[Impeller] fix clip culling with exp canvas.

impeller/aiks/experimental_canvas.cc

@@ -10,6 +10,7 @@
 #include "impeller/base/validation.h"
 #include "impeller/core/allocator.h"
 #include "impeller/core/formats.h"
+#include "impeller/entity/contents/clip_contents.h"
 #include "impeller/entity/contents/framebuffer_blend_contents.h"
 #include "impeller/entity/contents/text_contents.h"
 #include "impeller/entity/entity.h"
@@ -431,6 +432,14 @@ void ExperimentalCanvas::SaveLayer(
   entry.rendering_mode = Entity::RenderingMode::kSubpassAppendSnapshotTransform;
   transform_stack_.emplace_back(entry);
 
+  // The DisplayList bounds/rtree doesn't account for filters applied to parent
+  // layers, and so sub-DisplayLists are getting culled as if no filters are
+  // applied.
+  // See also: https://github.com/flutter/flutter/issues/139294
+  if (paint.image_filter) {
+    transform_stack_.back().cull_rect = std::nullopt;
+  }
+
   // Start non-collapsed subpasses with a fresh clip coverage stack limited by
   // the subpass coverage. This is important because image filters applied to
   // save layers may transform the subpass texture after it's rendered,
@@ -774,6 +783,14 @@ void ExperimentalCanvas::AddClipEntityToCurrentPass(Entity entity) {
         current_clip_coverage->Shift(-GetGlobalPassPosition());
   }
 
+  // Skip rendering the clip if it is fully contained by the current render
+  // target.
+  if (entity.GetContents()->CanSkip(
+          render_passes_.back().inline_pass_context->GetTexture()->GetSize(),
+          entity.GetTransform())) {
+    return;
+  }
+
   auto clip_coverage = entity.GetClipCoverage(current_clip_coverage);
   if (clip_coverage.coverage.has_value()) {
     clip_coverage.coverage =

impeller/entity/contents/clip_contents.cc

@@ -82,6 +82,20 @@ bool ClipContents::CanInheritOpacity(const Entity& entity) const {
 
 void ClipContents::SetInheritedOpacity(Scalar opacity) {}
 
+bool ClipContents::CanSkip(ISize render_pass_size, const Matrix& ctm) const {
+  if (clip_op_ == Entity::ClipOperation::kIntersect &&
+      geometry_->IsAxisAlignedRect() && ctm.IsTranslationScaleOnly()) {
+    std::optional<Rect> coverage = geometry_->GetCoverage(ctm);
+    if (coverage.has_value() &&
+        coverage->Contains(Rect::MakeSize(render_pass_size))) {
+      // Skip axis-aligned intersect clips that cover the whole render target
+      // since they won't draw anything to the depth buffer.
+      return true;
+    }
+  }
+  return false;
+}
+
 bool ClipContents::Render(const ContentContext& renderer,
                           const Entity& entity,
                           RenderPass& pass) const {
@@ -91,17 +105,8 @@ bool ClipContents::Render(const ContentContext& renderer,
 
   using VS = ClipPipeline::VertexShader;
 
-  if (clip_op_ == Entity::ClipOperation::kIntersect &&
-      geometry_->IsAxisAlignedRect() &&
-      entity.GetTransform().IsTranslationScaleOnly()) {
-    std::optional<Rect> coverage =
-        geometry_->GetCoverage(entity.GetTransform());
-    if (coverage.has_value() &&
-        coverage->Contains(Rect::MakeSize(pass.GetRenderTargetSize()))) {
-      // Skip axis-aligned intersect clips that cover the whole render target
-      // since they won't draw anything to the depth buffer.
-      return true;
-    }
+  if (CanSkip(pass.GetRenderTargetSize(), entity.GetTransform())) {
+    return true;
   }
 
   VS::FrameInfo info;

impeller/entity/contents/clip_contents.h

@@ -25,6 +25,8 @@ class ClipContents final : public Contents {
 
   void SetClipOperation(Entity::ClipOperation clip_op);
 
+  bool CanSkip(ISize render_pass_size, const Matrix& transform) const override;
+
   // |Contents|
   std::optional<Rect> GetCoverage(const Entity& entity) const override;
 

impeller/entity/contents/contents.cc

@@ -182,4 +182,8 @@ void Contents::SetColorSourceSize(Size size) {
   color_source_size_ = size;
 }
 
+bool Contents::CanSkip(ISize render_pass_size, const Matrix& transform) const {
+  return false;
+}
+
 }  // namespace impeller

impeller/entity/contents/contents.h

@@ -83,6 +83,13 @@ class Contents {
   ///
   void SetCoverageHint(std::optional<Rect> coverage_hint);
 
+  //----------------------------------------------------------------------------
+  /// @brief  Whether this entity can be entirely skipped during rendering.
+  ///
+  /// TODO(jonahwilliams): remove this method which was only added for clipping
+  /// once experimental canvas lands.
+  virtual bool CanSkip(ISize render_pass_size, const Matrix& transform) const;
+
   const std::optional<Rect>& GetCoverageHint() const;
 
   //----------------------------------------------------------------------------

impeller/entity/entity_unittests.cc

@@ -1532,6 +1532,35 @@ TEST_P(EntityTest, ClipContentsShouldRenderIsCorrect) {
   }
 }
 
+TEST_P(EntityTest, ClipContentsCanSkip) {
+  // Intersect Clips can be skipped if the render target coverage is fully
+  // inside of them.
+
+  auto clip = std::make_shared<ClipContents>();
+  clip->SetGeometry(Geometry::MakeRect(Rect::MakeLTRB(0, 0, 100, 100)));
+  clip->SetClipOperation(Entity::ClipOperation::kIntersect);
+
+  // Fully Contained
+  EXPECT_TRUE(clip->CanSkip(ISize::MakeWH(50, 50), {}));
+
+  // Not Intersect
+  clip->SetClipOperation(Entity::ClipOperation::kDifference);
+  EXPECT_FALSE(clip->CanSkip(ISize::MakeWH(50, 50), {}));
+
+  // Not Contained
+  clip->SetClipOperation(Entity::ClipOperation::kIntersect);
+  EXPECT_FALSE(clip->CanSkip(ISize::MakeWH(200, 200), {}));
+
+  // Not Scale Translate
+  clip->SetClipOperation(Entity::ClipOperation::kIntersect);
+  EXPECT_FALSE(
+      clip->CanSkip(ISize::MakeWH(50, 50), Matrix::MakeRotationX(Radians(2))));
+
+  // Not Axis Aligned Rectangle.
+  clip->SetGeometry(Geometry::MakeOval(Rect::MakeLTRB(0, 0, 50, 50)));
+  EXPECT_FALSE(clip->CanSkip(ISize::MakeWH(50, 50), {}));
+}
+
 TEST_P(EntityTest, ClipContentsGetClipCoverageIsCorrect) {
   // Intersection: No stencil coverage, no geometry.
   {