This provides a significant performance improvement especially for Present Windows.
Whenever a lanczos resampling is done the resulted texture is cached, till the
window is damaged or a texture of different size is required. This means that
for a taskbar thumbnail the resampling only occurs once unless the window is damaged
and for present windows it only occurs when the windows are resized and then only
after the windows have already been moved. Highlighting windows does not cause
a resampling any more.
See review request http://svn.reviewboard.kde.org/r/5708/
svn path=/trunk/KDE/kdebase/workspace/; revision=1191874
This makes it possible for the GLSL compiler to unroll it, which also
avoids the need to use relative addressing. With this change the shader
should hopefully work with the R300G driver.
The unused kernel weights are set to zero so they don't contribute
to the end result.
Thanks to Tom Stellard and Marek Olšák for their suggestions on how
to solve this problem.
CCBUG: 243191
svn path=/trunk/KDE/kdebase/workspace/; revision=1175021
