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31 .\" $Id: curs_util.3x,v 1.67 2023/03/11 20:28:02 tom Exp $
32 .TH curs_util 3X 2023-03-11 "ncurses 6.4" "Library calls"
55 \fBwunctrl\fP \- miscellaneous \fBcurses\fP utility routines
59 \fB#include <curses.h>\fP
61 \fBconst char *unctrl(chtype \fIc\fB);\fR
63 \fBwchar_t *wunctrl(cchar_t *\fIc\fB);\fR
65 \fBconst char *keyname(int \fIc\fB);\fR
67 \fBconst char *key_name(wchar_t \fIw\fB);\fR
69 \fBvoid filter(void);\fP
71 \fBvoid nofilter(void);\fP
73 \fBvoid use_env(bool \fIf\fB);\fR
75 \fBvoid use_tioctl(bool \fIf\fB);\fR
77 \fBint putwin(WINDOW *\fIwin\fB, FILE *\fIfilep\fB);\fR
79 \fBWINDOW *getwin(FILE *\fIfilep\fB);\fR
81 \fBint delay_output(int \fIms\fB);\fR
83 \fBint flushinp(void);\fP
88 The \fBunctrl\fP routine returns a character string which is a printable
89 representation of the character \fIc\fP, ignoring attributes.
90 Control characters are displayed in the \fB^\fIX\fR notation.
91 Printing characters are displayed as is.
93 The corresponding \fBwunctrl\fP returns a printable representation of
97 The \fBkeyname\fP routine returns a character string
98 corresponding to the key \fIc\fP:
100 Printable characters are displayed as themselves,
101 e.g., a one-character string containing the key.
103 Control characters are displayed in the \fB^\fIX\fR notation.
105 DEL (character 127) is displayed as \fB^?\fP.
107 Values above 128 are either meta characters
108 (if the screen has not been initialized,
109 or if \fBmeta\fP(3X) has been called with a \fBTRUE\fP parameter),
110 shown in the \fBM\-\fIX\fR notation,
111 or are displayed as themselves.
112 In the latter case, the values may not be printable;
113 this follows the X/Open specification.
115 Values above 256 may be the names of the names of function keys.
117 Otherwise (if there is no corresponding name) the function returns null,
119 X/Open also lists an \*(``UNKNOWN KEY\*('' return value,
120 which some implementations return rather than null.
122 The corresponding \fBkey_name\fP returns a character string corresponding
123 to the wide-character value \fIw\fP.
124 The two functions do not return the same set of strings;
125 the latter returns null where the former would display a meta character.
128 The \fBfilter\fP routine, if used, must be called before \fBinitscr\fP or
129 \fBnewterm\fP are called.
130 Calling \fBfilter\fP causes these changes in initialization:
132 \fBLINES\fP is set to 1;
144 the capability \fBed\fP is disabled if \fBbce\fP is set;
146 and the \fBhome\fP string is set to the value of \fBcr\fP.
148 The \fBnofilter\fP routine cancels the effect of a preceding \fBfilter\fP
150 That allows the caller to initialize a screen on a different device,
151 using a different value of \fB$TERM\fP.
152 The limitation arises because the \fBfilter\fP routine modifies the
153 in-memory copy of the terminal information.
156 The \fBuse_env\fP routine, if used,
157 should be called before \fBinitscr\fP or
158 \fBnewterm\fP are called
159 (because those compute the screen size).
160 It modifies the way \fBncurses\fP treats environment variables
161 when determining the screen size.
163 Normally \fBncurses\fP looks first at the terminal database for the screen size.
165 If \fBuse_env\fP was called with \fBFALSE\fP for parameter,
167 \fBuse_tioctl\fP was also called with \fBTRUE\fP for parameter.
169 Then it asks for the screen size via operating system calls.
171 it overrides the values from the terminal database.
173 Finally (unless \fBuse_env\fP was called with \fBFALSE\fP parameter),
174 \fBncurses\fP examines the \fBLINES\fP or \fBCOLUMNS\fP environment variables,
175 using a value in those to override the results
176 from the operating system or terminal database.
178 \fBNcurses\fP also updates the screen size in response to \fBSIGWINCH\fP,
179 unless overridden by the \fBLINES\fP or \fBCOLUMNS\fP environment variables,
182 The \fBuse_tioctl\fP routine, if used,
183 should be called before \fBinitscr\fP or \fBnewterm\fP are called
184 (because those compute the screen size).
185 After \fBuse_tioctl\fP is called with \fBTRUE\fP as an argument,
186 \fBncurses\fP modifies the last step in its computation
187 of screen size as follows:
189 checks if the \fBLINES\fP and \fBCOLUMNS\fP environment variables
190 are set to a number greater than zero.
192 for each, \fBncurses\fP updates the corresponding environment variable
193 with the value that it has obtained via operating system call
194 or from the terminal database.
196 \fBncurses\fP re-fetches the value of the environment variables so that
197 it is still the environment variables which set the screen size.
199 The \fBuse_env\fP and \fBuse_tioctl\fP routines combine as
206 \fBuse_env\fP/\fBuse_tioctl\fP/\fBSummary\fP
208 This is the default behavior.
209 \fBncurses\fP uses operating system calls
210 unless overridden by $LINES or $COLUMNS environment variables.
213 \fBncurses\fP updates $LINES and $COLUMNS based on operating system calls.
216 \fBncurses\fP ignores $LINES and $COLUMNS,
217 uses operating system calls to obtain size.
220 \fBncurses\fP relies on the terminal database to determine size.
225 The \fBputwin\fP routine writes all data associated
226 with window (or pad) \fIwin\fP into
227 the file to which \fIfilep\fP points.
228 This information can be later retrieved
229 using the \fBgetwin\fP function.
231 The \fBgetwin\fP routine reads window related data stored in the file by
233 The routine then creates and initializes a new window using that
235 It returns a pointer to the new window.
236 There are a few caveats:
238 the data written is a copy of the \fBWINDOW\fP structure,
239 and its associated character cells.
240 The format differs between the wide-character (\fBncursesw\fP) and
241 non-wide (\fBncurses\fP) libraries.
242 You can transfer data between the two, however.
244 the retrieved window is always created as a top-level window (or pad),
245 rather than a subwindow.
247 the window's character cells contain the color pair \fIvalue\fP,
248 but not the actual color \fInumbers\fP.
249 If cells in the retrieved window use color pairs which have not been
250 created in the application using \fBinit_pair\fP,
251 they will not be colored when the window is refreshed.
254 The \fBdelay_output\fP routine inserts an \fIms\fP millisecond pause
256 This routine should not be used extensively because
257 padding characters are used rather than a CPU pause.
258 If no padding character is specified,
259 this uses \fBnapms\fP to perform the delay.
262 The \fBflushinp\fP routine throws away any typeahead that has been typed by the
263 user and has not yet been read by the program.
265 Except for \fBflushinp\fP, routines that return an integer return \fBERR\fP
266 upon failure and \fBOK\fP (SVr4 specifies only "an integer value other than
267 \fBERR\fP") upon successful completion.
269 Routines that return pointers return \fBNULL\fP on error.
271 X/Open does not define any error conditions.
272 In this implementation
276 returns an error if the terminal was not initialized.
279 returns an error if the associated \fBfwrite\fP calls return an error.
284 The SVr4 documentation describes the action of \fBfilter\fP only in the vaguest
286 The description here is adapted from the XSI Curses standard (which
287 erroneously fails to describe the disabling of \fBcuu\fP).
290 The \fBkeyname\fP function may return the names of user-defined
291 string capabilities which are defined in the terminfo entry via the \fB\-x\fP
292 option of \fB@TIC@\fP.
293 This implementation automatically assigns at run-time keycodes to
294 user-defined strings which begin with \*(``k\*(''.
295 The keycodes start at KEY_MAX, but are not guaranteed to be
296 the same value for different runs because user-defined codes are
297 merged from all terminal descriptions which have been loaded.
298 The \fBuse_extended_names\fP(3X) function controls whether this data is
299 loaded when the terminal description is read by the library.
300 .SS nofilter/use_tioctl
302 The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to \fBncurses\fP.
303 They were not supported on Version 7, BSD or System V implementations.
304 It is recommended that any code depending on \fBncurses\fP extensions
305 be conditioned using NCURSES_VERSION.
306 .SS putwin/getwin file-format
308 The \fBputwin\fP and \fBgetwin\fP functions have several issues with
311 The files written and read by these functions
312 use an implementation-specific format.
313 Although the format is an obvious target for standardization,
314 it has been overlooked.
316 Interestingly enough, according to the copyright dates in Solaris source,
317 the functions (along with \fBscr_init\fP, etc.) originated with
318 the University of California, Berkeley (in 1982)
319 and were later (in 1988) incorporated into SVr4.
320 Oddly, there are no such functions in the 4.3BSD curses sources.
322 Most implementations simply dump the binary \fBWINDOW\fP structure to the file.
323 These include SVr4 curses, NetBSD and PDCurses,
324 as well as older \fBncurses\fP versions.
326 (as well as the X/Open variant of Solaris curses, dated 1995)
329 The implementations which use binary dumps use block-I/O
330 (the \fBfwrite\fP and \fBfread\fP functions).
331 Those that use textual dumps use buffered-I/O.
332 A few applications may happen to write extra data in the file using
334 Doing that can run into problems mixing block- and buffered-I/O.
335 This implementation reduces the problem on writes by flushing the output.
336 However, reading from a file written using mixed schemes may not be successful.
339 The XSI Curses standard, Issue 4 describes these functions.
340 It states that \fBunctrl\fP and \fBwunctrl\fP will return a null pointer if
341 unsuccessful, but does not define any error conditions.
342 This implementation checks for three cases:
344 the parameter is a 7-bit US\-ASCII code.
345 This is the case that X/Open Curses documented.
347 the parameter is in the range 128\-159, i.e., a C1 control code.
348 If \fBuse_legacy_coding\fP(3X) has been called with a \fB2\fP parameter,
349 \fBunctrl\fP returns the parameter, i.e., a one-character string with
350 the parameter as the first character.
351 Otherwise, it returns \*(``~@\*('', \*(``~A\*('', etc.,
352 analogous to \*(``^@\*('', \*(``^A\*('', C0 controls.
354 X/Open Curses does not document whether \fBunctrl\fP can be called before
356 This implementation permits that,
357 and returns the \*(``~@\*('', etc., values in that case.
359 parameter values outside the 0 to 255 range.
360 \fBunctrl\fP returns a null pointer.
362 The strings returned by \fBunctrl\fP in this implementation are determined
364 showing C1 controls from the upper-128 codes
365 with a \*(``~\*('' prefix rather than \*(``^\*(''.
366 Other implementations have different conventions.
367 For example, they may show both sets of control characters with \*(``^\*('',
368 and strip the parameter to 7 bits.
369 Or they may ignore C1 controls and treat all of the upper-128 codes as
371 This implementation uses 8 bits but does not modify the string to reflect
373 The \fBuse_legacy_coding\fP(3X) function allows the caller to
374 change the output of \fBunctrl\fP.
376 Likewise, the \fBmeta\fP(3X) function allows the caller to change the
377 output of \fBkeyname\fP, i.e.,
378 it determines whether to use the \*(``M\-\*('' prefix
379 for \*(``meta\*('' keys (codes in the range 128 to 255).
380 Both \fBuse_legacy_coding\fP(3X) and \fBmeta\fP(3X) succeed only after
381 curses is initialized.
382 X/Open Curses does not document the treatment of codes 128 to 159.
383 When treating them as \*(``meta\*('' keys
384 (or if \fBkeyname\fP is called before initializing curses),
385 this implementation returns strings \*(``M\-^@\*('', \*(``M\-^A\*('', etc.
387 X/Open Curses documents \fBunctrl\fP as declared in \fB<unctrl.h>\fP,
388 which \fBncurses\fP does.
389 However, \fBncurses\fP' \fB<curses.h>\fP includes \fB<unctrl.h>\fP,
390 matching the behavior of SVr4 curses.
391 Other implementations may not do that.
392 .SS use_env/use_tioctl
394 If \fBncurses\fP is configured to provide the sp-functions extension,
395 the state of \fBuse_env\fP and \fBuse_tioctl\fP may be updated before
396 creating each \fIscreen\fP rather than once only
397 (\fBcurs_sp_funcs\fP(3X)).
398 This feature of \fBuse_env\fP
399 is not provided by other implementation of curses.
402 \fBcurs_initscr\fP(3X),
403 \fBcurs_inopts\fP(3X),
404 \fBcurs_kernel\fP(3X),
405 \fBcurs_scr_dump\fP(3X),
406 \fBcurs_sp_funcs\fP(3X),
407 \fBcurs_variables\fP(3X),
408 \fBlegacy_coding\fP(3X).