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 nsBlockFrame;
  16 class nsBlockReflowState;
  17 struct nsHTMLReflowState;
  18 class nsLineBox;
  19 class nsPresContext;
  20 class nsLineLayout;
  21 struct nsBlockHorizontalAlign;
  22
  23 /**
  24  * An encapsulation of the state and algorithm for reflowing block frames.
  25  */
  26 class nsBlockReflowContext {
  27 public:
  28   nsBlockReflowContext(nsPresContext* aPresContext,
  29                        const nsHTMLReflowState& aParentRS);
  30   ~nsBlockReflowContext() { }
  31
  32   nsresult ReflowBlock(const nsRect&       aSpace,
  33                        bool                aApplyTopMargin,
  34                        nsCollapsingMargin& aPrevMargin,
  35                        nscoord             aClearance,
  36                        bool                aIsAdjacentWithTop,
  37                        nsLineBox*          aLine,
  38                        nsHTMLReflowState&  aReflowState,
  39                        nsReflowStatus&     aReflowStatus,
  40                        nsBlockReflowState& aState);
  41
  42   bool PlaceBlock(const nsHTMLReflowState& aReflowState,
  43                     bool                     aForceFit,
  44                     nsLineBox*               aLine,
  45                     nsCollapsingMargin&      aBottomMarginResult /* out */,
  46                     nsRect&                  aInFlowBounds,
  47                     nsOverflowAreas&         aOverflowAreas,
  48                     nsReflowStatus           aReflowStatus);
  49
  50   nsCollapsingMargin& GetCarriedOutBottomMargin() {
  51     return mMetrics.mCarriedOutBottomMargin;
  52   }
  53
  54   nscoord GetTopMargin() const {
  55     return mTopMargin.get();
  56   }
  57
  58   const nsHTMLReflowMetrics& GetMetrics() const {
  59     return mMetrics;
  60   }
  61
  62   /**
  63    * Computes the collapsed top margin for a block whose reflow state is in aRS.
  64    * The computed margin is added into aMargin.
  65    * If aClearanceFrame is null then this is the first optimistic pass which shall assume
  66    * that no frames have clearance, and we clear the HasClearance on all frames encountered.
  67    * If non-null, this is the second pass and
  68    * the caller has decided aClearanceFrame needs clearance (and we will
  69    * therefore stop collapsing there); also, this function is responsible for marking
  70    * it with SetHasClearance.
  71    * If in the optimistic pass any frame is encountered that might possibly need
  72    * clearance (i.e., if we really needed the optimism assumption) then we set aMayNeedRetry
  73    * to true.
  74    * We return true if we changed the clearance state of any line and marked it dirty.
  75    */
  76   static bool ComputeCollapsedTopMargin(const nsHTMLReflowState& aRS,
  77                                           nsCollapsingMargin* aMargin, nsIFrame* aClearanceFrame,
  78                                           bool* aMayNeedRetry, bool* aIsEmpty = nullptr);
  79
  80 protected:
  81   nsPresContext* mPresContext;
  82   const nsHTMLReflowState& mOuterReflowState;
  83
  84   nsIFrame* mFrame;
  85   nsRect mSpace;
  86
  87   nscoord mX, mY;
  88   nsHTMLReflowMetrics mMetrics;
  89   nsCollapsingMargin mTopMargin;
  90 };
  91
  92 #endif /* nsBlockReflowContext_h___ */