зеркало из https://github.com/mozilla/gecko-dev.git
208 строки
8.0 KiB
C++
208 строки
8.0 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* rendering object for the point that anchors out-of-flow rendering
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* objects such as floats and absolutely positioned elements
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*/
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/*
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* Destruction of a placeholder and its out-of-flow must observe the
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* following constraints:
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*
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* - The mapping from the out-of-flow to the placeholder must be
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* removed from the frame manager before the placeholder is destroyed.
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* - The mapping from the out-of-flow to the placeholder must be
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* removed from the frame manager before the out-of-flow is destroyed.
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* - The placeholder must be removed from the frame tree, or have the
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* mapping from it to its out-of-flow cleared, before the out-of-flow
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* is destroyed (so that the placeholder will not point to a destroyed
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* frame while it's in the frame tree).
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*
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* Furthermore, some code assumes that placeholders point to something
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* useful, so placeholders without an associated out-of-flow should not
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* remain in the tree.
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*
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* The placeholder's Destroy() implementation handles the destruction of
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* the placeholder and its out-of-flow. To avoid crashes, frame removal
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* and destruction code that works with placeholders must not assume
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* that the placeholder points to its out-of-flow.
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*/
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#ifndef nsPlaceholderFrame_h___
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#define nsPlaceholderFrame_h___
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#include "nsFrame.h"
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#include "nsGkAtoms.h"
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nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
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nsStyleContext* aContext,
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nsFrameState aTypeBit);
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// Frame state bits that are used to keep track of what this is a
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// placeholder for.
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#define PLACEHOLDER_FOR_FLOAT NS_FRAME_STATE_BIT(20)
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#define PLACEHOLDER_FOR_ABSPOS NS_FRAME_STATE_BIT(21)
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#define PLACEHOLDER_FOR_FIXEDPOS NS_FRAME_STATE_BIT(22)
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#define PLACEHOLDER_FOR_POPUP NS_FRAME_STATE_BIT(23)
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#define PLACEHOLDER_TYPE_MASK (PLACEHOLDER_FOR_FLOAT | \
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PLACEHOLDER_FOR_ABSPOS | \
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PLACEHOLDER_FOR_FIXEDPOS | \
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PLACEHOLDER_FOR_POPUP)
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/**
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* Implementation of a frame that's used as a placeholder for a frame that
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* has been moved out of the flow
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*/
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class nsPlaceholderFrame : public nsFrame {
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public:
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NS_DECL_FRAMEARENA_HELPERS
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/**
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* Create a new placeholder frame. aTypeBit must be one of the
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* PLACEHOLDER_FOR_* constants above.
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*/
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friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
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nsStyleContext* aContext,
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nsFrameState aTypeBit);
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nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit) :
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nsFrame(aContext)
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{
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NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT ||
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aTypeBit == PLACEHOLDER_FOR_ABSPOS ||
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aTypeBit == PLACEHOLDER_FOR_FIXEDPOS ||
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aTypeBit == PLACEHOLDER_FOR_POPUP,
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"Unexpected type bit");
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AddStateBits(aTypeBit);
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}
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virtual ~nsPlaceholderFrame();
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// Get/Set the associated out of flow frame
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nsIFrame* GetOutOfFlowFrame() const {return mOutOfFlowFrame;}
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void SetOutOfFlowFrame(nsIFrame* aFrame) {
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NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(),
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"OOF must be first continuation");
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mOutOfFlowFrame = aFrame;
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}
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// nsIHTMLReflow overrides
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// We need to override GetMinWidth and GetPrefWidth because XUL uses
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// placeholders not within lines.
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virtual nscoord GetMinWidth(nsRenderingContext *aRenderingContext);
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virtual nscoord GetPrefWidth(nsRenderingContext *aRenderingContext);
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virtual void AddInlineMinWidth(nsRenderingContext *aRenderingContext,
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InlineMinWidthData *aData);
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virtual void AddInlinePrefWidth(nsRenderingContext *aRenderingContext,
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InlinePrefWidthData *aData);
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virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState);
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virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState);
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virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState);
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NS_IMETHOD Reflow(nsPresContext* aPresContext,
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nsHTMLReflowMetrics& aDesiredSize,
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const nsHTMLReflowState& aReflowState,
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nsReflowStatus& aStatus);
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virtual void DestroyFrom(nsIFrame* aDestructRoot);
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// nsIFrame overrides
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#if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
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NS_IMETHOD BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsRect& aDirtyRect,
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const nsDisplayListSet& aLists);
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#endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
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#ifdef DEBUG
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NS_IMETHOD List(FILE* out, PRInt32 aIndent) const;
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#endif // DEBUG
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/**
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* Get the "type" of the frame
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*
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* @see nsGkAtoms::placeholderFrame
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*/
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virtual nsIAtom* GetType() const;
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#ifdef DEBUG
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NS_IMETHOD GetFrameName(nsAString& aResult) const;
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#endif
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virtual bool IsEmpty() { return true; }
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virtual bool IsSelfEmpty() { return true; }
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virtual bool CanContinueTextRun() const;
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#ifdef ACCESSIBILITY
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virtual already_AddRefed<nsAccessible> CreateAccessible()
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{
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nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
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return realFrame ? realFrame->CreateAccessible() :
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nsFrame::CreateAccessible();
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}
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#endif
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virtual nsIFrame* GetParentStyleContextFrame();
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/**
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* @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
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* aFrame
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*/
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static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
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NS_PRECONDITION(aFrame, "Must have a frame to work with");
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if (aFrame->GetType() == nsGkAtoms::placeholderFrame) {
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return GetRealFrameForPlaceholder(aFrame);
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}
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return aFrame;
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}
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/**
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* @return the out-of-flow for aFrame, which is known to be a placeholder
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*/
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static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
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NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame,
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"Must have placeholder frame as input");
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nsIFrame* outOfFlow =
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static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame();
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NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
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return outOfFlow;
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}
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protected:
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nsIFrame* mOutOfFlowFrame;
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};
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#endif /* nsPlaceholderFrame_h___ */
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