/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**

  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<nsBoxLayout>& aNewLayout);

class nsStackLayout : public nsBoxLayout
{
public:

  friend nsresult NS_NewStackLayout(nsIPresShell* aPresShell, nsCOMPtr<nsBoxLayout>& 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 nsBoxLayout* gInstance;

}; // class nsStackLayout



#endif

