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