Revert "Revert layer state stack (flutter#37090)"

This reverts commit b5c5256.

Author: flar

ci/licenses_golden/licenses_flutter

@@ -777,6 +777,9 @@ FILE: ../../../flutter/flow/layers/layer.cc
 FILE: ../../../flutter/flow/layers/layer.h
 FILE: ../../../flutter/flow/layers/layer_raster_cache_item.cc
 FILE: ../../../flutter/flow/layers/layer_raster_cache_item.h
+FILE: ../../../flutter/flow/layers/layer_state_stack.cc
+FILE: ../../../flutter/flow/layers/layer_state_stack.h
+FILE: ../../../flutter/flow/layers/layer_state_stack_unittests.cc
 FILE: ../../../flutter/flow/layers/layer_tree.cc
 FILE: ../../../flutter/flow/layers/layer_tree.h
 FILE: ../../../flutter/flow/layers/layer_tree_unittests.cc

display_list/display_list_builder.cc

@@ -709,6 +709,21 @@ SkRect DisplayListBuilder::getLocalClipBounds() {
   return kMaxCullRect_;
 }
 
+bool DisplayListBuilder::quickReject(const SkRect& bounds) const {
+  if (bounds.isEmpty()) {
+    return true;
+  }
+  SkMatrix matrix = getTransform();
+  // We don't need the inverse, but this method tells us if the matrix
+  // is singular in which case we can reject all rendering.
+  if (!matrix.invert(nullptr)) {
+    return true;
+  }
+  SkRect dev_bounds;
+  matrix.mapRect(bounds).roundOut(&dev_bounds);
+  return !current_layer_->clip_bounds.intersects(dev_bounds);
+}
+
 void DisplayListBuilder::drawPaint() {
   Push<DrawPaintOp>(0, 1);
   CheckLayerOpacityCompatibility();

display_list/display_list_builder.h

@@ -206,7 +206,7 @@ class DisplayListBuilder final : public virtual Dispatcher,
   /// Returns the 3x3 partial perspective transform representing all transform
   /// operations executed so far in this DisplayList within the enclosing
   /// save stack.
-  SkMatrix getTransform() { return current_layer_->matrix.asM33(); }
+  SkMatrix getTransform() const { return current_layer_->matrix.asM33(); }
 
   void clipRect(const SkRect& rect, SkClipOp clip_op, bool is_aa) override;
   void clipRRect(const SkRRect& rrect, SkClipOp clip_op, bool is_aa) override;
@@ -221,6 +221,11 @@ class DisplayListBuilder final : public virtual Dispatcher,
   /// recorded rendering operations are interpreted.
   SkRect getLocalClipBounds();
 
+  /// Return true iff the supplied bounds are easily shown to be outside
+  /// of the current clip bounds. This method may conservatively return
+  /// false if it cannot make the determination.
+  bool quickReject(const SkRect& bounds) const;
+
   void drawPaint() override;
   void drawPaint(const DlPaint& paint);
   void drawColor(DlColor color, DlBlendMode mode) override;

display_list/display_list_canvas_unittests.cc

@@ -2040,6 +2040,9 @@ class CanvasCompareTester {
       const uint32_t* test_row = test_pixels->addr32(0, y);
       for (int x = 0; x < test_pixels->width(); x++) {
         if (ref_row[x] != test_row[x]) {
+          if (should_match) {
+            FML_LOG(ERROR) << std::hex << ref_row[x] << " != " << test_row[x];
+          }
           pixels_different++;
         }
       }
@@ -3238,5 +3241,176 @@ TEST_F(DisplayListCanvas, DrawShadowDpr) {
       CanvasCompareTester::DefaultTolerance.addBoundsPadding(3, 3));
 }
 
+TEST_F(DisplayListCanvas, SaveLayerConsolidation) {
+  float commutable_color_matrix[]{
+      // clang-format off
+      0, 1, 0, 0, 0,
+      0, 0, 1, 0, 0,
+      1, 0, 0, 0, 0,
+      0, 0, 0, 1, 0,
+      // clang-format on
+  };
+  float non_commutable_color_matrix[]{
+      // clang-format off
+      0, 1, 0, .1, 0,
+      0, 0, 1, .1, 0,
+      1, 0, 0, .1, 0,
+      0, 0, 0, .7, 0,
+      // clang-format on
+  };
+  SkMatrix contract_matrix;
+  contract_matrix.setScale(0.9f, 0.9f, kRenderCenterX, kRenderCenterY);
+
+  std::vector<SkScalar> opacities = {
+      0,
+      0.5f,
+      SK_Scalar1,
+  };
+  std::vector<std::shared_ptr<DlColorFilter>> color_filters = {
+      std::make_shared<DlBlendColorFilter>(DlColor::kCyan(),
+                                           DlBlendMode::kSrcATop),
+      std::make_shared<DlMatrixColorFilter>(commutable_color_matrix),
+      std::make_shared<DlMatrixColorFilter>(non_commutable_color_matrix),
+      DlSrgbToLinearGammaColorFilter::instance,
+      DlLinearToSrgbGammaColorFilter::instance,
+  };
+  std::vector<std::shared_ptr<DlImageFilter>> image_filters = {
+      std::make_shared<DlBlurImageFilter>(5.0f, 5.0f, DlTileMode::kDecal),
+      std::make_shared<DlDilateImageFilter>(5.0f, 5.0f),
+      std::make_shared<DlErodeImageFilter>(5.0f, 5.0f),
+      std::make_shared<DlMatrixImageFilter>(contract_matrix,
+                                            DlImageSampling::kLinear),
+  };
+  RenderEnvironment env = RenderEnvironment::MakeN32();
+
+  auto render_content = [](DisplayListBuilder& builder) {
+    builder.drawRect(
+        SkRect{kRenderLeft, kRenderTop, kRenderCenterX, kRenderCenterY},
+        DlPaint().setColor(DlColor::kYellow()));
+    builder.drawRect(
+        SkRect{kRenderCenterX, kRenderTop, kRenderRight, kRenderCenterY},
+        DlPaint().setColor(DlColor::kRed()));
+    builder.drawRect(
+        SkRect{kRenderLeft, kRenderCenterY, kRenderCenterX, kRenderBottom},
+        DlPaint().setColor(DlColor::kBlue()));
+    builder.drawRect(
+        SkRect{kRenderCenterX, kRenderCenterY, kRenderRight, kRenderBottom},
+        DlPaint().setColor(DlColor::kRed().modulateOpacity(0.5f)));
+  };
+
+  // clang-format off
+  auto test_attributes = [&env, render_content]
+      (DlPaint& paint1, DlPaint& paint2, const DlPaint& paint_both,
+       bool same, bool rev_same, const std::string& desc1,
+       const std::string& desc2) {
+    // clang-format on
+    DisplayListBuilder nested_builder;
+    nested_builder.saveLayer(&kTestBounds, &paint1);
+    nested_builder.saveLayer(&kTestBounds, &paint2);
+    render_content(nested_builder);
+    auto nested_surface = env.MakeSurface();
+    nested_builder.Build()->RenderTo(nested_surface->canvas());
+
+    DisplayListBuilder reverse_builder;
+    reverse_builder.saveLayer(&kTestBounds, &paint2);
+    reverse_builder.saveLayer(&kTestBounds, &paint1);
+    render_content(reverse_builder);
+    auto reverse_surface = env.MakeSurface();
+    reverse_builder.Build()->RenderTo(reverse_surface->canvas());
+
+    DisplayListBuilder combined_builder;
+    combined_builder.saveLayer(&kTestBounds, &paint_both);
+    render_content(combined_builder);
+    auto combined_surface = env.MakeSurface();
+    combined_builder.Build()->RenderTo(combined_surface->canvas());
+
+    // Set this boolean to true to test if combinations that are marked
+    // as incompatible actually are compatible despite our predictions.
+    // Some of the combinations that we treat as incompatible actually
+    // are compatible with swapping the order of the operations, but
+    // it would take a bit of new infrastructure to really identify
+    // those combinations. The only hard constraint to test here is
+    // when we claim that they are compatible and they aren't.
+    const bool always = false;
+
+    if (always || same) {
+      CanvasCompareTester::quickCompareToReference(
+          nested_surface->pixmap(), combined_surface->pixmap(), same,
+          "nested " + desc1 + " then " + desc2);
+    }
+    if (always || rev_same) {
+      CanvasCompareTester::quickCompareToReference(
+          reverse_surface->pixmap(), combined_surface->pixmap(), rev_same,
+          "nested " + desc2 + " then " + desc1);
+    }
+  };
+
+  // CF then Opacity should always work.
+  // The reverse sometimes works.
+  for (size_t cfi = 0; cfi < color_filters.size(); cfi++) {
+    auto color_filter = color_filters[cfi];
+    std::string cf_desc = "color filter #" + std::to_string(cfi + 1);
+    DlPaint nested_paint1 = DlPaint().setColorFilter(color_filter);
+
+    for (size_t oi = 0; oi < opacities.size(); oi++) {
+      SkScalar opacity = opacities[oi];
+      std::string op_desc = "opacity " + std::to_string(opacity);
+      DlPaint nested_paint2 = DlPaint().setOpacity(opacity);
+
+      DlPaint combined_paint = nested_paint1;
+      combined_paint.setOpacity(opacity);
+
+      bool op_then_cf_works = opacity <= 0.0 || opacity >= 1.0 ||
+                              color_filter->can_commute_with_opacity();
+
+      test_attributes(nested_paint1, nested_paint2, combined_paint, true,
+                      op_then_cf_works, cf_desc, op_desc);
+    }
+  }
+
+  // Opacity then IF should always work.
+  // The reverse can also work for some values of opacity.
+  // The reverse should also theoretically work for some IFs, but we
+  // get some rounding errors that are more than just trivial.
+  for (size_t oi = 0; oi < opacities.size(); oi++) {
+    SkScalar opacity = opacities[oi];
+    std::string op_desc = "opacity " + std::to_string(opacity);
+    DlPaint nested_paint1 = DlPaint().setOpacity(opacity);
+
+    for (size_t ifi = 0; ifi < image_filters.size(); ifi++) {
+      auto image_filter = image_filters[ifi];
+      std::string if_desc = "image filter #" + std::to_string(ifi + 1);
+      DlPaint nested_paint2 = DlPaint().setImageFilter(image_filter);
+
+      DlPaint combined_paint = nested_paint1;
+      combined_paint.setImageFilter(image_filter);
+
+      bool if_then_op_works = opacity <= 0.0 || opacity >= 1.0;
+      test_attributes(nested_paint1, nested_paint2, combined_paint, true,
+                      if_then_op_works, op_desc, if_desc);
+    }
+  }
+
+  // CF then IF should always work.
+  // The reverse might work, but we lack the infrastructure to check it.
+  for (size_t cfi = 0; cfi < color_filters.size(); cfi++) {
+    auto color_filter = color_filters[cfi];
+    std::string cf_desc = "color filter #" + std::to_string(cfi + 1);
+    DlPaint nested_paint1 = DlPaint().setColorFilter(color_filter);
+
+    for (size_t ifi = 0; ifi < image_filters.size(); ifi++) {
+      auto image_filter = image_filters[ifi];
+      std::string if_desc = "image filter #" + std::to_string(ifi + 1);
+      DlPaint nested_paint2 = DlPaint().setImageFilter(image_filter);
+
+      DlPaint combined_paint = nested_paint1;
+      combined_paint.setImageFilter(image_filter);
+
+      test_attributes(nested_paint1, nested_paint2, combined_paint, true, false,
+                      cf_desc, if_desc);
+    }
+  }
+}
+
 }  // namespace testing
 }  // namespace flutter

display_list/display_list_color.h

@@ -14,6 +14,9 @@ struct DlColor {
   constexpr DlColor() : argb(0xFF000000) {}
   constexpr DlColor(uint32_t argb) : argb(argb) {}
 
+  static constexpr uint8_t toAlpha(SkScalar opacity) { return toC(opacity); }
+  static constexpr SkScalar toOpacity(uint8_t alpha) { return toF(alpha); }
+
   // clang-format off
   static constexpr DlColor kTransparent()        {return 0x00000000;};
   static constexpr DlColor kBlack()              {return 0xFF000000;};

display_list/display_list_color_filter.h

@@ -57,6 +57,11 @@ class DlColorFilter
   // pixels non-transparent and therefore expand the bounds.
   virtual bool modifies_transparent_black() const = 0;
 
+  // Return a boolean indicating whether the color filtering operation can
+  // be applied either before or after modulating the pixels with an opacity
+  // value without changing the operation.
+  virtual bool can_commute_with_opacity() const { return false; }
+
   // Return a DlBlendColorFilter pointer to this object iff it is a Blend
   // type of ColorFilter, otherwise return nullptr.
   virtual const DlBlendColorFilter* asBlend() const { return nullptr; }
@@ -150,6 +155,12 @@ class DlMatrixColorFilter final : public DlColorFilter {
            sk_filter->filterColor(SK_ColorTRANSPARENT) != SK_ColorTRANSPARENT;
   }
 
+  bool can_commute_with_opacity() const override {
+    return matrix_[3] == 0 && matrix_[8] == 0 && matrix_[13] == 0 &&
+           matrix_[15] == 0 && matrix_[16] == 0 && matrix_[17] == 0 &&
+           (matrix_[18] >= 0.0 && matrix_[18] <= 1.0) && matrix_[19] == 0;
+  }
+
   std::shared_ptr<DlColorFilter> shared() const override {
     return std::make_shared<DlMatrixColorFilter>(this);
   }
@@ -193,6 +204,7 @@ class DlSrgbToLinearGammaColorFilter final : public DlColorFilter {
   }
   size_t size() const override { return sizeof(*this); }
   bool modifies_transparent_black() const override { return false; }
+  bool can_commute_with_opacity() const override { return true; }
 
   std::shared_ptr<DlColorFilter> shared() const override { return instance; }
   sk_sp<SkColorFilter> skia_object() const override { return sk_filter_; }
@@ -225,6 +237,7 @@ class DlLinearToSrgbGammaColorFilter final : public DlColorFilter {
   }
   size_t size() const override { return sizeof(*this); }
   bool modifies_transparent_black() const override { return false; }
+  bool can_commute_with_opacity() const override { return true; }
 
   std::shared_ptr<DlColorFilter> shared() const override { return instance; }
   sk_sp<SkColorFilter> skia_object() const override { return sk_filter_; }

display_list/display_list_paint.h

@@ -104,6 +104,10 @@ class DlPaint {
     color_.argb = alpha << 24 | (color_.argb & 0x00FFFFFF);
     return *this;
   }
+  DlPaint& setOpacity(SkScalar opacity) {
+    setAlpha(SkScalarRoundToInt(opacity * 0xff));
+    return *this;
+  }
 
   DlBlendMode getBlendMode() const {
     return static_cast<DlBlendMode>(blendMode_);
@@ -166,7 +170,7 @@ class DlPaint {
     return colorFilter_;
   }
   const DlColorFilter* getColorFilterPtr() const { return colorFilter_.get(); }
-  DlPaint& setColorFilter(std::shared_ptr<const DlColorFilter> filter) {
+  DlPaint& setColorFilter(const std::shared_ptr<const DlColorFilter> filter) {
     colorFilter_ = filter ? filter->shared() : nullptr;
     return *this;
   }
@@ -179,7 +183,7 @@ class DlPaint {
     return imageFilter_;
   }
   const DlImageFilter* getImageFilterPtr() const { return imageFilter_.get(); }
-  DlPaint& setImageFilter(std::shared_ptr<const DlImageFilter> filter) {
+  DlPaint& setImageFilter(const std::shared_ptr<const DlImageFilter> filter) {
     imageFilter_ = filter;
     return *this;
   }

flow/BUILD.gn

@@ -45,6 +45,8 @@ source_set("flow") {
     "layers/layer.h",
     "layers/layer_raster_cache_item.cc",
     "layers/layer_raster_cache_item.h",
+    "layers/layer_state_stack.cc",
+    "layers/layer_state_stack.h",
     "layers/layer_tree.cc",
     "layers/layer_tree.h",
     "layers/offscreen_surface.cc",
@@ -156,6 +158,7 @@ if (enable_unittests) {
       "layers/container_layer_unittests.cc",
       "layers/display_list_layer_unittests.cc",
       "layers/image_filter_layer_unittests.cc",
+      "layers/layer_state_stack_unittests.cc",
       "layers/layer_tree_unittests.cc",
       "layers/offscreen_surface_unittests.cc",
       "layers/opacity_layer_unittests.cc",
@@ -170,7 +173,6 @@ if (enable_unittests) {
       "rtree_unittests.cc",
       "skia_gpu_object_unittests.cc",
       "surface_frame_unittests.cc",
-      "testing/auto_save_layer_unittests.cc",
       "testing/mock_layer_unittests.cc",
       "testing/mock_texture_unittests.cc",
       "texture_unittests.cc",

flow/embedded_view_params_unittests.cc

@@ -56,7 +56,6 @@ TEST(EmbeddedViewParams, GetBoundingRectAfterMutationsWithRotation90) {
   EmbeddedViewParams params(matrix, SkSize::Make(1, 1), stack);
   const SkRect& rect = params.finalBoundingRect();
 
-  FML_DLOG(ERROR) << rect.x();
   ASSERT_TRUE(SkScalarNearlyEqual(rect.x(), -1));
   ASSERT_TRUE(SkScalarNearlyEqual(rect.y(), 0));
   ASSERT_TRUE(SkScalarNearlyEqual(rect.width(), 1));

flow/embedded_views.cc

@@ -111,6 +111,12 @@ void MutatorsStack::Pop() {
   vector_.pop_back();
 };
 
+void MutatorsStack::PopTo(size_t stack_count) {
+  while (vector_.size() > stack_count) {
+    Pop();
+  }
+}
+
 const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator
 MutatorsStack::Top() const {
   return vector_.rend();

flow/embedded_views.h

@@ -192,6 +192,8 @@ class MutatorsStack {
   // and destroys it.
   void Pop();
 
+  void PopTo(size_t stack_count);
+
   // Returns a reverse iterator pointing to the top of the stack, which is the
   // mutator that is furtherest from the leaf node.
   const std::vector<std::shared_ptr<Mutator>>::const_reverse_iterator Top()
@@ -210,6 +212,7 @@ class MutatorsStack {
   const std::vector<std::shared_ptr<Mutator>>::const_iterator End() const;
 
   bool is_empty() const { return vector_.empty(); }
+  size_t stack_count() const { return vector_.size(); }
 
   bool operator==(const MutatorsStack& other) const {
     if (vector_.size() != other.vector_.size()) {