layout/generic/nsBlockReflowContext.h

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  38
  39 /* class that a parent frame uses to reflow a block frame */
  40
  41 #ifndef nsBlockReflowContext_h___
  42 #define nsBlockReflowContext_h___
  43
  44 #include "nsIFrame.h"
  45 #include "nsHTMLReflowMetrics.h"
  46
  47 class nsBlockFrame;
  48 class nsBlockReflowState;
  49 struct nsHTMLReflowState;
  50 class nsLineBox;
  51 class nsIFrame;
  52 class nsPresContext;
  53 class nsLineLayout;
  54 struct nsStylePosition;
  55 struct nsBlockHorizontalAlign;
  56
  57 /**
  58  * An encapsulation of the state and algorithm for reflowing block frames.
  59  */
  60 class nsBlockReflowContext {
  61 public:
  62   nsBlockReflowContext(nsPresContext* aPresContext,
  63                        const nsHTMLReflowState& aParentRS);
  64   ~nsBlockReflowContext() { }
  65
  66   nsresult ReflowBlock(const nsRect&       aSpace,
  67                        PRBool              aApplyTopMargin,
  68                        nsCollapsingMargin& aPrevMargin,
  69                        nscoord             aClearance,
  70                        PRBool              aIsAdjacentWithTop,
  71                        nsMargin&           aComputedOffsets,
  72                        nsLineBox*          aLine,
  73                        nsHTMLReflowState&  aReflowState,
  74                        nsReflowStatus&     aReflowStatus,
  75                        nsBlockReflowState& aState);
  76
  77   PRBool PlaceBlock(const nsHTMLReflowState& aReflowState,
  78                     PRBool                   aForceFit,
  79                     nsLineBox*               aLine,
  80                     const nsMargin&          aComputedOffsets,
  81                     nsCollapsingMargin&      aBottomMarginResult /* out */,
  82                     nsRect&                  aInFlowBounds,
  83                     nsRect&                  aCombinedRect,
  84                     nsReflowStatus           aReflowStatus);
  85
  86   nsCollapsingMargin& GetCarriedOutBottomMargin() {
  87     return mMetrics.mCarriedOutBottomMargin;
  88   }
  89
  90   nscoord GetTopMargin() const {
  91     return mTopMargin.get();
  92   }
  93
  94   const nsHTMLReflowMetrics& GetMetrics() const {
  95     return mMetrics;
  96   }
  97
  98   /**
  99    * Computes the collapsed top margin for a block whose reflow state is in aRS.
 100    * The computed margin is added into aMargin.
 101    * If aClearanceFrame is null then this is the first optimistic pass which shall assume
 102    * that no frames have clearance, and we clear the HasClearance on all frames encountered.
 103    * If non-null, this is the second pass and
 104    * the caller has decided aClearanceFrame needs clearance (and we will
 105    * therefore stop collapsing there); also, this function is responsible for marking
 106    * it with SetHasClearance.
 107    * If in the optimistic pass any frame is encountered that might possibly need
 108    * clearance (i.e., if we really needed the optimism assumption) then we set aMayNeedRetry
 109    * to true.
 110    * We return PR_TRUE if we changed the clearance state of any line and marked it dirty.
 111    */
 112   static PRBool ComputeCollapsedTopMargin(const nsHTMLReflowState& aRS,
 113                                           nsCollapsingMargin* aMargin, nsIFrame* aClearanceFrame,
 114                                           PRBool* aMayNeedRetry, PRBool* aIsEmpty = nsnull);
 115
 116 protected:
 117   nsPresContext* mPresContext;
 118   const nsHTMLReflowState& mOuterReflowState;
 119
 120   nsIFrame* mFrame;
 121   nsRect mSpace;
 122
 123   nscoord mX, mY;
 124   nsHTMLReflowMetrics mMetrics;
 125   nsCollapsingMargin mTopMargin;
 126 };
 127
 128 #endif /* nsBlockReflowContext_h___ */