[Bug 9262] Adobe Photoshop CS filter gallery preview doesn't work

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=9262





--- Comment #1 from Mikolaj Zalewski <mikolaj.zalewski at gmail.com>  2007-08-27 19:17:14 ---
Created an attachment (id=7844)
 --> (http://bugs.winehq.org/attachment.cgi?id=7844)
patches

This bug is caused by AlphaBlend ignoring the blendFunction.AlphaFormat field.
Currently we assume it's value is AC_SRC_ALPHA - the alpha data is available
for each pixel as an alpha channel in the DIB. However if this field is 0 we
should assume that each pixel have a constant alpha (it's written in a very
unclear way in the MSDN that this value is valid). With this patch the filter
gallery seems to be drawn correctly.

I don't know if this way of solving it is the best or there is a way to ask
XRender to do it for us. I will try to find some documentation of it. Also even
with this patch we ignore SourceConstantAlpha (Photoshop filter gallery doesn't
use it) - a factor by which we rescale the alpha values. It's probably rarely
used if there is an alpha channel but it's the way to manipulate transparency
without an alpha channel. Adding it only for the later case is trivial but I
will search if there is a way that would work for both 0 and AC_SRC_ALPHA.


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