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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * 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"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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#ifndef nsPlaceholderFrame_h___
#define nsPlaceholderFrame_h___

#include "nsSplittableFrame.h"
#include "nsLayoutAtoms.h"

nsresult NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsIFrame**  aInstancePtrResult);

/**
 * Implementation of a frame that's used as a placeholder for a frame that
 * has been moved out of the flow
 */
class nsPlaceholderFrame : public nsSplittableFrame {
public:
  /**
   * Create a new placeholder frame
   */
  friend nsresult NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsIFrame**  aInstancePtrResult);
  nsPlaceholderFrame();
  virtual ~nsPlaceholderFrame();

  // Get/Set the associated out of flow frame
  nsIFrame*  GetOutOfFlowFrame() const {return mOutOfFlowFrame;}
  void       SetOutOfFlowFrame(nsIFrame* aFrame) {mOutOfFlowFrame = aFrame;}

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

  NS_IMETHOD Destroy(nsPresContext* aPresContext);

  // nsIFrame overrides
#ifdef DEBUG
  NS_IMETHOD Paint(nsPresContext*      aPresContext,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect&        aDirtyRect,
                   nsFramePaintLayer    aWhichLayer,
                   PRUint32             aFlags = 0);
  NS_IMETHOD List(nsPresContext* aPresContext, FILE* out, PRInt32 aIndent) const;
#endif

  /**
   * Get the "type" of the frame
   *
   * @see nsLayoutAtoms::placeholderFrame
   */
  virtual nsIAtom* GetType() const;

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

  virtual PRBool IsEmpty() { return PR_TRUE; }
  virtual PRBool IsSelfEmpty() { return PR_TRUE; }

#ifdef ACCESSIBILITY
  NS_IMETHOD  GetAccessible(nsIAccessible** aAccessible)
  {
    nsIFrame *realFrame = GetRealFrameForPlaceholder(this);
    return realFrame ? realFrame->GetAccessible(aAccessible) :
                       nsSplittableFrame::GetAccessible(aAccessible);
  }
#endif

  /**
   * @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
   * aFrame
   */
  static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
    NS_PRECONDITION(aFrame, "Must have a frame to work with");
    if (aFrame->GetType() == nsLayoutAtoms::placeholderFrame) {
      return GetRealFrameForPlaceholder(aFrame);
    }
    return aFrame;
  }

  /**
   * @return the out-of-flow for aFrame, which is known to be a placeholder
   */
  static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
    NS_PRECONDITION(aFrame->GetType() == nsLayoutAtoms::placeholderFrame,
                    "Must have placeholder frame as input");
    nsIFrame* outOfFlow =
      NS_STATIC_CAST(nsPlaceholderFrame*, aFrame)->GetOutOfFlowFrame();
    NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
    return outOfFlow;
  }

protected:
  nsIFrame* mOutOfFlowFrame;
};

#endif /* nsPlaceholderFrame_h___ */