gecko-dev/layout/generic/nsAbsoluteContainingBlock.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * 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
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * code for managing absolutely positioned children of a rendering
 * object that is a containing block for them
 */

#ifndef nsAbsoluteContainingBlock_h___
#define nsAbsoluteContainingBlock_h___

#include "nsFrameList.h"
#include "nsHTMLReflowState.h"
#include "nsGkAtoms.h"
#include "nsContainerFrame.h"

class nsIAtom;
class nsIFrame;
class nsPresContext;

/**
 * This class contains the logic for being an absolute containing block.  This
 * class is used within viewport frames (for frames representing content with
 * fixed position) and blocks (for frames representing absolutely positioned
 * content), since each set of frames is absolutely positioned with respect to
 * its parent.
 *
 * There is no principal child list, just a named child list which contains
 * the absolutely positioned frames.
 *
 * All functions include as the first argument the frame that is delegating
 * the request.
 *
 * @see nsGkAtoms::absoluteList and nsGkAtoms::fixedList
 */
class nsAbsoluteContainingBlock
{
public:
  nsAbsoluteContainingBlock(nsIAtom* aChildListName)
#ifdef DEBUG
    : mChildListName(aChildListName)
#endif
  {
    NS_ASSERTION(mChildListName == nsGkAtoms::absoluteList ||
                 mChildListName == nsGkAtoms::fixedList,
                 "should either represent position:fixed or absolute content");
  }

#ifdef DEBUG
  nsIAtom* GetChildListName() const { return mChildListName; }
#endif

  const nsFrameList& GetChildList() const { return mAbsoluteFrames; }

  nsresult SetInitialChildList(nsIFrame*       aDelegatingFrame,
                               nsIAtom*        aListName,
                               nsFrameList&    aChildList);
  nsresult AppendFrames(nsIFrame*      aDelegatingFrame,
                        nsIAtom*       aListName,
                        nsFrameList&   aFrameList);
  nsresult InsertFrames(nsIFrame*      aDelegatingFrame,
                        nsIAtom*       aListName,
                        nsIFrame*      aPrevFrame,
                        nsFrameList&   aFrameList);
  void RemoveFrame(nsIFrame*      aDelegatingFrame,
                   nsIAtom*       aListName,
                   nsIFrame*      aOldFrame);

  // Called by the delegating frame after it has done its reflow first. This
  // function will reflow any absolutely positioned child frames that need to
  // be reflowed, e.g., because the absolutely positioned child frame has
  // 'auto' for an offset, or a percentage based width or height.
  // If aChildBounds is set, it returns (in the local coordinate space) the 
  // bounding rect of the absolutely positioned child elements taking into 
  // account their overflow area (if it is visible).
  // @param aForceReflow if this is false, reflow for some absolutely
  //        positioned frames may be skipped based on whether they use
  //        placeholders for positioning and on whether the containing block
  //        width or height changed.
  nsresult Reflow(nsContainerFrame*        aDelegatingFrame,
                  nsPresContext*           aPresContext,
                  const nsHTMLReflowState& aReflowState,
                  nsReflowStatus&          aReflowStatus,
                  nscoord                  aContainingBlockWidth,
                  nscoord                  aContainingBlockHeight,
                  PRBool                   aConstrainHeight,
                  PRBool                   aCBWidthChanged,
                  PRBool                   aCBHeightChanged,
                  nsRect*                  aChildBounds = nsnull);


  void DestroyFrames(nsIFrame* aDelegatingFrame,
                     nsIFrame* aDestructRoot);

  PRBool  HasAbsoluteFrames() {return mAbsoluteFrames.NotEmpty();}

  // Mark our size-dependent absolute frames with NS_FRAME_HAS_DIRTY_CHILDREN
  // so that we'll make sure to reflow them.
  void MarkSizeDependentFramesDirty();

  // Mark all our absolute frames with NS_FRAME_IS_DIRTY
  void MarkAllFramesDirty();

protected:
  // Returns PR_TRUE if the position of f depends on the position of
  // its placeholder or if the position or size of f depends on a
  // containing block dimension that changed.
  PRBool FrameDependsOnContainer(nsIFrame* f, PRBool aCBWidthChanged,
                                 PRBool aCBHeightChanged);

  nsresult ReflowAbsoluteFrame(nsIFrame*                aDelegatingFrame,
                               nsPresContext*          aPresContext,
                               const nsHTMLReflowState& aReflowState,
                               nscoord                  aContainingBlockWidth,
                               nscoord                  aContainingBlockHeight,
                               PRBool                   aConstrainHeight,
                               nsIFrame*                aKidFrame,
                               nsReflowStatus&          aStatus,
                               nsRect*                  aChildBounds);

  // Mark our absolute frames dirty.  If aMarkAllDirty is true, all will be
  // marked with NS_FRAME_IS_DIRTY.  Otherwise, the size-dependant ones will be
  // marked with NS_FRAME_HAS_DIRTY_CHILDREN.
  void DoMarkFramesDirty(PRBool aMarkAllDirty);

protected:
  nsFrameList mAbsoluteFrames;  // additional named child list

#ifdef DEBUG
  nsIAtom* const mChildListName; // nsGkAtoms::fixedList or nsGkAtoms::absoluteList

  // helper routine for debug printout
  void PrettyUC(nscoord aSize,
                char*   aBuf);
#endif
};

#endif /* nsnsAbsoluteContainingBlock_h___ */