tree 02a6a2b3076a5ebaa6a531b4b90bf81b9688148f
parent 764e546c3241dfd9f7cd0358f1173071a15550c2
author Mike Klein <mtklein@google.com> 1534870262 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1534871736 +0000

treat opaque dsts as src alpha type

Ignoring for the moment principled reasons to do this,
this has the following nice properties:

   1) in the absence of a color space transform,
      all sources are transformed to opaque by dropping
      their alpha channel (not part of the steps)

   2) premul sources are not unpremultiplied
      unless we need to transform color spaces

   3) unpremul sources are never premultiplied

This seems like the best generalization of 1) to cases
that require a color space transformation.

The alternative that we have at head treats opaque as
unpremul, so transforming from premul to opaque preserves
the abstract color but not the color composed on black.

Change-Id: Ic7d7ee24012da3d53378c20f5a4e54fa32405613
Reviewed-on: https://skia-review.googlesource.com/148388
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>