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 * Version: NPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Netscape 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
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 *
 * 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 Communicator client 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 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 nsScrollBoxFrame_h___
#define nsScrollBoxFrame_h___

#include "nsBoxFrame.h"
#include "nsIStatefulFrame.h"
#include "nsGUIEvent.h"

/**
 * The scroll frame creates and manages the scrolling view
 *
 * It only supports having a single child frame that typically is an area
 * frame, but doesn't have to be. The child frame must have a view, though
 *
 * Scroll frames don't support incremental changes, i.e. you can't replace
 * or remove the scrolled frame
 */
class nsScrollBoxFrame : public nsBoxFrame, public nsIStatefulFrame {
public:
  friend nsresult NS_NewScrollBoxFrame(nsIPresShell* aPresShell, nsIFrame** aNewFrame);

  NS_IMETHOD Init(nsIPresContext*  aPresContext,
                  nsIContent*      aContent,
                  nsIFrame*        aParent,
                  nsStyleContext*  aContext,
                  nsIFrame*        aPrevInFlow);

  // Called to set the one and only child frame. Returns NS_ERROR_INVALID_ARG
  // if the child frame is NULL, and NS_ERROR_UNEXPECTED if the child list
  // contains more than one frame
  NS_IMETHOD SetInitialChildList(nsIPresContext* aPresContext,
                                 nsIAtom*        aListName,
                                 nsIFrame*       aChildList);

  // Because there can be only one child frame, these two function return
  // NS_ERROR_FAILURE
  NS_IMETHOD AppendFrames(nsIPresContext* aPresContext,
                          nsIPresShell&   aPresShell,
                          nsIAtom*        aListName,
                          nsIFrame*       aFrameList);
  NS_IMETHOD InsertFrames(nsIPresContext* aPresContext,
                          nsIPresShell&   aPresShell,
                          nsIAtom*        aListName,
                          nsIFrame*       aPrevFrame,
                          nsIFrame*       aFrameList);

  // This function returns NS_ERROR_NOT_IMPLEMENTED
  NS_IMETHOD RemoveFrame(nsIPresContext* aPresContext,
                         nsIPresShell&   aPresShell,
                         nsIAtom*        aListName,
                         nsIFrame*       aOldFrame);


  NS_IMETHOD Paint(nsIPresContext*      aPresContext,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect&        aDirtyRect,
                   nsFramePaintLayer    aWhichLayer,
                   PRUint32             aFlags = 0);

  /**
   * Get the "type" of the frame
   *
   * @see nsLayoutAtoms::scrollFrame
   */
  virtual nsIAtom* GetType() const;
  
#ifdef NS_DEBUG
  NS_IMETHOD GetFrameName(nsAString& aResult) const;
#endif

  // nsIBox methods
  NS_DECL_ISUPPORTS

  NS_IMETHOD GetPrefSize(nsBoxLayoutState& aBoxLayoutState, nsSize& aSize);
  NS_IMETHOD GetMinSize(nsBoxLayoutState& aBoxLayoutState, nsSize& aSize);
  NS_IMETHOD GetMaxSize(nsBoxLayoutState& aBoxLayoutState, nsSize& aSize);
  NS_IMETHOD GetAscent(nsBoxLayoutState& aBoxLayoutState, nscoord& aAscent);
  NS_IMETHOD DoLayout(nsBoxLayoutState& aBoxLayoutState);
  NS_IMETHOD GetPadding(nsMargin& aMargin);
  NS_IMETHOD GetBorder(nsMargin& aMargin);
  NS_IMETHOD GetMargin(nsMargin& aMargin);

  virtual nsresult GetContentOf(nsIContent** aContent);
  
  void ScrollToRestoredPosition();

protected:
  nsScrollBoxFrame(nsIPresShell* aShell);

   // Creation of the widget for the scrolling view is factored into a virtual method so
   // that sub-classes may control widget creation.
  virtual nsresult CreateScrollingViewWidget(nsIView* aView, const nsStyleDisplay* aDisplay);
   // Getting the view for scollframe may be overriden to provide a parent view for te scroll frame
  virtual nsresult GetScrollingParentView(nsIPresContext* aPresContext,
                                          nsIFrame* aParent,
                                          nsIView** aParentView);

  //nsIStatefulFrame
  NS_IMETHOD SaveState(nsIPresContext* aPresContext, nsIPresState** aState);
  NS_IMETHOD RestoreState(nsIPresContext* aPresContext, nsIPresState* aState);

private:
  nsresult CreateScrollingView(nsIPresContext* aPresContext);
  PRPackedBool mVerticalOverflow;
  PRPackedBool mHorizontalOverflow;
  nsRect mRestoreRect;
  nsPoint mLastPos;
  
protected:
  virtual PRBool NeedsClipWidget();
  virtual void PostScrollPortEvent(nsIPresShell* aShell, PRBool aOverflow, nsScrollPortEvent::orientType aType);
  virtual void SetUpScrolledFrame(nsIPresContext* aPresContext);
};

#endif /* nsScrollBoxFrame_h___ */