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A few special routines sometimes need to be called before 72 it; these are <STRONG><A HREF="curs_slk.3x.html">slk_init(3x)</A></STRONG>, <STRONG>filter</STRONG>, <STRONG>ripoffline</STRONG>, <STRONG>use_env</STRONG>. For multiple- 73 terminal applications, <STRONG>newterm</STRONG> may be called before <STRONG>initscr</STRONG>. 74 75 The initscr code determines the terminal type and initializes all 76 <STRONG>curses</STRONG> data structures. <STRONG>initscr</STRONG> also causes the first call to 77 <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG> to clear the screen. If errors occur, <STRONG>initscr</STRONG> writes an 78 appropriate error message to standard error and exits; otherwise, a 79 pointer is returned to <STRONG>stdscr</STRONG>. 80 81 82</PRE><H3><a name="h3-newterm">newterm</a></H3><PRE> 83 A program that outputs to more than one terminal should use the <STRONG>newterm</STRONG> 84 routine for each terminal instead of <STRONG>initscr</STRONG>. A program that needs to 85 inspect capabilities, so it can continue to run in a line-oriented mode 86 if the terminal cannot support a screen-oriented program, would also 87 use <STRONG>newterm</STRONG>. 88 89 The routine <STRONG>newterm</STRONG> should be called once for each terminal. It 90 returns a variable of type <EM>SCREEN</EM> <EM>*</EM> which should be saved as a 91 reference to that terminal. <STRONG>newterm</STRONG>'s arguments are 92 93 <STRONG>o</STRONG> the <EM>type</EM> of the terminal to be used in place of <STRONG>$TERM</STRONG>, 94 95 <STRONG>o</STRONG> an output stream connected to the terminal, and 96 97 <STRONG>o</STRONG> an input stream connected to the terminal 98 99 If the <EM>type</EM> parameter is <STRONG>NULL</STRONG>, <STRONG>$TERM</STRONG> will be used. 100 101 The file descriptor of the output stream is passed to <STRONG><A HREF="curs_terminfo.3x.html">setupterm(3x)</A></STRONG>, 102 which returns a pointer to a <EM>TERMINAL</EM> structure. <STRONG>newterm</STRONG>'s return 103 value holds a pointer to the <EM>TERMINAL</EM> structure. 104 105 106</PRE><H3><a name="h3-endwin">endwin</a></H3><PRE> 107 The program must also call <STRONG>endwin</STRONG> for each terminal being used before 108 exiting from <STRONG>curses</STRONG>. If <STRONG>newterm</STRONG> is called more than once for the same 109 terminal, the first terminal referred to must be the last one for which 110 <STRONG>endwin</STRONG> is called. 111 112 A program should always call <STRONG>endwin</STRONG> before exiting or escaping from 113 <STRONG>curses</STRONG> mode temporarily. This routine 114 115 <STRONG>o</STRONG> resets colors to correspond with the default color pair 0, 116 117 <STRONG>o</STRONG> moves the cursor to the lower left-hand corner of the screen, 118 119 <STRONG>o</STRONG> clears the remainder of the line so that it uses the default 120 colors, 121 122 <STRONG>o</STRONG> sets the cursor to normal visibility (see <STRONG><A HREF="curs_kernel.3x.html">curs_set(3x)</A></STRONG>), 123 124 <STRONG>o</STRONG> stops cursor-addressing mode using the <EM>exit</EM><STRONG>_</STRONG><EM>ca</EM><STRONG>_</STRONG><EM>mode</EM> terminal 125 capability, 126 127 <STRONG>o</STRONG> restores tty modes (see <STRONG><A HREF="curs_kernel.3x.html">reset_shell_mode(3x)</A></STRONG>). 128 129 Calling <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG> or <STRONG><A HREF="curs_refresh.3x.html">doupdate(3x)</A></STRONG> after a temporary escape causes the 130 program to resume visual mode. 131 132 133</PRE><H3><a name="h3-isendwin">isendwin</a></H3><PRE> 134 The <STRONG>isendwin</STRONG> routine returns <STRONG>TRUE</STRONG> if <STRONG>endwin</STRONG> has been called without any 135 subsequent calls to <STRONG>wrefresh</STRONG>, and <STRONG>FALSE</STRONG> otherwise. 136 137 138</PRE><H3><a name="h3-set_term">set_term</a></H3><PRE> 139 The <STRONG>set_term</STRONG> routine is used to switch between different terminals. 140 The screen reference <EM>new</EM> becomes the new current terminal. The 141 previous terminal is returned by the routine. This is the only routine 142 which manipulates <EM>SCREEN</EM> pointers; all other routines affect only the 143 current terminal. 144 145 146</PRE><H3><a name="h3-delscreen">delscreen</a></H3><PRE> 147 The <STRONG>delscreen</STRONG> routine frees storage associated with the <EM>SCREEN</EM> data 148 structure. The <STRONG>endwin</STRONG> routine does not do this, so <STRONG>delscreen</STRONG> should be 149 called after <STRONG>endwin</STRONG> if a particular <EM>SCREEN</EM> is no longer needed. 150 151 152</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> 153 <STRONG>endwin</STRONG> returns the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> upon successful 154 completion. 155 156 Routines that return pointers always return <STRONG>NULL</STRONG> on error. 157 158 X/Open defines no error conditions. In this implementation 159 160 <STRONG>o</STRONG> <STRONG>endwin</STRONG> returns an error if 161 162 <STRONG>o</STRONG> the terminal was not initialized, or 163 164 <STRONG>o</STRONG> <STRONG>endwin</STRONG> is called more than once without updating the screen, or 165 166 <STRONG>o</STRONG> <STRONG><A HREF="curs_kernel.3x.html">reset_shell_mode(3x)</A></STRONG> returns an error. 167 168 <STRONG>o</STRONG> <STRONG>newterm</STRONG> returns an error if it cannot allocate the data structures 169 for the screen, or for the top-level windows within the screen, 170 i.e., <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, or <STRONG>stdscr</STRONG>. 171 172 <STRONG>o</STRONG> <STRONG>set_term</STRONG> returns no error. 173 174 175</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> 176 These functions were described in X/Open Curses, Issue 4. As of 2015, 177 the current document is X/Open Curses, Issue 7. 178 179 180</PRE><H3><a name="h3-Differences">Differences</a></H3><PRE> 181 X/Open Curses specifies that portable applications must not call 182 <STRONG>initscr</STRONG> more than once: 183 184 <STRONG>o</STRONG> The portable way to use <STRONG>initscr</STRONG> is once only, using <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG> to 185 restore the screen after <STRONG>endwin</STRONG>. 186 187 <STRONG>o</STRONG> This implementation allows using <STRONG>initscr</STRONG> after <STRONG>endwin</STRONG>. 188 189 Old versions of curses, e.g., BSD 4.4, would return a null pointer from 190 <STRONG>initscr</STRONG> when an error is detected, rather than exiting. It is safe but 191 redundant to check the return value of <STRONG>initscr</STRONG> in X/Open Curses. 192 193 Calling <STRONG>endwin</STRONG> does not dispose of the memory allocated in <STRONG>initscr</STRONG> or 194 <STRONG>newterm</STRONG>. Deleting a <EM>SCREEN</EM> provides a way to do this: 195 196 <STRONG>o</STRONG> X/Open Curses does not say what happens to <EM>WINDOW</EM>s when <STRONG>delscreen</STRONG> 197 "frees storage associated with the <EM>SCREEN</EM>" nor does the SVr4 198 documentation help, adding that it should be called after <STRONG>endwin</STRONG> if 199 a <EM>SCREEN</EM> is no longer needed. 200 201 <STRONG>o</STRONG> However, <EM>WINDOW</EM>s are implicitly associated with a <EM>SCREEN</EM>. so that 202 it is reasonable to expect <STRONG>delscreen</STRONG> to deal with these. 203 204 <STRONG>o</STRONG> SVr4 curses deletes the standard <EM>WINDOW</EM> structures <STRONG>stdscr</STRONG> and 205 <STRONG>curscr</STRONG> as well as a work area <STRONG>newscr</STRONG>. SVr4 curses ignores other 206 windows. 207 208 <STRONG>o</STRONG> Since version 4.0 (1996), <EM>ncurses</EM> has maintained a list of all 209 windows for each screen, using that information to delete those 210 windows when <STRONG>delscreen</STRONG> is called. 211 212 <STRONG>o</STRONG> NetBSD copied this feature of <EM>ncurses</EM> in 2001. PDCurses follows 213 the SVr4 model, deleting only the standard <EM>WINDOW</EM> structures. 214 215 216</PRE><H3><a name="h3-High-level-versus-Low-level">High-level versus Low-level</a></H3><PRE> 217 Different implementations may disagree regarding the level of some 218 functions. For example, <EM>SCREEN</EM> (returned by <STRONG>newterm</STRONG>) and <EM>TERMINAL</EM> 219 (returned by <STRONG><A HREF="curs_terminfo.3x.html">setupterm(3x)</A></STRONG>) hold file descriptors for the output 220 stream. If an application switches screens using <STRONG>set_term</STRONG>, or switches 221 terminals using <STRONG><A HREF="curs_terminfo.3x.html">set_curterm(3x)</A></STRONG>, applications which use the output file 222 descriptor can have different behavior depending on which structure 223 holds the corresponding descriptor. 224 225 For example 226 227 <STRONG>o</STRONG> NetBSD's <STRONG><A HREF="curs_termattrs.3x.html">baudrate(3x)</A></STRONG> function uses the descriptor in <EM>TERMINAL</EM>. 228 <EM>ncurses</EM> and SVr4 use the descriptor in <EM>SCREEN</EM>. 229 230 <STRONG>o</STRONG> NetBSD and <EM>ncurses</EM> use the descriptor in <EM>TERMINAL</EM> for terminal I/O 231 modes, e.g., <STRONG><A HREF="curs_kernel.3x.html">def_shell_mode(3x)</A></STRONG>, <STRONG><A HREF="curs_kernel.3x.html">def_prog_mode(3x)</A></STRONG>. SVr4 curses 232 uses the descriptor in <EM>SCREEN</EM>. 233 234 <STRONG>Unset</STRONG> <EM>TERM</EM> <STRONG>Variable</STRONG> 235 If the <EM>TERM</EM> variable is missing or empty, <STRONG>initscr</STRONG> uses the value 236 "unknown", which normally corresponds to a terminal entry with the 237 <EM>generic</EM> (<EM>gn</EM>) capability. Generic entries are detected by <STRONG><A HREF="curs_terminfo.3x.html">setupterm(3x)</A></STRONG> 238 and cannot be used for full-screen operation. Other implementations 239 may handle a missing/empty <EM>TERM</EM> variable differently. 240 241 242</PRE><H3><a name="h3-Signal-Handlers">Signal Handlers</a></H3><PRE> 243 Quoting from X/Open Curses Issue 7, section 3.1.1: 244 245 Curses implementations may provide for special handling of the 246 SIGINT, SIGQUIT, and SIGTSTP signals if their disposition is 247 SIG_DFL at the time <EM>initscr</EM> is called... 248 249 Any special handling for these signals may remain in effect for 250 the life of the process or until the process changes the 251 disposition of the signal. 252 253 None of the Curses functions are required to be safe with respect 254 to signals... 255 256 This implementation establishes signal handlers during initialization, 257 e.g., <STRONG>initscr</STRONG> or <STRONG>newterm</STRONG>. Applications which must handle these signals 258 should set up the corresponding handlers <EM>after</EM> initializing the 259 library: 260 261 <STRONG>SIGINT</STRONG> 262 The handler <EM>attempts</EM> to clean up the screen on exit. Although it 263 <EM>usually</EM> works as expected, there are limitations: 264 265 <STRONG>o</STRONG> Walking the <EM>SCREEN</EM> list is unsafe, since all list management 266 is done without any signal blocking. 267 268 <STRONG>o</STRONG> On systems which have <STRONG>REENTRANT</STRONG> turned on, <STRONG>set_term</STRONG> uses 269 functions which could deadlock or misbehave in other ways. 270 271 <STRONG>o</STRONG> <STRONG>endwin</STRONG> calls other functions, many of which use <STRONG>stdio(3)</STRONG> or 272 other library functions which are clearly unsafe. 273 274 <STRONG>SIGTERM</STRONG> 275 This uses the same handler as <STRONG>SIGINT</STRONG>, with the same limitations. 276 It is not mentioned in X/Open Curses, but is more suitable for 277 this purpose than <STRONG>SIGQUIT</STRONG> (which is used in debugging). 278 279 <STRONG>SIGTSTP</STRONG> 280 This handles the <EM>stop</EM> signal, used in job control. When resuming 281 the process, this implementation discards pending input with 282 <STRONG><A HREF="curs_util.3x.html">flushinp(3x)</A></STRONG>, and repaints the screen assuming that it has been 283 completely altered. It also updates the saved terminal modes with 284 <STRONG><A HREF="curs_kernel.3x.html">def_shell_mode(3x)</A></STRONG>. 285 286 <STRONG>SIGWINCH</STRONG> 287 This handles the window-size changes which were ignored in the 288 standardization efforts. The handler sets a (signal-safe) 289 variable which is later tested in <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG>. If <STRONG>keypad</STRONG> has been 290 enabled for the corresponding window, <STRONG>wgetch</STRONG> returns the key 291 symbol <STRONG>KEY_RESIZE</STRONG>. At the same time, <STRONG>wgetch</STRONG> calls <STRONG>resizeterm</STRONG> to 292 adjust the standard screen <STRONG>stdscr</STRONG>, and update other data such as 293 <STRONG>LINES</STRONG> and <STRONG>COLS</STRONG>. 294 295 296</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> 297 <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>, <STRONG><A HREF="curs_slk.3x.html">curs_slk(3x)</A></STRONG>, 298 <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><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG> 299 300 301 302ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG> 303</PRE> 304<div class="nav"> 305<ul> 306<li><a href="#h2-NAME">NAME</a></li> 307<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> 308<li><a href="#h2-DESCRIPTION">DESCRIPTION</a> 309<ul> 310<li><a href="#h3-initscr">initscr</a></li> 311<li><a href="#h3-newterm">newterm</a></li> 312<li><a href="#h3-endwin">endwin</a></li> 313<li><a href="#h3-isendwin">isendwin</a></li> 314<li><a href="#h3-set_term">set_term</a></li> 315<li><a href="#h3-delscreen">delscreen</a></li> 316</ul> 317</li> 318<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> 319<li><a href="#h2-PORTABILITY">PORTABILITY</a> 320<ul> 321<li><a href="#h3-Differences">Differences</a></li> 322<li><a href="#h3-High-level-versus-Low-level">High-level versus Low-level</a></li> 323<li><a href="#h3-Signal-Handlers">Signal Handlers</a></li> 324</ul> 325</li> 326<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 327</ul> 328</div> 329</BODY> 330</HTML> 331