[SPv175] Don't squash across a clip-path or mask boundary.

Otherwise a clip-path or mask will incorrectly apply to the squashed layers.

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I1b22732f2d4cb47bcd0d0869c5c901bd9141a639
Reviewed-on: https://chromium-review.googlesource.com/935822
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539058}

third_party/WebKit/Source/core/BUILD.gn

@@ -2048,6 +2048,7 @@ jumbo_source_set("unit_tests") {
     "paint/ViewPainterTest.cpp",
     "paint/compositing/CompositedLayerMappingTest.cpp",
     "paint/compositing/CompositingInputsUpdaterTest.cpp",
+    "paint/compositing/CompositingLayerAssignerTest.cpp",
     "paint/compositing/CompositingReasonFinderTest.cpp",
     "paint/compositing/PaintLayerCompositorTest.cpp",
     "paint/ng/ng_paint_fragment_test.cc",

third_party/WebKit/Source/core/paint/PaintLayer.cpp

@@ -161,7 +161,6 @@ PaintLayer::PaintLayer(LayoutBoxModelObject& layout_object)
       previous_paint_phase_descendant_block_backgrounds_was_empty_(false),
       has_descendant_with_clip_path_(false),
       has_non_isolated_descendant_with_blend_mode_(false),
-      has_ancestor_with_clip_path_(false),
       self_painting_status_changed_(false),
       filter_on_effect_node_dirty_(false),
       layout_object_(layout_object),
@@ -1086,11 +1085,9 @@ void PaintLayer::SetNeedsCompositingInputsUpdateInternal() {
 }
 
 void PaintLayer::UpdateAncestorDependentCompositingInputs(
-    const AncestorDependentCompositingInputs& compositing_inputs,
-    bool has_ancestor_with_clip_path) {
+    const AncestorDependentCompositingInputs& compositing_inputs) {
   ancestor_dependent_compositing_inputs_ =
       std::make_unique<AncestorDependentCompositingInputs>(compositing_inputs);
-  has_ancestor_with_clip_path_ = has_ancestor_with_clip_path;
   needs_ancestor_dependent_compositing_inputs_update_ = false;
 }
 

third_party/WebKit/Source/core/paint/PaintLayer.h

@@ -702,6 +702,8 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
         : opacity_ancestor(nullptr),
           transform_ancestor(nullptr),
           filter_ancestor(nullptr),
+          clip_path_ancestor(nullptr),
+          mask_ancestor(nullptr),
           ancestor_scrolling_layer(nullptr),
           nearest_fixed_position_layer(nullptr),
           scroll_parent(nullptr),
@@ -711,6 +713,8 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
     const PaintLayer* opacity_ancestor;
     const PaintLayer* transform_ancestor;
     const PaintLayer* filter_ancestor;
+    const PaintLayer* clip_path_ancestor;
+    const PaintLayer* mask_ancestor;
 
     // The fist ancestor which can scroll. This is a subset of the
     // ancestorOverflowLayer chain where the scrolling layer is visible and
@@ -750,8 +754,7 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
     ancestor_overflow_layer_ = ancestor_overflow_layer;
   }
   void UpdateAncestorDependentCompositingInputs(
-      const AncestorDependentCompositingInputs&,
-      bool has_ancestor_with_clip_path);
+      const AncestorDependentCompositingInputs&);
   void DidUpdateCompositingInputs();
 
   const IntRect& ClippedAbsoluteBoundingBox() const {
@@ -815,9 +818,17 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
                ? ancestor_dependent_compositing_inputs_->clip_parent
                : nullptr;
   }
-  bool HasAncestorWithClipPath() const {
+  const PaintLayer* ClipPathAncestor() const {
     DCHECK(!needs_ancestor_dependent_compositing_inputs_update_);
-    return has_ancestor_with_clip_path_;
+    return ancestor_dependent_compositing_inputs_
+               ? ancestor_dependent_compositing_inputs_->clip_path_ancestor
+               : nullptr;
+  }
+  const PaintLayer* MaskAncestor() const {
+    DCHECK(!needs_ancestor_dependent_compositing_inputs_update_);
+    return ancestor_dependent_compositing_inputs_
+               ? ancestor_dependent_compositing_inputs_->mask_ancestor
+               : nullptr;
   }
   bool HasDescendantWithClipPath() const {
     DCHECK(!needs_descendant_dependent_flags_update_);
@@ -1245,7 +1256,6 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
   // inputs.
   unsigned has_descendant_with_clip_path_ : 1;
   unsigned has_non_isolated_descendant_with_blend_mode_ : 1;
-  unsigned has_ancestor_with_clip_path_ : 1;
 
   unsigned self_painting_status_changed_ : 1;
 

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.cpp

@@ -2208,7 +2208,7 @@ bool PaintLayerScrollableArea::ComputeNeedsCompositedScrolling(
   }
 
   if (layer->GetLayoutObject().HasClip() ||
-      layer->HasDescendantWithClipPath() || layer->HasAncestorWithClipPath()) {
+      layer->HasDescendantWithClipPath() || !!layer->ClipPathAncestor()) {
     non_composited_main_thread_scrolling_reasons_ |=
         MainThreadScrollingReason::kHasClipRelatedProperty;
     needs_composited_scrolling = false;

third_party/WebKit/Source/core/paint/compositing/CompositingInputsUpdater.cpp

@@ -183,6 +183,12 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
       properties.filter_ancestor = parent->HasFilterInducingProperty()
                                        ? parent
                                        : parent->FilterAncestor();
+      properties.clip_path_ancestor = parent->GetLayoutObject().HasClipPath()
+                                          ? parent
+                                          : parent->ClipPathAncestor();
+      properties.mask_ancestor =
+          parent->GetLayoutObject().HasMask() ? parent : parent->MaskAncestor();
+
       bool layer_is_fixed_position =
           layer->GetLayoutObject().Style()->GetPosition() == EPosition::kFixed;
 
@@ -248,8 +254,7 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
       }
     }
 
-    layer->UpdateAncestorDependentCompositingInputs(
-        properties, info.has_ancestor_with_clip_path);
+    layer->UpdateAncestorDependentCompositingInputs(properties);
   }
 
   if (layer->StackingNode()->IsStackingContext())
@@ -264,9 +269,6 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
   if (layer->GetLayoutObject().HasClipRelatedProperty())
     info.has_ancestor_with_clip_related_property = true;
 
-  if (layer->GetLayoutObject().HasClipPath())
-    info.has_ancestor_with_clip_path = true;
-
   for (PaintLayer* child = layer->FirstChild(); child;
        child = child->NextSibling())
     UpdateRecursive(child, update_type, info);

third_party/WebKit/Source/core/paint/compositing/CompositingInputsUpdater.h

@@ -37,8 +37,7 @@ class CompositingInputsUpdater {
           enclosing_composited_layer(nullptr),
           last_overflow_clip_layer(nullptr),
           last_scrolling_ancestor(nullptr),
-          has_ancestor_with_clip_related_property(false),
-          has_ancestor_with_clip_path(false) {}
+          has_ancestor_with_clip_related_property(false) {}
 
     PaintLayer* ancestor_stacking_context;
     PaintLayer* enclosing_composited_layer;

third_party/WebKit/Source/core/paint/compositing/CompositingInputsUpdaterTest.cpp

@@ -127,4 +127,46 @@ TEST_P(CompositingInputsUpdaterTest, UnclippedAndClippedRectsUnderScroll) {
   }
 }
 
+TEST_P(CompositingInputsUpdaterTest, ClipPathAncestor) {
+  SetBodyInnerHTML(R"HTML(
+    <div id="parent" style="clip-path: circle(100%)">
+      <div id="child" style="width: 20px; height: 20px; will-change: transform">
+        <div id="grandchild" style="position: relative";
+      </div>
+    </div>
+  )HTML");
+
+  PaintLayer* parent =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("parent"))->Layer();
+  PaintLayer* child =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("child"))->Layer();
+  PaintLayer* grandchild =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("grandchild"))->Layer();
+
+  EXPECT_EQ(nullptr, parent->ClipPathAncestor());
+  EXPECT_EQ(parent, child->ClipPathAncestor());
+  EXPECT_EQ(parent, grandchild->ClipPathAncestor());
+}
+
+TEST_P(CompositingInputsUpdaterTest, MaskAncestor) {
+  SetBodyInnerHTML(R"HTML(
+    <div id="parent" style="-webkit-mask-image: linear-gradient(black, white);">
+      <div id="child" style="width: 20px; height: 20px; will-change: transform">
+        <div id="grandchild" style="position: relative";
+      </div>
+    </div>
+  )HTML");
+
+  PaintLayer* parent =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("parent"))->Layer();
+  PaintLayer* child =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("child"))->Layer();
+  PaintLayer* grandchild =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("grandchild"))->Layer();
+
+  EXPECT_EQ(nullptr, parent->MaskAncestor());
+  EXPECT_EQ(parent, child->MaskAncestor());
+  EXPECT_EQ(parent, grandchild->MaskAncestor());
+}
+
 }  // namespace blink

third_party/WebKit/Source/core/paint/compositing/CompositingLayerAssigner.cpp

@@ -208,6 +208,14 @@ CompositingLayerAssigner::GetReasonsPreventingSquashing(
   if (layer->EnclosingPaginationLayer())
     return SquashingDisallowedReason::kFragmentedContent;
 
+  if (layer->GetLayoutObject().HasClipPath() ||
+      layer->ClipPathAncestor() != squashing_layer.ClipPathAncestor())
+    return SquashingDisallowedReason::kClipPathMismatch;
+
+  if (layer->GetLayoutObject().HasMask() ||
+      layer->MaskAncestor() != squashing_layer.MaskAncestor())
+    return SquashingDisallowedReason::kMaskMismatch;
+
   return SquashingDisallowedReason::kNone;
 }
 

third_party/WebKit/Source/core/paint/compositing/CompositingLayerAssignerTest.cpp

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/layout/LayoutTestHelper.h"
+#include "core/paint/PaintLayer.h"
+#include "core/paint/compositing/CompositedLayerMapping.h"
+#include "platform/graphics/GraphicsLayer.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+class CompositedLayerAssignerTest : public RenderingTest {
+ private:
+  void SetUp() override {
+    RenderingTest::SetUp();
+    EnableCompositing();
+  }
+};
+
+TEST_F(CompositedLayerAssignerTest, SquashingSimple) {
+  SetBodyInnerHTML(R"HTML(
+    <div>
+      <div style="width: 20px; height: 20px; will-change: transform"></div>
+    </div>
+    <div id="squashed" style="position: absolute; top: 0; width: 100px;
+        height: 100px; background: green"></div>
+    )HTML");
+
+  PaintLayer* squashed =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("squashed"))->Layer();
+  EXPECT_EQ(kPaintsIntoGroupedBacking, squashed->GetCompositingState());
+}
+
+TEST_F(CompositedLayerAssignerTest, SquashingAcrossClipPathDisallowed) {
+  SetBodyInnerHTML(R"HTML(
+    <div style="clip-path: circle(100%)">
+      <div style="width: 20px; height: 20px; will-change: transform"></div>
+    </div>
+    <div id="squashed" style="position: absolute; top: 0; width: 100px;
+        height: 100px; background: green"></div>
+    )HTML");
+  // #squashed should not be squashed after all, because of the clip path above
+  // #squashing.
+  PaintLayer* squashed =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("squashed"))->Layer();
+  EXPECT_EQ(kPaintsIntoOwnBacking, squashed->GetCompositingState());
+}
+
+TEST_F(CompositedLayerAssignerTest, SquashingAcrossMaskDisallowed) {
+  SetBodyInnerHTML(R"HTML(
+    <div style="-webkit-mask-image: linear-gradient(black, white);">
+      <div style="width: 20px; height: 20px; will-change: transform"></div>
+    </div>
+    <div id="squashed" style="position: absolute; top: 0; width: 100px;
+        height: 100px; background: green"></div>
+    )HTML");
+  // #squashed should not be squashed after all, because of the mask above
+  // #squashing.
+  PaintLayer* squashed =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("squashed"))->Layer();
+  EXPECT_EQ(kPaintsIntoOwnBacking, squashed->GetCompositingState());
+}
+
+}  // namespace blink

third_party/WebKit/Source/platform/graphics/SquashingDisallowedReasons.cpp

@@ -73,6 +73,12 @@ constexpr SquashingDisallowedReasonStringMap
         {SquashingDisallowedReason::kFragmentedContent,
          "SquashingDisallowedReasonFragmentedContent",
          "Cannot squash layers that are inside fragmentation contexts."},
+        {SquashingDisallowedReason::kClipPathMismatch,
+         "SquashingDisallowedReasonClipPathMismatch",
+         "Cannot squash layers across clip-path boundaries."},
+        {SquashingDisallowedReason::kMaskMismatch,
+         "SquashingDisallowedReasonMaskMismatch",
+         "Cannot squash layers across mask boundaries."},
 };
 
 }  // anonymous namespace

third_party/WebKit/Source/platform/graphics/SquashingDisallowedReasons.h

@@ -28,7 +28,9 @@ using SquashingDisallowedReasons = unsigned;
   V(ScrollChildWithCompositedDescendants)       \
   V(SquashingLayerIsAnimating)                  \
   V(RenderingContextMismatch)                   \
-  V(FragmentedContent)
+  V(FragmentedContent)                          \
+  V(ClipPathMismatch)                           \
+  V(MaskMismatch)
 
 class PLATFORM_EXPORT SquashingDisallowedReason {
  private: