2 ****************************************************************************
3 * Copyright 2018-2019,2020 Thomas E. Dickey *
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29 ****************************************************************************
30 * Author: Thomas E. Dickey 1996-on
31 * @Id: resizeterm.3x,v 1.28 2020/10/17 23:55:41 tom Exp @
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43 <H1 class="no-header">resizeterm 3x</H1>
45 <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG> <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>is_term_resized</STRONG>, <STRONG>resize_term</STRONG>, <STRONG>resizeterm</STRONG> - change the curses terminal
55 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
56 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
58 <STRONG>bool</STRONG> <STRONG>is_term_resized(int</STRONG> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
59 <STRONG>int</STRONG> <STRONG>resize_term(int</STRONG> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
60 <STRONG>int</STRONG> <STRONG>resizeterm(int</STRONG> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
63 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
64 This is an extension to the curses library. It provides callers with a
65 hook into the <STRONG>ncurses</STRONG> data to resize windows, primarily for use by
66 programs running in an X Window terminal (e.g., xterm).
69 </PRE><H3><a name="h3-resizeterm">resizeterm</a></H3><PRE>
70 The function <STRONG>resizeterm</STRONG> resizes the standard and current windows to the
71 specified dimensions, and adjusts other bookkeeping data used by the
72 <STRONG>ncurses</STRONG> library that record the window dimensions such as the <STRONG>LINES</STRONG> and
73 <STRONG>COLS</STRONG> variables.
76 </PRE><H3><a name="h3-resize_term">resize_term</a></H3><PRE>
77 Most of the work is done by the inner function <STRONG>resize_term</STRONG>. The outer
78 function <STRONG>resizeterm</STRONG> adds bookkeeping for the <STRONG>SIGWINCH</STRONG> handler, as well
79 as repainting the soft-key area (see <STRONG><A HREF="curs_slk.3x.html">slk_touch(3x)</A></STRONG>).
81 When resizing the windows, <STRONG>resize_term</STRONG> blank-fills the areas that are
82 extended. The calling application should fill in these areas with
85 The <STRONG>resize_term</STRONG> function attempts to resize all windows. However, due
86 to the calling convention of pads, it is not possible to resize these
87 without additional interaction with the application.
89 When resizing windows, <STRONG>resize_term</STRONG> recursively adjusts subwindows,
90 keeping them within the updated parent window's limits. If a top-level
91 window happens to extend to the screen's limits, then on resizing the
92 window, <STRONG>resize_term</STRONG> will keep the window extending to the corresponding
93 limit, regardless of whether the screen has shrunk or grown.
96 </PRE><H3><a name="h3-is_term_resized">is_term_resized</a></H3><PRE>
97 A support function <STRONG>is_term_resized</STRONG> is provided so that applications can
98 check if the <STRONG>resize_term</STRONG> function would modify the window structures.
99 It returns <STRONG>TRUE</STRONG> if the windows would be modified, and <STRONG>FALSE</STRONG> otherwise.
102 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
103 Except as noted, these functions return the integer <STRONG>ERR</STRONG> upon failure
104 and <STRONG>OK</STRONG> on success. They will fail if either of the dimensions are less
105 than or equal to zero, or if an error occurs while (re)allocating
106 memory for the windows.
109 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
110 While these functions are intended to be used to support a signal
111 handler (i.e., for <STRONG>SIGWINCH</STRONG>), care should be taken to avoid invoking
112 them in a context where <STRONG>malloc</STRONG> or <STRONG>realloc</STRONG> may have been interrupted,
113 since it uses those functions.
115 If ncurses is configured to supply its own <STRONG>SIGWINCH</STRONG> handler,
117 <STRONG>o</STRONG> on receipt of a <STRONG>SIGWINCH</STRONG>, the handler sets a flag
119 <STRONG>o</STRONG> which is tested in <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> and <STRONG>doupdate</STRONG>,
121 <STRONG>o</STRONG> in turn, calling the <STRONG>resizeterm</STRONG> function,
123 <STRONG>o</STRONG> which <STRONG>ungetch</STRONG>'s a <STRONG>KEY_RESIZE</STRONG> which will be read on the next call to
124 <STRONG>wgetch</STRONG>.
126 The <STRONG>KEY_RESIZE</STRONG> alerts an application that the screen size has
127 changed, and that it should repaint special features such as pads
128 that cannot be done automatically.
130 Calling <STRONG>resizeterm</STRONG> or <STRONG>resize_term</STRONG> directly from a signal handler is
131 unsafe. This indirect method is used to provide a safe way to
132 resize the ncurses data structures.
134 If the environment variables <STRONG>LINES</STRONG> or <STRONG>COLUMNS</STRONG> are set, this overrides
135 the library's use of the window size obtained from the operating
136 system. Thus, even if a <STRONG>SIGWINCH</STRONG> is received, no screen size change
140 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
141 It is possible to resize the screen with SVr4 curses, by
143 <STRONG>o</STRONG> exiting curses with <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG> and
145 <STRONG>o</STRONG> resuming using <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>.
147 Doing that clears the screen and is visually distracting.
149 This extension of ncurses was introduced in mid-1995. It was adopted
150 in NetBSD curses (2001) and PDCurses (2003).
153 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
154 <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>.
157 </PRE><H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
158 Thomas Dickey (from an equivalent function written in 1988 for BSD
163 <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>
167 <li><a href="#h2-NAME">NAME</a></li>
168 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
169 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
171 <li><a href="#h3-resizeterm">resizeterm</a></li>
172 <li><a href="#h3-resize_term">resize_term</a></li>
173 <li><a href="#h3-is_term_resized">is_term_resized</a></li>
176 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
177 <li><a href="#h2-NOTES">NOTES</a></li>
178 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
179 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
180 <li><a href="#h2-AUTHOR">AUTHOR</a></li>