mirror of
https://github.com/classilla/tenfourfox.git
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169 lines
6.3 KiB
C++
169 lines
6.3 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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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 "mozilla/Attributes.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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#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 final : public nsFrame {
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public:
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NS_DECL_FRAMEARENA_HELPERS
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#ifdef DEBUG
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NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame)
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NS_DECL_QUERYFRAME
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#endif
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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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// 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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// nsIFrame overrides
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// We need to override GetMinSize and GetPrefSize because XUL uses
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// placeholders not within lines.
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virtual void AddInlineMinISize(nsRenderingContext* aRenderingContext,
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InlineMinISizeData* aData) override;
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virtual void AddInlinePrefISize(nsRenderingContext* aRenderingContext,
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InlinePrefISizeData* aData) override;
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virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) override;
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virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
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virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState) override;
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virtual void Reflow(nsPresContext* aPresContext,
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nsHTMLReflowMetrics& aDesiredSize,
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const nsHTMLReflowState& aReflowState,
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nsReflowStatus& aStatus) override;
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virtual void DestroyFrom(nsIFrame* aDestructRoot) override;
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#if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
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virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsRect& aDirtyRect,
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const nsDisplayListSet& aLists) override;
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#endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
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#ifdef DEBUG_FRAME_DUMP
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void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const override;
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virtual nsresult GetFrameName(nsAString& aResult) const override;
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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 override;
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virtual bool IsEmpty() override { return true; }
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virtual bool IsSelfEmpty() override { return true; }
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virtual bool CanContinueTextRun() const override;
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#ifdef ACCESSIBILITY
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virtual mozilla::a11y::AccType AccessibleType() override
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{
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nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
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return realFrame ? realFrame->AccessibleType() :
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nsFrame::AccessibleType();
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}
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#endif
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virtual nsStyleContext* GetParentStyleContext(nsIFrame** aProviderFrame) const override;
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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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