setMayNeedPaintInvalidation in setNeedsOverflowRecalcAfterStyleChange()

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

 // Copyright 2017 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/frame/FrameView.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
+#include "core/paint/PaintLayer.h"
 #include "platform/testing/RuntimeEnabledFeaturesTestHelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
 namespace {
 
 class PaintInvalidationTest : public ::testing::WithParamInterface<bool>,
                               private ScopedRootLayerScrollingForTest,
                               public RenderingTest {
@@ skipping 58 matching lines @@
             &childLayoutView->containerForPaintInvalidation());
   EXPECT_EQ(LayoutRect(10, 10, 100, 100), childLayoutView->visualRect());
 
   iframe->setAttribute(HTMLNames::styleAttr, "border: 20px solid blue");
   document().view()->updateAllLifecyclePhases();
   EXPECT_EQ(document().layoutView(),
             &childLayoutView->containerForPaintInvalidation());
   EXPECT_EQ(LayoutRect(30, 30, 100, 100), childLayoutView->visualRect());
 };
 
+// This is a simlified test case for crbug.com/704182.

[chrishtr, 2017/04/04 16:26:05]

nit: simplified

[Xianzhu, 2017/04/04 16:58:31]

Done.

+TEST_P(PaintInvalidationTest, InvisibleTransformUnderFixedOnScroll) {
+  enableCompositing();
+  setBodyInnerHTML(
+      "<div style='height: 2000px'></div>"

[chrishtr, 2017/04/04 16:26:05]

This test doesn't seem to result in a user-visible change. Is that
possible? I assume so because of this CL, but what is the testcase 
which demonstrates it?

[Xianzhu, 2017/04/04 16:58:31]

This test case ensures no paint time regression for the case of
crbug.com/704182. Line 114 checks the result of the new
setMayNeedPaintInvalidation() call, and line 117 checks we don't repaint because
there is no actual visual change.

The new setMayNeedPaintInvalidation() call is for
https://codereview.chromium.org/2792063002/ which actually uses the
needsPaintOffsetAndVisualRectUpdate flag. After that CL, several layout tests
will show the necessity of the setMayNeedPaintInvalidation call.

+      "<div id='fixed' style='position: fixed; top: 0; left: 0; width: 100px;"
+      "    height: 100px; visibility: hidden'>"
+      "  <div id='transform' style='will-change: transform'></div>"
+      "</div>");
+
+  auto& fixed = *document().getElementById("fixed");
+  auto& transform = *document().getElementById("transform");
+  const auto& fixedObject = *fixed.layoutObject();
+  const auto& fixedLayer = *toLayoutBoxModelObject(fixedObject).layer();
+  EXPECT_TRUE(fixedLayer.subtreeIsInvisible());
+
+  document().domWindow()->scrollTo(0, 100);
+  transform.setAttribute(HTMLNames::styleAttr,
+                         "transform: translate3d(10px, 20px, 30px)");
+  document().view()->updateLifecycleToCompositingCleanPlusScrolling();
+
+  EXPECT_TRUE(fixedLayer.subtreeIsInvisible());
+  // We skip invisible layers when setting non-composited fixed-position
+  // needing paint invalidation when the frame is scrolled.
+  EXPECT_FALSE(fixedObject.shouldDoFullPaintInvalidation());
+  // This was set when fixedObject is marked needsOverflowRecaldAfterStyleChange
+  // when child changed transform.
+  EXPECT_TRUE(fixedObject.mayNeedPaintInvalidation());
+
+  // We should not repaint anything because all contents are invisible.
+  document().view()->updateAllLifecyclePhasesExceptPaint();
+  EXPECT_FALSE(fixedLayer.needsRepaint());
+  document().view()->updateAllLifecyclePhases();
+}
+
 }  // namespace
 
 }  // namespace blink