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);
16 const char *key_name(wchar_t w);
17 void filter(void);
18 void nofilter(void);
19 void use_env(bool f);
20 void use_tioctl(bool f);
21 int putwin(WINDOW *win, FILE *filep);
22 WINDOW *getwin(FILE *filep);
23 int delay_output(int ms);
24 int flushinp(void);
25
27 unctrl
28 The unctrl routine returns a character string which is a printable rep‐
29 resentation of the character c, ignoring attributes. Control charac‐
30 ters are displayed in the ^X notation. Printing characters are dis‐
31 played as is. The corresponding wunctrl returns a printable represen‐
32 tation of a wide character.
33 keyname/key_name
35 The keyname routine returns a character string corresponding to the key
36 c:
37 · Printable characters are displayed as themselves, e.g., a one-char‐
39 acter string containing the key.
40 · Control characters are displayed in the ^X notation.
42 · DEL (character 127) is displayed as ^?.
44 · Values above 128 are either meta characters (if the screen has not
46 been initialized, or if meta(3X) has been called with a TRUE param‐
47 eter), shown in the M-X notation, or are displayed as themselves.
48 In the latter case, the values may not be printable; this follows
49 the X/Open specification.
50 · Values above 256 may be the names of the names of function keys.
52 · Otherwise (if there is no corresponding name) the function returns
54 null, to denote an error. X/Open also lists an “UNKNOWN KEY” re‐
55 turn value, which some implementations return rather than null.
56 The corresponding key_name returns a character string corresponding to
58 the wide-character value w. The two functions do not return the same
59 set of strings; the latter returns null where the former would display
60 a meta character.
61 filter/nofilter
63 The filter routine, if used, must be called before initscr or newterm
64 are called. Calling filter causes these changes in initialization:
65 · LINES is set to 1;
67 · the capabilities clear, cud1, cud, cup, cuu1, cuu, vpa are dis‐
69 abled;
70 · the capability ed is disabled if bce is set;
72 · and the home string is set to the value of cr.
74 The nofilter routine cancels the effect of a preceding filter call.
76 That allows the caller to initialize a screen on a different device,
77 using a different value of $TERM. The limitation arises because the
78 filter routine modifies the in-memory copy of the terminal information.
79 use_env
81 The use_env routine, if used, should be called before initscr or
82 newterm are called (because those compute the screen size). It modi‐
83 fies the way ncurses treats environment variables when determining the
84 screen size.
85 · Normally ncurses looks first at the terminal database for the
87 screen size.
88 If use_env was called with FALSE for parameter, it stops here un‐
90 less use_tioctl was also called with TRUE for parameter.
91 · Then it asks for the screen size via operating system calls. If
93 successful, it overrides the values from the terminal database.
94 · Finally (unless use_env was called with FALSE parameter), ncurses
96 examines the LINES or COLUMNS environment variables, using a value
97 in those to override the results from the operating system or ter‐
98 minal database.
99 Ncurses also updates the screen size in response to SIGWINCH, un‐
101 less overridden by the LINES or COLUMNS environment variables,
102 use_tioctl
104 The use_tioctl routine, if used, should be called before initscr or
105 newterm are called (because those compute the screen size). After
106 use_tioctl is called with TRUE as an argument, ncurses modifies the
107 last step in its computation of screen size as follows:
108 · checks if the LINES and COLUMNS environment variables are set to a
110 number greater than zero.
111 · for each, ncurses updates the corresponding environment variable
113 with the value that it has obtained via operating system call or
114 from the terminal database.
115 · ncurses re-fetches the value of the environment variables so that
117 it is still the environment variables which set the screen size.
118 The use_env and use_tioctl routines combine as summarized here:
120 use_env use_tioctl Summary
122 ────────────────────────────────────────────────────────────────
123 TRUE FALSE This is the default behavior. ncurses
124 uses operating system calls unless over‐
125 ridden by $LINES or $COLUMNS environment
126 variables.
127 TRUE TRUE ncurses updates $LINES and $COLUMNS
128 based on operating system calls.
129 FALSE TRUE ncurses ignores $LINES and $COLUMNS, us‐
130 es operating system calls to obtain
131 size.
132 FALSE FALSE ncurses relies on the terminal database
133 to determine size.
134 putwin/getwin
136 The putwin routine writes all data associated with window (or pad) win
137 into the file to which filep points. This information can be later re‐
138 trieved using the getwin function.
139 The getwin routine reads window related data stored in the file by
141 putwin. The routine then creates and initializes a new window using
142 that data. It returns a pointer to the new window. There are a few
143 caveats:
144 · the data written is a copy of the WINDOW structure, and its associ‐
146 ated character cells. The format differs between the wide-charac‐
147 ter (ncursesw) and non-wide (ncurses) libraries. You can transfer
148 data between the two, however.
149 · the retrieved window is always created as a top-level window (or
151 pad), rather than a subwindow.
152 · the window's character cells contain the color pair value, but not
154 the actual color numbers. If cells in the retrieved window use
155 color pairs which have not been created in the application using
156 init_pair, they will not be colored when the window is refreshed.
157 delay_output
159 The delay_output routine inserts an ms millisecond pause in output.
160 This routine should not be used extensively because padding characters
161 are used rather than a CPU pause. If no padding character is speci‐
162 fied, this uses napms to perform the delay.
163 flushinp
165 The flushinp routine throws away any typeahead that has been typed by
166 the user and has not yet been read by the program.
167
169 Except for flushinp, routines that return an integer return ERR upon
170 failure and OK (SVr4 specifies only "an integer value other than ERR")
171 upon successful completion.
172 Routines that return pointers return NULL on error.
174 X/Open does not define any error conditions. In this implementation
176 flushinp
178 returns an error if the terminal was not initialized.
179 putwin
181 returns an error if the associated fwrite calls return an er‐
182 ror.
183
185 filter
186 The SVr4 documentation describes the action of filter only in the
187 vaguest terms. The description here is adapted from the XSI Curses
188 standard (which erroneously fails to describe the disabling of cuu).
189 keyname
191 The keyname function may return the names of user-defined string capa‐
192 bilities which are defined in the terminfo entry via the -x option of
193 tic. This implementation automatically assigns at run-time keycodes to
194 user-defined strings which begin with “k”. The keycodes start at
195 KEY_MAX, but are not guaranteed to be the same value for different runs
196 because user-defined codes are merged from all terminal descriptions
197 which have been loaded. The use_extended_names(3X) function controls
198 whether this data is loaded when the terminal description is read by
199 the library.
200 nofilter/use_tioctl
202 The nofilter and use_tioctl routines are specific to ncurses. They
203 were not supported on Version 7, BSD or System V implementations. It
204 is recommended that any code depending on ncurses extensions be condi‐
205 tioned using NCURSES_VERSION.
206 putwin/getwin
208 The putwin and getwin functions have several issues with portability:
209 · The files written and read by these functions use an implementa‐
211 tion-specific format. Although the format is an obvious target for
212 standardization, it has been overlooked.
213 Interestingly enough, according to the copyright dates in Solaris
215 source, the functions (along with scr_init, etc.) originated with
216 the University of California, Berkeley (in 1982) and were later (in
217 1988) incorporated into SVr4. Oddly, there are no such functions
218 in the 4.3BSD curses sources.
219 · Most implementations simply dump the binary WINDOW structure to the
221 file. These include SVr4 curses, NetBSD and PDCurses, as well as
222 older ncurses versions. This implementation (as well as the X/Open
223 variant of Solaris curses, dated 1995) uses textual dumps.
224 The implementations which use binary dumps use block-I/O (the
226 fwrite and fread functions). Those that use textual dumps use
227 buffered-I/O. A few applications may happen to write extra data in
228 the file using these functions. Doing that can run into problems
229 mixing block- and buffered-I/O. This implementation reduces the
230 problem on writes by flushing the output. However, reading from a
231 file written using mixed schemes may not be successful.
232 unctrl/wunctrl
234 The XSI Curses standard, Issue 4 describes these functions. It states
235 that unctrl and wunctrl will return a null pointer if unsuccessful, but
236 does not define any error conditions. This implementation checks for
237 three cases:
238 · the parameter is a 7-bit US-ASCII code. This is the case that
240 X/Open Curses documented.
241 · the parameter is in the range 128-159, i.e., a C1 control code. If
243 use_legacy_coding has been called with a 2 parameter, unctrl re‐
244 turns the parameter, i.e., a one-character string with the parame‐
245 ter as the first character. Otherwise, it returns “~@”, “~A”,
246 etc., analogous to “^@”, “^A”, C0 controls.
247 X/Open Curses does not document whether unctrl can be called before
249 initializing curses. This implementation permits that, and returns
250 the “~@”, etc., values in that case.
251 · parameter values outside the 0 to 255 range. unctrl returns a null
253 pointer.
254 The strings returned by unctrl in this implementation are determined at
256 compile time, showing C1 controls from the upper-128 codes with a “~”
257 prefix rather than “^”. Other implementations have different conven‐
258 tions. For example, they may show both sets of control characters with
259 “^”, and strip the parameter to 7 bits. Or they may ignore C1 controls
260 and treat all of the upper-128 codes as printable. This implementation
261 uses 8 bits but does not modify the string to reflect locale. The
262 use_legacy_coding function allows the caller to change the output of
263 unctrl.
264 Likewise, the meta(3X) function allows the caller to change the output
266 of keyname, i.e., it determines whether to use the “M-” prefix for
267 “meta” keys (codes in the range 128 to 255). Both use_legacy_coding
268 and meta succeed only after curses is initialized. X/Open Curses does
269 not document the treatment of codes 128 to 159. When treating them as
270 “meta” keys (or if keyname is called before initializing curses), this
271 implementation returns strings “M-^@”, “M-^A”, etc.
272 X/Open Curses documents unctrl as declared in <unctrl.h>, which ncurses
274 does. However, ncurses' <curses.h> includes <unctrl.h>, matching the
275 behavior of SVr4 curses. Other implementations may not do that.
276 use_env/use_tioctl
278 If ncurses is configured to provide the sp-functions extension, the
279 state of use_env and use_tioctl may be updated before creating each
280 screen rather than once only (curs_sp_funcs(3X)). This feature of
281 use_env is not provided by other implementation of curses.
282
284 legacy_coding(3X), curses(3X), curs_initscr(3X), curs_inopts(3X),
285 curs_kernel(3X), curs_scr_dump(3X), curs_sp_funcs(3X), curs_vari‐
286 ables(3X), legacy_coding(3X).
287 curs_util(3X)