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28 ****************************************************************************
29 * Author: Thomas E. Dickey 1996-on
30 * @Id: resizeterm.3x,v 1.26 2019/09/21 23:44:41 tom Exp @
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42 <H1 class="no-header">resizeterm 3x</H1>
44 <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG> <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>is_term_resized</STRONG>, <STRONG>resize_term</STRONG>, <STRONG>resizeterm</STRONG> - change the curses terminal
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
57 <STRONG>bool</STRONG> <STRONG>is_term_resized(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
58 <STRONG>int</STRONG> <STRONG>resize_term(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
59 <STRONG>int</STRONG> <STRONG>resizeterm(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
62 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
63 This is an extension to the curses library. It provides callers with a
64 hook into the <STRONG>ncurses</STRONG> data to resize windows, primarily for use by pro-
65 grams running in an X Window terminal (e.g., xterm).
68 </PRE><H3><a name="h3-resizeterm">resizeterm</a></H3><PRE>
69 The function <STRONG>resizeterm</STRONG> resizes the standard and current windows to the
70 specified dimensions, and adjusts other bookkeeping data used by the
71 <STRONG>ncurses</STRONG> library that record the window dimensions such as the <STRONG>LINES</STRONG> and
72 <STRONG>COLS</STRONG> variables.
75 </PRE><H3><a name="h3-resize_term">resize_term</a></H3><PRE>
76 Most of the work is done by the inner function <STRONG>resize_term</STRONG>. The outer
77 function <STRONG>resizeterm</STRONG> adds bookkeeping for the <STRONG>SIGWINCH</STRONG> handler, as well
78 as repainting the soft-key area (see <STRONG><A HREF="slk_touch.3x.html">slk_touch(3x)</A></STRONG>).
80 When resizing the windows, <STRONG>resize_term</STRONG> blank-fills the areas that are
81 extended. The calling application should fill in these areas with
84 The <STRONG>resize_term</STRONG> function attempts to resize all windows. However, due
85 to the calling convention of pads, it is not possible to resize these
86 without additional interaction with the application.
88 When resizing windows, <STRONG>resize_term</STRONG> recursively adjusts subwindows,
89 keeping them within the updated parent window's limits. If a top-level
90 window happens to extend to the screen's limits, then on resizing the
91 window, <STRONG>resize_term</STRONG> will keep the window extending to the corresponding
92 limit, regardless of whether the screen has shrunk or grown.
95 </PRE><H3><a name="h3-is_term_resized">is_term_resized</a></H3><PRE>
96 A support function <STRONG>is_term_resized</STRONG> is provided so that applications can
97 check if the <STRONG>resize_term</STRONG> function would modify the window structures.
98 It returns <STRONG>TRUE</STRONG> if the windows would be modified, and <STRONG>FALSE</STRONG> otherwise.
101 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
102 Except as noted, these functions return the integer <STRONG>ERR</STRONG> upon failure
103 and <STRONG>OK</STRONG> on success. They will fail if either of the dimensions are less
104 than or equal to zero, or if an error occurs while (re)allocating mem-
108 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
109 While these functions are intended to be used to support a signal han-
110 dler (i.e., for <STRONG>SIGWINCH</STRONG>), care should be taken to avoid invoking them
111 in a context where <STRONG>malloc</STRONG> or <STRONG>realloc</STRONG> may have been interrupted, since
112 it uses those functions.
114 If ncurses is configured to supply its own <STRONG>SIGWINCH</STRONG> handler,
116 <STRONG>o</STRONG> on receipt of a <STRONG>SIGWINCH</STRONG>, the handler sets a flag
118 <STRONG>o</STRONG> which is tested in <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> and <STRONG>doupdate</STRONG>,
120 <STRONG>o</STRONG> in turn, calling the <STRONG>resizeterm</STRONG> function,
122 <STRONG>o</STRONG> which <STRONG>ungetch</STRONG>'s a <STRONG>KEY_RESIZE</STRONG> which will be read on the next call to
123 <STRONG>wgetch</STRONG>.
125 The <STRONG>KEY_RESIZE</STRONG> alerts an application that the screen size has
126 changed, and that it should repaint special features such as pads
127 that cannot be done automatically.
129 Calling <STRONG>resizeterm</STRONG> or <STRONG>resize_term</STRONG> directly from a signal handler is
130 unsafe. This indirect method is used to provide a safe way to
131 resize the ncurses data structures.
133 If the environment variables <STRONG>LINES</STRONG> or <STRONG>COLUMNS</STRONG> are set, this overrides
134 the library's use of the window size obtained from the operating sys-
135 tem. Thus, even if a <STRONG>SIGWINCH</STRONG> is received, no screen size change may
139 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
140 It is possible to resize the screen with SVr4 curses, by
142 <STRONG>o</STRONG> exiting curses with <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG> and
144 <STRONG>o</STRONG> resuming using <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>.
146 Doing that clears the screen and is visually distracting.
148 This extension of ncurses was introduced in mid-1995. It was adopted
149 in NetBSD curses (2001) and PDCurses (2003).
152 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
153 <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>.
156 </PRE><H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
157 Thomas Dickey (from an equivalent function written in 1988 for BSD
162 <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>
166 <li><a href="#h2-NAME">NAME</a></li>
167 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
168 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
170 <li><a href="#h3-resizeterm">resizeterm</a></li>
171 <li><a href="#h3-resize_term">resize_term</a></li>
172 <li><a href="#h3-is_term_resized">is_term_resized</a></li>
175 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
176 <li><a href="#h2-NOTES">NOTES</a></li>
177 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
178 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
179 <li><a href="#h2-AUTHOR">AUTHOR</a></li>