NAME

touchwin, touchline, untouchwin, wtouchln, is_linetouched, is_wintouched - control terminal output refresh in a curses window

SYNOPSIS

#include <ncurses/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

All routines return the integer ERR upon failure and an integer value other than ERR upon successful completion, unless otherwise noted in the preceding routine descriptions.

X/Open Curses does not specify any error conditions. In this implementation

is_linetouched: returns an error 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 error-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 an error if the window pointer is null, or if the line number is outside the window boundaries.

NOTES

All of these routines except wtouchln may be macros.

PORTABILITY

These functions were introduced by SVr4. The Solaris curses header file, for instance, defines both an actual function and macro for each. The macros give the same result as the actual functions. SVr4 curses does not check the window parameter win to ensure that it is not NULL; otherwise this implementation behaves the same as SVr4.

X/Open Curses, Issue 4 describes these functions, but defines no error conditions.