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/* -*- 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/. */
/*
* rendering object for the point that anchors out-of-flow rendering
* objects such as floats and absolutely positioned elements
*/
/*
* Destruction of a placeholder and its out-of-flow must observe the
* following constraints:
*
* - The mapping from the out-of-flow to the placeholder must be
* removed from the frame manager before the placeholder is destroyed.
* - The mapping from the out-of-flow to the placeholder must be
* removed from the frame manager before the out-of-flow is destroyed.
* - The placeholder must be removed from the frame tree, or have the
* mapping from it to its out-of-flow cleared, before the out-of-flow
* is destroyed (so that the placeholder will not point to a destroyed
* frame while it's in the frame tree).
*
* Furthermore, some code assumes that placeholders point to something
* useful, so placeholders without an associated out-of-flow should not
* remain in the tree.
*
* The placeholder's Destroy() implementation handles the destruction of
* the placeholder and its out-of-flow. To avoid crashes, frame removal
* and destruction code that works with placeholders must not assume
* that the placeholder points to its out-of-flow.
*/
#ifndef nsPlaceholderFrame_h___
#define nsPlaceholderFrame_h___
#include "mozilla/Attributes.h"
#include "nsFrame.h"
#include "nsGkAtoms.h"
nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
nsStyleContext* aContext,
nsFrameState aTypeBit);
// Frame state bits that are used to keep track of what this is a
// placeholder for.
#define PLACEHOLDER_FOR_FLOAT NS_FRAME_STATE_BIT(20)
#define PLACEHOLDER_FOR_ABSPOS NS_FRAME_STATE_BIT(21)
#define PLACEHOLDER_FOR_FIXEDPOS NS_FRAME_STATE_BIT(22)
#define PLACEHOLDER_FOR_POPUP NS_FRAME_STATE_BIT(23)
#define PLACEHOLDER_TYPE_MASK (PLACEHOLDER_FOR_FLOAT | \
PLACEHOLDER_FOR_ABSPOS | \
PLACEHOLDER_FOR_FIXEDPOS | \
PLACEHOLDER_FOR_POPUP)
/**
* Implementation of a frame that's used as a placeholder for a frame that
* has been moved out of the flow.
*/
class nsPlaceholderFrame MOZ_FINAL : public nsFrame {
public:
NS_DECL_FRAMEARENA_HELPERS
/**
* Create a new placeholder frame. aTypeBit must be one of the
* PLACEHOLDER_FOR_* constants above.
*/
friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
nsStyleContext* aContext,
nsFrameState aTypeBit);
nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit)
: nsFrame(aContext)
{
NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT ||
aTypeBit == PLACEHOLDER_FOR_ABSPOS ||
aTypeBit == PLACEHOLDER_FOR_FIXEDPOS ||
aTypeBit == PLACEHOLDER_FOR_POPUP,
"Unexpected type bit");
AddStateBits(aTypeBit);
}
// Get/Set the associated out of flow frame
nsIFrame* GetOutOfFlowFrame() const { return mOutOfFlowFrame; }
void SetOutOfFlowFrame(nsIFrame* aFrame) {
NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(),
"OOF must be first continuation");
mOutOfFlowFrame = aFrame;
}
// nsIFrame overrides
// We need to override GetMinSize and GetPrefSize because XUL uses
// placeholders not within lines.
virtual void AddInlineMinWidth(nsRenderingContext* aRenderingContext,
InlineMinWidthData* aData) MOZ_OVERRIDE;
virtual void AddInlinePrefWidth(nsRenderingContext* aRenderingContext,
InlinePrefWidthData* aData) MOZ_OVERRIDE;
virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
NS_IMETHOD Reflow(nsPresContext* aPresContext,
nsHTMLReflowMetrics& aDesiredSize,
const nsHTMLReflowState& aReflowState,
nsReflowStatus& aStatus) MOZ_OVERRIDE;
virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE;
#if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsRect& aDirtyRect,
const nsDisplayListSet& aLists) MOZ_OVERRIDE;
#endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
#ifdef DEBUG
NS_IMETHOD List(FILE* out, int32_t aIndent, uint32_t aFlags = 0) const MOZ_OVERRIDE;
NS_IMETHOD GetFrameName(nsAString& aResult) const MOZ_OVERRIDE;
#endif // DEBUG
/**
* Get the "type" of the frame
*
* @see nsGkAtoms::placeholderFrame
*/
virtual nsIAtom* GetType() const MOZ_OVERRIDE;
virtual bool IsEmpty() MOZ_OVERRIDE { return true; }
virtual bool IsSelfEmpty() MOZ_OVERRIDE { return true; }
virtual bool CanContinueTextRun() const MOZ_OVERRIDE;
#ifdef ACCESSIBILITY
virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE
{
nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
return realFrame ? realFrame->AccessibleType() :
nsFrame::AccessibleType();
}
#endif
virtual nsIFrame* GetParentStyleContextFrame() const MOZ_OVERRIDE;
/**
* @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
* aFrame
*/
static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
NS_PRECONDITION(aFrame, "Must have a frame to work with");
if (aFrame->GetType() == nsGkAtoms::placeholderFrame) {
return GetRealFrameForPlaceholder(aFrame);
}
return aFrame;
}
/**
* @return the out-of-flow for aFrame, which is known to be a placeholder
*/
static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame,
"Must have placeholder frame as input");
nsIFrame* outOfFlow =
static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame();
NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
return outOfFlow;
}
protected:
nsIFrame* mOutOfFlowFrame;
};
#endif /* nsPlaceholderFrame_h___ */
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