Separate repaint and layout requirements of StyleDifference (Step 1)

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index d79cd3f75902c5e8c1d3aae705e877adb5771435..760ebba3932af3d2fed99960e9d3b6757a493ccd 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -1840,62 +1840,62 @@ void RenderObject::handleDynamicFloatPositionChange()
     }
 }
 
-StyleDifference RenderObject::adjustStyleDifference(StyleDifference diff, unsigned contextSensitiveProperties) const
+StyleDifference RenderObject::adjustStyleDifference(StyleDifference diff) const
 {
     // If transform changed, and the layer does not paint into its own separate backing, then we need to do a layout.
     // FIXME: The comment above is what the code does, but it is technically not following spec. This means we will
     // not to layout for 3d transforms, but we should be invoking a simplified relayout. Is it possible we are avoiding
     // doing this for some performance reason at this time?
-    if (contextSensitiveProperties & ContextSensitivePropertyTransform) {
+    if (diff.transformChanged()) {
         // Text nodes share style with their parents but transforms don't apply to them,
         // hence the !isText() check.
         // FIXME: when transforms are taken into account for overflow, we will need to do a layout.
         if (!isText() && (!hasLayer() || !toRenderLayerModelObject(this)->layer()->hasDirectReasonsForCompositing())) {
-            // We need to set at least SimplifiedLayout, but if PositionedMovementOnly is already set
-            // then we actually need SimplifiedLayoutAndPositionedMovement.
+            diff.setNeedsRepaintLayer();
             if (!hasLayer())
-                diff = StyleDifferenceLayout; // FIXME: Do this for now since SimplifiedLayout cannot handle updating floating objects lists.
-            else if (diff < StyleDifferenceLayoutPositionedMovementOnly)
-                diff = StyleDifferenceSimplifiedLayout;
-            else if (diff < StyleDifferenceSimplifiedLayout)
-                diff = StyleDifferenceSimplifiedLayoutAndPositionedMovement;
-        } else if (diff < StyleDifferenceRecompositeLayer)
-            diff = StyleDifferenceRecompositeLayer;
+                diff.setNeedsFullLayout(); // FIXME: Do this for now since SimplifiedLayout cannot handle updating floating objects lists.
+            else
+                diff.setNeedsSimplifiedLayout();
+        } else {
+            diff.setNeedsRecompositeLayer();
+        }
     }
 
-    // If opacity or filters changed, and the layer does not paint into its own separate backing, then we need to repaint (also
+    // If opacity or zIndex changed, and the layer does not paint into its own separate backing, then we need to repaint (also
     // ignoring text nodes)
-    if (contextSensitiveProperties & ContextSensitivePropertyOpacity && diff <= StyleDifferenceRepaintLayer) {
+    if ((diff.opacityChanged() || diff.zIndexChanged()) && !diff.needsRepaintLayer()) {
         if (!isText() && (!hasLayer() || !toRenderLayerModelObject(this)->layer()->hasDirectReasonsForCompositing()))
-            diff = StyleDifferenceRepaintLayer;
-        else if (diff < StyleDifferenceRecompositeLayer)
-            diff = StyleDifferenceRecompositeLayer;
+            diff.setNeedsRepaintLayer();
+        else
+            diff.setNeedsRecompositeLayer();
     }
 
-    if ((contextSensitiveProperties & ContextSensitivePropertyFilter) && hasLayer() && diff <= StyleDifferenceRepaintLayer) {
+    // If filter changed, and the layer does not paint into its own separate backing or it paints with filters, then we need to repaint.
+    if (diff.filterChanged() && hasLayer() && !diff.needsRepaintLayer()) {
         RenderLayer* layer = toRenderLayerModelObject(this)->layer();
         if (!layer->hasDirectReasonsForCompositing() || layer->paintsWithFilters())
-            diff = StyleDifferenceRepaintLayer;
-        else if (diff < StyleDifferenceRecompositeLayer)
-            diff = StyleDifferenceRecompositeLayer;
+            diff.setNeedsRepaintLayer();
+        else
+            diff.setNeedsRecompositeLayer();
     }
 
-    if ((contextSensitiveProperties & ContextSensitivePropertyTextOrColor) && diff < StyleDifferenceRepaint
-        && hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor())
-        diff = StyleDifferenceRepaint;
+    if (!diff.needsRepaint() && diff.textOrColorChanged() && hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor())
+        diff.setNeedsRepaintSelf();
+
+    diff.resetContextSensitiveFlags();
 
     // The answer to layerTypeRequired() for plugins, iframes, and canvas can change without the actual
     // style changing, since it depends on whether we decide to composite these elements. When the
     // layer status of one of these elements changes, we need to force a layout.
-    if (diff == StyleDifferenceEqual && style() && isLayerModelObject()) {
+    if (!diff.needsFullLayout() && style() && isLayerModelObject()) {
         bool requiresLayer = toRenderLayerModelObject(this)->layerTypeRequired() != NoLayer;
         if (hasLayer() != requiresLayer)
-            diff = StyleDifferenceLayout;
+            diff.setNeedsFullLayout();
     }
 
     // If we have no layer(), just treat a RepaintLayer hint as a normal Repaint.
-    if (diff == StyleDifferenceRepaintLayer && !hasLayer())
-        diff = StyleDifferenceRepaint;
+    if (diff.needsRepaintLayer() && !hasLayer())
+        diff.setNeedsRepaintSelf();
 
     return diff;
 }
@@ -1947,12 +1947,11 @@ void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
         return;
     }
 
-    StyleDifference diff = StyleDifferenceEqual;
-    unsigned contextSensitiveProperties = ContextSensitivePropertyNone;
+    StyleDifference diff;
     if (m_style)
-        diff = m_style->visualInvalidationDiff(*style, contextSensitiveProperties);
+        diff = m_style->visualInvalidationDiff(*style);
 
-    diff = adjustStyleDifference(diff, contextSensitiveProperties);
+    diff = adjustStyleDifference(diff);
 
     styleWillChange(diff, *style);
 
@@ -1980,21 +1979,22 @@ void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
 
     // Now that the layer (if any) has been updated, we need to adjust the diff again,
     // check whether we should layout now, and decide if we need to repaint.
-    StyleDifference updatedDiff = adjustStyleDifference(diff, contextSensitiveProperties);
+    StyleDifference updatedDiff = adjustStyleDifference(diff);
 
-    if (diff <= StyleDifferenceLayoutPositionedMovementOnly) {
-        if (updatedDiff == StyleDifferenceLayout)
+    if (updatedDiff.needsFullLayout()) {
+        if (!diff.needsFullLayout())
             setNeedsLayoutAndPrefWidthsRecalc();
-        else if (updatedDiff == StyleDifferenceLayoutPositionedMovementOnly)
-            setNeedsPositionedMovementLayout();
-        else if (updatedDiff == StyleDifferenceSimplifiedLayoutAndPositionedMovement) {
-            setNeedsPositionedMovementLayout();
-            setNeedsSimplifiedNormalFlowLayout();
-        } else if (updatedDiff == StyleDifferenceSimplifiedLayout)
+    } else {
+        if (updatedDiff.needsSimplifiedLayout() && !diff.needsSimplifiedLayout())
             setNeedsSimplifiedNormalFlowLayout();
+        if (updatedDiff.needsPositionedMovementLayout() && !diff.needsPositionedMovementLayout())
+            setNeedsPositionedMovementLayout();
     }
 
-    if (updatedDiff == StyleDifferenceRepaint || updatedDiff == StyleDifferenceRepaintLayer) {
+    // FIXME: For now if needsFullLayout() or needsSimplifiedLayout(), repaint is handled during layout(),
+    // so don't repaint here to avoid duplicate repaints.
+    // Need to optimize repaint during layout() to reduce unnecessary repaints and duplicate code.
+    if (updatedDiff.needsRepaintSelf() && !updatedDiff.needsFullLayout() && !updatedDiff.needsSimplifiedLayout()) {
         // Do a repaint with the new style now, e.g., for example if we go from
         // not having an outline to having an outline.
         repaint();
@@ -2028,14 +2028,18 @@ void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle& newS
                     layer->setHasVisibleContent();
                 } else if (layer->hasVisibleContent() && (this == layer->renderer() || layer->renderer()->style()->visibility() != VISIBLE)) {
                     layer->dirtyVisibleContentStatus();
-                    if (diff > StyleDifferenceRepaintLayer)
+                    if (diff.needsLayout())
                         repaint();
                 }
             }
         }
 
-        if (m_parent && diff == StyleDifferenceRepaint)
+        // FIXME: For now if needsFullLayout() or needsSimplifiedLayout(), repaint is handled during layout(),
+        // so don't repaint here to avoid duplicate repaints.
+        // Need to optimize repaint during layout() to reduce unnecessary repaints and duplicate code.
+        if (m_parent && diff.needsRepaintSelf() && !diff.needsFullLayout() && !diff.needsSimplifiedLayout())
             repaint();
+
         if (isFloating() && (m_style->floating() != newStyle.floating()))
             // For changes in float styles, we need to conceivably remove ourselves
             // from the floating objects list.
@@ -2051,12 +2055,13 @@ void RenderObject::styleWillChange(StyleDifference diff, const RenderStyle& newS
 
         // Clearing these bits is required to avoid leaving stale renderers.
         // FIXME: We shouldn't need that hack if our logic was totally correct.
-        if (diff == StyleDifferenceLayout || diff == StyleDifferenceLayoutPositionedMovementOnly) {
+        if (diff.needsLayout()) {
             setFloating(false);
             clearPositionedState();
         }
-    } else
+    } else {
         s_affectsParentBlock = false;
+    }
 
     if (view()->frameView()) {
         bool shouldBlitOnFixedBackgroundImage = false;
@@ -2124,7 +2129,7 @@ void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldSt
     if (!m_parent)
         return;
 
-    if (diff == StyleDifferenceLayout || diff == StyleDifferenceSimplifiedLayout) {
+    if (diff.needsFullLayout() || diff.needsSimplifiedLayout()) {
         RenderCounter::rendererStyleChanged(*this, oldStyle, m_style.get());
 
         // If the object already needs layout, then setNeedsLayout won't do
@@ -2135,14 +2140,12 @@ void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldSt
         if (needsLayout() && oldStyle->position() != m_style->position())
             markContainingBlocksForLayout();
 
-        if (diff == StyleDifferenceLayout)
+        if (diff.needsFullLayout())
             setNeedsLayoutAndPrefWidthsRecalc();
         else
             setNeedsSimplifiedNormalFlowLayout();
-    } else if (diff == StyleDifferenceSimplifiedLayoutAndPositionedMovement) {
-        setNeedsPositionedMovementLayout();
-        setNeedsSimplifiedNormalFlowLayout();
-    } else if (diff == StyleDifferenceLayoutPositionedMovementOnly)
+    }
+    if (diff.needsPositionedMovementLayout())
         setNeedsPositionedMovementLayout();
 
     // Don't check for repaint here; we need to wait until the layer has been