Paint invalidation of local attachment backgrounds

third_party/WebKit/Source/core/paint/BoxPaintInvalidator.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/BoxPaintInvalidator.h"
 
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutView.h"
+#include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/paint/ObjectPaintInvalidator.h"
 #include "core/paint/PaintInvalidator.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/PaintLayerScrollableArea.h"
 #include "platform/geometry/LayoutRect.h"
 
 namespace blink {
 
 struct PreviousBoxGeometries {
   LayoutSize borderBoxSize;
@@ skipping 42 matching lines @@
                       newSize.width(), delta + extraHeight);
   }
   if (delta < 0) {
     return LayoutRect(location.x(),
                       location.y() + newSize.height() - extraHeight,
                       oldSize.width(), -delta + extraHeight);
   }
   return LayoutRect();
 }
 
-bool BoxPaintInvalidator::incrementallyInvalidatePaint() {
-  LayoutRect rightDelta;
-  LayoutRect bottomDelta;
-  if (m_box.isLayoutView() &&
-      !RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
-    // This corresponds to the special case in computePaintInvalidationReason()
-    // for LayoutView in non-rootLayerScrolling mode.
-    DCHECK(m_context.oldVisualRect.location() ==
-           m_context.newVisualRect.location());
-    rightDelta = computeRightDelta(m_context.newVisualRect.location(),
-                                   m_context.oldVisualRect.size(),
-                                   m_context.newVisualRect.size(), 0);
-    bottomDelta = computeBottomDelta(m_context.newVisualRect.location(),
-                                     m_context.oldVisualRect.size(),
-                                     m_context.newVisualRect.size(), 0);
-  } else {
-    LayoutSize oldBorderBoxSize =
-        previousBorderBoxSize(m_context.oldVisualRect.size());
-    LayoutSize newBorderBoxSize = m_box.size();
-    DCHECK(m_context.oldLocation == m_context.newLocation);
-    rightDelta = computeRightDelta(m_context.newLocation, oldBorderBoxSize,
-                                   newBorderBoxSize, m_box.borderRight());
-    bottomDelta = computeBottomDelta(m_context.newLocation, oldBorderBoxSize,
-                                     newBorderBoxSize, m_box.borderBottom());
-  }
+bool BoxPaintInvalidator::incrementallyInvalidatePaint(
+    PaintInvalidationReason reason,
+    const LayoutRect& oldRect,
+    const LayoutRect& newRect) {
+  DCHECK(oldRect.location() == newRect.location());
+  LayoutRect rightDelta = computeRightDelta(
+      newRect.location(), oldRect.size(), newRect.size(),
+      reason == PaintInvalidationIncremental ? m_box.borderRight() : 0);
+  LayoutRect bottomDelta = computeBottomDelta(
+      newRect.location(), oldRect.size(), newRect.size(),
+      reason == PaintInvalidationIncremental ? m_box.borderBottom() : 0);
 
   if (rightDelta.isEmpty() && bottomDelta.isEmpty())
     return false;
 
   ObjectPaintInvalidator objectPaintInvalidator(m_box);
   objectPaintInvalidator.invalidatePaintUsingContainer(
-      *m_context.paintInvalidationContainer, rightDelta,
-      PaintInvalidationIncremental);
+      *m_context.paintInvalidationContainer, rightDelta, reason);
   objectPaintInvalidator.invalidatePaintUsingContainer(
-      *m_context.paintInvalidationContainer, bottomDelta,
-      PaintInvalidationIncremental);
+      *m_context.paintInvalidationContainer, bottomDelta, reason);
   return true;
 }
 
 PaintInvalidationReason BoxPaintInvalidator::computePaintInvalidationReason() {
   PaintInvalidationReason reason =
       ObjectPaintInvalidatorWithContext(m_box, m_context)
           .computePaintInvalidationReason();
 
   if (reason != PaintInvalidationIncremental)
     return reason;
@@ skipping 12 matching lines @@
   }
 
   const ComputedStyle& style = m_box.styleRef();
 
   if ((style.backgroundLayers().thisOrNextLayersUseContentBox() ||
        style.maskLayers().thisOrNextLayersUseContentBox() ||
        style.boxSizing() == BoxSizingBorderBox) &&
       previousContentBoxRect() != m_box.contentBoxRect())
     return PaintInvalidationContentBoxChange;
 
-  if (style.backgroundLayers().thisOrNextLayersHaveLocalAttachment() &&
-      previousLayoutOverflowRect() != m_box.layoutOverflowRect())
-    return PaintInvalidationLayoutOverflowBoxChange;
-
-  LayoutSize oldBorderBoxSize =
-      previousBorderBoxSize(m_context.oldVisualRect.size());
+  LayoutSize oldBorderBoxSize = previousBorderBoxSize();
   LayoutSize newBorderBoxSize = m_box.size();
   bool borderBoxChanged = oldBorderBoxSize != newBorderBoxSize;
-
   if (!borderBoxChanged && m_context.oldVisualRect == m_context.newVisualRect)
     return PaintInvalidationNone;
 
   // If either border box changed or bounds changed, and old or new border box
   // doesn't equal old or new bounds, incremental invalidation is not
   // applicable. This captures the following cases:
   // - pixel snapping of paint invalidation bounds,
   // - scale, rotate, skew etc. transforms,
   // - visual overflows.
   if (m_context.oldVisualRect !=
@@ skipping 17 matching lines @@
   if (oldBorderBoxSize.width() != newBorderBoxSize.width() &&
       m_box.mustInvalidateBackgroundOrBorderPaintOnWidthChange())
     return PaintInvalidationBorderBoxChange;
   if (oldBorderBoxSize.height() != newBorderBoxSize.height() &&
       m_box.mustInvalidateBackgroundOrBorderPaintOnHeightChange())
     return PaintInvalidationBorderBoxChange;
 
   return PaintInvalidationIncremental;
 }
 
+bool BoxPaintInvalidator::backgroundGeometryDependsOnLayoutOverflowRect() {
+  return m_box.styleRef()
+      .backgroundLayers()
+      .thisOrNextLayersHaveLocalAttachment();
+}
+
+// Background positioning in layout overflow rect doesn't mean it will
+// paint onto the scrolling contents layer because some conditions prevent
+// it from that. We may also treat non-local solid color backgrounds as local
+// and paint onto the scrolling contents layer.
+// See PaintLayer::canPaintBackgroundOntoScrollingContentsLayer().
+bool BoxPaintInvalidator::backgroundPaintsOntoScrollingContentsLayer() {
+  if (!m_box.hasLayer())
+    return false;
+  if (auto* mapping = m_box.layer()->compositedLayerMapping())
+    return mapping->backgroundPaintsOntoScrollingContentsLayer();
+  return false;
+}
+
+bool BoxPaintInvalidator::shouldFullyInvalidateBackgroundOnLayoutOverflowChange(
+    const LayoutRect& oldLayoutOverflow,
+    const LayoutRect& newLayoutOverflow) {
+  DCHECK(oldLayoutOverflow != newLayoutOverflow);
+  if (newLayoutOverflow.isEmpty() || oldLayoutOverflow.isEmpty())
+    return true;
+  if (newLayoutOverflow.location() != oldLayoutOverflow.location())
+    return true;
+  if (newLayoutOverflow.width() != oldLayoutOverflow.width() &&
+      m_box.mustInvalidateFillLayersPaintOnHeightChange(

[chrishtr, 2016/11/17 20:42:36]

This part seems to be new in this CL. What is it for?

[Xianzhu, 2016/11/17 23:36:41]

Previously we always fully invalidated the scrolling contents layer with
following code:
1. in CompositedLayerMapping (when the layer is resized),
2. oldcode line 139-141 which forces full paint invalidation for
background-attachment:local on layout overflow change,
3. in ObjectPaintInvalidator::setBackingNeedsPaintInvalidationInRect() when
anything is invalidated on the container layer.

Now this allows us to do incremental invalidation of background on the scrolling
contents layer.

+          m_box.styleRef().backgroundLayers()))
+    return true;
+  if (newLayoutOverflow.height() != oldLayoutOverflow.height() &&
+      m_box.mustInvalidateFillLayersPaintOnHeightChange(
+          m_box.styleRef().backgroundLayers()))
+    return true;
+  return false;
+}
+
+void BoxPaintInvalidator::invalidateScrollingContentsBackgroundIfNeeded() {
+  bool paintsOntoScrollingContentsLayer =
+      backgroundPaintsOntoScrollingContentsLayer();
+  if (!paintsOntoScrollingContentsLayer &&
+      !backgroundGeometryDependsOnLayoutOverflowRect())
+    return;
+
+  const LayoutRect& oldLayoutOverflow = previousLayoutOverflowRect();
+  LayoutRect newLayoutOverflow = m_box.layoutOverflowRect();
+
+  bool shouldFullyInvalidateOnScrollingContentsLayer = false;
+  if (m_box.backgroundChangedSinceLastPaintInvalidation()) {
+    if (!paintsOntoScrollingContentsLayer) {
+      // The box should have been set needing full invalidation on style change.
+      DCHECK(m_box.shouldDoFullPaintInvalidation());
+      return;
+    }
+    shouldFullyInvalidateOnScrollingContentsLayer = true;
+  } else {
+    // Check change of layout overflow for incremental invalidation.
+    if (!m_box.hasPreviousBoxGeometries() ||
+        newLayoutOverflow == oldLayoutOverflow)
+      return;
+    if (!paintsOntoScrollingContentsLayer) {
+      if (m_box.isLayoutView() &&

[chrishtr, 2016/11/17 20:42:36]

Where did the implementation of 226-234 used to be?  This is if painting
of background was not onto the scrolling contents layer, which invalidated
somehow..

[Xianzhu, 2016/11/17 23:36:41]

See my last comment.

The LayoutView condition is wrong. Removed it. Added new tests to cover the case
(CompositedLayoutViewGradientResize and NonCompositedLayoutViewGradientResize).

+          !RuntimeEnabledFeatures::rootLayerScrollingEnabled())
+        return;
+      if (shouldFullyInvalidateBackgroundOnLayoutOverflowChange(
+              oldLayoutOverflow, newLayoutOverflow)) {
+        m_box.getMutableForPainting().setShouldDoFullPaintInvalidation(
+            PaintInvalidationLayoutOverflowBoxChange);
+      }
+      return;
+    }
+    shouldFullyInvalidateOnScrollingContentsLayer =
+        shouldFullyInvalidateBackgroundOnLayoutOverflowChange(
+            oldLayoutOverflow, newLayoutOverflow);
+  }
+
+  if (shouldFullyInvalidateOnScrollingContentsLayer ||
+      oldLayoutOverflow.isEmpty() || newLayoutOverflow.isEmpty()) {

[chrishtr, 2016/11/17 20:42:36]

Maybe move line 242 up and use the condition to set
shouldFullyInvalidateOnScrollingContentsLayer to true?

[Xianzhu, 2016/11/17 23:36:41]

Just noticed I already had the conditions in
shouldFullyInvalidateBackgroundOnLayoutOverflowChange(). Removed the conditions
here.

+    ObjectPaintInvalidatorWithContext(m_box, m_context)
+        .fullyInvalidatePaint(
+            PaintInvalidationBackgroundOnScrollingContentsLayer,
+            oldLayoutOverflow, newLayoutOverflow);
+  } else {
+    incrementallyInvalidatePaint(
+        PaintInvalidationBackgroundOnScrollingContentsLayer, oldLayoutOverflow,
+        newLayoutOverflow);
+  }
+
+  m_context.paintingLayer->setNeedsRepaint();
+  // Currently we use CompositedLayerMapping as the DisplayItemClient to paint
+  // background on the scrolling contents layer.
+  ObjectPaintInvalidator(m_box).invalidateDisplayItemClient(
+      *m_box.layer()->compositedLayerMapping()->scrollingContentsLayer(),
+      PaintInvalidationBackgroundOnScrollingContentsLayer);
+}
+
 PaintInvalidationReason BoxPaintInvalidator::invalidatePaintIfNeeded() {
+  invalidateScrollingContentsBackgroundIfNeeded();
+
   PaintInvalidationReason reason = computePaintInvalidationReason();
   if (reason == PaintInvalidationIncremental) {
-    if (incrementallyInvalidatePaint()) {
+    bool invalidated;
+    if (m_box.isLayoutView() &&
+        !RuntimeEnabledFeatures::rootLayerScrollingEnabled()) {
+      invalidated = incrementallyInvalidatePaint(
+          reason, m_context.oldVisualRect, m_context.newVisualRect);
+    } else {
+      invalidated = incrementallyInvalidatePaint(
+          reason, LayoutRect(m_context.oldLocation, previousBorderBoxSize()),
+          LayoutRect(m_context.newLocation, m_box.size()));
+    }
+    if (invalidated) {
       m_context.paintingLayer->setNeedsRepaint();
       m_box.invalidateDisplayItemClients(reason);
     } else {
       reason = PaintInvalidationNone;
     }
+
     // Though we have done incremental invalidation, we still need to call
     // ObjectPaintInvalidator with PaintInvalidationNone to do any other
     // required operations.
     reason = std::max(
         reason,
         ObjectPaintInvalidatorWithContext(m_box, m_context)
             .invalidatePaintIfNeededWithComputedReason(PaintInvalidationNone));
   } else {
     reason = ObjectPaintInvalidatorWithContext(m_box, m_context)
                  .invalidatePaintIfNeededWithComputedReason(reason);
@@ skipping 26 matching lines @@
     return true;
 
   // No need to save old border box size if we can use size of the old paint
   // rect as the old border box size in the next invalidation.
   if (paintInvalidationSize != m_box.size())
     return true;
 
   // Background and mask layers can depend on other boxes than border box. See
   // crbug.com/490533
   if (style.backgroundLayers().thisOrNextLayersUseContentBox() ||
-      style.backgroundLayers().thisOrNextLayersHaveLocalAttachment() ||
-      style.maskLayers().thisOrNextLayersUseContentBox())
+      style.maskLayers().thisOrNextLayersUseContentBox() ||
+      backgroundGeometryDependsOnLayoutOverflowRect() ||
+      backgroundPaintsOntoScrollingContentsLayer())
     return true;
 
   return false;
 }
 
 void BoxPaintInvalidator::savePreviousBoxGeometriesIfNeeded() {
   DCHECK(m_box.hasPreviousBoxGeometries() ==
          previousBoxGeometriesMap().contains(&m_box));
   if (!needsToSavePreviousBoxGeometries()) {
     if (m_box.hasPreviousBoxGeometries()) {
       previousBoxGeometriesMap().remove(&m_box);
       m_box.getMutableForPainting().setHasPreviousBoxGeometries(false);
     }
     return;
   }
 
-  PreviousBoxGeometries Geometries = {m_box.size(), m_box.contentBoxRect(),
+  PreviousBoxGeometries geometries = {m_box.size(), m_box.contentBoxRect(),
                                       m_box.layoutOverflowRect()};
-  previousBoxGeometriesMap().set(&m_box, Geometries);
+  previousBoxGeometriesMap().set(&m_box, geometries);
   m_box.getMutableForPainting().setHasPreviousBoxGeometries(true);
 }
 
-LayoutSize BoxPaintInvalidator::previousBorderBoxSize(
-    const LayoutSize& previousVisualRectSize) {
+LayoutSize BoxPaintInvalidator::previousBorderBoxSize() {
   DCHECK(m_box.hasPreviousBoxGeometries() ==
          previousBoxGeometriesMap().contains(&m_box));
   if (m_box.hasPreviousBoxGeometries())
     return previousBoxGeometriesMap().get(&m_box).borderBoxSize;
 
   // We didn't save the old border box size because it was the same as the size
   // of oldVisualRect.
-  return previousVisualRectSize;
+  return m_context.oldVisualRect.size();
 }
 
 LayoutRect BoxPaintInvalidator::previousContentBoxRect() {
   DCHECK(m_box.hasPreviousBoxGeometries() ==
          previousBoxGeometriesMap().contains(&m_box));
   return m_box.hasPreviousBoxGeometries()
              ? previousBoxGeometriesMap().get(&m_box).contentBoxRect
              : LayoutRect();
 }
 
 LayoutRect BoxPaintInvalidator::previousLayoutOverflowRect() {
   DCHECK(m_box.hasPreviousBoxGeometries() ==
          previousBoxGeometriesMap().contains(&m_box));
   return m_box.hasPreviousBoxGeometries()
              ? previousBoxGeometriesMap().get(&m_box).layoutOverflowRect
              : LayoutRect();
 }
 
 }  // namespace blink