update-drawing-with-cached-display-from-points update the drawing using the cached display, indicating the rectangle in which the
(argument to start-drawing-with-cached-display) needs to draw.
pane is the output pane to update. The other arguments specify the rectangle to be updated. The arguments are used in three ways: first they cause an implicit call to invalidate-rectangle with the appropriate arguments, secondly they define a mask that is used when calling the temp-display-callback , and third they provide arguments that are passed to the temp-display-callback .
In the case of
update-drawing-with-cached-display, the arguments specify the rectangle in the standard way (the same way that they are passed to the
default to 0,
defaults to the width of
defaults to the height of
In the case of
update-drawing-with-cached-display-from-points, the arguments specify two points, (
) and (
), which are corners of a rectangle. This rectangle is then extended horizontally in both directions by
, and extended vertically in both directions by
. The final result is:
Omitting the rectangle (that is, calling
update-drawing-with-cached-display with only the
argument) causes all of the pane to be redisplayed each time. On slow displays, that may cause the display to be sluggish. On Windows and Cocoa with the normal settings, it is probably always fast enough, at least with modern machines. On GTK+ it depends on the speed of the connection to the X server, which in many cases is too slow for medium-size panes.
CAPI User Guide and Reference Manual (Macintosh version) - 3 Aug 2017