/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (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/NPL/
 *
 * 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 Netscape are Copyright (C) 1998
 * Netscape Communications Corporation.  All Rights Reserved.
 */
#ifndef nsScrollFrame_h___
#define nsScrollFrame_h___

#include "nsHTMLContainerFrame.h"
#include "nsIAnonymousContentCreator.h"
#include "nsIBox.h"

class nsISupportsArray;
class nsGfxScrollFrameInner;

/**
 * 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 nsGfxScrollFrame : public nsHTMLContainerFrame, 
                         public nsIAnonymousContentCreator,
                         public nsIBox {
public:
  friend nsresult NS_NewGfxScrollFrame(nsIFrame** aNewFrame, nsIDocument* aDocument);

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

  virtual ~nsGfxScrollFrame();


  // 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);

  NS_IMETHOD Destroy(nsIPresContext& aPresContext);

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

  NS_IMETHOD DidReflow(nsIPresContext&   aPresContext,
                       nsDidReflowStatus aStatus);

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

  NS_IMETHOD Paint(nsIPresContext&      aPresContext,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect&        aDirtyRect,
                   nsFramePaintLayer    aWhichLayer);

  // nsIAnonymousContentCreator
  NS_IMETHOD CreateAnonymousContent(nsISupportsArray& aAnonymousItems);

  // nsIBox methods
  NS_IMETHOD GetBoxInfo(nsIPresContext& aPresContext, const nsHTMLReflowState& aReflowState, nsBoxInfo& aSize);
  NS_IMETHOD Dirty(nsIPresContext& aPresContext, const nsHTMLReflowState& aReflowState, nsIFrame*& aIncrementalChild);
  NS_IMETHOD QueryInterface(REFNSIID aIID, void** aInstancePtr); 
  NS_IMETHOD_(nsrefcnt) AddRef(void) { return NS_OK; }
  NS_IMETHOD_(nsrefcnt) Release(void) { return NS_OK; }

  /**
   * Get the "type" of the frame
   *
   * @see nsLayoutAtoms::scrollFrame
   */
  NS_IMETHOD GetFrameType(nsIAtom** aType) const;
  
  NS_IMETHOD GetFrameName(nsString& aResult) const;

protected:
  nsGfxScrollFrame(nsIDocument* aDocument);
  virtual PRIntn GetSkipSides() const;

private:
  friend class nsGfxScrollFrameInner;
  nsGfxScrollFrameInner* mInner;
  nsIPresContext*        mPresContext;  // weak reference
};

#endif /* nsScrollFrame_h___ */