- The scroll routine scrolls the window up one line. This involves mov-
- ing 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.
+ scroll scrolls the given window up one line. That is, every visible
+ line we might number i becomes line i-1. The text of the top line in
+ the window disappears and the bottom line is populated with blank
+ characters; see bkgd(3x) or bkgrnd(3x). As an optimization, if the
+ scrolling region of the window is the entire screen, the physical
+ screen may be scrolled at the same time; see curscr(3x).
- 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.
+ scrl and wscrl scroll stdscr or the specified window up or down
+ depending on the sign of n.
- For these functions to work, scrolling must be enabled via scrollok.
+ o For positive n, line i+n becomes i (scrolling up);
+ o for negative n, line i-n becomes i (scrolling down).
-
- These routines return ERR upon failure, and OK (SVr4 only specifies "an
- integer value other than ERR") upon successful completion.
+ The cursor does not move. These functions perform no operation unless
+ scrolling is enabled for the window via scrollok(3x).
- 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.
+
+ These functions return ERR upon failure and OK upon success.
+ ncurses returns ERR if scrolling is not enabled in the window, for
+ example with scrollok(3x), or if the WINDOW pointer is null.
-
- Note that scrl and scroll 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.
+
+ Unusually, there is no wscroll function; scroll behaves as one would
+ expect wscroll to, accepting a WINDOW pointer argument.
- Neither the SVr4 nor the XSI documentation specify whether the current
- attribute or current color-pair of blanks generated by the scroll func-
- tion is zeroed. Under this implementation it is.
+ scrl and scroll may be implemented as macros.
- The XSI Curses standard, Issue 4 describes these functions.
+ X/Open Curses, Issue 4 describes these functions. It defines no error
+ conditions.
+
+ SVr4 specifies only "an integer value other than ERR" as a successful
+ return value.
+
+ SVr4 indicates that the optimization of physically scrolling
+ immediately if the scroll region is the entire screen "is" performed,
+ not "may be" performed. ncurses 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 SVr4 curses nor X/Open Curses specify whether the current
+ attribute or current color pair of blanks generated by the scroll
+ function are zeroed. ncurses does so.