Use updated interest rect when layer needs repainting.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMappingTest.cpp

 // Copyright 2014 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/compositing/CompositedLayerMapping.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/api/LayoutViewItem.h"
@@ skipping 403 matching lines @@
     EXPECT_RECT_EQ(IntRect(0, 5000, 800, 5000), recomputeInterestRect(rootScrollingLayer));
     EXPECT_RECT_EQ(IntRect(0, 1400, 800, 8600), previousInterestRect(rootScrollingLayer));
 
     document().view()->setScrollPosition(IntPoint(0, 2000), ProgrammaticScroll);
     // Use recomputed interest rect because it changed enough.
     document().view()->updateAllLifecyclePhases();
     EXPECT_RECT_EQ(IntRect(0, 0, 800, 6600), recomputeInterestRect(rootScrollingLayer));
     EXPECT_RECT_EQ(IntRect(0, 0, 800, 6600), previousInterestRect(rootScrollingLayer));
 }
 
+TEST_F(CompositedLayerMappingTest, InterestRectChangeOnShrunkenViewport)
+{
+    setBodyInnerHTML(
+        "<style>"
+        "  ::-webkit-scrollbar { width: 0; height: 0; }"
+        "  body { margin: 0; }"
+        "</style>"
+        "<div id='div' style='width: 100px; height: 10000px'>Text</div>");
+
+    document().view()->updateAllLifecyclePhases();
+    GraphicsLayer* rootScrollingLayer = document().layoutViewItem().layer()->graphicsLayerBackingForScrolling();
+    EXPECT_RECT_EQ(IntRect(0, 0, 800, 4600), previousInterestRect(rootScrollingLayer));
+
+    document().view()->setFrameRect(IntRect(0, 0, 800, 60));
+    document().view()->updateAllLifecyclePhases();
+    // Repaint required, so interest rect should be updated to shrunken size.
+    EXPECT_RECT_EQ(IntRect(0, 0, 800, 4060), recomputeInterestRect(rootScrollingLayer));
+    EXPECT_RECT_EQ(IntRect(0, 0, 800, 4060), previousInterestRect(rootScrollingLayer));
+}
+
 TEST_F(CompositedLayerMappingTest, InterestRectChangeOnScroll)
 {
     document().frame()->settings()->setPreferCompositingToLCDTextEnabled(true);
 
     setBodyInnerHTML(
         "<style>"
         "  ::-webkit-scrollbar { width: 0; height: 0; }"
         "  body { margin: 0; }"
         "</style>"
         "<div id='scroller' style='width: 400px; height: 400px; overflow: scroll'>"
@@ skipping 28 matching lines @@
     EXPECT_RECT_EQ(IntRect(0, 5000, 400, 5000), recomputeInterestRect(scrollingLayer));
     EXPECT_RECT_EQ(IntRect(0, 1400, 400, 8600), previousInterestRect(scrollingLayer));
 
     scroller->setScrollTop(2000);
     // Use recomputed interest rect because it changed enough.
     document().view()->updateAllLifecyclePhases();
     EXPECT_RECT_EQ(IntRect(0, 0, 400, 6600), recomputeInterestRect(scrollingLayer));
     EXPECT_RECT_EQ(IntRect(0, 0, 400, 6600), previousInterestRect(scrollingLayer));
 }
 
-TEST_F(CompositedLayerMappingTest, InterestRectShouldNotChangeOnPaintInvalidation)
+TEST_F(CompositedLayerMappingTest, InterestRectShouldChangeOnPaintInvalidation)
 {
     document().frame()->settings()->setPreferCompositingToLCDTextEnabled(true);
 
     setBodyInnerHTML(
         "<style>"
         "  ::-webkit-scrollbar { width: 0; height: 0; }"
         "  body { margin: 0; }"
         "</style>"
         "<div id='scroller' style='width: 400px; height: 400px; overflow: scroll'>"
         "  <div id='content' style='width: 100px; height: 10000px'>Text</div>"
         "</div");
 
     document().view()->updateAllLifecyclePhases();
     Element* scroller = document().getElementById("scroller");
     GraphicsLayer* scrollingLayer = scroller->layoutBox()->layer()->graphicsLayerBackingForScrolling();
 
     scroller->setScrollTop(5400);
     document().view()->updateAllLifecyclePhases();
     scroller->setScrollTop(9400);
     // The above code creates an interest rect bigger than the interest rect if recomputed now.
     document().view()->updateAllLifecyclePhases();
     EXPECT_RECT_EQ(IntRect(0, 5400, 400, 4600), recomputeInterestRect(scrollingLayer));
     EXPECT_RECT_EQ(IntRect(0, 1400, 400, 8600), previousInterestRect(scrollingLayer));
 
-    // Paint invalidation and repaint should not change previous paint interest rect.
+    // Paint invalidation and repaint should change previous paint interest rect.
     document().getElementById("content")->setTextContent("Change");
     document().view()->updateAllLifecyclePhases();
     EXPECT_RECT_EQ(IntRect(0, 5400, 400, 4600), recomputeInterestRect(scrollingLayer));
-    EXPECT_RECT_EQ(IntRect(0, 1400, 400, 8600), previousInterestRect(scrollingLayer));
+    EXPECT_RECT_EQ(IntRect(0, 5400, 400, 4600), previousInterestRect(scrollingLayer));
 }
 
 TEST_F(CompositedLayerMappingTest, InterestRectOfSquashingLayerWithNegativeOverflow)
 {
     setBodyInnerHTML(
         "<style>body { margin: 0; font-size: 16px; }</style>"
         "<div style='position: absolute; top: -500px; width: 200px; height: 700px; will-change: transform'></div>"
         "<div id='squashed' style='position: absolute; top: 190px;'>"
         "  <div id='inside' style='width: 100px; height: 100px; text-indent: -10000px'>text</div>"
         "</div>");
@@ skipping 108 matching lines @@
     negativeCompositedChild->parentNode()->removeChild(negativeCompositedChild);
     document().view()->updateAllLifecyclePhases();
 
     mapping = toLayoutBlock(getLayoutObjectByElementId("container"))->layer()->compositedLayerMapping();
     ASSERT_TRUE(mapping->scrollingContentsLayer());
     EXPECT_EQ(static_cast<GraphicsLayerPaintingPhase>(GraphicsLayerPaintOverflowContents | GraphicsLayerPaintCompositedScroll | GraphicsLayerPaintForeground), mapping->scrollingContentsLayer()->paintingPhase());
     EXPECT_FALSE(mapping->foregroundLayer());
 }
 
 } // namespace blink