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- * @Id: curs_scr_dump.3x,v 1.35 2023/11/25 11:29:34 tom Exp @
+ * @Id: curs_scr_dump.3x,v 1.45 2024/06/01 22:29:45 tom Exp @
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-<H1 class="no-header">curs_scr_dump 3x 2023-11-25 ncurses 6.4 Library calls</H1>
+<H1 class="no-header">curs_scr_dump 3x 2024-06-01 ncurses 6.5 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-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>
+ <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>
- The <STRONG>scr_dump</STRONG> routine dumps the current contents of the <EM>virtual</EM> <EM>screen</EM>
- to the file <EM>filename</EM>.
+ <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>
- The <STRONG>scr_restore</STRONG> routine sets the <EM>virtual</EM> <EM>screen</EM> to the contents of
- <EM>filename</EM>, which must have been written using <STRONG>scr_dump</STRONG>. The next call
- to <STRONG>doupdate</STRONG> restores the <EM>physical</EM> <EM>screen</EM> to the way it looked in the
- dump file.
+ <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>
- The <STRONG>scr_init</STRONG> routine reads in the contents of <EM>filename</EM> and uses them to
- initialize the <STRONG>curses</STRONG> data structures about what the terminal currently
- has on its screen. If the data is determined to be valid, <STRONG>curses</STRONG> bases
- its next update of the screen on this information rather than clearing
- the screen and starting from scratch. <STRONG>scr_init</STRONG> is used after
- <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG> or a <STRONG>system(3)</STRONG> call to share the screen with another
- process which has done a <STRONG>scr_dump</STRONG> after its <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG> call. The data
- is declared invalid
+ <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.
- <STRONG>o</STRONG> if the terminfo capabilities <STRONG>rmcup</STRONG> and <STRONG>nrrmc</STRONG> exist, also
+ <EM>curses</EM> regards the terminal being in an invalid state for computation
+ of updates based on the contents of <EM>filename</EM> if
- <STRONG>o</STRONG> if the terminal has been written to since the preceding <STRONG>scr_dump</STRONG>
- call.
+ <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>), or
+ <STRONG>o</STRONG> <EM>curses</EM> knows that the terminal has been written to since the
+ preceding <STRONG>scr_dump</STRONG> call.
+
+ 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 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>
- The <STRONG>scr_set</STRONG> routine is a combination of <STRONG>scr_restore</STRONG> and <STRONG>scr_init</STRONG>. It
- tells the program that the information in <EM>filename</EM> is what is currently
- on the screen, and also what the program wants on the screen. This can
- be thought of as a screen inheritance function.
- To read (write) a window from (to) a file, use the <STRONG>getwin</STRONG> and <STRONG>putwin</STRONG>
- routines [see <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>].
+</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>
- All routines return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> upon success.
+ These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
- X/Open defines no error conditions. In this implementation, each will
- return an error if the file cannot be opened.
+ 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>
- Note that <STRONG>scr_init</STRONG>, <STRONG>scr_set</STRONG>, and <STRONG>scr_restore</STRONG> may be macros.
+ <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>
- These functions are described in the XSI Curses standard, Issue 4,
- which adds <EM>const</EM> qualifiers to the arguments.
+ X/Open Curses, Issue 4 describes these functions. It specifies no
+ error conditions for them.
+
+ SVr4 omitted the <EM>const</EM> qualifiers.
- The SVr4 docs merely say under <STRONG>scr_init</STRONG> that the dump data is also
- considered invalid "if the time-stamp of the tty is old" but do not
+ SVr4 documentation describes <STRONG>scr_init</STRONG> such that the dump data is also
+ considered invalid "if the time-stamp of the tty is old" but does not
define "old".
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ SVr3 (1987) introduced <STRONG>scr_dump</STRONG>, <STRONG>scr_init</STRONG>, and <STRONG>scr_restore</STRONG>. SVr3.1
+ added <STRONG>scr_set</STRONG>.
+
+
</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>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>
-ncurses 6.4 2023-11-25 <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>
+ncurses 6.5 2024-06-01 <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<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>