https://invisible-island.net/ncurses/man/
curs_scr_dump(3x) Library calls curs_scr_dump(3x)
scr_dump, scr_restore, scr_init, scr_set - read/write a curses screen
from/to a file
#include <curses.h>
int scr_dump(const char * filename);
int scr_restore(const char * filename);
int scr_init(const char * filename);
int scr_set(const char * filename);
curses 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 getwin(3x) and putwin(3x),
respectively.
scr_dump writes to filename the contents of the virtual screen; see
curscr(3x).
scr_restore updates the virtual screen to match the contents of
filename (if validly written with scr_dump). curses does not perform a
refresh; after making any desired changes, call doupdate(3x) or
similar.
scr_init reads filename, using it to initialize curses data structures
describing the state of the terminal screen. curses 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.
curses regards the terminal as in an invalid state for computation of
updates based on the contents of filename if
o curses knows that the terminal has been written to since the
preceding scr_dump call, or
o the terminal type supports the terminfo capabilities exit_ca_mode
(rmcup) or non_rev_rmcup (nrrmc).
Either of the foregoing conditions means that curses cannot assume that
the terminal's contents match their representation in filename. The
former is due to terminal features (such as xterm(1)'s "alternate
screen") that couple cursor-positioning mode with a local cache of
screen contents. curses cannot know whether the terminal is displaying
from that local cache at the time the application calls scr_init, so it
makes a pessimistic assumption that a full redraw is required; see
subsection "Cursor Motions" of terminfo(5).
scr_init could be used after initscr(3x) or system(3) to share the
screen with another process that has done a scr_dump after endwin(3x).
An application that supports suspending its state on exit and
subsequent resumption upon later execution might use scr_dump and
scr_init thus.
scr_set combines scr_restore and scr_init, synchronizing the contents
of filename with the virtual screen. It can be regarded as a screen
inheritance function; consider a real-time screen-sharing application.
These functions return OK on success and ERR on failure.
In ncurses, each function returns ERR if it cannot open filename.
scr_init, scr_restore, and scr_set return ERR if the contents of
filename are invalid.
scr_init, scr_restore, and scr_set may be implemented as macros.
X/Open Curses, Issue 4 describes these functions. It specifies no
error conditions for them.
SVr4 omitted the const qualifiers.
SVr4 documentation describes scr_init 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, PDCurses provides these functions. NetBSD curses does not
provide these functions, although it provides getwin.
Other implementations of curses store the window in binary form. One
drawback to binary form is that this makes the dump dependent upon the
curses library's internal data structures. Rather than do that,
ncurses stores the dump in textual form, allowing more flexible use of
the data. For instance, SVr4 curses scr_restore requires that the
dumped window have the same dimensions as the restored window. ncurses
uses wresize to adjust the restored window size.
SVr3 (1987) introduced scr_dump, scr_init, and scr_restore. SVr3.1
added scr_set.
curses(3x), curs_initscr(3x), curs_refresh(3x), curs_util(3x),
system(3), scr_dump(5), terminfo(5), wresize(3x)
ncurses 6.5 2024-09-21 curs_scr_dump(3x)