curs_touch
Section: Library calls (3X)
Updated: 202-0-18
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NAME
touchwin,
touchline,
untouchwin,
wtouchln,
is_linetouched,
is_wintouched -
control terminal output refresh in a
curses window
SYNOPSIS
#include <curses.h>
int touchline(WINDOW *win, int start, int count);
int touchwin(WINDOW *win);
int wtouchln(WINDOW *win, int y, int n, int changed);
int untouchwin(WINDOW *win);
bool is_linetouched(WINDOW *win, int line);
bool is_wintouched(WINDOW *win);
DESCRIPTION
The
touchwin and
touchline routines throw away all
optimization information about which parts of the window have been
touched, by pretending that the entire window has been drawn on.
This
is sometimes necessary when using overlapping windows, since a change
to one window affects the other window, but the records of which lines
have been changed in the other window do not reflect the change.
The
routine
touchline only pretends that
count lines have been
changed, beginning with line
start.
The untouchwin routine marks all lines in the window as unchanged since
the last call to wrefresh.
The wtouchln routine makes n lines in the window, starting
at line y, look as if they have (changed=1) or have
not (changed=0) been changed since the last call to
wrefresh.
The is_linetouched and is_wintouched routines return
TRUE if the specified line/window was modified since the last
call to wrefresh; otherwise they return FALSE. In
addition, is_linetouched returns ERR if line is not
valid for the given window.
RETURN VALUE
Functions returning integers return
ERR
upon failure and
OK
upon success.
In
ncurses,
-
- is_linetouched
-
returns
ERR
if the window pointer is null, or
if the line number is outside the window boundaries.
-
The constant ERR is distinct from TRUE and FALSE,
which are the normal return values of this function.
Because the function returns a bool,
returning ERR (which is neither TRUE nor FALSE)
may not be supported by the compiler.
-
To provide erro-checking and also match the X/Open function prototype,
the ERR is provided by a macro named is_linetouched.
The actual function returns FALSE when it detects an error.
- wtouchln
-
returns
ERR
if the window pointer is null, or
if the line number is outside the window boundaries.
NOTES
All of these functions except
wtouchln
may be implemented as macros.
PORTABILITY
X/Open Curses Issue 4 describes these functions.
It specifies no error conditions for them.
SVr4 describes a successful return value
except where "otherwise noted"
as
"an integer value other than
ERR".
SVr4 does not check
win
to ensure that it is not a null pointer.
HISTORY
SVr2 (1984) introduced
touchwin,
SVr3 (1987) added
touchline.
SVr3.1 later that year supplied
is_linetouched,
is_wintouched,
untouchwin,
and
wtouchln.
SEE ALSO
curses(3X),
curs_refresh(3X),
curs_variables(3X)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- NOTES
-
- PORTABILITY
-
- HISTORY
-
- SEE ALSO
-
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