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 char *unctrl(chtype c);
14 wchar_t *wunctrl(cchar_t *c);
15 char *keyname(int c);
16 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 The unctrl routine returns a character string which is a printable rep‐
28 resentation of the character c, ignoring attributes. Control charac‐
29 ters are displayed in the ^X notation. Printing characters are dis‐
30 played as is. The corresponding wunctrl returns a printable represen‐
31 tation of a wide character.
32 The keyname routine returns a character string corresponding to the key
34 c:
35 · Printable characters are displayed as themselves, e.g., a one-
37 character string containing the key.
38 · Control characters are displayed in the ^X notation.
40 · DEL (character 127) is displayed as ^?.
42 · Values above 128 are either meta characters (if the screen has
44 not been initialized, or if meta has been called with a TRUE pa‐
45 rameter), shown in the M-X notation, or are displayed as them‐
46 selves. In the latter case, the values may not be printable;
47 this follows the X/Open specification.
48 · Values above 256 may be the names of the names of function keys.
50 · Otherwise (if there is no corresponding name) the function re‐
52 turns null, to denote an error. X/Open also lists an "UNKNOWN
53 KEY" return value, which some implementations return rather than
54 null.
55 The corresponding key_name returns a character string corresponding to
57 the wide-character value w. The two functions do not return the same
58 set of strings; the latter returns null where the former would display
59 a meta character.
60 The filter routine, if used, must be called before initscr or newterm
62 are called. The effect is that, during those calls, LINES is set to 1;
63 the capabilities clear, cup, cud, cud1, cuu1, cuu, vpa are disabled;
64 and the home string is set to the value of cr.
65 The nofilter routine cancels the effect of a preceding filter call.
67 That allows the caller to initialize a screen on a different device,
68 using a different value of $TERM. The limitation arises because the
69 filter routine modifies the in-memory copy of the terminal information.
70 The use_env routine, if used, should be called before initscr or
72 newterm are called (because those compute the screen size). It modi‐
73 fies the way ncurses treats environment variables when determining the
74 screen size.
75 · Normally ncurses looks first at the terminal database for the
77 screen size.
78 If use_env was called with FALSE for parameter, it stops here un‐
80 less If use_tioctl was also called with TRUE for parameter.
81 · Then it asks for the screen size via operating system calls. If
83 successful, it overrides the values from the terminal database.
84 · Finally (unless use_env was called with FALSE parameter), ncurses
86 examines the LINES or COLUMNS environment variables, using a value
87 in those to override the results from the operating system or ter‐
88 minal database.
89 Ncurses also updates the screen size in response to SIGWINCH, un‐
91 less overridden by the LINES or COLUMNS environment variables,
92 The use_tioctl routine, if used, should be called before initscr or
94 newterm are called (because those compute the screen size). After
95 use_tioctl is called with TRUE as an argument, ncurses modifies the
96 last step in its computation of screen size as follows:
97 · checks if the LINES and COLUMNS environment variables are set to a
99 number greater than zero.
100 · for each, ncurses updates the corresponding environment variable
102 with the value that it has obtained via operating system call or
103 from the terminal database.
104 · ncurses re-fetches the value of the environment variables so that
106 it is still the environment variables which set the screen size.
107 The use_env and use_tioctl routines combine as summarized here:
109 use_env use_tioctl Summary
111 ────────────────────────────────────────────────────────────────
112 TRUE FALSE This is the default behavior. ncurses
113 uses operating system calls unless over‐
114 ridden by $LINES or $COLUMNS environment
115 variables.
116 TRUE TRUE ncurses updates $LINES and $COLUMNS
117 based on operating system calls.
118 FALSE TRUE ncurses ignores $LINES and $COLUMNS, us‐
119 es operating system calls to obtain
120 size.
121 FALSE FALSE ncurses relies on the terminal database
122 to determine size.
123 The putwin routine writes all data associated with window win into the
125 file to which filep points. This information can be later retrieved
126 using the getwin function.
127 The getwin routine reads window related data stored in the file by
129 putwin. The routine then creates and initializes a new window using
130 that data. It returns a pointer to the new window.
131 The delay_output routine inserts an ms millisecond pause in output.
133 This routine should not be used extensively because padding characters
134 are used rather than a CPU pause. If no padding character is speci‐
135 fied, this uses napms to perform the delay.
136 The flushinp routine throws away any typeahead that has been typed by
138 the user and has not yet been read by the program.
139
141 Except for flushinp, routines that return an integer return ERR upon
142 failure and OK (SVr4 specifies only "an integer value other than ERR")
143 upon successful completion.
144 Routines that return pointers return NULL on error.
146 X/Open does not define any error conditions. In this implementation
148 flushinp
150 returns an error if the terminal was not initialized.
151 meta returns an error if the terminal was not initialized.
153 putwin
155 returns an error if the associated fwrite calls return an er‐
156 ror.
157
159 The XSI Curses standard, Issue 4 describes these functions. It states
160 that unctrl and wunctrl will return a null pointer if unsuccessful, but
161 does not define any error conditions. This implementation checks for
162 three cases:
163 · the parameter is a 7-bit US-ASCII code. This is the case that
165 X/Open Curses documented.
166 · the parameter is in the range 128-159, i.e., a C1 control code.
168 If use_legacy_coding has been called with a 2 parameter, unctrl
169 returns the parameter, i.e., a one-character string with the pa‐
170 rameter as the first character. Otherwise, it returns ``~@'',
171 ``~A'', etc., analogous to ``^@'', ``^A'', C0 controls.
172 X/Open Curses does not document whether unctrl can be called be‐
174 fore initializing curses. This implementation permits that, and
175 returns the ``~@'', etc., values in that case.
176 · parameter values outside the 0 to 255 range. unctrl returns a
178 null pointer.
179 The SVr4 documentation describes the action of filter only in the
181 vaguest terms. The description here is adapted from the XSI Curses
182 standard (which erroneously fails to describe the disabling of cuu).
183 The strings returned by unctrl in this implementation are determined at
185 compile time, showing C1 controls from the upper-128 codes with a `~'
186 prefix rather than `^'. Other implementations have different conven‐
187 tions. For example, they may show both sets of control characters with
188 `^', and strip the parameter to 7 bits. Or they may ignore C1 controls
189 and treat all of the upper-128 codes as printable. This implementation
190 uses 8 bits but does not modify the string to reflect locale. The
191 use_legacy_coding function allows the caller to change the output of
192 unctrl.
193 Likewise, the meta function allows the caller to change the output of
195 keyname, i.e., it determines whether to use the `M-' prefix for
196 ``meta'' keys (codes in the range 128 to 255). Both use_legacy_coding
197 and meta succeed only after curses is initialized. X/Open Curses does
198 not document the treatment of codes 128 to 159. When treating them as
199 ``meta'' keys (or if keyname is called before initializing curses),
200 this implementation returns strings ``M-^@'', ``M-^A'', etc.
201 The keyname function may return the names of user-defined string capa‐
203 bilities which are defined in the terminfo entry via the -x option of
204 tic. This implementation automatically assigns at run-time keycodes to
205 user-defined strings which begin with "k". The keycodes start at
206 KEY_MAX, but are not guaranteed to be the same value for different runs
207 because user-defined codes are merged from all terminal descriptions
208 which have been loaded. The use_extended_names function controls
209 whether this data is loaded when the terminal description is read by
210 the library.
211 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
218 legacy_coding(3X), curses(3X), curs_initscr(3X), curs_kernel(3X),
219 curs_scr_dump(3X), curs_variables(3X), legacy_coding(3X).
220 curs_util(3X)