1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/generic/nsPlaceholderFrame.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,168 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/*
1.10 + * rendering object for the point that anchors out-of-flow rendering
1.11 + * objects such as floats and absolutely positioned elements
1.12 + */
1.13 +
1.14 +/*
1.15 + * Destruction of a placeholder and its out-of-flow must observe the
1.16 + * following constraints:
1.17 + *
1.18 + * - The mapping from the out-of-flow to the placeholder must be
1.19 + * removed from the frame manager before the placeholder is destroyed.
1.20 + * - The mapping from the out-of-flow to the placeholder must be
1.21 + * removed from the frame manager before the out-of-flow is destroyed.
1.22 + * - The placeholder must be removed from the frame tree, or have the
1.23 + * mapping from it to its out-of-flow cleared, before the out-of-flow
1.24 + * is destroyed (so that the placeholder will not point to a destroyed
1.25 + * frame while it's in the frame tree).
1.26 + *
1.27 + * Furthermore, some code assumes that placeholders point to something
1.28 + * useful, so placeholders without an associated out-of-flow should not
1.29 + * remain in the tree.
1.30 + *
1.31 + * The placeholder's Destroy() implementation handles the destruction of
1.32 + * the placeholder and its out-of-flow. To avoid crashes, frame removal
1.33 + * and destruction code that works with placeholders must not assume
1.34 + * that the placeholder points to its out-of-flow.
1.35 + */
1.36 +
1.37 +#ifndef nsPlaceholderFrame_h___
1.38 +#define nsPlaceholderFrame_h___
1.39 +
1.40 +#include "mozilla/Attributes.h"
1.41 +#include "nsFrame.h"
1.42 +#include "nsGkAtoms.h"
1.43 +
1.44 +nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
1.45 + nsStyleContext* aContext,
1.46 + nsFrameState aTypeBit);
1.47 +
1.48 +#define PLACEHOLDER_TYPE_MASK (PLACEHOLDER_FOR_FLOAT | \
1.49 + PLACEHOLDER_FOR_ABSPOS | \
1.50 + PLACEHOLDER_FOR_FIXEDPOS | \
1.51 + PLACEHOLDER_FOR_POPUP)
1.52 +
1.53 +/**
1.54 + * Implementation of a frame that's used as a placeholder for a frame that
1.55 + * has been moved out of the flow.
1.56 + */
1.57 +class nsPlaceholderFrame MOZ_FINAL : public nsFrame {
1.58 +public:
1.59 + NS_DECL_FRAMEARENA_HELPERS
1.60 +#ifdef DEBUG
1.61 + NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame)
1.62 + NS_DECL_QUERYFRAME
1.63 +#endif
1.64 +
1.65 + /**
1.66 + * Create a new placeholder frame. aTypeBit must be one of the
1.67 + * PLACEHOLDER_FOR_* constants above.
1.68 + */
1.69 + friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
1.70 + nsStyleContext* aContext,
1.71 + nsFrameState aTypeBit);
1.72 + nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit)
1.73 + : nsFrame(aContext)
1.74 + {
1.75 + NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT ||
1.76 + aTypeBit == PLACEHOLDER_FOR_ABSPOS ||
1.77 + aTypeBit == PLACEHOLDER_FOR_FIXEDPOS ||
1.78 + aTypeBit == PLACEHOLDER_FOR_POPUP,
1.79 + "Unexpected type bit");
1.80 + AddStateBits(aTypeBit);
1.81 + }
1.82 +
1.83 + // Get/Set the associated out of flow frame
1.84 + nsIFrame* GetOutOfFlowFrame() const { return mOutOfFlowFrame; }
1.85 + void SetOutOfFlowFrame(nsIFrame* aFrame) {
1.86 + NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(),
1.87 + "OOF must be first continuation");
1.88 + mOutOfFlowFrame = aFrame;
1.89 + }
1.90 +
1.91 + // nsIFrame overrides
1.92 + // We need to override GetMinSize and GetPrefSize because XUL uses
1.93 + // placeholders not within lines.
1.94 + virtual void AddInlineMinWidth(nsRenderingContext* aRenderingContext,
1.95 + InlineMinWidthData* aData) MOZ_OVERRIDE;
1.96 + virtual void AddInlinePrefWidth(nsRenderingContext* aRenderingContext,
1.97 + InlinePrefWidthData* aData) MOZ_OVERRIDE;
1.98 + virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
1.99 + virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
1.100 + virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
1.101 +
1.102 + virtual nsresult Reflow(nsPresContext* aPresContext,
1.103 + nsHTMLReflowMetrics& aDesiredSize,
1.104 + const nsHTMLReflowState& aReflowState,
1.105 + nsReflowStatus& aStatus) MOZ_OVERRIDE;
1.106 +
1.107 + virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE;
1.108 +
1.109 +#if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
1.110 + virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
1.111 + const nsRect& aDirtyRect,
1.112 + const nsDisplayListSet& aLists) MOZ_OVERRIDE;
1.113 +#endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
1.114 +
1.115 +#ifdef DEBUG_FRAME_DUMP
1.116 + void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const MOZ_OVERRIDE;
1.117 + virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE;
1.118 +#endif // DEBUG
1.119 +
1.120 + /**
1.121 + * Get the "type" of the frame
1.122 + *
1.123 + * @see nsGkAtoms::placeholderFrame
1.124 + */
1.125 + virtual nsIAtom* GetType() const MOZ_OVERRIDE;
1.126 +
1.127 + virtual bool IsEmpty() MOZ_OVERRIDE { return true; }
1.128 + virtual bool IsSelfEmpty() MOZ_OVERRIDE { return true; }
1.129 +
1.130 + virtual bool CanContinueTextRun() const MOZ_OVERRIDE;
1.131 +
1.132 +#ifdef ACCESSIBILITY
1.133 + virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE
1.134 + {
1.135 + nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
1.136 + return realFrame ? realFrame->AccessibleType() :
1.137 + nsFrame::AccessibleType();
1.138 + }
1.139 +#endif
1.140 +
1.141 + virtual nsIFrame* GetParentStyleContextFrame() const MOZ_OVERRIDE;
1.142 +
1.143 + /**
1.144 + * @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
1.145 + * aFrame
1.146 + */
1.147 + static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
1.148 + NS_PRECONDITION(aFrame, "Must have a frame to work with");
1.149 + if (aFrame->GetType() == nsGkAtoms::placeholderFrame) {
1.150 + return GetRealFrameForPlaceholder(aFrame);
1.151 + }
1.152 + return aFrame;
1.153 + }
1.154 +
1.155 + /**
1.156 + * @return the out-of-flow for aFrame, which is known to be a placeholder
1.157 + */
1.158 + static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
1.159 + NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame,
1.160 + "Must have placeholder frame as input");
1.161 + nsIFrame* outOfFlow =
1.162 + static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame();
1.163 + NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
1.164 + return outOfFlow;
1.165 + }
1.166 +
1.167 +protected:
1.168 + nsIFrame* mOutOfFlowFrame;
1.169 +};
1.170 +
1.171 +#endif /* nsPlaceholderFrame_h___ */
