Source code

Revision control

Other Tools

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsIFrame.h"
#include "nsGkAtoms.h"
namespace mozilla {
class PresShell;
} // namespace mozilla
class nsPlaceholderFrame;
nsPlaceholderFrame* NS_NewPlaceholderFrame(mozilla::PresShell* aPresShell,
mozilla::ComputedStyle* aStyle,
nsFrameState aTypeBits);
#define PLACEHOLDER_TYPE_MASK \
(PLACEHOLDER_FOR_FLOAT | PLACEHOLDER_FOR_ABSPOS | PLACEHOLDER_FOR_FIXEDPOS | \
PLACEHOLDER_FOR_POPUP | PLACEHOLDER_FOR_TOPLAYER)
/**
* Implementation of a frame that's used as a placeholder for a frame that
* has been moved out of the flow.
*/
class nsPlaceholderFrame final : public nsIFrame {
public:
NS_DECL_FRAMEARENA_HELPERS(nsPlaceholderFrame)
#ifdef DEBUG
NS_DECL_QUERYFRAME
#endif
/**
* Create a new placeholder frame. aTypeBit must be one of the
* PLACEHOLDER_FOR_* constants above.
*/
friend nsPlaceholderFrame* NS_NewPlaceholderFrame(
mozilla::PresShell* aPresShell, ComputedStyle* aStyle,
nsFrameState aTypeBits);
nsPlaceholderFrame(ComputedStyle* aStyle, nsPresContext* aPresContext,
nsFrameState aTypeBits)
: nsIFrame(aStyle, aPresContext, kClassID), mOutOfFlowFrame(nullptr) {
MOZ_ASSERT(
aTypeBits == PLACEHOLDER_FOR_FLOAT ||
aTypeBits == PLACEHOLDER_FOR_ABSPOS ||
aTypeBits == PLACEHOLDER_FOR_FIXEDPOS ||
aTypeBits == PLACEHOLDER_FOR_POPUP ||
aTypeBits == (PLACEHOLDER_FOR_TOPLAYER | PLACEHOLDER_FOR_ABSPOS) ||
aTypeBits == (PLACEHOLDER_FOR_TOPLAYER | PLACEHOLDER_FOR_FIXEDPOS),
"Unexpected type bit");
AddStateBits(aTypeBits);
}
// 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 GetXULMinSize and GetXULPrefSize because XUL uses
// placeholders not within lines.
virtual void AddInlineMinISize(gfxContext* aRenderingContext,
InlineMinISizeData* aData) override;
virtual void AddInlinePrefISize(gfxContext* aRenderingContext,
InlinePrefISizeData* aData) override;
virtual nsSize GetXULMinSize(nsBoxLayoutState& aBoxLayoutState) override;
virtual nsSize GetXULPrefSize(nsBoxLayoutState& aBoxLayoutState) override;
virtual nsSize GetXULMaxSize(nsBoxLayoutState& aBoxLayoutState) override;
virtual void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
const ReflowInput& aReflowInput,
nsReflowStatus& aStatus) override;
virtual void DestroyFrom(nsIFrame* aDestructRoot,
PostDestroyData& aPostDestroyData) override;
#if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
const nsDisplayListSet& aLists) override;
#endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
#ifdef DEBUG_FRAME_DUMP
void List(FILE* out = stderr, const char* aPrefix = "",
ListFlags aFlags = ListFlags()) const override;
virtual nsresult GetFrameName(nsAString& aResult) const override;
#endif // DEBUG
virtual bool IsEmpty() override { return true; }
virtual bool IsSelfEmpty() override { return true; }
virtual bool CanContinueTextRun() const override;
void SetLineIsEmptySoFar(bool aValue) {
AddOrRemoveStateBits(PLACEHOLDER_LINE_IS_EMPTY_SO_FAR, aValue);
AddStateBits(PLACEHOLDER_HAVE_LINE_IS_EMPTY_SO_FAR);
}
bool GetLineIsEmptySoFar(bool* aResult) const {
bool haveValue = HasAnyStateBits(PLACEHOLDER_HAVE_LINE_IS_EMPTY_SO_FAR);
if (haveValue) {
*aResult = HasAnyStateBits(PLACEHOLDER_LINE_IS_EMPTY_SO_FAR);
}
return haveValue;
}
void ForgetLineIsEmptySoFar() {
RemoveStateBits(PLACEHOLDER_HAVE_LINE_IS_EMPTY_SO_FAR);
}
#ifdef ACCESSIBILITY
virtual mozilla::a11y::AccType AccessibleType() override {
nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
return realFrame ? realFrame->AccessibleType() : nsIFrame::AccessibleType();
}
#endif
ComputedStyle* GetParentComputedStyleForOutOfFlow(
nsIFrame** aProviderFrame) const;
// Like GetParentComputedStyleForOutOfFlow, but ignores display:contents bits.
ComputedStyle* GetLayoutParentStyleForOutOfFlow(
nsIFrame** aProviderFrame) const;
bool RenumberFrameAndDescendants(int32_t* aOrdinal, int32_t aDepth,
int32_t aIncrement,
bool aForCounting) override {
return mOutOfFlowFrame->RenumberFrameAndDescendants(
aOrdinal, aDepth, aIncrement, aForCounting);
}
/**
* @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
* aFrame
*/
static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
MOZ_ASSERT(aFrame, "Must have a frame to work with");
if (aFrame->IsPlaceholderFrame()) {
return GetRealFrameForPlaceholder(aFrame);
}
return aFrame;
}
/**
* @return the out-of-flow for aFrame, which is known to be a placeholder
*/
static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
MOZ_ASSERT(aFrame->IsPlaceholderFrame(),
"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___ */