layout/generic/nsBlockReflowContext.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 // vim:cindent:ts=2:et:sw=2:
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* class that a parent frame uses to reflow a block frame */
   8
   9 #ifndef nsBlockReflowContext_h___
  10 #define nsBlockReflowContext_h___
  11
  12 #include "nsIFrame.h"
  13 #include "nsHTMLReflowMetrics.h"
  14
  15 class nsBlockReflowState;
  16 struct nsHTMLReflowState;
  17 class nsLineBox;
  18 class nsPresContext;
  19 class nsLineLayout;
  20 struct nsBlockHorizontalAlign;
  21
  22 /**
  23  * An encapsulation of the state and algorithm for reflowing block frames.
  24  */
  25 class nsBlockReflowContext {
  26 public:
  27   nsBlockReflowContext(nsPresContext* aPresContext,
  28                        const nsHTMLReflowState& aParentRS);
  29   ~nsBlockReflowContext() { }
  30
  31   void ReflowBlock(const nsRect&       aSpace,
  32                    bool                aApplyBStartMargin,
  33                    nsCollapsingMargin& aPrevMargin,
  34                    nscoord             aClearance,
  35                    bool                aIsAdjacentWithBStart,
  36                    nsLineBox*          aLine,
  37                    nsHTMLReflowState&  aReflowState,
  38                    nsReflowStatus&     aReflowStatus,
  39                    nsBlockReflowState& aState);
  40
  41   bool PlaceBlock(const nsHTMLReflowState& aReflowState,
  42                   bool                     aForceFit,
  43                   nsLineBox*               aLine,
  44                   nsCollapsingMargin&      aBEndMarginResult /* out */,
  45                   nsOverflowAreas&         aOverflowAreas,
  46                   nsReflowStatus           aReflowStatus);
  47
  48   nsCollapsingMargin& GetCarriedOutBEndMargin() {
  49     return mMetrics.mCarriedOutBEndMargin;
  50   }
  51
  52   const nsHTMLReflowMetrics& GetMetrics() const {
  53     return mMetrics;
  54   }
  55
  56   /**
  57    * Computes the collapsed block-start margin (in the context's parent's
  58    * writing mode) for a block whose reflow state is in aRS.
  59    * The computed margin is added into aMargin, whose writing mode is the
  60    * parent's mode as found in mMetrics.GetWritingMode(); note this may not be
  61    * the block's own writing mode as found in aRS.
  62    * If aClearanceFrame is null then this is the first optimistic pass which
  63    * shall assume that no frames have clearance, and we clear the HasClearance
  64    * on all frames encountered.
  65    * If non-null, this is the second pass and the caller has decided
  66    * aClearanceFrame needs clearance (and we will therefore stop collapsing
  67    * there); also, this function is responsible for marking it with
  68    * SetHasClearance.
  69    * If in the optimistic pass any frame is encountered that might possibly
  70    * need clearance (i.e., if we really needed the optimism assumption) then
  71    * we set aMayNeedRetry to true.
  72    * We return true if we changed the clearance state of any line and marked it
  73    * dirty.
  74    */
  75   bool ComputeCollapsedBStartMargin(const nsHTMLReflowState& aRS,
  76                                     nsCollapsingMargin* aMargin,
  77                                     nsIFrame* aClearanceFrame,
  78                                     bool* aMayNeedRetry,
  79                                     bool* aIsEmpty = nullptr);
  80
  81 protected:
  82   nsPresContext* mPresContext;
  83   const nsHTMLReflowState& mOuterReflowState;
  84
  85   nsIFrame* mFrame;
  86   mozilla::LogicalRect mSpace;
  87
  88   nscoord mICoord, mBCoord, mContainerWidth;
  89   mozilla::WritingMode mWritingMode;
  90   nsHTMLReflowMetrics mMetrics;
  91   nsCollapsingMargin mBStartMargin;
  92 };
  93
  94 #endif /* nsBlockReflowContext_h___ */