michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * rendering object for the point that anchors out-of-flow rendering
michael@0:  * objects such as floats and absolutely positioned elements
michael@0:  */
michael@0: 
michael@0: /*
michael@0:  * Destruction of a placeholder and its out-of-flow must observe the
michael@0:  * following constraints:
michael@0:  *
michael@0:  * - The mapping from the out-of-flow to the placeholder must be
michael@0:  *   removed from the frame manager before the placeholder is destroyed.
michael@0:  * - The mapping from the out-of-flow to the placeholder must be
michael@0:  *   removed from the frame manager before the out-of-flow is destroyed.
michael@0:  * - The placeholder must be removed from the frame tree, or have the
michael@0:  *   mapping from it to its out-of-flow cleared, before the out-of-flow
michael@0:  *   is destroyed (so that the placeholder will not point to a destroyed
michael@0:  *   frame while it's in the frame tree).
michael@0:  *
michael@0:  * Furthermore, some code assumes that placeholders point to something
michael@0:  * useful, so placeholders without an associated out-of-flow should not
michael@0:  * remain in the tree.
michael@0:  *
michael@0:  * The placeholder's Destroy() implementation handles the destruction of
michael@0:  * the placeholder and its out-of-flow. To avoid crashes, frame removal
michael@0:  * and destruction code that works with placeholders must not assume
michael@0:  * that the placeholder points to its out-of-flow.
michael@0:  */
michael@0: 
michael@0: #ifndef nsPlaceholderFrame_h___
michael@0: #define nsPlaceholderFrame_h___
michael@0: 
michael@0: #include "mozilla/Attributes.h"
michael@0: #include "nsFrame.h"
michael@0: #include "nsGkAtoms.h"
michael@0: 
michael@0: nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
michael@0:                                  nsStyleContext* aContext,
michael@0:                                  nsFrameState aTypeBit);
michael@0: 
michael@0: #define PLACEHOLDER_TYPE_MASK    (PLACEHOLDER_FOR_FLOAT | \
michael@0:                                   PLACEHOLDER_FOR_ABSPOS | \
michael@0:                                   PLACEHOLDER_FOR_FIXEDPOS | \
michael@0:                                   PLACEHOLDER_FOR_POPUP)
michael@0: 
michael@0: /**
michael@0:  * Implementation of a frame that's used as a placeholder for a frame that
michael@0:  * has been moved out of the flow.
michael@0:  */
michael@0: class nsPlaceholderFrame MOZ_FINAL : public nsFrame {
michael@0: public:
michael@0:   NS_DECL_FRAMEARENA_HELPERS
michael@0: #ifdef DEBUG
michael@0:   NS_DECL_QUERYFRAME_TARGET(nsPlaceholderFrame)
michael@0:   NS_DECL_QUERYFRAME
michael@0: #endif
michael@0: 
michael@0:   /**
michael@0:    * Create a new placeholder frame.  aTypeBit must be one of the
michael@0:    * PLACEHOLDER_FOR_* constants above.
michael@0:    */
michael@0:   friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
michael@0:                                           nsStyleContext* aContext,
michael@0:                                           nsFrameState aTypeBit);
michael@0:   nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit)
michael@0:     : nsFrame(aContext)
michael@0:   {
michael@0:     NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT ||
michael@0:                     aTypeBit == PLACEHOLDER_FOR_ABSPOS ||
michael@0:                     aTypeBit == PLACEHOLDER_FOR_FIXEDPOS ||
michael@0:                     aTypeBit == PLACEHOLDER_FOR_POPUP,
michael@0:                     "Unexpected type bit");
michael@0:     AddStateBits(aTypeBit);
michael@0:   }
michael@0: 
michael@0:   // Get/Set the associated out of flow frame
michael@0:   nsIFrame*  GetOutOfFlowFrame() const { return mOutOfFlowFrame; }
michael@0:   void       SetOutOfFlowFrame(nsIFrame* aFrame) {
michael@0:                NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(),
michael@0:                             "OOF must be first continuation");
michael@0:                mOutOfFlowFrame = aFrame;
michael@0:              }
michael@0: 
michael@0:   // nsIFrame overrides
michael@0:   // We need to override GetMinSize and GetPrefSize because XUL uses
michael@0:   // placeholders not within lines.
michael@0:   virtual void AddInlineMinWidth(nsRenderingContext* aRenderingContext,
michael@0:                                  InlineMinWidthData* aData) MOZ_OVERRIDE;
michael@0:   virtual void AddInlinePrefWidth(nsRenderingContext* aRenderingContext,
michael@0:                                   InlinePrefWidthData* aData) MOZ_OVERRIDE;
michael@0:   virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
michael@0:   virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
michael@0:   virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual nsresult Reflow(nsPresContext* aPresContext,
michael@0:                           nsHTMLReflowMetrics& aDesiredSize,
michael@0:                           const nsHTMLReflowState& aReflowState,
michael@0:                           nsReflowStatus& aStatus) MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE;
michael@0: 
michael@0: #if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
michael@0:   virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
michael@0:                                 const nsRect&           aDirtyRect,
michael@0:                                 const nsDisplayListSet& aLists) MOZ_OVERRIDE;
michael@0: #endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
michael@0:   
michael@0: #ifdef DEBUG_FRAME_DUMP
michael@0:   void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const MOZ_OVERRIDE;
michael@0:   virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE;
michael@0: #endif // DEBUG
michael@0: 
michael@0:   /**
michael@0:    * Get the "type" of the frame
michael@0:    *
michael@0:    * @see nsGkAtoms::placeholderFrame
michael@0:    */
michael@0:   virtual nsIAtom* GetType() const MOZ_OVERRIDE;
michael@0: 
michael@0:   virtual bool IsEmpty() MOZ_OVERRIDE { return true; }
michael@0:   virtual bool IsSelfEmpty() MOZ_OVERRIDE { return true; }
michael@0: 
michael@0:   virtual bool CanContinueTextRun() const MOZ_OVERRIDE;
michael@0: 
michael@0: #ifdef ACCESSIBILITY
michael@0:   virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE
michael@0:   {
michael@0:     nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
michael@0:     return realFrame ? realFrame->AccessibleType() :
michael@0:                        nsFrame::AccessibleType();
michael@0:   }
michael@0: #endif
michael@0: 
michael@0:   virtual nsIFrame* GetParentStyleContextFrame() const MOZ_OVERRIDE;
michael@0: 
michael@0:   /**
michael@0:    * @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
michael@0:    * aFrame
michael@0:    */
michael@0:   static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
michael@0:     NS_PRECONDITION(aFrame, "Must have a frame to work with");
michael@0:     if (aFrame->GetType() == nsGkAtoms::placeholderFrame) {
michael@0:       return GetRealFrameForPlaceholder(aFrame);
michael@0:     }
michael@0:     return aFrame;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * @return the out-of-flow for aFrame, which is known to be a placeholder
michael@0:    */
michael@0:   static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
michael@0:     NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame,
michael@0:                     "Must have placeholder frame as input");
michael@0:     nsIFrame* outOfFlow =
michael@0:       static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame();
michael@0:     NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
michael@0:     return outOfFlow;
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   nsIFrame* mOutOfFlowFrame;
michael@0: };
michael@0: 
michael@0: #endif /* nsPlaceholderFrame_h___ */