Separate repaint and layout requirements of StyleDifference (Step 3)

Source/core/rendering/style/StyleDifference.h

 // Copyright 2014 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.
 
 #ifndef StyleDifference_h
 #define StyleDifference_h
 
+#include "wtf/Assertions.h"
+
 namespace WebCore {
 
 // This class represents the difference between two computed styles (RenderStyle).
-// The difference can be of 3 types:
-// - Layout difference
-// - Repaint difference
-// - Recompositing difference
+// The difference can be combination of 3 types according to the actions needed:
+// - Difference needing layout
+// - Difference needing repaint
+// - Difference needing recompositing layers
 class StyleDifference {
 public:
     StyleDifference()
         : m_needsRecompositeLayer(false)
         , m_repaintType(NoRepaint)
         , m_layoutType(NoLayout) { }
 
     // The two styles are identical.
     bool hasNoChange() const { return !m_needsRecompositeLayer && !m_repaintType && !m_layoutType; }
 
     // The layer needs its position and transform updated. Implied by other repaint and layout flags.
     bool needsRecompositeLayer() const { return m_needsRecompositeLayer || needsRepaint() || needsLayout(); }
     void setNeedsRecompositeLayer() { m_needsRecompositeLayer = true; }
 
     bool needsRepaint() const { return m_repaintType != NoRepaint; }
     void clearNeedsRepaint() { m_repaintType = NoRepaint; }
 
     // The object just needs to be repainted.
-    bool needsRepaintObjectOnly() const { return m_repaintType == RepaintObjectOnly; }
+    bool needsRepaintObject() const { return m_repaintType == RepaintObject; }
     void setNeedsRepaintObject()
     {
-        if (!needsRepaintLayer())
-            m_repaintType = RepaintObjectOnly;
+        ASSERT(!needsRepaintLayer());
+        m_repaintType = RepaintObject;
     }
 
     // The layer and its descendant layers need to be repainted.
     bool needsRepaintLayer() const { return m_repaintType == RepaintLayer; }
     void setNeedsRepaintLayer() { m_repaintType = RepaintLayer; }
 
     bool needsLayout() const { return m_layoutType != NoLayout; }
     void clearNeedsLayout() { m_layoutType = NoLayout; }
 
     // The offset of this positioned object has been updated.
-    bool needsPositionedMovementLayout() const { return m_layoutType & PositionedMovement; }
+    bool needsPositionedMovementLayout() const { return m_layoutType == PositionedMovement; }
     void setNeedsPositionedMovementLayout()
     {
-        if (!needsFullLayout())
-            m_layoutType |= PositionedMovement;
-        // FIXME: This is temporary to keep the StyleDifferenceLegacy behavior.
-        m_repaintType = NoRepaint;
+        ASSERT(!needsFullLayout());
+        m_layoutType = PositionedMovement;
     }
 
     bool needsFullLayout() const { return m_layoutType == FullLayout; }
-    void setNeedsFullLayout()
-    {
-        m_layoutType = FullLayout;
-        // FIXME: This is temporary to keep the StyleDifferenceLegacy behavior.
-        m_repaintType = NoRepaint;
-    }
+    void setNeedsFullLayout() { m_layoutType = FullLayout; }
 
 private:
     unsigned m_needsRecompositeLayer : 1;
 
     enum RepaintType {
         NoRepaint = 0,
-        RepaintObjectOnly,
+        RepaintObject,
         RepaintLayer
     };
     unsigned m_repaintType : 2;
 
     enum LayoutType {
         NoLayout = 0,
-        PositionedMovement = 1 << 0,
-        FullLayout = 1 << 1
+        PositionedMovement,
+        FullLayout
     };
     unsigned m_layoutType : 2;
 };
 
 } // namespace WebCore
 
 #endif // StyleDifference_h