mirror of
https://github.com/mozilla/gecko-dev.git
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184 lines
6.7 KiB
C++
184 lines
6.7 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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* Therefore the safe order of teardown is to:
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*
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* 1) Unregister the placeholder from the frame manager.
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* 2) Destroy the placeholder
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* 3) Destroy the out of flow
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*
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* In certain cases it may be possible to replace step (2) with:
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*
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* 2') Null out the mOutOfFlowFrame pointer in the placeholder
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*
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* and add
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*
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* 4) Destroy the placeholder
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*
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* but this is somewhat dangerous, since lots of code assumes that
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* placeholders point to something useful.
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*/
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#ifndef nsPlaceholderFrame_h___
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#define nsPlaceholderFrame_h___
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#include "nsSplittableFrame.h"
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#include "nsGkAtoms.h"
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nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
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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 nsSplittableFrame {
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public:
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/**
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* Create a new placeholder frame
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*/
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friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsStyleContext* aContext);
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nsPlaceholderFrame(nsStyleContext* aContext) : nsSplittableFrame(aContext) {}
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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) {mOutOfFlowFrame = aFrame;}
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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(nsIRenderingContext *aRenderingContext);
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virtual nscoord GetPrefWidth(nsIRenderingContext *aRenderingContext);
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virtual void AddInlineMinWidth(nsIRenderingContext *aRenderingContext,
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InlineMinWidthData *aData);
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virtual void AddInlinePrefWidth(nsIRenderingContext *aRenderingContext,
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InlinePrefWidthData *aData);
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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 Destroy();
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virtual nsSplittableType GetSplittableType() const;
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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 PRBool IsEmpty() { return PR_TRUE; }
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virtual PRBool IsSelfEmpty() { return PR_TRUE; }
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virtual PRBool CanContinueTextRun() const;
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#ifdef ACCESSIBILITY
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NS_IMETHOD GetAccessible(nsIAccessible** aAccessible)
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{
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nsIFrame *realFrame = GetRealFrameForPlaceholder(this);
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return realFrame ? realFrame->GetAccessible(aAccessible) :
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nsSplittableFrame::GetAccessible(aAccessible);
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}
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#endif
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NS_IMETHOD GetParentStyleContextFrame(nsPresContext* aPresContext,
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nsIFrame** aProviderFrame,
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PRBool* aIsChild);
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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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