[Impeller] CPU applied color filters can run twice. #139569
Description
We are currently applying the CPU filters twice:
- https://github.com/flutter/engine/blob/main/impeller/aiks/paint.cc#L54-L59
- https://github.com/flutter/engine/blob/main/impeller/aiks/paint.cc#L75
For example, see the following Aiks test:
TEST_P(AiksTest, CanRenderLinearGradientDecalWithColorFilter) {
Canvas canvas;
canvas.Scale(GetContentScale());
Paint paint;
canvas.Translate({100.0f, 0, 0});
std::vector<Color> colors = {Color{0.9568, 0.2627, 0.2118, 1.0},
Color{0.1294, 0.5882, 0.9529, 0.0}};
std::vector<Scalar> stops = {0.0, 1.0};
paint.color_source = ColorSource::MakeLinearGradient(
{0, 0}, {200, 200}, std::move(colors), std::move(stops),
Entity::TileMode::kDecal, {});
// Overlay the gradient with 25% green. This should appear as the entire
// rectangle being drawn with 25% green, including the border area outside the
// decal gradient.
paint.color_filter = ColorFilter::MakeBlend(BlendMode::kSourceOver,
Color::Green().WithAlpha(0.25));
paint.color = Color(1.0, 1.0, 1.0, 1.0);
canvas.DrawRect(Rect::MakeXYWH(0, 0, 600, 600), paint);
ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
}