tree 8647ca08782e9ae632ee436c1c0e023f1bd7f214
parent fba8a742cb5a4cb09d60d877a0f6b79276a07550
author Brian Osman <brianosman@google.com> 1623782177 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> 1623938783 +0000

Add the concept of an "input" FP to GrSkSLFP

FPs are used to represent effects with varying semantics. In particular,
shaders (that generate colors with no real input), and color filters
(that always have a "primary" input color on which they operate).

Even FPs that are not directly tied to a particular SkShader or
SkColorFilter tend to fall into these two categories. GrSkSLFP was
tailored to the shader semantics. It always supported having child FPs,
but these weren't considered "special" in any way - there could be
multiple, and each one could be sampled in whatever way the SkSL wanted.

This CL adds a dedicated "input" FP slot, so that color filters (and FPs
that resemble color filters) can naturally map better. Previously, we
had to inject an additional FP to do composition of the input and the
SkSL. That worked fine - this change is really about cutting down on
allocations and extra CPU work for that extra FP in the tree.

Change-Id: Ic37457b31f8ed7b4aa8d814a5e78806caa19e1c5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/418739
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>