Replace LayoutObject::skipInvalidationWhenLaidOutChildren() with paintedOutputOfObjectHasNoEffect

third_party/WebKit/Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 336 matching lines @@
     }
 
     void assertSubtreeClearedPaintInvalidationFlags() const
     {
         for (const LayoutObject* layoutObject = this; layoutObject; layoutObject = layoutObject->nextInPreOrder())
             layoutObject->assertClearedPaintInvalidationFlags();
     }
 
 #endif
 
-    // Correct version of !layoutObjectHasNoBoxEffectObsolete().
-    bool hasBoxEffect() const
-    {
-        return hasBoxDecorationBackground() || style()->hasVisualOverflowingEffect();
-    }
-
     // LayoutObject tree manipulation
     //////////////////////////////////////////
     virtual bool canHaveChildren() const { return virtualChildren(); }
     virtual bool isChildAllowed(LayoutObject*, const ComputedStyle&) const { return true; }
 
     // This function is called whenever a child is inserted under |this|.
     //
     // The main purpose of this function is to generate a consistent layout
     // tree, which means generating the missing anonymous objects. Most of the
     // time there'll be no anonymous objects to generate.
@@ skipping 64 matching lines @@
     void setNeedsLayoutIsForbidden(bool flag) { m_setNeedsLayoutForbidden = flag; }
 #endif
 
     void addAbsoluteRectForLayer(IntRect& result);
     bool requiresAnonymousTableWrappers(const LayoutObject*) const;
 
     // Gets pseudoStyle from Shadow host(in case of input elements)
     // or from Parent element.
     PassRefPtr<ComputedStyle> getUncachedPseudoStyleFromParentOrShadowHost() const;
 
-    bool skipInvalidationWhenLaidOutChildren() const;
-
 public:
 #ifndef NDEBUG
     void showTreeForThis() const;
     void showLayoutTreeForThis() const;
     void showLineTreeForThis() const;
 
     void showLayoutObject() const;
     // We don't make stringBuilder an optional parameter so that
     // showLayoutObject can be called from gdb easily.
     void showLayoutObject(StringBuilder&) const;
@@ skipping 228 matching lines @@
     enum BoxDecorationBackgroundState {
         NoBoxDecorationBackground,
         HasBoxDecorationBackgroundObscurationStatusInvalid,
         HasBoxDecorationBackgroundKnownToBeObscured,
         HasBoxDecorationBackgroundMayBeVisible,
     };
     bool hasBoxDecorationBackground() const { return m_bitfields.getBoxDecorationBackgroundState() != NoBoxDecorationBackground; }
     bool boxDecorationBackgroundIsKnownToBeObscured() const;
     bool hasBackground() const { return style()->hasBackground(); }
 
-    bool needsLayoutBecauseOfChildren() const { return needsLayout() && !selfNeedsLayout() && !needsPositionedMovementLayout() && !needsSimplifiedNormalFlowLayout(); }
-
     bool needsLayout() const
     {
         return m_bitfields.selfNeedsLayout() || m_bitfields.normalChildNeedsLayout() || m_bitfields.posChildNeedsLayout()
             || m_bitfields.needsSimplifiedNormalFlowLayout() || m_bitfields.needsPositionedMovementLayout();
     }
 
     bool selfNeedsLayout() const { return m_bitfields.selfNeedsLayout(); }
     bool needsPositionedMovementLayout() const { return m_bitfields.needsPositionedMovementLayout(); }
 
     bool posChildNeedsLayout() const { return m_bitfields.posChildNeedsLayout(); }
@@ skipping 415 matching lines @@
     // Invalidate the paint of a specific subrectangle within a given object. The rect is in the object's coordinate space.
     void invalidatePaintRectangle(const LayoutRect&) const;
 
     // Walk the tree after layout issuing paint invalidations for layoutObjects that have changed or moved, updating bounds that have changed, and clearing paint invalidation state.
     virtual void invalidateTreeIfNeeded(const PaintInvalidationState&);
 
     void invalidatePaintIncludingNonCompositingDescendants();
     void invalidatePaintIncludingNonSelfPaintingLayerDescendants(const LayoutBoxModelObject& paintInvalidationContainer);
     void setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants();
 
+    // Returns true if the object will not generate any effective painted output.
+    // It's used to skip unforced paint invalidation (which is when shouldDoFullPaintInvalidation
+    // is false, but mayNeedPaintInvalidation or childShouldCheckForPaintInvalidation is true) to
+    // avoid unnecessary paint invalidations of empty areas covered by such objects.
+    virtual bool paintedOutputOfObjectHasNoEffect() const { return false; }
+
     // Returns the rect that should have paint invalidated whenever this object changes. The rect is in the view's
     // coordinate space. This method deals with outlines and overflow.
     virtual LayoutRect absoluteClippedOverflowRect() const;
 
     // Returns the rect that should have paint invalidated whenever this object changes. The rect is in the object's
     // local coordinate space. This is for non-SVG objects and LayoutSVGRoot only. SVG objects (except LayoutSVGRoot)
     // should use paintInvalidationRectInLocalSVGCoordinates() and map with SVG transforms instead.
     virtual LayoutRect localOverflowRectForPaintInvalidation() const;
 
     // Given a rect in the object's coordinate space, mutates the rect into one representing the size of its visual painted
@@ skipping 404 matching lines @@
     //
     // If we don't meet the criteria for an incremental paint, the
     // alternative is a full paint invalidation.
     virtual void incrementallyInvalidatePaint(const LayoutBoxModelObject& paintInvalidationContainer, const LayoutRect& oldBounds, const LayoutRect& newBounds, const LayoutPoint& positionFromPaintInvalidationBacking);
 
     virtual bool hasNonCompositedScrollbars() const { return false; }
 
 #if ENABLE(ASSERT)
     virtual bool paintInvalidationStateIsDirty() const
     {
-        return m_bitfields.neededLayoutBecauseOfChildren() || shouldCheckForPaintInvalidationRegardlessOfPaintInvalidationState();
+        return shouldCheckForPaintInvalidationRegardlessOfPaintInvalidationState();
     }
 #endif
 
     // This function walks the descendants of |this|, following a
     // layout ordering.
     //
     // The ordering is important for PaintInvalidationState, as
     // it requires to be called following a descendant/container
     // relationship.
     //
@@ skipping 172 matching lines @@
             , m_normalChildNeedsLayout(false)
             , m_posChildNeedsLayout(false)
             , m_needsSimplifiedNormalFlowLayout(false)
             , m_selfNeedsOverflowRecalcAfterStyleChange(false)
             , m_childNeedsOverflowRecalcAfterStyleChange(false)
             , m_preferredLogicalWidthsDirty(false)
             , m_childShouldCheckForPaintInvalidation(false)
             , m_mayNeedPaintInvalidation(false)
             , m_mayNeedPaintInvalidationSubtree(false)
             , m_shouldInvalidateSelection(false)
-            , m_neededLayoutBecauseOfChildren(false)
             , m_floating(false)
             , m_isAnonymous(!node)
             , m_isText(false)
             , m_isBox(false)
             , m_isInline(true)
             , m_isAtomicInlineLevel(false)
             , m_horizontalWritingMode(true)
             , m_isDragging(false)
             , m_hasLayer(false)
             , m_hasOverflowClip(false)
@@ skipping 13 matching lines @@
             , m_lastBoxDecorationBackgroundObscured(false)
             , m_isBackgroundAttachmentFixedObject(false)
             , m_isScrollAnchorObject(false)
             , m_positionedState(IsStaticallyPositioned)
             , m_selectionState(SelectionNone)
             , m_boxDecorationBackgroundState(NoBoxDecorationBackground)
             , m_fullPaintInvalidationReason(PaintInvalidationNone)
         {
         }
 
-        // 32 bits have been used in the first word, and 17 in the second.
+        // 32 bits have been used in the first word, and 16 in the second.
 
         // Self needs layout means that this layout object is marked for a full layout.
         // This is the default layout but it is expensive as it recomputes everything.
         // For CSS boxes, this includes the width (laying out the line boxes again), the margins
         // (due to block collapsing margins), the positions, the height and the potential overflow.
         ADD_BOOLEAN_BITFIELD(selfNeedsLayout, SelfNeedsLayout);
 
         // A positioned movement layout is a specialized type of layout used on positioned objects
         // that only visually moved. This layout is used when changing 'top'/'left' on a positioned
         // element or margins on an out-of-flow one. Because the following operations don't impact
@@ skipping 30 matching lines @@
 
         // This boolean marks preferred logical widths for lazy recomputation.
         //
         // See INTRINSIC SIZES / PREFERRED LOGICAL WIDTHS above about those
         // widths.
         ADD_BOOLEAN_BITFIELD(preferredLogicalWidthsDirty, PreferredLogicalWidthsDirty);
 
         ADD_BOOLEAN_BITFIELD(childShouldCheckForPaintInvalidation, ChildShouldCheckForPaintInvalidation);
         ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidation, MayNeedPaintInvalidation);
         ADD_BOOLEAN_BITFIELD(mayNeedPaintInvalidationSubtree, MayNeedPaintInvalidationSubtree);
-        ADD_BOOLEAN_BITFIELD(shouldInvalidateSelection, ShouldInvalidateSelection); // TODO(wangxianzhu): Remove for slimming paint v2.
-        ADD_BOOLEAN_BITFIELD(neededLayoutBecauseOfChildren, NeededLayoutBecauseOfChildren); // TODO(wangxianzhu): Remove for slimming paint v2.
+        ADD_BOOLEAN_BITFIELD(shouldInvalidateSelection, ShouldInvalidateSelection);
 
         // This boolean is the cached value of 'float'
         // (see ComputedStyle::isFloating).
         ADD_BOOLEAN_BITFIELD(floating, Floating);
 
         ADD_BOOLEAN_BITFIELD(isAnonymous, IsAnonymous);
         ADD_BOOLEAN_BITFIELD(isText, IsText);
         ADD_BOOLEAN_BITFIELD(isBox, IsBox);
 
         // This boolean represents whether the LayoutObject is 'inline-level'
@@ skipping 196 matching lines @@
 {
     setNeedsLayout(reason, markParents, layouter);
     setShouldDoFullPaintInvalidation();
 }
 
 inline void LayoutObject::clearNeedsLayout()
 {
     // Set flags for later stages/cycles.
     setEverHadLayout();
     setMayNeedPaintInvalidation();
-    m_bitfields.setNeededLayoutBecauseOfChildren(needsLayoutBecauseOfChildren());
 
     // Clear needsLayout flags.
     setSelfNeedsLayout(false);
     setPosChildNeedsLayout(false);
     setNeedsSimplifiedNormalFlowLayout(false);
     setNormalChildNeedsLayout(false);
     setNeedsPositionedMovementLayout(false);
     setAncestorLineBoxDirty(false);
 
 #if ENABLE(ASSERT)
@@ skipping 122 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h