Only store previous clip rects for PaintLayers that support subsequences.

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

 // Copyright 2016 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/layout/LayoutTreeAsText.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/paint/ObjectPaintProperties.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintPropertyTreePrinter.h"
+#include "core/paint/PrePaintTreeWalk.h"
 #include "platform/graphics/paint/GeometryMapper.h"
 #include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
 #include "platform/testing/RuntimeEnabledFeaturesTestHelpers.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "platform/text/TextStream.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "wtf/HashMap.h"
 #include "wtf/Vector.h"
 
@@ skipping 24 matching lines @@
   const TransformPaintPropertyNode* FrameScrollTranslation() {
     FrameView* frame_view = GetDocument().View();
     if (RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
       return frame_view->GetLayoutView()
           ->PaintProperties()
           ->ScrollTranslation();
     }
     return frame_view->ScrollTranslation();
   }
 
+ protected:
+  PaintLayer* GetPaintLayerByElementId(const char* id) {
+    return ToLayoutBoxModelObject(GetLayoutObjectByElementId(id))->Layer();
+  }
+
  private:
   void SetUp() override {
     Settings::SetMockScrollbarsEnabled(true);
 
     RenderingTest::SetUp();
     EnableCompositing();
   }
 
   void TearDown() override {
     RenderingTest::TearDown();
@@ skipping 140 matching lines @@
   EXPECT_TRUE(child_paint_layer->NeedsRepaint());
 }
 
 TEST_P(PrePaintTreeWalkTest, ClearSubsequenceCachingClipChangePosAbs) {
   SetBodyInnerHTML(
       "<style>"
       "  .clip { overflow: hidden }"
       "</style>"
       "<div id='parent' style='transform: translateZ(0); width: 100px;"
       "  height: 100px; position: absolute'>"
-      "  <div id='child' style='overflow: hidden; z-index: 0; width: 50px;"
-      "      height: 50px'>"
+      "  <div id='child' style='overflow: hidden; position: relative;"
+      "      z-index: 0; width: 50px; height: 50px'>"
       "    content"
       "  </div>"
       "</div>");
 
   auto* parent = GetDocument().GetElementById("parent");
   auto* child = GetDocument().GetElementById("child");
   auto* child_paint_layer =
       ToLayoutBoxModelObject(child->GetLayoutObject())->Layer();
   EXPECT_FALSE(child_paint_layer->NeedsRepaint());
   EXPECT_FALSE(child_paint_layer->NeedsPaintPhaseFloat());
@@ skipping 27 matching lines @@
   EXPECT_FALSE(child_paint_layer->NeedsPaintPhaseFloat());
 
   // This changes clips for absolute-positioned descendants of "child" but not
   // normal-position ones, which are already clipped to 50x50.
   parent->setAttribute(HTMLNames::classAttr, "clip");
   GetDocument().View()->UpdateAllLifecyclePhasesExceptPaint();
 
   EXPECT_TRUE(child_paint_layer->NeedsRepaint());
 }
 
+TEST_P(PrePaintTreeWalkTest, ClipRects) {
+  SetBodyInnerHTML(
+      "<div id='parent' style='isolation: isolate'>"
+      "  <div id='child' style='position: relative'>"
+      "    <div id='grandchild' style='isolation: isolate'>"
+      "      <div style='position: relative'></div>"
+      "    </div>"
+      "  </div>"
+      "</div>");
+
+  auto* parent = GetPaintLayerByElementId("parent");
+  auto* child = GetPaintLayerByElementId("child");
+  auto* grandchild = GetPaintLayerByElementId("grandchild");
+
+  EXPECT_TRUE(parent->PreviousPaintingClipRects());
+  EXPECT_FALSE(child->PreviousPaintingClipRects());
+  EXPECT_TRUE(grandchild->PreviousPaintingClipRects());
+
+  grandchild->ClearPreviousPaintingClipRects();
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  // Still no rects, because the walk early-outed at the LayoutView.
+  EXPECT_FALSE(grandchild->PreviousPaintingClipRects());
+
+  GetDocument().View()->GetLayoutView()->SetNeedsPaintPropertyUpdate();
+  GetDocument().View()->UpdateAllLifecyclePhases();
+  EXPECT_TRUE(grandchild->PreviousPaintingClipRects());
+}
+
 }  // namespace blink