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29 * @Id: curs_initscr.3x,v 1.24 2015/07/21 23:01:38 tom Exp @
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36 <TITLE>curs_initscr
3x
</TITLE>
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href=
"mailto:bug-ncurses@gnu.org">
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41 <H1 class=
"no-header">curs_initscr
3x
</H1>
43 <STRONG><A HREF=
"curs_initscr.3x.html">curs_initscr(
3x)
</A></STRONG> <STRONG><A HREF=
"curs_initscr.3x.html">curs_initscr(
3x)
</A></STRONG>
49 <H2><a name=
"h2-NAME">NAME
</a></H2><PRE>
50 <STRONG>initscr
</STRONG>,
<STRONG>newterm
</STRONG>,
<STRONG>endwin
</STRONG>,
<STRONG>isendwin
</STRONG>,
<STRONG>set_term
</STRONG>,
<STRONG>delscreen
</STRONG> -
51 <STRONG>curses
</STRONG> screen initialization and manipulation routines
55 <H2><a name=
"h2-SYNOPSIS">SYNOPSIS
</a></H2><PRE>
56 <STRONG>#include
</STRONG> <STRONG><curses.h
></STRONG>
58 <STRONG>WINDOW
</STRONG> <STRONG>*initscr(void);
</STRONG>
59 <STRONG>int
</STRONG> <STRONG>endwin(void);
</STRONG>
60 <STRONG>bool
</STRONG> <STRONG>isendwin(void);
</STRONG>
61 <STRONG>SCREEN
</STRONG> <STRONG>*newterm(char
</STRONG> <STRONG>*
</STRONG><EM>type
</EM><STRONG>,
</STRONG> <STRONG>FILE
</STRONG> <STRONG>*
</STRONG><EM>outfd
</EM><STRONG>,
</STRONG> <STRONG>FILE
</STRONG> <STRONG>*
</STRONG><EM>infd
</EM><STRONG>);
</STRONG>
62 <STRONG>SCREEN
</STRONG> <STRONG>*set_term(SCREEN
</STRONG> <STRONG>*
</STRONG><EM>new
</EM><STRONG>);
</STRONG>
63 <STRONG>void
</STRONG> <STRONG>delscreen(SCREEN*
</STRONG> <EM>sp
</EM><STRONG>);
</STRONG>
67 <H2><a name=
"h2-DESCRIPTION">DESCRIPTION
</a></H2><PRE>
70 <H3><a name=
"h3-initscr">initscr
</a></H3><PRE>
71 <STRONG>initscr
</STRONG> is normally the first
<STRONG>curses
</STRONG> routine to call when
72 initializing a program. A few special routines sometimes
73 need to be called before it; these are
<STRONG>slk_init
</STRONG>,
<STRONG>filter
</STRONG>,
74 <STRONG>ripoffline
</STRONG>,
<STRONG>use_env
</STRONG>. For multiple-terminal applications,
75 <STRONG>newterm
</STRONG> may be called before
<STRONG>initscr
</STRONG>.
77 The initscr code determines the terminal type and initial-
78 izes all
<STRONG>curses
</STRONG> data structures.
<STRONG>initscr
</STRONG> also causes the
79 first call to
<STRONG>refresh
</STRONG> to clear the screen. If errors oc-
80 cur,
<STRONG>initscr
</STRONG> writes an appropriate error message to stan-
81 dard error and exits; otherwise, a pointer is returned to
82 <STRONG>stdscr
</STRONG>.
86 <H3><a name=
"h3-newterm">newterm
</a></H3><PRE>
87 A program that outputs to more than one terminal should
88 use the
<STRONG>newterm
</STRONG> routine for each terminal instead of
89 <STRONG>initscr
</STRONG>. A program that needs to inspect capabilities, so
90 it can continue to run in a line-oriented mode if the ter-
91 minal cannot support a screen-oriented program, would also
92 use
<STRONG>newterm
</STRONG>. The routine
<STRONG>newterm
</STRONG> should be called once
93 for each terminal. It returns a variable of type
<STRONG>SCREEN
</STRONG> <STRONG>*
</STRONG>
94 which should be saved as a reference to that terminal.
95 <STRONG>newterm
</STRONG>'s arguments are
97 <STRONG>o
</STRONG> the
<EM>type
</EM> of the terminal to be used in place of
<STRONG>$TERM
</STRONG>,
99 <STRONG>o
</STRONG> a file pointer for output to the terminal, and
101 <STRONG>o
</STRONG> another file pointer for input from the terminal
103 If the
<EM>type
</EM> parameter is
<STRONG>NULL
</STRONG>,
<STRONG>$TERM
</STRONG> will be used.
107 <H3><a name=
"h3-endwin">endwin
</a></H3><PRE>
108 The program must also call
<STRONG>endwin
</STRONG> for each terminal being
109 used before exiting from
<STRONG>curses
</STRONG>. If
<STRONG>newterm
</STRONG> is called
110 more than once for the same terminal, the first terminal
111 referred to must be the last one for which
<STRONG>endwin
</STRONG> is
114 A program should always call
<STRONG>endwin
</STRONG> before exiting or es-
115 caping from
<STRONG>curses
</STRONG> mode temporarily. This routine
117 <STRONG>o
</STRONG> restores tty modes,
119 <STRONG>o
</STRONG> moves the cursor to the lower left-hand corner of the
122 <STRONG>o
</STRONG> resets the terminal into the proper non-visual mode.
124 Calling
<STRONG>refresh
</STRONG> or
<STRONG>doupdate
</STRONG> after a temporary escape caus-
125 es the program to resume visual mode.
129 <H3><a name=
"h3-isendwin">isendwin
</a></H3><PRE>
130 The
<STRONG>isendwin
</STRONG> routine returns
<STRONG>TRUE
</STRONG> if
<STRONG>endwin
</STRONG> has been
131 called without any subsequent calls to
<STRONG>wrefresh
</STRONG>, and
<STRONG>FALSE
</STRONG>
136 <H3><a name=
"h3-set_term">set_term
</a></H3><PRE>
137 The
<STRONG>set_term
</STRONG> routine is used to switch between different
138 terminals. The screen reference
<STRONG>new
</STRONG> becomes the new cur-
139 rent terminal. The previous terminal is returned by the
140 routine. This is the only routine which manipulates
141 <STRONG>SCREEN
</STRONG> pointers; all other routines affect only the cur-
146 <H3><a name=
"h3-delscreen">delscreen
</a></H3><PRE>
147 The
<STRONG>delscreen
</STRONG> routine frees storage associated with the
148 <STRONG>SCREEN
</STRONG> data structure. The
<STRONG>endwin
</STRONG> routine does not do
149 this, so
<STRONG>delscreen
</STRONG> should be called after
<STRONG>endwin
</STRONG> if a par-
150 ticular
<STRONG>SCREEN
</STRONG> is no longer needed.
154 <H2><a name=
"h2-RETURN-VALUE">RETURN VALUE
</a></H2><PRE>
155 <STRONG>endwin
</STRONG> returns the integer
<STRONG>ERR
</STRONG> upon failure and
<STRONG>OK
</STRONG> upon
156 successful completion.
158 Routines that return pointers always return
<STRONG>NULL
</STRONG> on error.
160 X/Open defines no error conditions. In this implementa-
163 <STRONG>o
</STRONG> <STRONG>endwin
</STRONG> returns an error if the terminal was not ini-
166 <STRONG>o
</STRONG> <STRONG>newterm
</STRONG> returns an error if it cannot allocate the da-
167 ta structures for the screen, or for the top-level
168 windows within the screen, i.e.,
<STRONG>curscr
</STRONG>,
<STRONG>newscr
</STRONG>, or
169 <STRONG>stdscr
</STRONG>.
171 <STRONG>o
</STRONG> <STRONG>set_term
</STRONG> returns no error.
175 <H2><a name=
"h2-NOTES">NOTES
</a></H2><PRE>
176 Note that
<STRONG>initscr
</STRONG> and
<STRONG>newterm
</STRONG> may be macros.
180 <H2><a name=
"h2-PORTABILITY">PORTABILITY
</a></H2><PRE>
181 These functions were described in the XSI Curses standard,
182 Issue
4. As of
2015, the current document is X/Open Curs-
187 <H3><a name=
"h3-Differences">Differences
</a></H3><PRE>
188 X/Open specifies that portable applications must not call
189 <STRONG>initscr
</STRONG> more than once:
191 <STRONG>o
</STRONG> The portable way to use
<STRONG>initscr
</STRONG> is once only, using
192 <STRONG>refresh
</STRONG> (see
<STRONG><A HREF=
"curs_refresh.3x.html">curs_refresh(
3x)
</A></STRONG>) to restore the screen
193 after
<STRONG>endwin
</STRONG>.
195 <STRONG>o
</STRONG> This implementation allows using
<STRONG>initscr
</STRONG> after
<STRONG>endwin
</STRONG>.
197 Old versions of curses, e.g., BSD
4.4, may have returned a
198 null pointer from
<STRONG>initscr
</STRONG> when an error is detected,
199 rather than exiting. It is safe but redundant to check
200 the return value of
<STRONG>initscr
</STRONG> in XSI Curses.
204 <H3><a name=
"h3-Unset-TERM-Variable">Unset TERM Variable
</a></H3><PRE>
205 If the TERM variable is missing or empty,
<STRONG>initscr
</STRONG> uses the
206 value
"unknown", which normally corresponds to a terminal
207 entry with the
<EM>generic
</EM> (
<EM>gn
</EM>) capability. Generic entries
208 are detected by
<STRONG>setupterm
</STRONG> (see
<STRONG><A HREF=
"curs_terminfo.3x.html">curs_terminfo(
3x)
</A></STRONG>) and can-
209 not be used for full-screen operation. Other implementa-
210 tions may handle a missing/empty TERM variable different-
215 <H3><a name=
"h3-Signal-Handlers">Signal Handlers
</a></H3><PRE>
216 Quoting from X/Open Curses, section
3.1.1:
218 <EM>Curses
</EM> <EM>implementations
</EM> <EM>may
</EM> <EM>provide
</EM> <EM>for
</EM> <EM>special
</EM> <EM>han-
</EM>
219 <EM>dling
</EM> <EM>of
</EM> <EM>the
</EM> <EM>SIGINT,
</EM> <EM>SIGQUIT
</EM> <EM>and
</EM> <EM>SIGTSTP
</EM> <EM>signals
</EM> <EM>if
</EM>
220 <EM>their
</EM> <EM>disposition
</EM> <EM>is
</EM> <EM>SIG
</EM><STRONG>_
</STRONG><EM>DFL
</EM> <EM>at
</EM> <EM>the
</EM> <EM>time
</EM> <STRONG>initscr()
</STRONG> <EM>is
</EM>
221 <EM>called
</EM> <STRONG>...
</STRONG>
223 <EM>Any
</EM> <EM>special
</EM> <EM>handling
</EM> <EM>for
</EM> <EM>these
</EM> <EM>signals
</EM> <EM>may
</EM> <EM>remain
</EM> <EM>in
</EM>
224 <EM>effect
</EM> <EM>for
</EM> <EM>the
</EM> <EM>life
</EM> <EM>of
</EM> <EM>the
</EM> <EM>process
</EM> <EM>or
</EM> <EM>until
</EM> <EM>the
</EM>
225 <EM>process
</EM> <EM>changes
</EM> <EM>the
</EM> <EM>disposition
</EM> <EM>of
</EM> <EM>the
</EM> <EM>signal.
</EM>
227 <EM>None
</EM> <EM>of
</EM> <EM>the
</EM> <EM>Curses
</EM> <EM>functions
</EM> <EM>are
</EM> <EM>required
</EM> <EM>to
</EM> <EM>be
</EM> <EM>safe
</EM>
228 <EM>with
</EM> <EM>respect
</EM> <EM>to
</EM> <EM>signals
</EM> ...
230 This implementation establishes signal handlers during
231 initialization, e.g.,
<STRONG>initscr
</STRONG> or
<STRONG>newterm
</STRONG>. Applications
232 which must handle these signals should set up the corre-
233 sponding handlers
<EM>after
</EM> initializing the library:
235 <STRONG>SIGINT
</STRONG>
236 The handler
<EM>attempts
</EM> to cleanup the screen on exit.
237 Although it
<EM>usually
</EM> works as expected, there are lim-
240 <STRONG>o
</STRONG> Walking the
<STRONG>SCREEN
</STRONG> list is unsafe, since all list
241 management is done without any signal blocking.
243 <STRONG>o
</STRONG> On systems which have
<STRONG>REENTRANT
</STRONG> turned on,
244 <STRONG>set_term
</STRONG> uses functions which could deadlock or
245 misbehave in other ways.
247 <STRONG>o
</STRONG> <STRONG>endwin
</STRONG> calls other functions, many of which use
248 stdio or other library functions which are clear-
251 <STRONG>SIGTERM
</STRONG>
252 This uses the same handler as
<STRONG>SIGINT
</STRONG>, with the same
253 limitations. It is not mentioned in X/Open Curses,
254 but is more suitable for this purpose than
<STRONG>SIGQUIT
</STRONG>
255 (which is used in debugging).
257 <STRONG>SIGTSTP
</STRONG>
258 This handles the
<EM>stop
</EM> signal, used in job control.
259 When resuming the process, this implementation dis-
260 cards pending input with
<STRONG>flushinput
</STRONG> (see
261 <STRONG><A HREF=
"curs_util.3x.html">curs_util(
3x)
</A></STRONG>), and repaints the screen assuming that
262 it has been completely altered. It also updates the
263 saved terminal modes with
<STRONG>def_shell_mode
</STRONG> (see
264 <STRONG><A HREF=
"curs_kernel.3x.html">curs_kernel(
3x)
</A></STRONG>).
266 <STRONG>SIGWINCH
</STRONG>
267 This handles the window-size changes which were ini-
268 tially ignored in the standardization efforts. The
269 handler sets a (signal-safe) variable which is later
270 tested in
<STRONG>wgetch
</STRONG> (see
<STRONG><A HREF=
"curs_getch.3x.html">curs_getch(
3x)
</A></STRONG>). If
<STRONG>keypad
</STRONG> has
271 been enabled for the corresponding window,
<STRONG>wgetch
</STRONG> re-
272 turns the key symbol
<STRONG>KEY_RESIZE
</STRONG>. At the same time,
273 <STRONG>wgetch
</STRONG> calls
<STRONG>resizeterm
</STRONG> to adjust the standard screen
274 <STRONG>stdscr
</STRONG>, and update other data such as
<STRONG>LINES
</STRONG> and
<STRONG>COLS
</STRONG>.
278 <H2><a name=
"h2-SEE-ALSO">SEE ALSO
</a></H2><PRE>
279 <STRONG><A HREF=
"ncurses.3x.html">curses(
3x)
</A></STRONG>,
<STRONG><A HREF=
"curs_kernel.3x.html">curs_kernel(
3x)
</A></STRONG>,
<STRONG><A HREF=
"curs_refresh.3x.html">curs_refresh(
3x)
</A></STRONG>,
280 <STRONG><A HREF=
"curs_slk.3x.html">curs_slk(
3x)
</A></STRONG>,
<STRONG><A HREF=
"curs_terminfo.3x.html">curs_terminfo(
3x)
</A></STRONG>,
<STRONG><A HREF=
"curs_util.3x.html">curs_util(
3x)
</A></STRONG>,
<STRONG>curs_vari-
</STRONG>
281 <STRONG><A HREF=
"curs_variables.3x.html">ables(
3x)
</A></STRONG>.
285 <STRONG><A HREF=
"curs_initscr.3x.html">curs_initscr(
3x)
</A></STRONG>
289 <li><a href=
"#h2-NAME">NAME
</a></li>
290 <li><a href=
"#h2-SYNOPSIS">SYNOPSIS
</a></li>
291 <li><a href=
"#h2-DESCRIPTION">DESCRIPTION
</a>
293 <li><a href=
"#h3-initscr">initscr
</a></li>
294 <li><a href=
"#h3-newterm">newterm
</a></li>
295 <li><a href=
"#h3-endwin">endwin
</a></li>
296 <li><a href=
"#h3-isendwin">isendwin
</a></li>
297 <li><a href=
"#h3-set_term">set_term
</a></li>
298 <li><a href=
"#h3-delscreen">delscreen
</a></li>
301 <li><a href=
"#h2-RETURN-VALUE">RETURN VALUE
</a></li>
302 <li><a href=
"#h2-NOTES">NOTES
</a></li>
303 <li><a href=
"#h2-PORTABILITY">PORTABILITY
</a>
305 <li><a href=
"#h3-Differences">Differences
</a></li>
306 <li><a href=
"#h3-Unset-TERM-Variable">Unset TERM Variable
</a></li>
307 <li><a href=
"#h3-Signal-Handlers">Signal Handlers
</a></li>
310 <li><a href=
"#h2-SEE-ALSO">SEE ALSO
</a></li>