GUI: Less CPU-intensive credits scroll
|Reported by:||eriktorbjorn||Owned by:||fingolfin|
Currently the credits scroll in the ScummVM "About"
window is agonizingly slow. This is because each time
the text is updated it issues a full redraw, which will
redraw both of the active dialogs. Both of them will
call the blendRect() function to draw the transparent
On my 450 MHz PIII each call to blendRect() takes
something like a tenth of a second, possibly a bit
longer. The overhead from drawing the remaining parts
of the dialogs is trivial by comparision.
This patch is an attempt to speed things up. The first
time the dialog is drawn, it makes a "snapshot" of the
blended background. Then, instead of issuing a full
redraw every time it redraws only the "About" dialog
itself, and this time it uses that snapshot as
background. (The snapshot will be regenerated if the
It is, perhaps, a bit hackish, but I really don't see
any other way.
Ticket imported from: #1183808. Ticket imported from: patches/524.