Section: Miscellaneous Library Functions (3X)
- scroll a curses
int scroll(WINDOW *win);
int scrl(int n);
int wscrl(WINDOW *win, int n);
routine scrolls the window up one line.
This involves moving
the lines in the window data structure.
As an optimization, if the scrolling
region of the window is the entire screen,
the physical screen
may be scrolled at the same time.
For positive n, the scrl and wscrl routines scroll the
window up n lines (line i+n becomes i); otherwise
scroll the window down n lines.
This involves moving the lines in the
window character image structure.
The current cursor position is not changed.
For these functions to work, scrolling must be enabled via scrollok.
These routines return ERR
upon failure, and OK
(SVr4 only specifies
"an integer value other than ERR
") upon successful completion.
X/Open defines no error conditions.
This implementation returns an error
if the window pointer is null, or
if scrolling is not enabled in the window, e.g., with scrollok.
Note that scrl
may be macros.
The SVr4 documentation says that the optimization of physically scrolling
immediately if the scroll region is the entire screen "is" performed, not
"may be" performed.
This implementation deliberately does not guarantee
that this will occur, to leave open the possibility of smarter
optimization of multiple scroll actions on the next update.
Neither the SVr4 nor the XSI documentation specify whether the current
current color-pair of blanks generated by the scroll function is zeroed.
Under this implementation it is.
The XSI Curses standard, Issue 4 describes these functions.