Updates:
Status: Started
Comment #7 on issue 22700 by [email protected]: Skia color alpha
blending calculation is slightly different from other webkit libs
http://code.google.com/p/chromium/issues/detail?id=22700
There are actually two problems here:
1) The way division by 255 is done in Skia for blending (scaling alpha 255
-> 256 and
using >> 8) introduces inaccuracies over CG's pixel-perfect blending.
2) Skia's unpremultiplying code does division by alpha in fixed-point,
which also
introduces inaccuracies.
Fixing the second is straightforward, but fixing the first has fairly deep
ramifications, so we'll have to get buy-in from the Skia guys, or at least
wrap it in
#ifdefs before proceeding. I believe attaining pixel-accurate blending is
worth
doing, since it is also the cause of a number of other bugs, such as
http://crbug.com/9993.
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