Create FP GrFragmentProcessor::UseDestColorAsInput.
Returns a fragment processor which samples the passed-in fragment
processor using `args.fDestColor` as its input color. Pass a null FP
and it will return `args.fDestColor` directly. (This is only meaningful
in contexts like blenders, which use a source and dest color.)
This also fixes a bug in invokeChild which failed to forward along the
dest color when one blend function invokes another blend function, and
fixes an edge case where GrSkSLFP where it would fail to enable the
blend-function mode when the dstFP is null.
Change-Id: I46c8bffeb602d0c0b2b4dd1723a893582f3007ed
Bug: skia:12257
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/434681
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
5 files changed
