layout/generic/nsBlockReflowContext.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   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 "mozilla/ReflowOutput.h"
  13
  14 class nsIFrame;
  15 class nsLineBox;
  16 class nsPresContext;
  17 class nsReflowStatus;
  18 namespace mozilla {
  19 class BlockReflowState;
  20 }  // namespace mozilla
  21
  22 /**
  23  * An encapsulation of the state and algorithm for reflowing block frames.
  24  */
  25 class nsBlockReflowContext {
  26   using BlockReflowState = mozilla::BlockReflowState;
  27   using ReflowInput = mozilla::ReflowInput;
  28   using ReflowOutput = mozilla::ReflowOutput;
  29
  30  public:
  31   nsBlockReflowContext(nsPresContext* aPresContext,
  32                        const ReflowInput& aParentRI);
  33   ~nsBlockReflowContext() = default;
  34
  35   void ReflowBlock(const mozilla::LogicalRect& aSpace, bool aApplyBStartMargin,
  36                    nsCollapsingMargin& aPrevMargin, nscoord aClearance,
  37                    nsLineBox* aLine, ReflowInput& aReflowInput,
  38                    nsReflowStatus& aReflowStatus, BlockReflowState& aState);
  39
  40   bool PlaceBlock(const ReflowInput& aReflowInput, bool aForceFit,
  41                   nsLineBox* aLine,
  42                   nsCollapsingMargin& aBEndMarginResult /* out */,
  43                   mozilla::OverflowAreas& aOverflowAreas,
  44                   const nsReflowStatus& aReflowStatus);
  45
  46   nsCollapsingMargin& GetCarriedOutBEndMargin() {
  47     return mMetrics.mCarriedOutBEndMargin;
  48   }
  49
  50   const ReflowOutput& GetMetrics() const { return mMetrics; }
  51
  52   /**
  53    * Computes the collapsed block-start margin (in the context's parent's
  54    * writing mode) for a block whose reflow input is in aRI.
  55    * The computed margin is added into aMargin, whose writing mode is the
  56    * parent's mode as found in mMetrics.GetWritingMode(); note this may not be
  57    * the block's own writing mode as found in aRI.
  58    * If aClearanceFrame is null then this is the first optimistic pass which
  59    * shall assume that no frames have clearance, and we clear the HasClearance
  60    * on all frames encountered.
  61    * If non-null, this is the second pass and the caller has decided
  62    * aClearanceFrame needs clearance (and we will therefore stop collapsing
  63    * there); also, this function is responsible for marking it with
  64    * SetHasClearance.
  65    * If in the optimistic pass any frame is encountered that might possibly
  66    * need clearance (i.e., if we really needed the optimism assumption) then
  67    * we set aMayNeedRetry to true.
  68    * We return true if we changed the clearance state of any line and marked it
  69    * dirty.
  70    */
  71   bool ComputeCollapsedBStartMargin(const ReflowInput& aRI,
  72                                     nsCollapsingMargin* aMargin,
  73                                     nsIFrame* aClearanceFrame,
  74                                     bool* aMayNeedRetry,
  75                                     bool* aIsEmpty = nullptr);
  76
  77  protected:
  78   nsPresContext* mPresContext;
  79   const ReflowInput& mOuterReflowInput;
  80
  81   nsIFrame* mFrame;
  82   mozilla::LogicalRect mSpace;
  83
  84   nscoord mICoord, mBCoord;
  85   nsSize mContainerSize;
  86   mozilla::WritingMode mWritingMode;
  87   ReflowOutput mMetrics;
  88   nsCollapsingMargin mBStartMargin;
  89 };
  90
  91 #endif /* nsBlockReflowContext_h___ */