layout/generic/nsSplittableFrame.h

   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  * base class for rendering objects that can be split across lines,
   8  * columns, or pages
   9  */
  10
  11 #ifndef nsSplittableFrame_h___
  12 #define nsSplittableFrame_h___
  13
  14 #include "mozilla/Attributes.h"
  15 #include "nsFrame.h"
  16
  17 // Derived class that allows splitting
  18 class nsSplittableFrame : public nsFrame
  19 {
  20 public:
  21   NS_DECL_FRAMEARENA_HELPERS
  22
  23   virtual void Init(nsIContent*       aContent,
  24                     nsContainerFrame* aParent,
  25                     nsIFrame*         aPrevInFlow) MOZ_OVERRIDE;
  26
  27   virtual nsSplittableType GetSplittableType() const MOZ_OVERRIDE;
  28
  29   virtual void DestroyFrom(nsIFrame* aDestructRoot) MOZ_OVERRIDE;
  30
  31   /*
  32    * Frame continuations can be either fluid or not:
  33    * Fluid continuations ("in-flows") are the result of line breaking,
  34    * column breaking, or page breaking.
  35    * Other (non-fluid) continuations can be the result of BiDi frame splitting.
  36    * A "flow" is a chain of fluid continuations.
  37    */
  38
  39   // Get the previous/next continuation, regardless of its type (fluid or non-fluid).
  40   virtual nsIFrame* GetPrevContinuation() const MOZ_OVERRIDE;
  41   virtual nsIFrame* GetNextContinuation() const MOZ_OVERRIDE;
  42
  43   // Set a previous/next non-fluid continuation.
  44   virtual void SetPrevContinuation(nsIFrame*) MOZ_OVERRIDE;
  45   virtual void SetNextContinuation(nsIFrame*) MOZ_OVERRIDE;
  46
  47   // Get the first/last continuation for this frame.
  48   virtual nsIFrame* FirstContinuation() const MOZ_OVERRIDE;
  49   virtual nsIFrame* LastContinuation() const MOZ_OVERRIDE;
  50
  51 #ifdef DEBUG
  52   // Can aFrame2 be reached from aFrame1 by following prev/next continuations?
  53   static bool IsInPrevContinuationChain(nsIFrame* aFrame1, nsIFrame* aFrame2);
  54   static bool IsInNextContinuationChain(nsIFrame* aFrame1, nsIFrame* aFrame2);
  55 #endif
  56
  57   // Get the previous/next continuation, only if it is fluid (an "in-flow").
  58   nsIFrame* GetPrevInFlow() const;
  59   nsIFrame* GetNextInFlow() const;
  60
  61   virtual nsIFrame* GetPrevInFlowVirtual() const MOZ_OVERRIDE { return GetPrevInFlow(); }
  62   virtual nsIFrame* GetNextInFlowVirtual() const MOZ_OVERRIDE { return GetNextInFlow(); }
  63
  64   // Set a previous/next fluid continuation.
  65   virtual void SetPrevInFlow(nsIFrame*) MOZ_OVERRIDE;
  66   virtual void SetNextInFlow(nsIFrame*) MOZ_OVERRIDE;
  67
  68   // Get the first/last frame in the current flow.
  69   virtual nsIFrame* FirstInFlow() const MOZ_OVERRIDE;
  70   virtual nsIFrame* LastInFlow() const MOZ_OVERRIDE;
  71
  72   // Remove the frame from the flow. Connects the frame's prev-in-flow
  73   // and its next-in-flow. This should only be called in frame Destroy() methods.
  74   static void RemoveFromFlow(nsIFrame* aFrame);
  75
  76 protected:
  77   explicit nsSplittableFrame(nsStyleContext* aContext) : nsFrame(aContext) {}
  78
  79   /**
  80    * Determine the height consumed by our previous-in-flows.
  81    *
  82    * @note (bz) This makes laying out a splittable frame with N in-flows
  83    *       O(N^2)! So, use this function with caution and minimize the number
  84    *       of calls to this method.
  85    */
  86   nscoord GetConsumedBSize() const;
  87
  88   /**
  89    * Retrieve the effective computed block size of this frame, which is the
  90    * computed block size, minus the block size consumed by any previous in-flows.
  91    */
  92   nscoord GetEffectiveComputedBSize(const nsHTMLReflowState& aReflowState,
  93                                     nscoord aConsumed = NS_INTRINSICSIZE) const;
  94
  95   /**
  96    * @see nsIFrame::GetLogicalSkipSides()
  97    */
  98   virtual LogicalSides GetLogicalSkipSides(const nsHTMLReflowState* aReflowState = nullptr) const MOZ_OVERRIDE;
  99
 100 #ifdef DEBUG
 101   virtual void DumpBaseRegressionData(nsPresContext* aPresContext, FILE* out, int32_t aIndent) MOZ_OVERRIDE;
 102 #endif
 103
 104   nsIFrame*   mPrevContinuation;
 105   nsIFrame*   mNextContinuation;
 106 };
 107
 108 #endif /* nsSplittableFrame_h___ */