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<H1 class="no-header">curs_scr_dump 3x 2025-01-18 ncurses 6.6 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>scr_dump</STRONG>, <STRONG>scr_restore</STRONG>, <STRONG>scr_init</STRONG>, <STRONG>scr_set</STRONG> - read/write a <EM>curses</EM> screen
from/to a file
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>scr_dump(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>scr_restore(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>scr_init(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>scr_set(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <EM>filename</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
<EM>curses</EM> provides applications the ability to write the contents of the
screen to a file and read them back. To read/write a window (rather
than the whole screen) from/to a file, use <STRONG><A HREF="curs_util.3x.html">getwin(3x)</A></STRONG> and <STRONG><A HREF="curs_util.3x.html">putwin(3x)</A></STRONG>,
respectively.
</PRE><H3><a name="h3-scr_dump">scr_dump</a></H3><PRE>
<STRONG>scr_dump</STRONG> writes to <EM>filename</EM> the contents of the virtual screen; see
<STRONG><A HREF="curs_variables.3x.html">curscr(3x)</A></STRONG>.
</PRE><H3><a name="h3-scr_restore">scr_restore</a></H3><PRE>
<STRONG>scr_restore</STRONG> updates the virtual screen to match the contents of
<EM>filename</EM> (if validly written with <STRONG>scr_dump</STRONG>). <EM>curses</EM> does not perform a
refresh; after making any desired changes, call <STRONG><A HREF="curs_refresh.3x.html">doupdate(3x)</A></STRONG> or
similar.
</PRE><H3><a name="h3-scr_init">scr_init</a></H3><PRE>
<STRONG>scr_init</STRONG> reads <EM>filename</EM>, using it to initialize <EM>curses</EM> data structures
describing the state of the terminal screen. <EM>curses</EM> then, if it
decides the terminal state is valid, bases its next update of the
screen on this information rather than clearing it and starting from
scratch.
<EM>curses</EM> regards the terminal as in an invalid state for computation of
updates based on the contents of <EM>filename</EM> if
<STRONG>o</STRONG> <EM>curses</EM> knows that the terminal has been written to since the
preceding <STRONG>scr_dump</STRONG> call, or
<STRONG>o</STRONG> the terminal type supports the <EM>terminfo</EM> capabilities <STRONG>exit_ca_mode</STRONG>
(<STRONG>rmcup</STRONG>) or <STRONG>non_rev_rmcup</STRONG> (<STRONG>nrrmc</STRONG>).
Either of the foregoing conditions means that <EM>curses</EM> cannot assume that
the terminal's contents match their representation in <EM>filename</EM>. The
former is due to terminal features (such as <STRONG>xterm(1)</STRONG>'s "alternate
screen") that couple cursor-positioning mode with a local cache of
screen contents. <EM>curses</EM> cannot know whether the terminal is displaying
from that local cache at the time the application calls <STRONG>scr_init</STRONG>, so it
makes a pessimistic assumption that a full redraw is required; see
subsection "Cursor Motions" of <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>.
<STRONG>scr_init</STRONG> could be used after <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG> or <STRONG>system(3)</STRONG> to share the
screen with another process that has done a <STRONG>scr_dump</STRONG> after <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG>.
An application that supports suspending its state on exit and
subsequent resumption upon later execution might use <STRONG>scr_dump</STRONG> and
<STRONG>scr_init</STRONG> thus.
</PRE><H3><a name="h3-scr_set">scr_set</a></H3><PRE>
<STRONG>scr_set</STRONG> combines <STRONG>scr_restore</STRONG> and <STRONG>scr_init</STRONG>, synchronizing the contents
of <EM>filename</EM> with the virtual screen. It can be regarded as a screen
inheritance function; consider a real-time screen-sharing application.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
In <EM>ncurses</EM>, each function returns <STRONG>ERR</STRONG> if it cannot open <EM>filename</EM>.
<STRONG>scr_init</STRONG>, <STRONG>scr_restore</STRONG>, and <STRONG>scr_set</STRONG> return <STRONG>ERR</STRONG> if the contents of
<EM>filename</EM> are invalid.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
<STRONG>scr_init</STRONG>, <STRONG>scr_restore</STRONG>, and <STRONG>scr_set</STRONG> may be implemented as macros.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
X/Open Curses Issue 4 describes these functions. It specifies no error
conditions for them.
SVr4 omitted the <EM>const</EM> qualifiers.
SVr4 documentation describes <EM>scr</EM><STRONG>_</STRONG><EM>init</EM> such that the dump data is also
considered invalid "if the time-stamp of the tty is old" but does not
define "old".
As of 2024, <EM>PDCurses</EM> provides these functions. NetBSD <EM>curses</EM> does not.
Other implementations of <EM>curses</EM> store the window in binary form, which
makes the dump dependent upon the <EM>curses</EM> library's internal data
structures. <EM>ncurses</EM> avoids this drawback by storing the dump in
textual form, allowing more flexible use of the data. For instance,
the <EM>scr</EM><STRONG>_</STRONG><EM>restore</EM> of SVr4 <EM>curses</EM> requires that the dumped window have the
same dimensions as the restored window. <EM>ncurses</EM> uses its <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>
extension to adjust the restored window size.
</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
SVr3 (1987) introduced <EM>scr</EM><STRONG>_</STRONG><EM>dump</EM>, <EM>scr</EM><STRONG>_</STRONG><EM>init</EM>, and <EM>scr</EM><STRONG>_</STRONG><EM>restore</EM>. SVr3.1
added <EM>scr</EM><STRONG>_</STRONG><EM>set</EM>.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>,
<STRONG>system(3)</STRONG>, <STRONG><A HREF="scr_dump.5.html">scr_dump(5)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>, <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>
ncurses 6.6 2025-01-18 <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-scr_dump">scr_dump</a></li>
<li><a href="#h3-scr_restore">scr_restore</a></li>
<li><a href="#h3-scr_init">scr_init</a></li>
<li><a href="#h3-scr_set">scr_set</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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