ncurses 6.0 - patch 20160326
[ncurses.git] / doc / html / man / curs_initscr.3x.html
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41 <H1 class="no-header">curs_initscr 3x</H1>
42 <PRE>
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>
44
45
46
47
48 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
49        <STRONG>initscr</STRONG>, <STRONG>newterm</STRONG>, <STRONG>endwin</STRONG>, <STRONG>isendwin</STRONG>, <STRONG>set_term</STRONG>, <STRONG>delscreen</STRONG> -
50        <STRONG>curses</STRONG> screen initialization and manipulation routines
51
52
53 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
54        <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
55
56        <STRONG>WINDOW</STRONG> <STRONG>*initscr(void);</STRONG>
57        <STRONG>int</STRONG> <STRONG>endwin(void);</STRONG>
58        <STRONG>bool</STRONG> <STRONG>isendwin(void);</STRONG>
59        <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>
60        <STRONG>SCREEN</STRONG> <STRONG>*set_term(SCREEN</STRONG> <STRONG>*</STRONG><EM>new</EM><STRONG>);</STRONG>
61        <STRONG>void</STRONG> <STRONG>delscreen(SCREEN*</STRONG> <EM>sp</EM><STRONG>);</STRONG>
62
63
64 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
65
66 </PRE><H3><a name="h3-initscr">initscr</a></H3><PRE>
67        <STRONG>initscr</STRONG> is normally the first <STRONG>curses</STRONG> routine to call  when
68        initializing  a program.  A few special routines sometimes
69        need to be called before it; these are  <STRONG>slk_init</STRONG>,  <STRONG>filter</STRONG>,
70        <STRONG>ripoffline</STRONG>,  <STRONG>use_env</STRONG>.  For multiple-terminal applications,
71        <STRONG>newterm</STRONG> may be called before <STRONG>initscr</STRONG>.
72
73        The initscr code determines the terminal type and initial-
74        izes  all <STRONG>curses</STRONG> data structures.  <STRONG>initscr</STRONG> also causes the
75        first call to <STRONG>refresh</STRONG> to clear the screen.  If errors  oc-
76        cur,  <STRONG>initscr</STRONG> writes an appropriate error message to stan-
77        dard error and exits; otherwise, a pointer is returned  to
78        <STRONG>stdscr</STRONG>.
79
80
81 </PRE><H3><a name="h3-newterm">newterm</a></H3><PRE>
82        A  program  that  outputs to more than one terminal should
83        use the <STRONG>newterm</STRONG>  routine  for  each  terminal  instead  of
84        <STRONG>initscr</STRONG>.  A program that needs to inspect capabilities, so
85        it can continue to run in a line-oriented mode if the ter-
86        minal cannot support a screen-oriented program, would also
87        use <STRONG>newterm</STRONG>.  The routine <STRONG>newterm</STRONG> should  be  called  once
88        for each terminal.  It returns a variable of type <STRONG>SCREEN</STRONG> <STRONG>*</STRONG>
89        which should be saved as a  reference  to  that  terminal.
90        <STRONG>newterm</STRONG>'s arguments are
91
92        <STRONG>o</STRONG>   the <EM>type</EM> of the terminal to be used in place of <STRONG>$TERM</STRONG>,
93
94        <STRONG>o</STRONG>   a file pointer for output to the terminal, and
95
96        <STRONG>o</STRONG>   another file pointer for input from the terminal
97
98        If the <EM>type</EM> parameter is <STRONG>NULL</STRONG>, <STRONG>$TERM</STRONG> will be used.
99
100
101 </PRE><H3><a name="h3-endwin">endwin</a></H3><PRE>
102        The  program must also call <STRONG>endwin</STRONG> for each terminal being
103        used before exiting from <STRONG>curses</STRONG>.   If  <STRONG>newterm</STRONG>  is  called
104        more  than  once for the same terminal, the first terminal
105        referred to must be the  last  one  for  which  <STRONG>endwin</STRONG>  is
106        called.
107
108        A  program should always call <STRONG>endwin</STRONG> before exiting or es-
109        caping from <STRONG>curses</STRONG> mode temporarily.  This routine
110
111        <STRONG>o</STRONG>   restores tty modes,
112
113        <STRONG>o</STRONG>   moves the cursor to the lower left-hand corner of  the
114            screen and
115
116        <STRONG>o</STRONG>   resets the terminal into the proper non-visual mode.
117
118        Calling <STRONG>refresh</STRONG> or <STRONG>doupdate</STRONG> after a temporary escape caus-
119        es the program to resume visual mode.
120
121
122 </PRE><H3><a name="h3-isendwin">isendwin</a></H3><PRE>
123        The <STRONG>isendwin</STRONG> routine  returns  <STRONG>TRUE</STRONG>  if  <STRONG>endwin</STRONG>  has  been
124        called without any subsequent calls to <STRONG>wrefresh</STRONG>, and <STRONG>FALSE</STRONG>
125        otherwise.
126
127
128 </PRE><H3><a name="h3-set_term">set_term</a></H3><PRE>
129        The <STRONG>set_term</STRONG> routine is used to switch  between  different
130        terminals.   The screen reference <STRONG>new</STRONG> becomes the new cur-
131        rent terminal.  The previous terminal is returned  by  the
132        routine.   This  is  the  only  routine  which manipulates
133        <STRONG>SCREEN</STRONG> pointers; all other routines affect only  the  cur-
134        rent terminal.
135
136
137 </PRE><H3><a name="h3-delscreen">delscreen</a></H3><PRE>
138        The  <STRONG>delscreen</STRONG>  routine  frees storage associated with the
139        <STRONG>SCREEN</STRONG> data structure.  The <STRONG>endwin</STRONG>  routine  does  not  do
140        this, so <STRONG>delscreen</STRONG> should be called after <STRONG>endwin</STRONG> if a par-
141        ticular <STRONG>SCREEN</STRONG> is no longer needed.
142
143
144 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
145        <STRONG>endwin</STRONG> returns the integer <STRONG>ERR</STRONG> upon failure  and  <STRONG>OK</STRONG>  upon
146        successful completion.
147
148        Routines that return pointers always return <STRONG>NULL</STRONG> on error.
149
150        X/Open  defines  no error conditions.  In this implementa-
151        tion
152
153        <STRONG>o</STRONG>   <STRONG>endwin</STRONG> returns an error if the terminal was  not  ini-
154            tialized.
155
156        <STRONG>o</STRONG>   <STRONG>newterm</STRONG> returns an error if it cannot allocate the da-
157            ta structures for the screen,  or  for  the  top-level
158            windows  within  the  screen, i.e., <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, or
159            <STRONG>stdscr</STRONG>.
160
161        <STRONG>o</STRONG>   <STRONG>set_term</STRONG> returns no error.
162
163
164 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
165        Note that <STRONG>initscr</STRONG> and <STRONG>newterm</STRONG> may be macros.
166
167
168 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
169        These functions were described in the XSI Curses standard,
170        Issue 4.  As of 2015, the current document is X/Open Curs-
171        es, Issue 7.
172
173
174 </PRE><H3><a name="h3-Differences">Differences</a></H3><PRE>
175        X/Open specifies that portable applications must not  call
176        <STRONG>initscr</STRONG> more than once:
177
178        <STRONG>o</STRONG>   The  portable  way  to use <STRONG>initscr</STRONG> is once only, using
179            <STRONG>refresh</STRONG> (see <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>) to restore  the  screen
180            after <STRONG>endwin</STRONG>.
181
182        <STRONG>o</STRONG>   This implementation allows using <STRONG>initscr</STRONG> after <STRONG>endwin</STRONG>.
183
184        Old versions of curses, e.g., BSD 4.4, may have returned a
185        null pointer from  <STRONG>initscr</STRONG>  when  an  error  is  detected,
186        rather  than  exiting.   It is safe but redundant to check
187        the return value of <STRONG>initscr</STRONG> in XSI Curses.
188
189
190 </PRE><H3><a name="h3-Unset-TERM-Variable">Unset TERM Variable</a></H3><PRE>
191        If the TERM variable is missing or empty, <STRONG>initscr</STRONG> uses the
192        value  "unknown", which normally corresponds to a terminal
193        entry with the <EM>generic</EM> (<EM>gn</EM>) capability.   Generic  entries
194        are detected by <STRONG>setupterm</STRONG> (see <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>) and can-
195        not be used for full-screen operation.  Other  implementa-
196        tions  may handle a missing/empty TERM variable different-
197        ly.
198
199
200 </PRE><H3><a name="h3-Signal-Handlers">Signal Handlers</a></H3><PRE>
201        Quoting from X/Open Curses, section 3.1.1:
202
203             <EM>Curses</EM> <EM>implementations</EM> <EM>may</EM> <EM>provide</EM> <EM>for</EM>  <EM>special</EM>  <EM>han-</EM>
204             <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>
205             <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>
206             <EM>called</EM> <STRONG>...</STRONG>
207
208             <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>
209             <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>
210             <EM>process</EM> <EM>changes</EM> <EM>the</EM> <EM>disposition</EM> <EM>of</EM> <EM>the</EM> <EM>signal.</EM>
211
212             <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>
213             <EM>with</EM> <EM>respect</EM> <EM>to</EM> <EM>signals</EM> ...
214
215        This implementation  establishes  signal  handlers  during
216        initialization,  e.g.,  <STRONG>initscr</STRONG>  or <STRONG>newterm</STRONG>.  Applications
217        which must handle these signals should set up  the  corre-
218        sponding handlers <EM>after</EM> initializing the library:
219
220        <STRONG>SIGINT</STRONG>
221             The  handler  <EM>attempts</EM> to cleanup the screen on exit.
222             Although it <EM>usually</EM> works as expected, there are lim-
223             itations:
224
225             <STRONG>o</STRONG>   Walking the <STRONG>SCREEN</STRONG> list is unsafe, since all list
226                 management is done without any signal blocking.
227
228             <STRONG>o</STRONG>   On  systems  which  have  <STRONG>REENTRANT</STRONG>  turned   on,
229                 <STRONG>set_term</STRONG>  uses  functions which could deadlock or
230                 misbehave in other ways.
231
232             <STRONG>o</STRONG>   <STRONG>endwin</STRONG> calls other functions, many of  which  use
233                 stdio or other library functions which are clear-
234                 ly unsafe.
235
236        <STRONG>SIGTERM</STRONG>
237             This uses the same handler as <STRONG>SIGINT</STRONG>, with  the  same
238             limitations.   It  is not mentioned in X/Open Curses,
239             but is more suitable for this  purpose  than  <STRONG>SIGQUIT</STRONG>
240             (which is used in debugging).
241
242        <STRONG>SIGTSTP</STRONG>
243             This  handles  the  <EM>stop</EM> signal, used in job control.
244             When resuming the process, this  implementation  dis-
245             cards    pending    input    with   <STRONG>flushinput</STRONG>   (see
246             <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>), and repaints the screen assuming that
247             it  has been completely altered.  It also updates the
248             saved  terminal  modes   with   <STRONG>def_shell_mode</STRONG>   (see
249             <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>).
250
251        <STRONG>SIGWINCH</STRONG>
252             This  handles the window-size changes which were ini-
253             tially ignored in the standardization  efforts.   The
254             handler  sets a (signal-safe) variable which is later
255             tested in <STRONG>wgetch</STRONG> (see <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>).  If <STRONG>keypad</STRONG> has
256             been enabled for the corresponding window, <STRONG>wgetch</STRONG> re-
257             turns the key symbol <STRONG>KEY_RESIZE</STRONG>.  At the  same  time,
258             <STRONG>wgetch</STRONG> calls <STRONG>resizeterm</STRONG> to adjust the standard screen
259             <STRONG>stdscr</STRONG>, and update other data such as <STRONG>LINES</STRONG> and <STRONG>COLS</STRONG>.
260
261
262 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
263        <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>,
264        <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>
265        <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>.
266
267
268
269                                                        <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>
270 </PRE>
271 <div class="nav">
272 <ul>
273 <li><a href="#h2-NAME">NAME</a></li>
274 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
275 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
276 <ul>
277 <li><a href="#h3-initscr">initscr</a></li>
278 <li><a href="#h3-newterm">newterm</a></li>
279 <li><a href="#h3-endwin">endwin</a></li>
280 <li><a href="#h3-isendwin">isendwin</a></li>
281 <li><a href="#h3-set_term">set_term</a></li>
282 <li><a href="#h3-delscreen">delscreen</a></li>
283 </ul>
284 </li>
285 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
286 <li><a href="#h2-NOTES">NOTES</a></li>
287 <li><a href="#h2-PORTABILITY">PORTABILITY</a>
288 <ul>
289 <li><a href="#h3-Differences">Differences</a></li>
290 <li><a href="#h3-Unset-TERM-Variable">Unset TERM Variable</a></li>
291 <li><a href="#h3-Signal-Handlers">Signal Handlers</a></li>
292 </ul>
293 </li>
294 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
295 </ul>
296 </div>
297 </BODY>
298 </HTML>