WebCore/rendering/RenderLayer.h
changeset 0 4f2f89ce4247
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/rendering/RenderLayer.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,704 @@
+/*
+ * Copyright (C) 2003, 2009 Apple Inc. All rights reserved.
+ *
+ * Portions are Copyright (C) 1998 Netscape Communications Corporation.
+ *
+ * Other contributors:
+ *   Robert O'Callahan <roc+@cs.cmu.edu>
+ *   David Baron <dbaron@fas.harvard.edu>
+ *   Christian Biesinger <cbiesinger@web.de>
+ *   Randall Jesup <rjesup@wgate.com>
+ *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
+ *   Josh Soref <timeless@mac.com>
+ *   Boris Zbarsky <bzbarsky@mit.edu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Alternatively, the contents of this file may be used under the terms
+ * of either the Mozilla Public License Version 1.1, found at
+ * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
+ * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
+ * (the "GPL"), in which case the provisions of the MPL or the GPL are
+ * applicable instead of those above.  If you wish to allow use of your
+ * version of this file only under the terms of one of those two
+ * licenses (the MPL or the GPL) and not to allow others to use your
+ * version of this file under the LGPL, indicate your decision by
+ * deletingthe provisions above and replace them with the notice and
+ * other provisions required by the MPL or the GPL, as the case may be.
+ * If you do not delete the provisions above, a recipient may use your
+ * version of this file under any of the LGPL, the MPL or the GPL.
+ */
+
+#ifndef RenderLayer_h
+#define RenderLayer_h
+
+#include "RenderBox.h"
+#include "ScrollBehavior.h"
+#include "ScrollbarClient.h"
+#include "Timer.h"
+#include <wtf/OwnPtr.h>
+
+namespace WebCore {
+
+class CachedResource;
+class HitTestRequest;
+class HitTestResult;
+class HitTestingTransformState;
+class RenderFrameSet;
+class RenderMarquee;
+class RenderReplica;
+class RenderScrollbarPart;
+class RenderStyle;
+class RenderTable;
+class RenderText;
+class RenderView;
+class Scrollbar;
+class TransformationMatrix;
+
+#if USE(ACCELERATED_COMPOSITING)
+class RenderLayerBacking;
+class RenderLayerCompositor;
+#endif
+
+class ClipRects {
+public:
+    ClipRects()
+        : m_refCnt(0)
+        , m_fixed(false)
+    {
+    }
+
+    ClipRects(const IntRect& r)
+        : m_overflowClipRect(r)
+        , m_fixedClipRect(r)
+        , m_posClipRect(r)
+        , m_refCnt(0)
+        , m_fixed(false)
+    {
+    }
+
+    ClipRects(const ClipRects& other)
+        : m_overflowClipRect(other.overflowClipRect())
+        , m_fixedClipRect(other.fixedClipRect())
+        , m_posClipRect(other.posClipRect())
+        , m_refCnt(0)
+        , m_fixed(other.fixed())
+    {
+    }
+
+    void reset(const IntRect& r)
+    {
+        m_overflowClipRect = r;
+        m_fixedClipRect = r;
+        m_posClipRect = r;
+        m_fixed = false;
+    }
+    
+    const IntRect& overflowClipRect() const { return m_overflowClipRect; }
+    void setOverflowClipRect(const IntRect& r) { m_overflowClipRect = r; }
+
+    const IntRect& fixedClipRect() const { return m_fixedClipRect; }
+    void setFixedClipRect(const IntRect&r) { m_fixedClipRect = r; }
+
+    const IntRect& posClipRect() const { return m_posClipRect; }
+    void setPosClipRect(const IntRect& r) { m_posClipRect = r; }
+
+    bool fixed() const { return m_fixed; }
+    void setFixed(bool fixed) { m_fixed = fixed; }
+
+    void ref() { m_refCnt++; }
+    void deref(RenderArena* renderArena) { if (--m_refCnt == 0) destroy(renderArena); }
+
+    void destroy(RenderArena*);
+
+    // Overloaded new operator.
+    void* operator new(size_t, RenderArena*) throw();
+
+    // Overridden to prevent the normal delete from being called.
+    void operator delete(void*, size_t);
+
+    bool operator==(const ClipRects& other) const
+    {
+        return m_overflowClipRect == other.overflowClipRect() &&
+               m_fixedClipRect == other.fixedClipRect() &&
+               m_posClipRect == other.posClipRect() &&
+               m_fixed == other.fixed();
+    }
+
+    ClipRects& operator=(const ClipRects& other)
+    {
+        m_overflowClipRect = other.overflowClipRect();
+        m_fixedClipRect = other.fixedClipRect();
+        m_posClipRect = other.posClipRect();
+        m_fixed = other.fixed();
+        return *this;
+    }
+    
+    static IntRect infiniteRect() { return IntRect(INT_MIN/2, INT_MIN/2, INT_MAX, INT_MAX); }
+
+private:
+    // The normal operator new is disallowed on all render objects.
+    void* operator new(size_t) throw();
+
+private:
+    IntRect m_overflowClipRect;
+    IntRect m_fixedClipRect;
+    IntRect m_posClipRect;
+    unsigned m_refCnt : 31;
+    bool m_fixed : 1;
+};
+
+class RenderLayer : public ScrollbarClient {
+public:
+    friend class RenderReplica;
+
+    RenderLayer(RenderBoxModelObject*);
+    ~RenderLayer();
+
+    RenderBoxModelObject* renderer() const { return m_renderer; }
+    RenderBox* renderBox() const { return m_renderer && m_renderer->isBox() ? toRenderBox(m_renderer) : 0; }
+    RenderLayer* parent() const { return m_parent; }
+    RenderLayer* previousSibling() const { return m_previous; }
+    RenderLayer* nextSibling() const { return m_next; }
+    RenderLayer* firstChild() const { return m_first; }
+    RenderLayer* lastChild() const { return m_last; }
+
+    void addChild(RenderLayer* newChild, RenderLayer* beforeChild = 0);
+    RenderLayer* removeChild(RenderLayer*);
+
+    void removeOnlyThisLayer();
+    void insertOnlyThisLayer();
+
+    void repaintIncludingDescendants();
+
+#if USE(ACCELERATED_COMPOSITING)
+    // Indicate that the layer contents need to be repainted. Only has an effect
+    // if layer compositing is being used,
+    void setBackingNeedsRepaint();
+    void setBackingNeedsRepaintInRect(const IntRect& r); // r is in the coordinate space of the layer's render object
+    void repaintIncludingNonCompositingDescendants(RenderBoxModelObject* repaintContainer);
+#endif
+
+    void styleChanged(StyleDifference, const RenderStyle*);
+
+    RenderMarquee* marquee() const { return m_marquee; }
+
+    bool isNormalFlowOnly() const { return m_isNormalFlowOnly; }
+    bool isSelfPaintingLayer() const;
+
+    bool requiresSlowRepaints() const;
+
+    bool isTransparent() const;
+    RenderLayer* transparentPaintingAncestor();
+    void beginTransparencyLayers(GraphicsContext*, const RenderLayer* rootLayer, PaintBehavior);
+
+    bool hasReflection() const { return renderer()->hasReflection(); }
+    bool isReflection() const { return renderer()->isReplica(); }
+    RenderReplica* reflection() const { return m_reflection; }
+    RenderLayer* reflectionLayer() const;
+
+    const RenderLayer* root() const
+    {
+        const RenderLayer* curr = this;
+        while (curr->parent())
+            curr = curr->parent();
+        return curr;
+    }
+    
+    int x() const { return m_x; }
+    int y() const { return m_y; }
+    void setLocation(int x, int y)
+    {
+        m_x = x;
+        m_y = y;
+    }
+
+    int width() const { return m_width; }
+    int height() const { return m_height; }
+    IntSize size() const { return IntSize(m_width, m_height); }
+    
+    void setWidth(int w) { m_width = w; }
+    void setHeight(int h) { m_height = h; }
+
+    int scrollWidth();
+    int scrollHeight();
+
+    void panScrollFromPoint(const IntPoint&);
+
+    // Scrolling methods for layers that can scroll their overflow.
+    void scrollByRecursively(int xDelta, int yDelta);
+
+    IntSize scrolledContentOffset() const { return IntSize(scrollXOffset() + m_scrollLeftOverflow, scrollYOffset()); }
+
+    int scrollXOffset() const { return m_scrollX + m_scrollOriginX; }
+    int scrollYOffset() const { return m_scrollY; }
+
+    void scrollToOffset(int x, int y, bool updateScrollbars = true, bool repaint = true);
+    void scrollToXOffset(int x) { scrollToOffset(x, m_scrollY); }
+    void scrollToYOffset(int y) { scrollToOffset(m_scrollX + m_scrollOriginX, y); }
+    void scrollRectToVisible(const IntRect&, bool scrollToAnchor = false, const ScrollAlignment& alignX = ScrollAlignment::alignCenterIfNeeded, const ScrollAlignment& alignY = ScrollAlignment::alignCenterIfNeeded);
+
+    IntRect getRectToExpose(const IntRect& visibleRect, const IntRect& exposeRect, const ScrollAlignment& alignX, const ScrollAlignment& alignY);
+
+    void setHasHorizontalScrollbar(bool);
+    void setHasVerticalScrollbar(bool);
+
+    PassRefPtr<Scrollbar> createScrollbar(ScrollbarOrientation);
+    void destroyScrollbar(ScrollbarOrientation);
+
+    Scrollbar* horizontalScrollbar() const { return m_hBar.get(); }
+    Scrollbar* verticalScrollbar() const { return m_vBar.get(); }
+
+    int verticalScrollbarWidth() const;
+    int horizontalScrollbarHeight() const;
+
+    bool hasOverflowControls() const;
+    void positionOverflowControls(int tx, int ty);
+    bool isPointInResizeControl(const IntPoint& absolutePoint) const;
+    bool hitTestOverflowControls(HitTestResult&, const IntPoint& localPoint);
+    IntSize offsetFromResizeCorner(const IntPoint& absolutePoint) const;
+
+    void paintOverflowControls(GraphicsContext*, int tx, int ty, const IntRect& damageRect);
+    void paintScrollCorner(GraphicsContext*, int tx, int ty, const IntRect& damageRect);
+    void paintResizer(GraphicsContext*, int tx, int ty, const IntRect& damageRect);
+
+    void updateScrollInfoAfterLayout();
+
+    bool scroll(ScrollDirection, ScrollGranularity, float multiplier = 1.0f);
+    void autoscroll();
+
+    void resize(const PlatformMouseEvent&, const IntSize&);
+    bool inResizeMode() const { return m_inResizeMode; }
+    void setInResizeMode(bool b) { m_inResizeMode = b; }
+
+    bool isRootLayer() const { return renderer()->isRenderView(); }
+    
+#if USE(ACCELERATED_COMPOSITING)
+    RenderLayerCompositor* compositor() const;
+    
+    // Notification from the renderer that its content changed (e.g. current frame of image changed).
+    // Allows updates of layer content without repainting.
+    void rendererContentChanged();
+#endif
+
+    // Returns true if the accelerated compositing is enabled
+    bool hasAcceleratedCompositing() const;
+    
+    void updateLayerPosition();
+    
+    enum UpdateLayerPositionsFlag {
+        DoFullRepaint = 1,
+        CheckForRepaint = 1 << 1,
+        IsCompositingUpdateRoot = 1 << 2,
+        UpdateCompositingLayers = 1 << 3,
+        UpdatePagination = 1 << 4
+    };
+    typedef unsigned UpdateLayerPositionsFlags;
+    void updateLayerPositions(UpdateLayerPositionsFlags = DoFullRepaint | IsCompositingUpdateRoot | UpdateCompositingLayers, IntPoint* cachedOffset = 0);
+
+    void updateTransform();
+
+    void relativePositionOffset(int& relX, int& relY) const { relX += m_relX; relY += m_relY; }
+    IntSize relativePositionOffset() const { return IntSize(m_relX, m_relY); }
+
+    void clearClipRectsIncludingDescendants();
+    void clearClipRects();
+
+    void addBlockSelectionGapsBounds(const IntRect&);
+    void clearBlockSelectionGapsBounds();
+    void repaintBlockSelectionGaps();
+
+    // Get the enclosing stacking context for this layer.  A stacking context is a layer
+    // that has a non-auto z-index.
+    RenderLayer* stackingContext() const;
+    bool isStackingContext() const { return !hasAutoZIndex() || renderer()->isRenderView(); }
+
+    void dirtyZOrderLists();
+    void dirtyStackingContextZOrderLists();
+    void updateZOrderLists();
+    Vector<RenderLayer*>* posZOrderList() const { return m_posZOrderList; }
+    Vector<RenderLayer*>* negZOrderList() const { return m_negZOrderList; }
+
+    void dirtyNormalFlowList();
+    void updateNormalFlowList();
+    Vector<RenderLayer*>* normalFlowList() const { return m_normalFlowList; }
+
+    bool hasVisibleContent() const { return m_hasVisibleContent; }
+    bool hasVisibleDescendant() const { return m_hasVisibleDescendant; }
+    void setHasVisibleContent(bool);
+    void dirtyVisibleContentStatus();
+
+    // Gets the nearest enclosing positioned ancestor layer (also includes
+    // the <html> layer and the root layer).
+    RenderLayer* enclosingPositionedAncestor() const;
+
+    // The layer relative to which clipping rects for this layer are computed.
+    RenderLayer* clippingRoot() const;
+
+#if USE(ACCELERATED_COMPOSITING)
+    // Enclosing compositing layer; if includeSelf is true, may return this.
+    RenderLayer* enclosingCompositingLayer(bool includeSelf = true) const;
+    // Ancestor compositing layer, excluding this.
+    RenderLayer* ancestorCompositingLayer() const { return enclosingCompositingLayer(false); }
+#endif
+
+    void convertToLayerCoords(const RenderLayer* ancestorLayer, int& x, int& y) const;
+
+    bool hasAutoZIndex() const { return renderer()->style()->hasAutoZIndex(); }
+    int zIndex() const { return renderer()->style()->zIndex(); }
+
+    // The two main functions that use the layer system.  The paint method
+    // paints the layers that intersect the damage rect from back to
+    // front.  The hitTest method looks for mouse events by walking
+    // layers that intersect the point from front to back.
+    void paint(GraphicsContext*, const IntRect& damageRect, PaintBehavior = PaintBehaviorNormal, RenderObject* paintingRoot = 0);
+    bool hitTest(const HitTestRequest&, HitTestResult&);
+
+    // This method figures out our layerBounds in coordinates relative to
+    // |rootLayer}.  It also computes our background and foreground clip rects
+    // for painting/event handling.
+    void calculateRects(const RenderLayer* rootLayer, const IntRect& paintDirtyRect, IntRect& layerBounds,
+                        IntRect& backgroundRect, IntRect& foregroundRect, IntRect& outlineRect, bool temporaryClipRects = false) const;
+
+    // Compute and cache clip rects computed with the given layer as the root
+    void updateClipRects(const RenderLayer* rootLayer);
+    // Compute and return the clip rects. If useCached is true, will used previously computed clip rects on ancestors
+    // (rather than computing them all from scratch up the parent chain).
+    void calculateClipRects(const RenderLayer* rootLayer, ClipRects&, bool useCached = false) const;
+    ClipRects* clipRects() const { return m_clipRects; }
+
+    IntRect childrenClipRect() const; // Returns the foreground clip rect of the layer in the document's coordinate space.
+    IntRect selfClipRect() const; // Returns the background clip rect of the layer in the document's coordinate space.
+
+    bool intersectsDamageRect(const IntRect& layerBounds, const IntRect& damageRect, const RenderLayer* rootLayer) const;
+
+    // Bounding box relative to some ancestor layer.
+    IntRect boundingBox(const RenderLayer* rootLayer) const;
+    // Bounding box in the coordinates of this layer.
+    IntRect localBoundingBox() const;
+    // Bounding box relative to the root.
+    IntRect absoluteBoundingBox() const;
+
+    void updateHoverActiveState(const HitTestRequest&, HitTestResult&);
+
+    // Return a cached repaint rect, computed relative to the layer renderer's containerForRepaint.
+    IntRect repaintRect() const { return m_repaintRect; }
+    IntRect repaintRectIncludingDescendants() const;
+    void computeRepaintRects();
+    void updateRepaintRectsAfterScroll(bool fixed = false);
+    void setNeedsFullRepaint(bool f = true) { m_needsFullRepaint = f; }
+    
+    int staticX() const { return m_staticX; }
+    int staticY() const { return m_staticY; }
+    void setStaticX(int staticX) { m_staticX = staticX; }
+    void setStaticY(int staticY) { m_staticY = staticY; }
+
+    bool hasTransform() const { return renderer()->hasTransform(); }
+    // Note that this transform has the transform-origin baked in.
+    TransformationMatrix* transform() const { return m_transform.get(); }
+    // currentTransform computes a transform which takes accelerated animations into account. The
+    // resulting transform has transform-origin baked in. If the layer does not have a transform,
+    // returns the identity matrix.
+    TransformationMatrix currentTransform() const;
+    TransformationMatrix renderableTransform(PaintBehavior) const;
+    
+    // Get the perspective transform, which is applied to transformed sublayers.
+    // Returns true if the layer has a -webkit-perspective.
+    // Note that this transform has the perspective-origin baked in.
+    TransformationMatrix perspectiveTransform() const;
+    FloatPoint perspectiveOrigin() const;
+    bool preserves3D() const { return renderer()->style()->transformStyle3D() == TransformStyle3DPreserve3D; }
+    bool has3DTransform() const { return m_transform && !m_transform->isAffine(); }
+
+     // Overloaded new operator.  Derived classes must override operator new
+    // in order to allocate out of the RenderArena.
+    void* operator new(size_t, RenderArena*) throw();
+
+    // Overridden to prevent the normal delete from being called.
+    void operator delete(void*, size_t);
+
+#if USE(ACCELERATED_COMPOSITING)
+    bool isComposited() const { return m_backing != 0; }
+    bool hasCompositedMask() const;
+    RenderLayerBacking* backing() const { return m_backing.get(); }
+    RenderLayerBacking* ensureBacking();
+    void clearBacking();
+#else
+    bool isComposited() const { return false; }
+    bool hasCompositedMask() const { return false; }
+#endif
+
+    bool paintsWithTransparency(PaintBehavior paintBehavior) const
+    {
+        return isTransparent() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || !isComposited());
+    }
+
+    bool paintsWithTransform(PaintBehavior paintBehavior) const
+    {
+        return transform() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || !isComposited());
+    }
+
+private:
+    // The normal operator new is disallowed on all render objects.
+    void* operator new(size_t) throw();
+
+private:
+    void setNextSibling(RenderLayer* next) { m_next = next; }
+    void setPreviousSibling(RenderLayer* prev) { m_previous = prev; }
+    void setParent(RenderLayer* parent);
+    void setFirstChild(RenderLayer* first) { m_first = first; }
+    void setLastChild(RenderLayer* last) { m_last = last; }
+
+    int renderBoxX() const { return renderer()->isBox() ? toRenderBox(renderer())->x() : 0; }
+    int renderBoxY() const { return renderer()->isBox() ? toRenderBox(renderer())->y() : 0; }
+
+    void collectLayers(Vector<RenderLayer*>*&, Vector<RenderLayer*>*&);
+
+    void updateLayerListsIfNeeded();
+    void updateCompositingAndLayerListsIfNeeded();
+    
+    enum PaintLayerFlag {
+        PaintLayerHaveTransparency = 1,
+        PaintLayerAppliedTransform = 1 << 1,
+        PaintLayerTemporaryClipRects = 1 << 2,
+        PaintLayerPaintingReflection = 1 << 3
+    };
+    
+    typedef unsigned PaintLayerFlags;
+
+    void paintLayer(RenderLayer* rootLayer, GraphicsContext*, const IntRect& paintDirtyRect,
+                    PaintBehavior, RenderObject* paintingRoot, OverlapTestRequestMap* = 0,
+                    PaintLayerFlags = 0);
+    void paintList(Vector<RenderLayer*>*, RenderLayer* rootLayer, GraphicsContext* p,
+                   const IntRect& paintDirtyRect, PaintBehavior,
+                   RenderObject* paintingRoot, OverlapTestRequestMap*,
+                   PaintLayerFlags);
+    void paintPaginatedChildLayer(RenderLayer* childLayer, RenderLayer* rootLayer, GraphicsContext*,
+                                  const IntRect& paintDirtyRect, PaintBehavior,
+                                  RenderObject* paintingRoot, OverlapTestRequestMap*,
+                                  PaintLayerFlags);
+    void paintChildLayerIntoColumns(RenderLayer* childLayer, RenderLayer* rootLayer, GraphicsContext*,
+                                    const IntRect& paintDirtyRect, PaintBehavior,
+                                    RenderObject* paintingRoot, OverlapTestRequestMap*,
+                                    PaintLayerFlags, const Vector<RenderLayer*>& columnLayers, size_t columnIndex);
+
+    RenderLayer* hitTestLayer(RenderLayer* rootLayer, RenderLayer* containerLayer, const HitTestRequest& request, HitTestResult& result,
+                              const IntRect& hitTestRect, const IntPoint& hitTestPoint, bool appliedTransform,
+                              const HitTestingTransformState* transformState = 0, double* zOffset = 0);
+    RenderLayer* hitTestList(Vector<RenderLayer*>*, RenderLayer* rootLayer, const HitTestRequest& request, HitTestResult& result,
+                             const IntRect& hitTestRect, const IntPoint& hitTestPoint,
+                             const HitTestingTransformState* transformState, double* zOffsetForDescendants, double* zOffset,
+                             const HitTestingTransformState* unflattenedTransformState, bool depthSortDescendants);
+    RenderLayer* hitTestPaginatedChildLayer(RenderLayer* childLayer, RenderLayer* rootLayer, const HitTestRequest& request, HitTestResult& result,
+                                            const IntRect& hitTestRect, const IntPoint& hitTestPoint,
+                                            const HitTestingTransformState* transformState, double* zOffset);
+    RenderLayer* hitTestChildLayerColumns(RenderLayer* childLayer, RenderLayer* rootLayer, const HitTestRequest& request, HitTestResult& result,
+                                          const IntRect& hitTestRect, const IntPoint& hitTestPoint,
+                                          const HitTestingTransformState* transformState, double* zOffset,
+                                          const Vector<RenderLayer*>& columnLayers, size_t columnIndex);
+                                    
+    PassRefPtr<HitTestingTransformState> createLocalTransformState(RenderLayer* rootLayer, RenderLayer* containerLayer,
+                            const IntRect& hitTestRect, const IntPoint& hitTestPoint,
+                            const HitTestingTransformState* containerTransformState) const;
+    
+    bool hitTestContents(const HitTestRequest&, HitTestResult&, const IntRect& layerBounds, const IntPoint& hitTestPoint, HitTestFilter) const;
+    
+    void computeScrollDimensions(bool* needHBar = 0, bool* needVBar = 0);
+
+    bool shouldBeNormalFlowOnly() const; 
+
+    // ScrollBarClient interface
+    virtual void valueChanged(Scrollbar*);
+    virtual void invalidateScrollbarRect(Scrollbar*, const IntRect&);
+    virtual bool isActive() const;
+    virtual bool scrollbarCornerPresent() const;
+    virtual IntRect convertFromScrollbarToContainingView(const Scrollbar*, const IntRect&) const;
+    virtual IntRect convertFromContainingViewToScrollbar(const Scrollbar*, const IntRect&) const;
+    virtual IntPoint convertFromScrollbarToContainingView(const Scrollbar*, const IntPoint&) const;
+    virtual IntPoint convertFromContainingViewToScrollbar(const Scrollbar*, const IntPoint&) const;
+    
+    IntSize scrollbarOffset(const Scrollbar*) const;
+    
+    void updateOverflowStatus(bool horizontalOverflow, bool verticalOverflow);
+
+    void childVisibilityChanged(bool newVisibility);
+    void dirtyVisibleDescendantStatus();
+    void updateVisibilityStatus();
+
+    // This flag is computed by RenderLayerCompositor, which knows more about 3d hierarchies than we do.
+    void setHas3DTransformedDescendant(bool b) { m_has3DTransformedDescendant = b; }
+    bool has3DTransformedDescendant() const { return m_has3DTransformedDescendant; }
+    
+    void dirty3DTransformedDescendantStatus();
+    // Both updates the status, and returns true if descendants of this have 3d.
+    bool update3DTransformedDescendantStatus();
+
+    Node* enclosingElement() const;
+
+    void createReflection();
+    void removeReflection();
+
+    void updateReflectionStyle();
+    bool paintingInsideReflection() const { return m_paintingInsideReflection; }
+    void setPaintingInsideReflection(bool b) { m_paintingInsideReflection = b; }
+    
+    void parentClipRects(const RenderLayer* rootLayer, ClipRects&, bool temporaryClipRects = false) const;
+    IntRect backgroundClipRect(const RenderLayer* rootLayer, bool temporaryClipRects) const;
+
+    RenderLayer* enclosingTransformedAncestor() const;
+
+    // Convert a point in absolute coords into layer coords, taking transforms into account
+    IntPoint absoluteToContents(const IntPoint&) const;
+
+    void updateScrollCornerStyle();
+    void updateResizerStyle();
+
+    void updatePagination();
+    bool isPaginated() const { return m_isPaginated; }
+
+#if USE(ACCELERATED_COMPOSITING)    
+    bool hasCompositingDescendant() const { return m_hasCompositingDescendant; }
+    void setHasCompositingDescendant(bool b)  { m_hasCompositingDescendant = b; }
+    
+    bool mustOverlapCompositedLayers() const { return m_mustOverlapCompositedLayers; }
+    void setMustOverlapCompositedLayers(bool b) { m_mustOverlapCompositedLayers = b; }
+#endif
+
+private:
+    friend class RenderLayerBacking;
+    friend class RenderLayerCompositor;
+    friend class RenderBoxModelObject;
+
+    // Only safe to call from RenderBoxModelObject::destroyLayer(RenderArena*)
+    void destroy(RenderArena*);
+
+protected:
+    RenderBoxModelObject* m_renderer;
+
+    RenderLayer* m_parent;
+    RenderLayer* m_previous;
+    RenderLayer* m_next;
+    RenderLayer* m_first;
+    RenderLayer* m_last;
+
+    IntRect m_repaintRect; // Cached repaint rects. Used by layout.
+    IntRect m_outlineBox;
+
+    // Our current relative position offset.
+    int m_relX;
+    int m_relY;
+
+    // Our (x,y) coordinates are in our parent layer's coordinate space.
+    int m_x;
+    int m_y;
+
+    // The layer's width/height
+    int m_width;
+    int m_height;
+
+    // Our scroll offsets if the view is scrolled.
+    int m_scrollX;
+    int m_scrollY;
+    int m_scrollOriginX;        // only non-zero for rtl content
+    int m_scrollLeftOverflow;   // only non-zero for rtl content
+
+    // The width/height of our scrolled area.
+    int m_scrollWidth;
+    int m_scrollHeight;
+
+    // For layers with overflow, we have a pair of scrollbars.
+    RefPtr<Scrollbar> m_hBar;
+    RefPtr<Scrollbar> m_vBar;
+
+    // Keeps track of whether the layer is currently resizing, so events can cause resizing to start and stop.
+    bool m_inResizeMode;
+
+    // For layers that establish stacking contexts, m_posZOrderList holds a sorted list of all the
+    // descendant layers within the stacking context that have z-indices of 0 or greater
+    // (auto will count as 0).  m_negZOrderList holds descendants within our stacking context with negative
+    // z-indices.
+    Vector<RenderLayer*>* m_posZOrderList;
+    Vector<RenderLayer*>* m_negZOrderList;
+
+    // This list contains child layers that cannot create stacking contexts.  For now it is just
+    // overflow layers, but that may change in the future.
+    Vector<RenderLayer*>* m_normalFlowList;
+
+    ClipRects* m_clipRects;      // Cached clip rects used when painting and hit testing.
+#ifndef NDEBUG
+    const RenderLayer* m_clipRectsRoot;   // Root layer used to compute clip rects.
+#endif
+
+    bool m_scrollDimensionsDirty : 1;
+    bool m_zOrderListsDirty : 1;
+    bool m_normalFlowListDirty: 1;
+    bool m_isNormalFlowOnly : 1;
+
+    bool m_usedTransparency : 1; // Tracks whether we need to close a transparent layer, i.e., whether
+                                 // we ended up painting this layer or any descendants (and therefore need to
+                                 // blend).
+    bool m_paintingInsideReflection : 1;  // A state bit tracking if we are painting inside a replica.
+    bool m_inOverflowRelayout : 1;
+    bool m_needsFullRepaint : 1;
+
+    bool m_overflowStatusDirty : 1;
+    bool m_horizontalOverflow : 1;
+    bool m_verticalOverflow : 1;
+    bool m_visibleContentStatusDirty : 1;
+    bool m_hasVisibleContent : 1;
+    bool m_visibleDescendantStatusDirty : 1;
+    bool m_hasVisibleDescendant : 1;
+
+    bool m_isPaginated : 1; // If we think this layer is split by a multi-column ancestor, then this bit will be set.
+
+    bool m_3DTransformedDescendantStatusDirty : 1;
+    bool m_has3DTransformedDescendant : 1;  // Set on a stacking context layer that has 3D descendants anywhere
+                                            // in a preserves3D hierarchy. Hint to do 3D-aware hit testing.
+#if USE(ACCELERATED_COMPOSITING)
+    bool m_hasCompositingDescendant : 1;
+    bool m_mustOverlapCompositedLayers : 1;
+#endif
+
+    RenderMarquee* m_marquee; // Used by layers with overflow:marquee
+    
+    // Cached normal flow values for absolute positioned elements with static left/top values.
+    int m_staticX;
+    int m_staticY;
+    
+    OwnPtr<TransformationMatrix> m_transform;
+    
+    // May ultimately be extended to many replicas (with their own paint order).
+    RenderReplica* m_reflection;
+    
+    // Renderers to hold our custom scroll corner and resizer.
+    RenderScrollbarPart* m_scrollCorner;
+    RenderScrollbarPart* m_resizer;
+
+private:
+    IntRect m_blockSelectionGapsBounds;
+
+#if USE(ACCELERATED_COMPOSITING)
+    OwnPtr<RenderLayerBacking> m_backing;
+#endif
+};
+
+} // namespace WebCore
+
+#ifndef NDEBUG
+// Outside the WebCore namespace for ease of invocation from gdb.
+void showLayerTree(const WebCore::RenderLayer* layer);
+#endif
+
+#endif // RenderLayer_h