Re: Speed of scrolling with a background pixmap
Kyle Jones <kyle_jones(a)wonderworks.com> writes:
Hrvoje Niksic writes:
> [...]
> Whether you use a bg pixmap or not, try comparing scrolling speed with
> and without a bg pixmap. For me, scrolling is much slower without a
> bg pixmap, even though the pixmap itself doesn't scroll.
I assume you meant that scrolling is slower WITH a background
pixmap.
Of course; sorry for the confusion.
Repainting an X window with a pixmap is slower than clearing the
same window to a single color. Repainting a window to a single
color can probably be done with a single instruction sent to the
video card. Repainting a pixmap region is going to require data to
be copied from main memory to VRAM on the card.
Would it help if the X server be made to remember the picture? For
instance, is it possible to tell X that the letters are a layer over
the background image, which will be removed and replaced with new
ones? I assume the graphical 2D acceleration hardware has *some*
optimizations for these cases?