Paint solid color background into both scrolling contents layer and graphics layer.

third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.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/paint/PaintLayerScrollableArea.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/paint/PaintLayer.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/testing/RuntimeEnabledFeaturesTestHelpers.h"
 
 namespace blink {
 
 class PaintLayerScrollableAreaTest : public RenderingTest {
  public:
   PaintLayerScrollableAreaTest()
       : RenderingTest(SingleChildFrameLoaderClient::create()) {}
 
-  bool canPaintBackgroundOntoScrollingContentsLayer(const char* elementId) {
+  BackgroundPaintLocation backgroundPaintLocation(const char* elementId) {

[chrishtr, 2016/11/17 20:55:39]

Is one of the tests below exercising solid-color backgrounds?

[flackr, 2016/11/17 23:38:00]

Yes, scroller10 and scroller13 test solid color backgrounds which paint into
both layers. But I just realized I should add a test for a partially transparent
background which definitely cannot be painted into both layers, which I've added
as scroller17.

     PaintLayer* paintLayer =
         toLayoutBoxModelObject(getLayoutObjectByElementId(elementId))->layer();
-    return paintLayer->canPaintBackgroundOntoScrollingContentsLayer();
+    return paintLayer->backgroundPaintLocation();
   }
 
  private:
   void SetUp() override {
     RenderingTest::SetUp();
     enableCompositing();
   }
 };
 
 TEST_F(PaintLayerScrollableAreaTest,
@@ skipping 44 matching lines @@
       "1px solid black; outline: 1px solid blue; outline-offset: -1px;'><div "
       "class='spacer'></div></div>"
       "<div id='scroller15' class='scroller' style='background: white; border: "
       "1px solid black; outline: 1px solid blue; outline-offset: -2px;'><div "
       "class='spacer'></div></div>"
       "<div id='scroller16' class='scroller' style='background: white; clip: "
       "rect(0px,10px,10px,0px);'><div class='spacer'></div></div>");
 
   // #scroller1 cannot paint background into scrolling contents layer because it
   // has a negative z-index child.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller1"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller1"));
 
   // #scroller2 cannot paint background into scrolling contents layer because it
   // has a content-box clip without local attachment.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller2"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller2"));
 
   // #scroller3 can paint background into scrolling contents layer.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller3"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller3"));
 
   // #scroller4 cannot paint background into scrolling contents layer because
   // the background image is not locally attached.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller4"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller4"));
 
   // #scroller5 can paint background into scrolling contents layer because both
   // the image and color are locally attached.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller5"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller5"));
 
   // #scroller6 can paint background into scrolling contents layer because the
   // image is locally attached and even though the color is not, it is filled to
   // the padding box so it will be drawn the same as a locally attached
   // background.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller6"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller6"));
 
   // #scroller7 cannot paint background into scrolling contents layer because
   // the color is filled to the content box and we have padding so it is not
   // equivalent to a locally attached background.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller7"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller7"));
 
   // #scroller8 can paint background into scrolling contents layer because its
   // border-box is equivalent to its padding box since it has no border.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller8"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller8"));
 
   // #scroller9 can paint background into scrolling contents layer because its
   // border is opaque so it completely covers the background outside of the
   // padding-box.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller9"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller9"));
 
-  // #scroller10 cannot paint background into scrolling contents layer because
-  // its border is partially transparent so the background must be drawn to the
+  // #scroller10 paints the background into both layers because its border is
+  // partially transparent so the background must be drawn to the
   // border-box edges.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller10"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer | BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller10"));
 
   // #scroller11 can paint background into scrolling contents layer because its
   // content-box is equivalent to its padding box since it has no padding.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller11"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller11"));
 
   // #scroller12 cannot paint background into scrolling contents layer because
   // it has padding so its content-box is not equivalent to its padding-box.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller12"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller12"));
 
-  // #scroller13 cannot paint background into scrolling contents layer because
-  // it has a custom scrollbar which the background may need to draw under.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller13"));
+  // #scroller13 paints the background into both layers because it has a custom
+  // scrollbar which the background may need to draw under.
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer | BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller13"));
 
   // #scroller14 can paint background into scrolling contents layer because the
   // outline is drawn outside the padding box.
-  EXPECT_TRUE(canPaintBackgroundOntoScrollingContentsLayer("scroller14"));
+  EXPECT_EQ(BackgroundPaintInScrollingContents,
+            backgroundPaintLocation("scroller14"));
 
   // #scroller15 cannot paint background into scrolling contents layer because
   // the outline is drawn inside the padding box.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller15"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller15"));
 
   // #scroller16 cannot paint background into scrolling contents layer because
   // the scroller has a clip which would not be respected by the scrolling
   // contents layer.
-  EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller16"));
+  EXPECT_EQ(BackgroundPaintInGraphicsLayer,
+            backgroundPaintLocation("scroller16"));
 }
 
 TEST_F(PaintLayerScrollableAreaTest, OpaqueLayersPromoted) {
   RuntimeEnabledFeatures::setCompositeOpaqueScrollersEnabled(true);
 
   setBodyInnerHTML(
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
       "white local content-box; border: 10px solid rgba(0, 255, 0, 0.5); }"
       "#scrolled { height: 300px; }"
@@ skipping 234 matching lines @@
   ASSERT_TRUE(blackLayer);
 
   ASSERT_EQ(ScrollbarOverlayColorTheme::ScrollbarOverlayColorThemeDark,
             noneLayer->getScrollableArea()->getScrollbarOverlayColorTheme());
   ASSERT_EQ(ScrollbarOverlayColorTheme::ScrollbarOverlayColorThemeDark,
             whiteLayer->getScrollableArea()->getScrollbarOverlayColorTheme());
   ASSERT_EQ(ScrollbarOverlayColorTheme::ScrollbarOverlayColorThemeLight,
             blackLayer->getScrollableArea()->getScrollbarOverlayColorTheme());
 }
 }