The Tor Browser / file comparison
comparison: layout/generic/nsPlaceholderFrame.h
layout/generic/nsPlaceholderFrame.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:4042354ab5c9 |
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| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 /* | |
| 7 * rendering object for the point that anchors out-of-flow rendering | |
| 8 * objects such as floats and absolutely positioned elements | |
| 9 */ | |
| 10 | |
| 11 /* | |
| 12 * Destruction of a placeholder and its out-of-flow must observe the | |
| 13 * following constraints: | |
| 14 * | |
| 15 * - The mapping from the out-of-flow to the placeholder must be | |
| 16 * removed from the frame manager before the placeholder is destroyed. | |
| 17 * - The mapping from the out-of-flow to the placeholder must be | |
| 18 * removed from the frame manager before the out-of-flow is destroyed. | |
| 19 * - The placeholder must be removed from the frame tree, or have the | |
| 20 * mapping from it to its out-of-flow cleared, before the out-of-flow | |
| 21 * is destroyed (so that the placeholder will not point to a destroyed | |
| 22 * frame while it's in the frame tree). | |
| 23 * | |
| 24 * Furthermore, some code assumes that placeholders point to something | |
| 25 * useful, so placeholders without an associated out-of-flow should not | |
| 26 * remain in the tree. | |
| 27 * | |
| 28 * The placeholder's Destroy() implementation handles the destruction of | |
| 29 * the placeholder and its out-of-flow. To avoid crashes, frame removal | |
| 30 * and destruction code that works with placeholders must not assume | |
| 31 * that the placeholder points to its out-of-flow. | |
| 32 */ | |
| 33 | |
| 34 #ifndef nsPlaceholderFrame_h___ | |
| 35 #define nsPlaceholderFrame_h___ | |
| 36 | |
| 37 #include "mozilla/Attributes.h" | |
| 38 #include "nsFrame.h" | |
| 39 #include "nsGkAtoms.h" | |
| 40 | |
| 41 nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell, | |
| 42 nsStyleContext* aContext, | |
| 43 nsFrameState aTypeBit); | |
| 44 | |
| 45 #define PLACEHOLDER_TYPE_MASK (PLACEHOLDER_FOR_FLOAT | \ | |
| 46 PLACEHOLDER_FOR_ABSPOS | \ | |
| 47 PLACEHOLDER_FOR_FIXEDPOS | \ | |
| 48 PLACEHOLDER_FOR_POPUP) | |
| 49 | |
| 50 /** | |
| 51 * Implementation of a frame that's used as a placeholder for a frame that | |
| 52 * has been moved out of the flow. | |
| 53 */ | |
| 54 class nsPlaceholderFrame MOZ_FINAL : public nsFrame { | |
| 55 public: | |
| 56 NS_DECL_FRAMEARENA_HELPERS | |
| 57 #ifdef DEBUG | |
| 58 NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame) | |
| 59 NS_DECL_QUERYFRAME | |
| 60 #endif | |
| 61 | |
| 62 /** | |
| 63 * Create a new placeholder frame. aTypeBit must be one of the | |
| 64 * PLACEHOLDER_FOR_* constants above. | |
| 65 */ | |
| 66 friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell, | |
| 67 nsStyleContext* aContext, | |
| 68 nsFrameState aTypeBit); | |
| 69 nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit) | |
| 70 : nsFrame(aContext) | |
| 71 { | |
| 72 NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT || | |
| 73 aTypeBit == PLACEHOLDER_FOR_ABSPOS || | |
| 74 aTypeBit == PLACEHOLDER_FOR_FIXEDPOS || | |
| 75 aTypeBit == PLACEHOLDER_FOR_POPUP, | |
| 76 "Unexpected type bit"); | |
| 77 AddStateBits(aTypeBit); | |
| 78 } | |
| 79 | |
| 80 // Get/Set the associated out of flow frame | |
| 81 nsIFrame* GetOutOfFlowFrame() const { return mOutOfFlowFrame; } | |
| 82 void SetOutOfFlowFrame(nsIFrame* aFrame) { | |
| 83 NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(), | |
| 84 "OOF must be first continuation"); | |
| 85 mOutOfFlowFrame = aFrame; | |
| 86 } | |
| 87 | |
| 88 // nsIFrame overrides | |
| 89 // We need to override GetMinSize and GetPrefSize because XUL uses | |
| 90 // placeholders not within lines. | |
| 91 virtual void AddInlineMinWidth(nsRenderingContext* aRenderingContext, | |
| 92 InlineMinWidthData* aData) MOZ_OVERRIDE; | |
| 93 virtual void AddInlinePrefWidth(nsRenderingContext* aRenderingContext, | |
| 94 InlinePrefWidthData* aData) MOZ_OVERRIDE; | |
| 95 virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE; | |
| 96 virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE; | |
| 97 virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE; | |
| 98 | |
| 99 virtual nsresult Reflow(nsPresContext* aPresContext, | |
| 100 nsHTMLReflowMetrics& aDesiredSize, | |
| 101 const nsHTMLReflowState& aReflowState, | |
| 102 nsReflowStatus& aStatus) MOZ_OVERRIDE; | |
| 103 | |
| 104 virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE; | |
| 105 | |
| 106 #if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF)) | |
| 107 virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder, | |
| 108 const nsRect& aDirtyRect, | |
| 109 const nsDisplayListSet& aLists) MOZ_OVERRIDE; | |
| 110 #endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF) | |
| 111 | |
| 112 #ifdef DEBUG_FRAME_DUMP | |
| 113 void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const MOZ_OVERRIDE; | |
| 114 virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE; | |
| 115 #endif // DEBUG | |
| 116 | |
| 117 /** | |
| 118 * Get the "type" of the frame | |
| 119 * | |
| 120 * @see nsGkAtoms::placeholderFrame | |
| 121 */ | |
| 122 virtual nsIAtom* GetType() const MOZ_OVERRIDE; | |
| 123 | |
| 124 virtual bool IsEmpty() MOZ_OVERRIDE { return true; } | |
| 125 virtual bool IsSelfEmpty() MOZ_OVERRIDE { return true; } | |
| 126 | |
| 127 virtual bool CanContinueTextRun() const MOZ_OVERRIDE; | |
| 128 | |
| 129 #ifdef ACCESSIBILITY | |
| 130 virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE | |
| 131 { | |
| 132 nsIFrame* realFrame = GetRealFrameForPlaceholder(this); | |
| 133 return realFrame ? realFrame->AccessibleType() : | |
| 134 nsFrame::AccessibleType(); | |
| 135 } | |
| 136 #endif | |
| 137 | |
| 138 virtual nsIFrame* GetParentStyleContextFrame() const MOZ_OVERRIDE; | |
| 139 | |
| 140 /** | |
| 141 * @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise | |
| 142 * aFrame | |
| 143 */ | |
| 144 static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) { | |
| 145 NS_PRECONDITION(aFrame, "Must have a frame to work with"); | |
| 146 if (aFrame->GetType() == nsGkAtoms::placeholderFrame) { | |
| 147 return GetRealFrameForPlaceholder(aFrame); | |
| 148 } | |
| 149 return aFrame; | |
| 150 } | |
| 151 | |
| 152 /** | |
| 153 * @return the out-of-flow for aFrame, which is known to be a placeholder | |
| 154 */ | |
| 155 static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) { | |
| 156 NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame, | |
| 157 "Must have placeholder frame as input"); | |
| 158 nsIFrame* outOfFlow = | |
| 159 static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame(); | |
| 160 NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?"); | |
| 161 return outOfFlow; | |
| 162 } | |
| 163 | |
| 164 protected: | |
| 165 nsIFrame* mOutOfFlowFrame; | |
| 166 }; | |
| 167 | |
| 168 #endif /* nsPlaceholderFrame_h___ */ |
