/* -*- 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); #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 nsFrame { public: NS_DECL_FRAMEARENA_HELPERS #ifdef DEBUG NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame) NS_DECL_QUERYFRAME #endif /** * 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 || aTypeBit == PLACEHOLDER_FOR_TOPLAYER, "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 GetXULMinSize and GetXULPrefSize because XUL uses // placeholders not within lines. virtual void AddInlineMinISize(nsRenderingContext* aRenderingContext, InlineMinISizeData* aData) override; virtual void AddInlinePrefISize(nsRenderingContext* 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) override; #if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF)) virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder, const nsRect& aDirtyRect, 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 = "", uint32_t aFlags = 0) const override; virtual nsresult GetFrameName(nsAString& aResult) const override; #endif // DEBUG /** * Get the "type" of the frame * * @see nsGkAtoms::placeholderFrame */ virtual nsIAtom* GetType() const override; virtual bool IsEmpty() override { return true; } virtual bool IsSelfEmpty() override { return true; } virtual bool CanContinueTextRun() const override; #ifdef ACCESSIBILITY virtual mozilla::a11y::AccType AccessibleType() override { nsIFrame* realFrame = GetRealFrameForPlaceholder(this); return realFrame ? realFrame->AccessibleType() : nsFrame::AccessibleType(); } #endif virtual nsStyleContext* GetParentStyleContext(nsIFrame** aProviderFrame) const override; 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) { 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___ */