[Impeller] Fix and reland drawPaint collapsing optimization. (#43097)
Collapses DrawPaint calls into clear colors when possible.
issue https://github.com/flutter/flutter/issues/129292
relands https://github.com/flutter/engine/pull/41711
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diff --git a/impeller/aiks/aiks_unittests.cc b/impeller/aiks/aiks_unittests.cc
index 464dc00..37b13e5 100644
--- a/impeller/aiks/aiks_unittests.cc
+++ b/impeller/aiks/aiks_unittests.cc
@@ -1992,6 +1992,18 @@
ASSERT_TRUE(delegate->CanCollapseIntoParentPass(entity_pass.get()));
}
+TEST_P(AiksTest, DrawPaintAbsorbsClears) {
+ Canvas canvas;
+ canvas.DrawPaint({.color = Color::Red(), .blend_mode = BlendMode::kSource});
+ canvas.DrawPaint(
+ {.color = Color::CornflowerBlue(), .blend_mode = BlendMode::kSource});
+
+ Picture picture = canvas.EndRecordingAsPicture();
+
+ ASSERT_EQ(picture.pass->GetElementCount(), 0u);
+ ASSERT_EQ(picture.pass->GetClearColor(), Color::CornflowerBlue());
+}
+
TEST_P(AiksTest, ForegroundBlendSubpassCollapseOptimization) {
Canvas canvas;
diff --git a/impeller/aiks/canvas.cc b/impeller/aiks/canvas.cc
index 3e2962e..204f842 100644
--- a/impeller/aiks/canvas.cc
+++ b/impeller/aiks/canvas.cc
@@ -172,6 +172,16 @@
}
void Canvas::DrawPaint(const Paint& paint) {
+ if (xformation_stack_.size() == 1 && // If we're recording the root pass,
+ GetCurrentPass().GetElementCount() == 0 && // and this is the first item,
+ (paint.blend_mode == BlendMode::kSourceOver ||
+ paint.blend_mode == BlendMode::kSource) &&
+ paint.color.alpha >= 1.0f) {
+ // Then we can absorb this drawPaint as the clear color of the pass.
+ GetCurrentPass().SetClearColor(paint.color);
+ return;
+ }
+
Entity entity;
entity.SetTransformation(GetCurrentTransformation());
entity.SetStencilDepth(GetStencilDepth());
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index 87ff23e..0c02217 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -478,7 +478,7 @@
renderer, // renderer
subpass_size, // size
subpass->GetTotalPassReads(renderer) > 0, // readable
- clear_color_.Premultiply()); // clear_color
+ Color::BlackTransparent()); // clear_color
if (!subpass_target.IsValid()) {
VALIDATION_LOG << "Subpass render target is invalid.";
diff --git a/impeller/renderer/render_target.cc b/impeller/renderer/render_target.cc
index 47ade6e..0b52640 100644
--- a/impeller/renderer/render_target.cc
+++ b/impeller/renderer/render_target.cc
@@ -313,7 +313,7 @@
// Color attachment.
ColorAttachment color0;
- color0.clear_color = Color::BlackTransparent();
+ color0.clear_color = color_attachment_config.clear_color;
color0.load_action = color_attachment_config.load_action;
color0.store_action = color_attachment_config.store_action;
color0.texture = color0_msaa_tex;
