tree d5c12299faaf99a1f494235805919ede8e7eb2c7
parent b2566c84b0ecfca64a67add2cc932a086d462a00
author senorblanco@chromium.org <senorblanco@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> 1370022552 +0000
committer senorblanco@chromium.org <senorblanco@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> 1370022552 +0000

Implement SkXfermode image filter. This required changing the signature of SkXfermode::asNewEffectOrCoeffs(), to add an optional background texture.

For the raster path, we do a straightforward 2-pass method: draw background, then composite the foreground over it.

For the GPU path, if the xfermode can be expressed as an effect, we build an effect with the background texture incorporated, then do a single-pass draw fetching both foreground and background textures, and compositing to the result. If the xfermode is expressed as src/dst coefficients, we do a 2-pass draw as in the raster path and use fixed-function blending.

R=bsalomon@google.com, reed@google.com

Review URL: https://codereview.chromium.org/16125008

git-svn-id: http://skia.googlecode.com/svn/trunk/include@9373 2bbb7eff-a529-9590-31e7-b0007b416f81