tree c9f149daeffceaba40edc8b830562661c6fe3eb0
parent 5b83d05bf4505f180364424ef94e3e1126622ffc
author Nigel Tao <nigeltao@google.com> 1550116253 +1100
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1550176618 +0000

Have Wuffs output to BGRA, not indexed color

This lets us set the yet-to-be-decoded pixels for a partially decoded
image to be transparent. Prior to this commit, we decoded to an indexed
color buffer, which was not guaranteed to be able to represent
transparent pixels.

This is also one step towards fewer post-decode passes. The current
model has multiple separate passes: SkSwizzler handles expanding pixel
indexes to BGRA and subsetting / scaling, SkWuffsCodec handles blending
potentially transparent pixels over the previous frame and skcms handles
color correction. The long term plan is to remove the SkSwizzler from
that chain.

Bug: skia:8235
Change-Id: I9651fb8ec7a7811dd2cd77b22c9527c8b8a9963d
Reviewed-on: https://skia-review.googlesource.com/c/177960
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>