/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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
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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.
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 * Contributor(s):
 *   David Hyatt (hyatt@netscape.com)
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
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/**

  Eric D Vaughan
  A frame that can have multiple children. Only one child may be displayed at one time. So the
  can be flipped though like a deck of cards.
 
**/

#ifndef nsStackLayout_h___
#define nsStackLayout_h___

#include "nsBoxLayout.h"
#include "nsCOMPtr.h"

nsresult NS_NewStackLayout(nsIPresShell* aPresShell, nsCOMPtr<nsIBoxLayout>& aNewLayout);

class nsStackLayout : public nsBoxLayout
{
public:

  friend nsresult NS_NewStackLayout(nsIPresShell* aPresShell, nsCOMPtr<nsIBoxLayout>& aNewLayout);
  static void Shutdown();

  nsStackLayout();

  NS_IMETHOD Layout(nsIBox* aBox, nsBoxLayoutState& aState);

  virtual nsSize GetPrefSize(nsIBox* aBox, nsBoxLayoutState& aBoxLayoutState);
  virtual nsSize GetMinSize(nsIBox* aBox, nsBoxLayoutState& aBoxLayoutState);
  virtual nsSize GetMaxSize(nsIBox* aBox, nsBoxLayoutState& aBoxLayoutState);
  virtual nscoord GetAscent(nsIBox* aBox, nsBoxLayoutState& aBoxLayoutState);

  // get the child offsets for aChild and set them in aMargin. Returns a
  // bitfield mask of the SPECIFIED_LEFT, SPECIFIED_RIGHT, SPECIFIED_TOP and
  // SPECIFIED_BOTTOM offsets indicating which sides have been specified by
  // attributes. 
  static PRUint8 GetOffset(nsBoxLayoutState& aState, nsIBox* aChild, nsMargin& aMargin);

private:
  static nsIBoxLayout* gInstance;

}; // class nsStackLayout



#endif

