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 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
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 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
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 * Contributor(s):
 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#ifndef nsViewportFrame_h___
#define nsViewportFrame_h___

#include "nsContainerFrame.h"
#include "nsLayoutAtoms.h"
#include "nsPresContext.h"
#include "nsReflowPath.h"
#include "nsIPresShell.h"
#include "nsAbsoluteContainingBlock.h"

class nsFixedContainingBlock : public nsAbsoluteContainingBlock {
public:
  nsFixedContainingBlock() { }          // useful for debugging

  virtual ~nsFixedContainingBlock() { } // useful for debugging

  virtual nsIAtom* GetChildListName() const { return nsLayoutAtoms::fixedList; }
};

/**
  * ViewportFrame is the parent of a single child - the doc root frame or a scroll frame 
  * containing the doc root frame. ViewportFrame stores this child in its primary child 
  * list. It stores fixed positioned items in a secondary child list and its mFixedContainer 
  * delegate handles them. 
  */
class ViewportFrame : public nsContainerFrame {
public:
  ViewportFrame() { }          // useful for debugging

  virtual ~ViewportFrame() { } // useful for debugging

  NS_IMETHOD Destroy(nsPresContext* aPresContext);

  NS_IMETHOD SetInitialChildList(nsPresContext* aPresContext,
                                 nsIAtom*        aListName,
                                 nsIFrame*       aChildList);

  NS_IMETHOD GetFrameForPoint(const nsPoint&    aPoint, 
                              nsFramePaintLayer aWhichLayer,
                              nsIFrame**        aFrame);

  NS_IMETHOD AppendFrames(nsIAtom*        aListName,
                          nsIFrame*       aFrameList);

  NS_IMETHOD InsertFrames(nsIAtom*        aListName,
                          nsIFrame*       aPrevFrame,
                          nsIFrame*       aFrameList);

  NS_IMETHOD RemoveFrame(nsIAtom*        aListName,
                         nsIFrame*       aOldFrame);

  virtual nsIAtom* GetAdditionalChildListName(PRInt32 aIndex) const;

  virtual nsIFrame* GetFirstChild(nsIAtom* aListName) const;

  NS_IMETHOD Reflow(nsPresContext*          aPresContext,
                    nsHTMLReflowMetrics&     aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus&          aStatus);

  virtual PRBool CanPaintBackground() { return PR_FALSE; }
  
  /**
   * Get the "type" of the frame
   *
   * @see nsLayoutAtoms::viewportFrame
   */
  virtual nsIAtom* GetType() const;
  
  virtual PRBool IsContainingBlock() const;

#ifdef DEBUG
  NS_IMETHOD GetFrameName(nsAString& aResult) const;
#endif

protected:
  nsPoint AdjustReflowStateForScrollbars(nsHTMLReflowState* aReflowState) const;

protected:
  nsFixedContainingBlock mFixedContainer;
};


#endif // nsViewportFrame_h___
