There is no more 'inout half4 color'. Effects return their output color.
If an effect wants the input color, it must use the (already existing)
approach of sampling a nullptr input shader.
The change is guarded for Chromium (so we can update their runtime color
filters in skia_renderer.cc).
For the GPU backend, FPs can now override usesExplicitReturn to indicate
that their emitCode will generate a return statement. If that's true,
then writeProcessorFunction doesn't inject the automatic return of the
output color, and emitFragProc will *always* wrap that FP in a helper
function, even as a top-level FP. GrSkSLFP opts in to this behavior, so
that the user-supplied return becomes the actual return in the FP's
emitCode.
Adapting the skvm code to this wasn't too bad: It looks fragile (what
happens if there are multiple returns?), but that's not really possible
today, without varying control flow.
Bug: skia:10613
Change-Id: I205b81fd87dd32bab30b6d6d5fc78853485da036
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/310756
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
767f444feb