[SPInvalidation] Handle pixel-snapping of paint invalidation rects

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

Index: third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
index c090e7da9c634b1213abb742103762a9d7b1b185..9b93b77117dcf9d0e5aa062e12998a61d615c0c4 100644
--- a/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
@@ -47,7 +47,8 @@ static LayoutRect mapLocalRectToPaintInvalidationBacking(
     GeometryMapper& geometryMapper,
     const LayoutObject& object,
     const FloatRect& localRect,
-    const PaintInvalidatorContext& context) {
+    const PaintInvalidatorContext& context,
+    bool& coversExtraPixels) {
   // TODO(wkorman): The flip below is required because visual rects are
   // currently in "physical coordinates with flipped block-flow direction"
   // (see LayoutBoxModelObject.h) but we need them to be in physical
@@ -72,6 +73,14 @@ static LayoutRect mapLocalRectToPaintInvalidationBacking(
   if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     // In SPv2, visual rects are in the space of their local transform node.
     rect.moveBy(FloatPoint(context.treeBuilderContext.current.paintOffset));
+    // Use enclosingIntRect to ensure the final visual rect will cover the
+    // rect in source coordinates no matter if the painting will use pixel
+    // snapping.
+    IntRect intRect = enclosingIntRect(rect);
+    if (FloatRect(intRect) != rect) {
+      coversExtraPixels = true;
+      return LayoutRect(intRect);
+    }
     return LayoutRect(rect);
   }
 
@@ -84,6 +93,16 @@ static LayoutRect mapLocalRectToPaintInvalidationBacking(
     result = LayoutRect(rect);
   } else {
     rect.moveBy(FloatPoint(context.treeBuilderContext.current.paintOffset));
+    if ((!object.isSVG() || object.isSVGRoot()) && !rect.isEmpty()) {
+      // Use enclosingIntRect to ensure the final visual rect will cover the
+      // rect in source coordinates no matter if the painting will use pixel
+      // snapping.
+      IntRect intRect = enclosingIntRect(rect);
+      if (FloatRect(intRect) != rect) {
+        coversExtraPixels = true;
+        rect = intRect;
+      }
+    }
 
     PropertyTreeState currentTreeState(
         context.treeBuilderContext.current.transform,
@@ -95,6 +114,9 @@ static LayoutRect mapLocalRectToPaintInvalidationBacking(
     auto containerContentsProperties =
         containerPaintProperties->contentsProperties();
 
+    // TODO(wangxianzhu): Set coversExtraPixels if there are any non-translate
+    // transforms. Currently this case is handled in BoxPaintInvalidator by
+    // checking transforms.
     bool success = false;
     result = LayoutRect(geometryMapper.mapToVisualRectInDestinationSpace(
         rect, currentTreeState, containerContentsProperties.propertyTreeState,
@@ -115,28 +137,32 @@ void PaintInvalidatorContext::mapLocalRectToPaintInvalidationBacking(
     const LayoutObject& object,
     LayoutRect& rect) const {
   GeometryMapper geometryMapper;
-  rect = blink::mapLocalRectToPaintInvalidationBacking(geometryMapper, object,
-                                                       FloatRect(rect), *this);
+  bool coversExtraPixels;
+  rect = blink::mapLocalRectToPaintInvalidationBacking(
+      geometryMapper, object, FloatRect(rect), *this, coversExtraPixels);
 }
 
 LayoutRect PaintInvalidator::mapLocalRectToPaintInvalidationBacking(
     const LayoutObject& object,
     const FloatRect& localRect,
-    const PaintInvalidatorContext& context) {
-  return blink::mapLocalRectToPaintInvalidationBacking(m_geometryMapper, object,
-                                                       localRect, context);
+    const PaintInvalidatorContext& context,
+    bool& coversExtraPixels) {
+  return blink::mapLocalRectToPaintInvalidationBacking(
+      m_geometryMapper, object, localRect, context, coversExtraPixels);
 }
 
 LayoutRect PaintInvalidator::computePaintInvalidationRectInBacking(
     const LayoutObject& object,
-    const PaintInvalidatorContext& context) {
+    const PaintInvalidatorContext& context,
+    bool& coversExtraPixels) {
   FloatRect localRect;
   if (object.isSVG() && !object.isSVGRoot())
     localRect = SVGLayoutSupport::localOverflowRectForPaintInvalidation(object);
   else
     localRect = FloatRect(object.localOverflowRectForPaintInvalidation());
 
-  return mapLocalRectToPaintInvalidationBacking(object, localRect, context);
+  return mapLocalRectToPaintInvalidationBacking(object, localRect, context,
+                                                coversExtraPixels);
 }
 
 LayoutPoint PaintInvalidator::computeLocationFromPaintInvalidationBacking(
@@ -311,8 +337,11 @@ void PaintInvalidator::updateContext(const LayoutObject& object,
         PaintInvalidatorContext::ForcedSubtreeSlowPathRect;
 
   context.oldBounds = object.previousPaintInvalidationRect();
+  context.oldBoundsCoversExtraPixels =
+      object.previousPaintInvalidationRectCoversExtraPixels();
   context.oldLocation = object.previousPositionFromPaintInvalidationBacking();
-  context.newBounds = computePaintInvalidationRectInBacking(object, context);
+  context.newBounds = computePaintInvalidationRectInBacking(
+      object, context, context.newBoundsCoversExtraPixels);
   context.newLocation =
       computeLocationFromPaintInvalidationBacking(object, context);
 
@@ -322,7 +351,7 @@ void PaintInvalidator::updateContext(const LayoutObject& object,
   context.newBounds.move(adjustment);
 
   object.getMutableForPainting().setPreviousPaintInvalidationRect(
-      context.newBounds);
+      context.newBounds, context.newBoundsCoversExtraPixels);
   object.getMutableForPainting()
       .setPreviousPositionFromPaintInvalidationBacking(context.newLocation);
 }