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// 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 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 needsRepaintObject() const { return m_repaintType == RepaintObject; }
void setNeedsRepaintObject()
{
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; }
void setNeedsPositionedMovementLayout()
{
ASSERT(!needsFullLayout());
m_layoutType = PositionedMovement;
}
bool needsFullLayout() const { return m_layoutType == FullLayout; }
void setNeedsFullLayout() { m_layoutType = FullLayout; }
private:
unsigned m_needsRecompositeLayer : 1;
enum RepaintType {
NoRepaint = 0,
RepaintObject,
RepaintLayer
};
unsigned m_repaintType : 2;
enum LayoutType {
NoLayout = 0,
PositionedMovement,
FullLayout
};
unsigned m_layoutType : 2;
};
} // namespace WebCore
#endif // StyleDifference_h
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