the field on the screen, without affecting in any way the data
1613 in the field buffer.
1616 int set_field_fore(FIELD *field, /* field to alter */
1617 chtype attr); /* attribute to set */
1619 chtype field_fore(FIELD *field); /* field to query */
1621 int set_field_back(FIELD *field, /* field to alter */
1622 chtype attr); /* attribute to set */
1624 chtype field_back(FIELD *field); /* field to query */
1626 int set_field_pad(FIELD *field, /* field to alter */
1627 int pad); /* pad character to set */
1629 chtype field_pad(FIELD *field);
1631 int set_new_page(FIELD *field, /* field to alter */
1632 int flag); /* TRUE to force new page */
1634 chtype new_page(FIELD *field); /* field to query */
1637 The attributes set and returned by the first four functions are normal
1638 <CODE>curses(3x)</CODE> display attribute values (<CODE>A_STANDOUT</CODE>,
1639 <CODE>A_BOLD</CODE>, <CODE>A_REVERSE</CODE> etc).
1641 The page bit of a field controls whether it is displayed at the start of
1644 <H3><A NAME="foptions">Field Option Bits</A></H3>
1646 There is also a large collection of field option bits you can set to control
1647 various aspects of forms processing. You can manipulate them with these
1651 int set_field_opts(FIELD *field, /* field to alter */
1652 int attr); /* attribute to set */
1654 int field_opts_on(FIELD *field, /* field to alter */
1655 int attr); /* attributes to turn on */
1657 int field_opts_off(FIELD *field, /* field to alter */
1658 int attr); /* attributes to turn off */
1660 int field_opts(FIELD *field); /* field to query */
1663 By default, all options are on. Here are the available option bits:
1666 <DD> Controls whether the field is visible on the screen. Can be used
1667 during form processing to hide or pop up fields depending on the value
1670 <DD> Controls whether the field is active during forms processing (i.e.
1671 visited by form navigation keys). Can be used to make labels or derived
1672 fields with buffer values alterable by the forms application, not the user.
1674 <DD> Controls whether data is displayed during field entry. If this option is
1675 turned off on a field, the library will accept and edit data in that field,
1676 but it will not be displayed and the visible field cursor will not move.
1677 You can turn off the O_PUBLIC bit to define password fields.
1679 <DD> Controls whether the field's data can be modified. When this option is
1680 off, all editing requests except <CODE>REQ_PREV_CHOICE</CODE> and
1681 <CODE>REQ_NEXT_CHOICE</CODE> will fail. Such read-only fields may be useful for
1684 <DD> Controls word-wrapping in multi-line fields. Normally, when any
1685 character of a (blank-separated) word reaches the end of the current line, the
1686 entire word is wrapped to the next line (assuming there is one). When this
1687 option is off, the word will be split across the line break.
1689 <DD> Controls field blanking. When this option is on, entering a character at
1690 the first field position erases the entire field (except for the just-entered
1693 <DD> Controls automatic skip to next field when this one fills. Normally,
1694 when the forms user tries to type more data into a field than will fit,
1695 the editing location jumps to next field. When this option is off, the
1696 user's cursor will hang at the end of the field. This option is ignored
1697 in dynamic fields that have not reached their size limit.
1699 <DD> Controls whether <A HREF="#fvalidation">validation</A> is applied to
1700 blank fields. Normally, it is not; the user can leave a field blank
1701 without invoking the usual validation check on exit. If this option is
1702 off on a field, exit from it will invoke a validation check.
1704 <DD> Controls whether validation occurs on every exit, or only after
1705 the field is modified. Normally the latter is true. Setting O_PASSOK
1706 may be useful if your field's validation function may change during
1709 <DD> Controls whether the field is fixed to its initial dimensions. If you
1710 turn this off, the field becomes <A HREF="#fdynamic">dynamic</A> and will
1711 stretch to fit entered data.
1714 A field's options cannot be changed while the field is currently selected.
1715 However, options may be changed on posted fields that are not current. <P>
1717 The option values are bit-masks and can be composed with logical-or in
1720 <H2><A NAME="fstatus">Field Status</A></H2>
1722 Every field has a status flag, which is set to FALSE when the field is
1723 created and TRUE when the value in field buffer 0 changes. This flag can
1724 be queried and set directly:
1727 int set_field_status(FIELD *field, /* field to alter */
1728 int status); /* mode to set */
1730 int field_status(FIELD *field); /* fetch mode of field */
1733 Setting this flag under program control can be useful if you use the same
1734 form repeatedly, looking for modified fields each time. <P>
1736 Calling <CODE>field_status()</CODE> on a field not currently selected
1737 for input will return a correct value. Calling <CODE>field_status()</CODE> on a
1738 field that is currently selected for input may not necessarily give a
1739 correct field status value, because entered data isn't necessarily copied to
1740 buffer zero before the exit validation check.
1742 To guarantee that the returned status value reflects reality, call
1743 <CODE>field_status()</CODE> either (1) in the field's exit validation check
1744 routine, (2) from the field's or form's initialization or termination
1745 hooks, or (3) just after a <CODE>REQ_VALIDATION</CODE> request has been
1746 processed by the forms driver.
1748 <H2><A NAME="fuser">Field User Pointer</A></H2>
1750 Each field structure contains one character pointer slot that is not used
1751 by the forms library. It is intended to be used by applications to store
1752 private per-field data. You can manipulate it with:
1755 int set_field_userptr(FIELD *field, /* field to alter */
1756 char *userptr); /* mode to set */
1758 char *field_userptr(FIELD *field); /* fetch mode of field */
1761 (Properly, this user pointer field ought to have <CODE>(void *)</CODE> type.
1762 The <CODE>(char *)</CODE> type is retained for System V compatibility.) <P>
1764 It is valid to set the user pointer of the default field (with a
1765 <CODE>set_field_userptr()</CODE> call passed a NULL field pointer.)
1766 When a new field is created, the default-field user pointer is copied
1767 to initialize the new field's user pointer.
1769 <H2><A NAME="fdynamic">Variable-Sized Fields</A></H2>
1771 Normally, a field is fixed at the size specified for it at creation
1772 time. If, however, you turn off its O_STATIC bit, it becomes
1773 <DFN>dynamic</DFN> and will automatically resize itself to accommodate
1774 data as it is entered. If the field has extra buffers associated with it,
1775 they will grow right along with the main input buffer. <P>
1777 A one-line dynamic field will have a fixed height (1) but variable
1778 width, scrolling horizontally to display data within the field area as
1779 originally dimensioned and located. A multi-line dynamic field will
1780 have a fixed width, but variable height (number of rows), scrolling
1781 vertically to display data within the field area as originally
1782 dimensioned and located. <P>
1784 Normally, a dynamic field is allowed to grow without limit. But it is
1785 possible to set an upper limit on the size of a dynamic field. You do
1786 it with this function:
1789 int set_max_field(FIELD *field, /* field to alter (may not be NULL) */
1790 int max_size); /* upper limit on field size */
1793 If the field is one-line, <CODE>max_size</CODE> is taken to be a column size
1794 limit; if it is multi-line, it is taken to be a line size limit. To disable
1795 any limit, use an argument of zero. The growth limit can be changed whether
1796 or not the O_STATIC bit is on, but has no effect until it is. <P>
1798 The following properties of a field change when it becomes dynamic:
1801 <LI>If there is no growth limit, there is no final position of the field;
1802 therefore <CODE>O_AUTOSKIP</CODE> and <CODE>O_NL_OVERLOAD</CODE> are ignored.
1803 <LI>Field justification will be ignored (though whatever justification is
1804 set up will be retained internally and can be queried).
1805 <LI>The <CODE>dup_field()</CODE> and <CODE>link_field()</CODE> calls copy
1806 dynamic-buffer sizes. If the <CODE>O_STATIC</CODE> option is set on one of a
1807 collection of links, buffer resizing will occur only when the field is
1808 edited through that link.
1809 <LI>The call <CODE>field_info()</CODE> will retrieve the original static size of
1810 the field; use <CODE>dynamic_field_info()</CODE> to get the actual dynamic size.
1813 <H2><A NAME="fvalidation">Field Validation</A></H2>
1815 By default, a field will accept any data that will fit in its input buffer.
1816 However, it is possible to attach a validation type to a field. If you do
1817 this, any attempt to leave the field while it contains data that doesn't
1818 match the validation type will fail. Some validation types also have a
1819 character-validity check for each time a character is entered in the field. <P>
1821 A field's validation check (if any) is not called when
1822 <CODE>set_field_buffer()</CODE> modifies the input buffer, nor when that buffer
1823 is changed through a linked field. <P>
1825 The <CODE>form</CODE> library provides a rich set of pre-defined validation
1826 types, and gives you the capability to define custom ones of your own. You
1827 can examine and change field validation attributes with the following
1831 int set_field_type(FIELD *field, /* field to alter */
1832 FIELDTYPE *ftype, /* type to associate */
1833 ...); /* additional arguments*/
1835 FIELDTYPE *field_type(FIELD *field); /* field to query */
1838 The validation type of a field is considered an attribute of the field. As
1839 with other field attributes, Also, doing <CODE>set_field_type()</CODE> with a
1840 <CODE>NULL</CODE> field default will change the system default for validation of
1841 newly-created fields. <P>
1843 Here are the pre-defined validation types:
1845 <H3><A NAME="ftype_alpha">TYPE_ALPHA</A></H3>
1847 This field type accepts alphabetic data; no blanks, no digits, no special
1848 characters (this is checked at character-entry time). It is set up with:
1851 int set_field_type(FIELD *field, /* field to alter */
1852 TYPE_ALPHA, /* type to associate */
1853 int width); /* maximum width of field */
1856 The <CODE>width</CODE> argument sets a minimum width of data. Typically
1857 you'll want to set this to the field width; if it's greater than the
1858 field width, the validation check will always fail. A minimum width
1859 of zero makes field completion optional.
1861 <H3><A NAME="ftype_alnum">TYPE_ALNUM</A></H3>
1863 This field type accepts alphabetic data and digits; no blanks, no special
1864 characters (this is checked at character-entry time). It is set up with:
1867 int set_field_type(FIELD *field, /* field to alter */
1868 TYPE_ALNUM, /* type to associate */
1869 int width); /* maximum width of field */
1872 The <CODE>width</CODE> argument sets a minimum width of data. As with
1873 TYPE_ALPHA, typically you'll want to set this to the field width; if it's
1874 greater than the field width, the validation check will always fail. A
1875 minimum width of zero makes field completion optional.
1877 <H3><A NAME="ftype_enum">TYPE_ENUM</A></H3>
1879 This type allows you to restrict a field's values to be among a specified
1880 set of string values (for example, the two-letter postal codes for U.S.
1881 states). It is set up with:
1884 int set_field_type(FIELD *field, /* field to alter */
1885 TYPE_ENUM, /* type to associate */
1886 char **valuelist; /* list of possible values */
1887 int checkcase; /* case-sensitive? */
1888 int checkunique); /* must specify uniquely? */
1891 The <CODE>valuelist</CODE> parameter must point at a NULL-terminated list of
1892 valid strings. The <CODE>checkcase</CODE> argument, if true, makes comparison
1893 with the string case-sensitive. <P>
1895 When the user exits a TYPE_ENUM field, the validation procedure tries to
1896 complete the data in the buffer to a valid entry. If a complete choice string
1897 has been entered, it is of course valid. But it is also possible to enter a
1898 prefix of a valid string and have it completed for you. <P>
1900 By default, if you enter such a prefix and it matches more than one value
1901 in the string list, the prefix will be completed to the first matching
1902 value. But the <CODE>checkunique</CODE> argument, if true, requires prefix
1903 matches to be unique in order to be valid. <P>
1905 The <CODE>REQ_NEXT_CHOICE</CODE> and <CODE>REQ_PREV_CHOICE</CODE> input requests
1906 can be particularly useful with these fields.
1908 <H3><A NAME="ftype_integer">TYPE_INTEGER</A></H3>
1910 This field type accepts an integer. It is set up as follows:
1913 int set_field_type(FIELD *field, /* field to alter */
1914 TYPE_INTEGER, /* type to associate */
1915 int padding, /* # places to zero-pad to */
1916 int vmin, int vmax); /* valid range */
1919 Valid characters consist of an optional leading minus and digits.
1920 The range check is performed on exit. If the range maximum is less
1921 than or equal to the minimum, the range is ignored. <P>
1923 If the value passes its range check, it is padded with as many leading
1924 zero digits as necessary to meet the padding argument. <P>
1926 A <CODE>TYPE_INTEGER</CODE> value buffer can conveniently be interpreted
1927 with the C library function <CODE>atoi(3)</CODE>.
1929 <H3><A NAME="ftype_numeric">TYPE_NUMERIC</A></H3>
1931 This field type accepts a decimal number. It is set up as follows:
1934 int set_field_type(FIELD *field, /* field to alter */
1935 TYPE_NUMERIC, /* type to associate */
1936 int padding, /* # places of precision */
1937 double vmin, double vmax); /* valid range */
1940 Valid characters consist of an optional leading minus and digits. possibly
1941 including a decimal point. If your system supports locale's, the decimal point
1942 character used must be the one defined by your locale. The range check is
1943 performed on exit. If the range maximum is less than or equal to the minimum,
1944 the range is ignored. <P>
1946 If the value passes its range check, it is padded with as many trailing
1947 zero digits as necessary to meet the padding argument. <P>
1949 A <CODE>TYPE_NUMERIC</CODE> value buffer can conveniently be interpreted
1950 with the C library function <CODE>atof(3)</CODE>.
1952 <H3><A NAME="ftype_regexp">TYPE_REGEXP</A></H3>
1954 This field type accepts data matching a regular expression. It is set up
1958 int set_field_type(FIELD *field, /* field to alter */
1959 TYPE_REGEXP, /* type to associate */
1960 char *regexp); /* expression to match */
1963 The syntax for regular expressions is that of <CODE>regcomp(3)</CODE>.
1964 The check for regular-expression match is performed on exit.
1966 <H2><A NAME="fbuffer">Direct Field Buffer Manipulation</A></H2>
1968 The chief attribute of a field is its buffer contents. When a form has
1969 been completed, your application usually needs to know the state of each
1970 field buffer. You can find this out with:
1973 char *field_buffer(FIELD *field, /* field to query */
1974 int bufindex); /* number of buffer to query */
1977 Normally, the state of the zero-numbered buffer for each field is set by
1978 the user's editing actions on that field. It's sometimes useful to be able
1979 to set the value of the zero-numbered (or some other) buffer from your
1983 int set_field_buffer(FIELD *field, /* field to alter */
1984 int bufindex, /* number of buffer to alter */
1985 char *value); /* string value to set */
1988 If the field is not large enough and cannot be resized to a sufficiently
1989 large size to contain the specified value, the value will be truncated
1992 Calling <CODE>field_buffer()</CODE> with a null field pointer will raise an
1993 error. Calling <CODE>field_buffer()</CODE> on a field not currently selected
1994 for input will return a correct value. Calling <CODE>field_buffer()</CODE> on a
1995 field that is currently selected for input may not necessarily give a
1996 correct field buffer value, because entered data isn't necessarily copied to
1997 buffer zero before the exit validation check.
1999 To guarantee that the returned buffer value reflects on-screen reality,
2000 call <CODE>field_buffer()</CODE> either (1) in the field's exit validation
2001 check routine, (2) from the field's or form's initialization or termination
2002 hooks, or (3) just after a <CODE>REQ_VALIDATION</CODE> request has been processed
2003 by the forms driver.
2005 <H2><A NAME="formattrs">Attributes of Forms</A></H2>
2007 As with field attributes, form attributes inherit a default from a
2008 system default form structure. These defaults can be queried or set by
2009 of these functions using a form-pointer argument of <CODE>NULL</CODE>. <P>
2011 The principal attribute of a form is its field list. You can query
2012 and change this list with:
2015 int set_form_fields(FORM *form, /* form to alter */
2016 FIELD **fields); /* fields to connect */
2018 char *form_fields(FORM *form); /* fetch fields of form */
2020 int field_count(FORM *form); /* count connect fields */
2023 The second argument of <CODE>set_form_fields()</CODE> may be a
2024 NULL-terminated field pointer array like the one required by
2025 <CODE>new_form()</CODE>. In that case, the old fields of the form are
2026 disconnected but not freed (and eligible to be connected to other
2027 forms), then the new fields are connected. <P>
2029 It may also be null, in which case the old fields are disconnected
2030 (and not freed) but no new ones are connected. <P>
2032 The <CODE>field_count()</CODE> function simply counts the number of fields
2033 connected to a given from. It returns -1 if the form-pointer argument
2036 <H2><A NAME="fdisplay">Control of Form Display</A></H2>
2038 In the overview section, you saw that to display a form you normally
2039 start by defining its size (and fields), posting it, and refreshing
2040 the screen. There is an hidden step before posting, which is the
2041 association of the form with a frame window (actually, a pair of
2042 windows) within which it will be displayed. By default, the forms
2043 library associates every form with the full-screen window
2044 <CODE>stdscr</CODE>. <P>
2046 By making this step explicit, you can associate a form with a declared
2047 frame window on your screen display. This can be useful if you want to
2048 adapt the form display to different screen sizes, dynamically tile
2049 forms on the screen, or use a form as part of an interface layout
2050 managed by <A HREF="#panels">panels</A>. <P>
2052 The two windows associated with each form have the same functions as
2053 their analogues in the <A HREF="#menu">menu library</A>. Both these
2054 windows are painted when the form is posted and erased when the form
2057 The outer or frame window is not otherwise touched by the form
2058 routines. It exists so the programmer can associate a title, a
2059 border, or perhaps help text with the form and have it properly
2060 refreshed or erased at post/unpost time. The inner window or subwindow
2061 is where the current form page is actually displayed. <P>
2063 In order to declare your own frame window for a form, you'll need to
2064 know the size of the form's bounding rectangle. You can get this
2068 int scale_form(FORM *form, /* form to query */
2069 int *rows, /* form rows */
2070 int *cols); /* form cols */
2073 The form dimensions are passed back in the locations pointed to by
2074 the arguments. Once you have this information, you can use it to
2075 declare of windows, then use one of these functions:
2078 int set_form_win(FORM *form, /* form to alter */
2079 WINDOW *win); /* frame window to connect */
2081 WINDOW *form_win(FORM *form); /* fetch frame window of form */
2083 int set_form_sub(FORM *form, /* form to alter */
2084 WINDOW *win); /* form subwindow to connect */
2086 WINDOW *form_sub(FORM *form); /* fetch form subwindow of form */
2089 Note that curses operations, including <CODE>refresh()</CODE>, on the form,
2090 should be done on the frame window, not the form subwindow. <P>
2092 It is possible to check from your application whether all of a
2093 scrollable field is actually displayed within the menu subwindow. Use
2097 int data_ahead(FORM *form); /* form to be queried */
2099 int data_behind(FORM *form); /* form to be queried */
2102 The function <CODE>data_ahead()</CODE> returns TRUE if (a) the current
2103 field is one-line and has undisplayed data off to the right, (b) the current
2104 field is multi-line and there is data off-screen below it. <P>
2106 The function <CODE>data_behind()</CODE> returns TRUE if the first (upper
2107 left hand) character position is off-screen (not being displayed). <P>
2109 Finally, there is a function to restore the form window's cursor to the
2110 value expected by the forms driver:
2113 int pos_form_cursor(FORM *) /* form to be queried */
2116 If your application changes the form window cursor, call this function before
2117 handing control back to the forms driver in order to re-synchronize it.
2119 <H2><A NAME="fdriver">Input Processing in the Forms Driver</A></H2>
2121 The function <CODE>form_driver()</CODE> handles virtualized input requests
2122 for form navigation, editing, and validation requests, just as
2123 <CODE>menu_driver</CODE> does for menus (see the section on <A
2124 HREF="#minput">menu input handling</A>).
2127 int form_driver(FORM *form, /* form to pass input to */
2128 int request); /* form request code */
2131 Your input virtualization function needs to take input and then convert it
2132 to either an alphanumeric character (which is treated as data to be
2133 entered in the currently-selected field), or a forms processing request. <P>
2135 The forms driver provides hooks (through input-validation and
2136 field-termination functions) with which your application code can check
2137 that the input taken by the driver matched what was expected.
2139 <H3><A NAME="fpage">Page Navigation Requests</A></H3>
2141 These requests cause page-level moves through the form,
2142 triggering display of a new form screen.
2145 <DT> <CODE>REQ_NEXT_PAGE</CODE>
2146 <DD> Move to the next form page.
2147 <DT> <CODE>REQ_PREV_PAGE</CODE>
2148 <DD> Move to the previous form page.
2149 <DT> <CODE>REQ_FIRST_PAGE</CODE>
2150 <DD> Move to the first form page.
2151 <DT> <CODE>REQ_LAST_PAGE</CODE>
2152 <DD> Move to the last form page.
2155 These requests treat the list as cyclic; that is, <CODE>REQ_NEXT_PAGE</CODE>
2156 from the last page goes to the first, and <CODE>REQ_PREV_PAGE</CODE> from
2157 the first page goes to the last.
2159 <H3><A NAME="#ffield">Inter-Field Navigation Requests</A></H3>
2161 These requests handle navigation between fields on the same page.
2164 <DT> <CODE>REQ_NEXT_FIELD</CODE>
2165 <DD> Move to next field.
2166 <DT> <CODE>REQ_PREV_FIELD</CODE>
2167 <DD> Move to previous field.
2168 <DT> <CODE>REQ_FIRST_FIELD</CODE>
2169 <DD> Move to the first field.
2170 <DT> <CODE>REQ_LAST_FIELD</CODE>
2171 <DD> Move to the last field.
2172 <DT> <CODE>REQ_SNEXT_FIELD</CODE>
2173 <DD> Move to sorted next field.
2174 <DT> <CODE>REQ_SPREV_FIELD</CODE>
2175 <DD> Move to sorted previous field.
2176 <DT> <CODE>REQ_SFIRST_FIELD</CODE>
2177 <DD> Move to the sorted first field.
2178 <DT> <CODE>REQ_SLAST_FIELD</CODE>
2179 <DD> Move to the sorted last field.
2180 <DT> <CODE>REQ_LEFT_FIELD</CODE>
2181 <DD> Move left to field.
2182 <DT> <CODE>REQ_RIGHT_FIELD</CODE>
2183 <DD> Move right to field.
2184 <DT> <CODE>REQ_UP_FIELD</CODE>
2185 <DD> Move up to field.
2186 <DT> <CODE>REQ_DOWN_FIELD</CODE>
2187 <DD> Move down to field.
2190 These requests treat the list of fields on a page as cyclic; that is,
2191 <CODE>REQ_NEXT_FIELD</CODE> from the last field goes to the first, and
2192 <CODE>REQ_PREV_FIELD</CODE> from the first field goes to the last. The
2193 order of the fields for these (and the <CODE>REQ_FIRST_FIELD</CODE> and
2194 <CODE>REQ_LAST_FIELD</CODE> requests) is simply the order of the field
2195 pointers in the form array (as set up by <CODE>new_form()</CODE> or
2196 <CODE>set_form_fields()</CODE> <P>
2198 It is also possible to traverse the fields as if they had been sorted in
2199 screen-position order, so the sequence goes left-to-right and top-to-bottom.
2200 To do this, use the second group of four sorted-movement requests. <P>
2202 Finally, it is possible to move between fields using visual directions up,
2203 down, right, and left. To accomplish this, use the third group of four
2204 requests. Note, however, that the position of a form for purposes of these
2205 requests is its upper-left corner. <P>
2207 For example, suppose you have a multi-line field B, and two
2208 single-line fields A and C on the same line with B, with A to the left
2209 of B and C to the right of B. A <CODE>REQ_MOVE_RIGHT</CODE> from A will
2210 go to B only if A, B, and C <EM>all</EM> share the same first line;
2211 otherwise it will skip over B to C.
2213 <H3><A NAME="#fifield">Intra-Field Navigation Requests</A></H3>
2215 These requests drive movement of the edit cursor within the currently
2219 <DT> <CODE>REQ_NEXT_CHAR</CODE>
2220 <DD> Move to next character.
2221 <DT> <CODE>REQ_PREV_CHAR</CODE>
2222 <DD> Move to previous character.
2223 <DT> <CODE>REQ_NEXT_LINE</CODE>
2224 <DD> Move to next line.
2225 <DT> <CODE>REQ_PREV_LINE</CODE>
2226 <DD> Move to previous line.
2227 <DT> <CODE>REQ_NEXT_WORD</CODE>
2228 <DD> Move to next word.
2229 <DT> <CODE>REQ_PREV_WORD</CODE>
2230 <DD> Move to previous word.
2231 <DT> <CODE>REQ_BEG_FIELD</CODE>
2232 <DD> Move to beginning of field.
2233 <DT> <CODE>REQ_END_FIELD</CODE>
2234 <DD> Move to end of field.
2235 <DT> <CODE>REQ_BEG_LINE</CODE>
2236 <DD> Move to beginning of line.
2237 <DT> <CODE>REQ_END_LINE</CODE>
2238 <DD> Move to end of line.
2239 <DT> <CODE>REQ_LEFT_CHAR</CODE>
2240 <DD> Move left in field.
2241 <DT> <CODE>REQ_RIGHT_CHAR</CODE>
2242 <DD> Move right in field.
2243 <DT> <CODE>REQ_UP_CHAR</CODE>
2244 <DD> Move up in field.
2245 <DT> <CODE>REQ_DOWN_CHAR</CODE>
2246 <DD> Move down in field.
2249 Each <EM>word</EM> is separated from the previous and next characters
2250 by whitespace. The commands to move to beginning and end of line or field
2251 look for the first or last non-pad character in their ranges.
2253 <H3><A NAME="fscroll">Scrolling Requests</A></H3>
2255 Fields that are dynamic and have grown and fields explicitly created
2256 with offscreen rows are scrollable. One-line fields scroll horizontally;
2257 multi-line fields scroll vertically. Most scrolling is triggered by
2258 editing and intra-field movement (the library scrolls the field to keep the
2259 cursor visible). It is possible to explicitly request scrolling with the
2263 <DT> <CODE>REQ_SCR_FLINE</CODE>
2264 <DD> Scroll vertically forward a line.
2265 <DT> <CODE>REQ_SCR_BLINE</CODE>
2266 <DD> Scroll vertically backward a line.
2267 <DT> <CODE>REQ_SCR_FPAGE</CODE>
2268 <DD> Scroll vertically forward a page.
2269 <DT> <CODE>REQ_SCR_BPAGE</CODE>
2270 <DD> Scroll vertically backward a page.
2271 <DT> <CODE>REQ_SCR_FHPAGE</CODE>
2272 <DD> Scroll vertically forward half a page.
2273 <DT> <CODE>REQ_SCR_BHPAGE</CODE>
2274 <DD> Scroll vertically backward half a page.
2275 <DT> <CODE>REQ_SCR_FCHAR</CODE>
2276 <DD> Scroll horizontally forward a character.
2277 <DT> <CODE>REQ_SCR_BCHAR</CODE>
2278 <DD> Scroll horizontally backward a character.
2279 <DT> <CODE>REQ_SCR_HFLINE</CODE>
2280 <DD> Scroll horizontally one field width forward.
2281 <DT> <CODE>REQ_SCR_HBLINE</CODE>
2282 <DD> Scroll horizontally one field width backward.
2283 <DT> <CODE>REQ_SCR_HFHALF</CODE>
2284 <DD> Scroll horizontally one half field width forward.
2285 <DT> <CODE>REQ_SCR_HBHALF</CODE>
2286 <DD> Scroll horizontally one half field width backward.
2289 For scrolling purposes, a <EM>page</EM> of a field is the height
2290 of its visible part.
2292 <H3><A NAME="fedit">Editing Requests</A></H3>
2294 When you pass the forms driver an ASCII character, it is treated as a
2295 request to add the character to the field's data buffer. Whether this
2296 is an insertion or a replacement depends on the field's edit mode
2297 (insertion is the default. <P>
2299 The following requests support editing the field and changing the edit
2303 <DT> <CODE>REQ_INS_MODE</CODE>
2304 <DD> Set insertion mode.
2305 <DT> <CODE>REQ_OVL_MODE</CODE>
2306 <DD> Set overlay mode.
2307 <DT> <CODE>REQ_NEW_LINE</CODE>
2308 <DD> New line request (see below for explanation).
2309 <DT> <CODE>REQ_INS_CHAR</CODE>
2310 <DD> Insert space at character location.
2311 <DT> <CODE>REQ_INS_LINE</CODE>
2312 <DD> Insert blank line at character location.
2313 <DT> <CODE>REQ_DEL_CHAR</CODE>
2314 <DD> Delete character at cursor.
2315 <DT> <CODE>REQ_DEL_PREV</CODE>
2316 <DD> Delete previous word at cursor.
2317 <DT> <CODE>REQ_DEL_LINE</CODE>
2318 <DD> Delete line at cursor.
2319 <DT> <CODE>REQ_DEL_WORD</CODE>
2320 <DD> Delete word at cursor.
2321 <DT> <CODE>REQ_CLR_EOL</CODE>
2322 <DD> Clear to end of line.
2323 <DT> <CODE>REQ_CLR_EOF</CODE>
2324 <DD> Clear to end of field.
2325 <DT> <CODE>REQ_CLEAR_FIELD</CODE>
2326 <DD> Clear entire field.
2329 The behavior of the <CODE>REQ_NEW_LINE</CODE> and <CODE>REQ_DEL_PREV</CODE> requests
2330 is complicated and partly controlled by a pair of forms options.
2331 The special cases are triggered when the cursor is at the beginning of
2332 a field, or on the last line of the field. <P>
2334 First, we consider <CODE>REQ_NEW_LINE</CODE>: <P>
2336 The normal behavior of <CODE>REQ_NEW_LINE</CODE> in insert mode is to break the
2337 current line at the position of the edit cursor, inserting the portion of
2338 the current line after the cursor as a new line following the current
2339 and moving the cursor to the beginning of that new line (you may think
2340 of this as inserting a newline in the field buffer). <P>
2342 The normal behavior of <CODE>REQ_NEW_LINE</CODE> in overlay mode is to clear the
2343 current line from the position of the edit cursor to end of line.
2344 The cursor is then moved to the beginning of the next line. <P>
2346 However, <CODE>REQ_NEW_LINE</CODE> at the beginning of a field, or on the
2347 last line of a field, instead does a <CODE>REQ_NEXT_FIELD</CODE>.
2348 <CODE>O_NL_OVERLOAD</CODE> option is off, this special action is
2351 Now, let us consider <CODE>REQ_DEL_PREV</CODE>: <P>
2353 The normal behavior of <CODE>REQ_DEL_PREV</CODE> is to delete the previous
2354 character. If insert mode is on, and the cursor is at the start of a
2355 line, and the text on that line will fit on the previous one, it
2356 instead appends the contents of the current line to the previous one
2357 and deletes the current line (you may think of this as deleting a
2358 newline from the field buffer). <P>
2360 However, <CODE>REQ_DEL_PREV</CODE> at the beginning of a field is instead
2361 treated as a <CODE>REQ_PREV_FIELD</CODE>. <P> If the
2362 <CODE>O_BS_OVERLOAD</CODE> option is off, this special action is
2363 disabled and the forms driver just returns <CODE>E_REQUEST_DENIED</CODE>. <P>
2365 See <A HREF="#frmoptions">Form Options</A> for discussion of how to set
2366 and clear the overload options.
2368 <H3><A NAME="forder">Order Requests</A></H3>
2370 If the type of your field is ordered, and has associated functions
2371 for getting the next and previous values of the type from a given value,
2372 there are requests that can fetch that value into the field buffer:
2375 <DT> <CODE>REQ_NEXT_CHOICE</CODE>
2376 <DD> Place the successor value of the current value in the buffer.
2377 <DT> <CODE>REQ_PREV_CHOICE</CODE>
2378 <DD> Place the predecessor value of the current value in the buffer.
2381 Of the built-in field types, only <CODE>TYPE_ENUM</CODE> has built-in successor
2382 and predecessor functions. When you define a field type of your own
2383 (see <A HREF="#fcustom">Custom Validation Types</A>), you can associate
2384 our own ordering functions.
2386 <H3><A NAME="fappcmds">Application Commands</A></H3>
2388 Form requests are represented as integers above the <CODE>curses</CODE> value
2389 greater than <CODE>KEY_MAX</CODE> and less than or equal to the constant
2390 <CODE>MAX_COMMAND</CODE>. If your input-virtualization routine returns a
2391 value above <CODE>MAX_COMMAND</CODE>, the forms driver will ignore it.
2393 <H2><A NAME="fhooks">Field Change Hooks</A></H2>
2395 It is possible to set function hooks to be executed whenever the
2396 current field or form changes. Here are the functions that support this:
2399 typedef void (*HOOK)(); /* pointer to function returning void */
2401 int set_form_init(FORM *form, /* form to alter */
2402 HOOK hook); /* initialization hook */
2404 HOOK form_init(FORM *form); /* form to query */
2406 int set_form_term(FORM *form, /* form to alter */
2407 HOOK hook); /* termination hook */
2409 HOOK form_term(FORM *form); /* form to query */
2411 int set_field_init(FORM *form, /* form to alter */
2412 HOOK hook); /* initialization hook */
2414 HOOK field_init(FORM *form); /* form to query */
2416 int set_field_term(FORM *form, /* form to alter */
2417 HOOK hook); /* termination hook */
2419 HOOK field_term(FORM *form); /* form to query */
2422 These functions allow you to either set or query four different hooks.
2423 In each of the set functions, the second argument should be the
2424 address of a hook function. These functions differ only in the timing
2429 <DD> This hook is called when the form is posted; also, just after
2430 each page change operation.
2432 <DD> This hook is called when the form is posted; also, just after
2435 <DD> This hook is called just after field validation; that is, just before
2436 the field is altered. It is also called when the form is unposted.
2438 <DD> This hook is called when the form is unposted; also, just before
2439 each page change operation.
2442 Calls to these hooks may be triggered
2444 <LI>When user editing requests are processed by the forms driver
2445 <LI>When the current page is changed by <CODE>set_current_field()</CODE> call
2446 <LI>When the current field is changed by a <CODE>set_form_page()</CODE> call
2449 See <A NAME="ffocus">Field Change Commands</A> for discussion of the latter
2452 You can set a default hook for all fields by passing one of the set functions
2453 a NULL first argument. <P>
2455 You can disable any of these hooks by (re)setting them to NULL, the default
2458 <H2><A HREF="#ffocus">Field Change Commands</A></H2>
2460 Normally, navigation through the form will be driven by the user's
2461 input requests. But sometimes it is useful to be able to move the
2462 focus for editing and viewing under control of your application, or
2463 ask which field it currently is in. The following functions help you
2467 int set_current_field(FORM *form, /* form to alter */
2468 FIELD *field); /* field to shift to */
2470 FIELD *current_field(FORM *form); /* form to query */
2472 int field_index(FORM *form, /* form to query */
2473 FIELD *field); /* field to get index of */
2476 The function <CODE>field_index()</CODE> returns the index of the given field
2477 in the given form's field array (the array passed to <CODE>new_form()</CODE> or
2478 <CODE>set_form_fields()</CODE>). <P>
2480 The initial current field of a form is the first active field on the
2481 first page. The function <CODE>set_form_fields()</CODE> resets this.<P>
2483 It is also possible to move around by pages.
2486 int set_form_page(FORM *form, /* form to alter */
2487 int page); /* page to go to (0-origin) */
2489 int form_page(FORM *form); /* return form's current page */
2492 The initial page of a newly-created form is 0. The function
2493 <CODE>set_form_fields()</CODE> resets this.
2495 <H2><A NAME="frmoptions">Form Options</A></H2>
2497 Like fields, forms may have control option bits. They can be changed
2498 or queried with these functions:
2501 int set_form_opts(FORM *form, /* form to alter */
2502 int attr); /* attribute to set */
2504 int form_opts_on(FORM *form, /* form to alter */
2505 int attr); /* attributes to turn on */
2507 int form_opts_off(FORM *form, /* form to alter */
2508 int attr); /* attributes to turn off */
2510 int form_opts(FORM *form); /* form to query */
2513 By default, all options are on. Here are the available option bits:
2517 <DD> Enable overloading of <CODE>REQ_NEW_LINE</CODE> as described in <A
2518 NAME="fedit">Editing Requests</A>. The value of this option is
2519 ignored on dynamic fields that have not reached their size limit;
2520 these have no last line, so the circumstances for triggering a
2521 <CODE>REQ_NEXT_FIELD</CODE> never arise.
2523 <DD> Enable overloading of <CODE>REQ_DEL_PREV</CODE> as described in
2524 <A NAME="fedit">Editing Requests</A>.
2527 The option values are bit-masks and can be composed with logical-or in
2530 <H2><A NAME="fcustom">Custom Validation Types</A></H2>
2532 The <CODE>form</CODE> library gives you the capability to define custom
2533 validation types of your own. Further, the optional additional arguments
2534 of <CODE>set_field_type</CODE> effectively allow you to parameterize validation
2535 types. Most of the complications in the validation-type interface have to
2536 do with the handling of the additional arguments within custom validation
2539 <H3><A NAME="flinktypes">Union Types</A></H3>
2541 The simplest way to create a custom data type is to compose it from two
2545 FIELD *link_fieldtype(FIELDTYPE *type1,
2549 This function creates a field type that will accept any of the values
2550 legal for either of its argument field types (which may be either
2551 predefined or programmer-defined).
2553 If a <CODE>set_field_type()</CODE> call later requires arguments, the new
2554 composite type expects all arguments for the first type, than all arguments
2555 for the second. Order functions (see <A HREF="#forder">Order Requests</A>)
2556 associated with the component types will work on the composite; what it does
2557 is check the validation function for the first type, then for the second, to
2558 figure what type the buffer contents should be treated as.
2560 <H3><A NAME="fnewtypes">New Field Types</A></H3>
2562 To create a field type from scratch, you need to specify one or both of the
2566 <LI>A character-validation function, to check each character as it is entered.
2567 <LI>A field-validation function to be applied on exit from the field.
2570 Here's how you do that:
2572 typedef int (*HOOK)(); /* pointer to function returning int */
2574 FIELDTYPE *new_fieldtype(HOOK f_validate, /* field validator */
2575 HOOK c_validate) /* character validator */
2578 int free_fieldtype(FIELDTYPE *ftype); /* type to free */
2581 At least one of the arguments of <CODE>new_fieldtype()</CODE> must be
2582 non-NULL. The forms driver will automatically call the new type's
2583 validation functions at appropriate points in processing a field of
2586 The function <CODE>free_fieldtype()</CODE> deallocates the argument
2587 fieldtype, freeing all storage associated with it. <P>
2589 Normally, a field validator is called when the user attempts to
2590 leave the field. Its first argument is a field pointer, from which it
2591 can get to field buffer 0 and test it. If the function returns TRUE,
2592 the operation succeeds; if it returns FALSE, the edit cursor stays in
2595 A character validator gets the character passed in as a first argument.
2596 It too should return TRUE if the character is valid, FALSE otherwise.
2598 <H3><A NAME="fcheckargs">Validation Function Arguments</A></H3>
2600 Your field- and character- validation functions will be passed a
2601 second argument as well. This second argument is the address of a
2602 structure (which we'll call a <EM>pile</EM>) built from any of the
2603 field-type-specific arguments passed to <CODE>set_field_type()</CODE>. If
2604 no such arguments are defined for the field type, this pile pointer
2605 argument will be NULL. <P>
2607 In order to arrange for such arguments to be passed to your validation
2608 functions, you must associate a small set of storage-management functions
2609 with the type. The forms driver will use these to synthesize a pile
2610 from the trailing arguments of each <CODE>set_field_type()</CODE> argument, and
2611 a pointer to the pile will be passed to the validation functions. <P>
2613 Here is how you make the association:
2616 typedef char *(*PTRHOOK)(); /* pointer to function returning (char *) */
2617 typedef void (*VOIDHOOK)(); /* pointer to function returning void */
2619 int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */
2620 PTRHOOK make_str, /* make structure from args */
2621 PTRHOOK copy_str, /* make copy of structure */
2622 VOIDHOOK free_str); /* free structure storage */
2625 Here is how the storage-management hooks are used:
2628 <DT> <CODE>make_str</CODE>
2629 <DD> This function is called by <CODE>set_field_type()</CODE>. It gets one
2630 argument, a <CODE>va_list</CODE> of the type-specific arguments passed to
2631 <CODE>set_field_type()</CODE>. It is expected to return a pile pointer to a data
2632 structure that encapsulates those arguments.
2633 <DT> <CODE>copy_str</CODE>
2634 <DD> This function is called by form library functions that allocate new
2635 field instances. It is expected to take a pile pointer, copy the pile
2636 to allocated storage, and return the address of the pile copy.
2637 <DT> <CODE>free_str</CODE>
2638 <DD> This function is called by field- and type-deallocation routines in the
2639 library. It takes a pile pointer argument, and is expected to free the
2640 storage of that pile.
2643 The <CODE>make_str</CODE> and <CODE>copy_str</CODE> functions may return NULL to
2644 signal allocation failure. The library routines will that call them will
2645 return error indication when this happens. Thus, your validation functions
2646 should never see a NULL file pointer and need not check specially for it.
2648 <H3><A NAME="fcustorder">Order Functions For Custom Types</A></H3>
2650 Some custom field types are simply ordered in the same well-defined way
2651 that <CODE>TYPE_ENUM</CODE> is. For such types, it is possible to define
2652 successor and predecessor functions to support the <CODE>REQ_NEXT_CHOICE</CODE>
2653 and <CODE>REQ_PREV_CHOICE</CODE> requests. Here's how:
2656 typedef int (*INTHOOK)(); /* pointer to function returning int */
2658 int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */
2659 INTHOOK succ, /* get successor value */
2660 INTHOOK pred); /* get predecessor value */
2663 The successor and predecessor arguments will each be passed two arguments;
2664 a field pointer, and a pile pointer (as for the validation functions). They
2665 are expected to use the function <CODE>field_buffer()</CODE> to read the
2666 current value, and <CODE>set_field_buffer()</CODE> on buffer 0 to set the next
2667 or previous value. Either hook may return TRUE to indicate success (a
2668 legal next or previous value was set) or FALSE to indicate failure.
2670 <H3><A NAME="fcustprobs">Avoiding Problems</A></H3>
2672 The interface for defining custom types is complicated and tricky.
2673 Rather than attempting to create a custom type entirely from scratch,
2674 you should start by studying the library source code for whichever of
2675 the pre-defined types seems to be closest to what you want. <P>
2677 Use that code as a model, and evolve it towards what you really want.
2678 You will avoid many problems and annoyances that way. The code
2679 in the <CODE>ncurses</CODE> library has been specifically exempted from
2680 the package copyright to support this. <P>
2682 If your custom type defines order functions, have do something intuitive
2683 with a blank field. A useful convention is to make the successor of a
2684 blank field the types minimum value, and its predecessor the maximum.
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