1curs_util(3X) curs_util(3X)
2
6 delay_output, filter, flushinp, getwin, key_name, keyname, nofilter,
7 putwin, unctrl, use_env, use_tioctl, wunctrl - miscellaneous curses
8 utility routines
9
11 #include <curses.h>
12 const char *unctrl(chtype c);
14 wchar_t *wunctrl(cchar_t *c);
15 const char *keyname(int c);
17 const char *key_name(wchar_t w);
18 void filter(void);
20 void nofilter(void);
21 void use_env(bool f);
23 void use_tioctl(bool f);
24 int putwin(WINDOW *win, FILE *filep);
26 WINDOW *getwin(FILE *filep);
27 int delay_output(int ms);
29 int flushinp(void);
30
32 unctrl
33 The unctrl routine returns a character string which is a printable rep‐
34 resentation of the character c, ignoring attributes. Control charac‐
35 ters are displayed in the ^X notation. Printing characters are dis‐
36 played as is.
37 The corresponding wunctrl returns a printable representation of a wide
39 character.
40 keyname/key_name
42 The keyname routine returns a character string corresponding to the key
43 c:
44 • Printable characters are displayed as themselves, e.g., a one-char‐
46 acter string containing the key.
47 • Control characters are displayed in the ^X notation.
49 • DEL (character 127) is displayed as ^?.
51 • Values above 128 are either meta characters (if the screen has not
53 been initialized, or if meta(3X) has been called with a TRUE param‐
54 eter), shown in the M-X notation, or are displayed as themselves.
55 In the latter case, the values may not be printable; this follows
56 the X/Open specification.
57 • Values above 256 may be the names of the names of function keys.
59 • Otherwise (if there is no corresponding name) the function returns
61 null, to denote an error. X/Open also lists an “UNKNOWN KEY” re‐
62 turn value, which some implementations return rather than null.
63 The corresponding key_name returns a character string corresponding to
65 the wide-character value w. The two functions do not return the same
66 set of strings; the latter returns null where the former would display
67 a meta character.
68 filter/nofilter
70 The filter routine, if used, must be called before initscr or newterm
71 are called. Calling filter causes these changes in initialization:
72 • LINES is set to 1;
74 • the capabilities clear, cud1, cud, cup, cuu1, cuu, vpa are dis‐
76 abled;
77 • the capability ed is disabled if bce is set;
79 • and the home string is set to the value of cr.
81 The nofilter routine cancels the effect of a preceding filter call.
83 That allows the caller to initialize a screen on a different device,
84 using a different value of $TERM. The limitation arises because the
85 filter routine modifies the in-memory copy of the terminal information.
86 use_env
88 The use_env routine, if used, should be called before initscr or
89 newterm are called (because those compute the screen size). It modi‐
90 fies the way ncurses treats environment variables when determining the
91 screen size.
92 • Normally ncurses looks first at the terminal database for the
94 screen size.
95 If use_env was called with FALSE for parameter, it stops here un‐
97 less use_tioctl was also called with TRUE for parameter.
98 • Then it asks for the screen size via operating system calls. If
100 successful, it overrides the values from the terminal database.
101 • Finally (unless use_env was called with FALSE parameter), ncurses
103 examines the LINES or COLUMNS environment variables, using a value
104 in those to override the results from the operating system or ter‐
105 minal database.
106 Ncurses also updates the screen size in response to SIGWINCH, un‐
108 less overridden by the LINES or COLUMNS environment variables,
109 use_tioctl
111 The use_tioctl routine, if used, should be called before initscr or
112 newterm are called (because those compute the screen size). After
113 use_tioctl is called with TRUE as an argument, ncurses modifies the
114 last step in its computation of screen size as follows:
115 • checks if the LINES and COLUMNS environment variables are set to a
117 number greater than zero.
118 • for each, ncurses updates the corresponding environment variable
120 with the value that it has obtained via operating system call or
121 from the terminal database.
122 • ncurses re-fetches the value of the environment variables so that
124 it is still the environment variables which set the screen size.
125 The use_env and use_tioctl routines combine as summarized here:
127 use_env use_tioctl Summary
129 ────────────────────────────────────────────────────────────────
130 TRUE FALSE This is the default behavior. ncurses
134 uses operating system calls unless over‐
135 ridden by $LINES or $COLUMNS environment
136 variables.
137 TRUE TRUE ncurses updates $LINES and $COLUMNS
138 based on operating system calls.
139 FALSE TRUE ncurses ignores $LINES and $COLUMNS, us‐
140 es operating system calls to obtain
141 size.
142 FALSE FALSE ncurses relies on the terminal database
143 to determine size.
144 putwin/getwin
146 The putwin routine writes all data associated with window (or pad) win
147 into the file to which filep points. This information can be later re‐
148 trieved using the getwin function.
149 The getwin routine reads window related data stored in the file by
151 putwin. The routine then creates and initializes a new window using
152 that data. It returns a pointer to the new window. There are a few
153 caveats:
154 • the data written is a copy of the WINDOW structure, and its associ‐
156 ated character cells. The format differs between the wide-charac‐
157 ter (ncursesw) and non-wide (ncurses) libraries. You can transfer
158 data between the two, however.
159 • the retrieved window is always created as a top-level window (or
161 pad), rather than a subwindow.
162 • the window's character cells contain the color pair value, but not
164 the actual color numbers. If cells in the retrieved window use
165 color pairs which have not been created in the application using
166 init_pair, they will not be colored when the window is refreshed.
167 delay_output
169 The delay_output routine inserts an ms millisecond pause in output.
170 This routine should not be used extensively because padding characters
171 are used rather than a CPU pause. If no padding character is speci‐
172 fied, this uses napms to perform the delay.
173 flushinp
175 The flushinp routine throws away any typeahead that has been typed by
176 the user and has not yet been read by the program.
177
179 Except for flushinp, routines that return an integer return ERR upon
180 failure and OK (SVr4 specifies only "an integer value other than ERR")
181 upon successful completion.
182 Routines that return pointers return NULL on error.
184 X/Open does not define any error conditions. In this implementation
186 flushinp
188 returns an error if the terminal was not initialized.
189 putwin
191 returns an error if the associated fwrite calls return an er‐
192 ror.
193
195 filter
196 The SVr4 documentation describes the action of filter only in the
197 vaguest terms. The description here is adapted from the XSI Curses
198 standard (which erroneously fails to describe the disabling of cuu).
199 keyname
201 The keyname function may return the names of user-defined string capa‐
202 bilities which are defined in the terminfo entry via the -x option of
203 tic. This implementation automatically assigns at run-time keycodes to
204 user-defined strings which begin with “k”. The keycodes start at
205 KEY_MAX, but are not guaranteed to be the same value for different runs
206 because user-defined codes are merged from all terminal descriptions
207 which have been loaded. The use_extended_names(3X) function controls
208 whether this data is loaded when the terminal description is read by
209 the library.
210 nofilter/use_tioctl
212 The nofilter and use_tioctl routines are specific to ncurses. They
213 were not supported on Version 7, BSD or System V implementations. It
214 is recommended that any code depending on ncurses extensions be condi‐
215 tioned using NCURSES_VERSION.
216 putwin/getwin file-format
218 The putwin and getwin functions have several issues with portability:
219 • The files written and read by these functions use an implementa‐
221 tion-specific format. Although the format is an obvious target for
222 standardization, it has been overlooked.
223 Interestingly enough, according to the copyright dates in Solaris
225 source, the functions (along with scr_init, etc.) originated with
226 the University of California, Berkeley (in 1982) and were later (in
227 1988) incorporated into SVr4. Oddly, there are no such functions
228 in the 4.3BSD curses sources.
229 • Most implementations simply dump the binary WINDOW structure to the
231 file. These include SVr4 curses, NetBSD and PDCurses, as well as
232 older ncurses versions. This implementation (as well as the X/Open
233 variant of Solaris curses, dated 1995) uses textual dumps.
234 The implementations which use binary dumps use block-I/O (the
236 fwrite and fread functions). Those that use textual dumps use
237 buffered-I/O. A few applications may happen to write extra data in
238 the file using these functions. Doing that can run into problems
239 mixing block- and buffered-I/O. This implementation reduces the
240 problem on writes by flushing the output. However, reading from a
241 file written using mixed schemes may not be successful.
242 unctrl/wunctrl
244 The XSI Curses standard, Issue 4 describes these functions. It states
245 that unctrl and wunctrl will return a null pointer if unsuccessful, but
246 does not define any error conditions. This implementation checks for
247 three cases:
248 • the parameter is a 7-bit US-ASCII code. This is the case that
250 X/Open Curses documented.
251 • the parameter is in the range 128-159, i.e., a C1 control code. If
253 use_legacy_coding(3X) has been called with a 2 parameter, unctrl
254 returns the parameter, i.e., a one-character string with the param‐
255 eter as the first character. Otherwise, it returns “~@”, “~A”,
256 etc., analogous to “^@”, “^A”, C0 controls.
257 X/Open Curses does not document whether unctrl can be called before
259 initializing curses. This implementation permits that, and returns
260 the “~@”, etc., values in that case.
261 • parameter values outside the 0 to 255 range. unctrl returns a null
263 pointer.
264 The strings returned by unctrl in this implementation are determined at
266 compile time, showing C1 controls from the upper-128 codes with a “~”
267 prefix rather than “^”. Other implementations have different conven‐
268 tions. For example, they may show both sets of control characters with
269 “^”, and strip the parameter to 7 bits. Or they may ignore C1 controls
270 and treat all of the upper-128 codes as printable. This implementation
271 uses 8 bits but does not modify the string to reflect locale. The
272 use_legacy_coding(3X) function allows the caller to change the output
273 of unctrl.
274 Likewise, the meta(3X) function allows the caller to change the output
276 of keyname, i.e., it determines whether to use the “M-” prefix for
277 “meta” keys (codes in the range 128 to 255). Both use_legacy_cod‐
278 ing(3X) and meta(3X) succeed only after curses is initialized. X/Open
279 Curses does not document the treatment of codes 128 to 159. When
280 treating them as “meta” keys (or if keyname is called before initializ‐
281 ing curses), this implementation returns strings “M-^@”, “M-^A”, etc.
282 X/Open Curses documents unctrl as declared in <unctrl.h>, which ncurses
284 does. However, ncurses' <curses.h> includes <unctrl.h>, matching the
285 behavior of SVr4 curses. Other implementations may not do that.
286 use_env/use_tioctl
288 If ncurses is configured to provide the sp-functions extension, the
289 state of use_env and use_tioctl may be updated before creating each
290 screen rather than once only (curs_sp_funcs(3X)). This feature of
291 use_env is not provided by other implementation of curses.
292
294 curses(3X), curs_initscr(3X), curs_inopts(3X), curs_kernel(3X),
295 curs_scr_dump(3X), curs_sp_funcs(3X), curs_variables(3X), legacy_cod‐
296 ing(3X).
297 curs_util(3X)