nsBlockReflowContext.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* class that a parent frame uses to reflow a block frame */

#ifndef nsBlockReflowContext_h___

#define nsBlockReflowContext_h___

#include "mozilla/ReflowOutput.h"

class nsIFrame;

class nsLineBox;

class nsPresContext;

class nsReflowStatus;

namespace mozilla {

class BlockReflowState;

}  // namespace mozilla

/**

 * An encapsulation of the state and algorithm for reflowing block frames.

*/

class nsBlockReflowContext {

  using BlockReflowState = mozilla::BlockReflowState;

  using ReflowInput = mozilla::ReflowInput;

  using ReflowOutput = mozilla::ReflowOutput;

 public:

  nsBlockReflowContext(nsPresContext* aPresContext,

                       const ReflowInput& aParentRI);

  ~nsBlockReflowContext() = default;

  void ReflowBlock(const mozilla::LogicalRect& aSpace, bool aApplyBStartMargin,

                   mozilla::CollapsingMargin& aPrevMargin, nscoord aClearance,

                   nsLineBox* aLine, ReflowInput& aReflowInput,

                   nsReflowStatus& aReflowStatus, BlockReflowState& aState);

  bool PlaceBlock(const ReflowInput& aReflowInput, bool aForceFit,

                  nsLineBox* aLine,

                  mozilla::CollapsingMargin& aBEndMarginResult /* out */,

                  mozilla::OverflowAreas& aOverflowAreas,

                  const nsReflowStatus& aReflowStatus);

  mozilla::CollapsingMargin& GetCarriedOutBEndMargin() {

    return mMetrics.mCarriedOutBEndMargin;

  const ReflowOutput& GetMetrics() const { return mMetrics; }

/**

   * Computes the collapsed block-start margin (in the context's parent's

   * writing mode) for a block whose reflow input is in aRI.

   * The computed margin is added into aMargin, whose writing mode is the

   * parent's mode as found in mMetrics.GetWritingMode(); note this may not be

   * the block's own writing mode as found in aRI.

   * If aClearanceFrame is null then this is the first optimistic pass which

   * shall assume that no frames have clearance, and we clear the HasClearance

   * on all frames encountered.

   * If non-null, this is the second pass and the caller has decided

   * aClearanceFrame needs clearance (and we will therefore stop collapsing

   * there); also, this function is responsible for marking it with

   * SetHasClearance.

   * If in the optimistic pass any frame is encountered that might possibly

   * need clearance (i.e., if we really needed the optimism assumption) then

   * we set aMayNeedRetry to true.

   * We return true if we changed the clearance state of any line and marked it

   * dirty.

*/

  bool ComputeCollapsedBStartMargin(const ReflowInput& aRI,

                                    mozilla::CollapsingMargin* aMargin,

                                    nsIFrame* aClearanceFrame,

                                    bool* aMayNeedRetry,

                                    bool* aIsEmpty = nullptr);

 protected:

  nsPresContext* mPresContext;

  const ReflowInput& mOuterReflowInput;

  nsIFrame* mFrame;

  mozilla::LogicalRect mSpace;

  nscoord mICoord, mBCoord;

  nsSize mContainerSize;

  mozilla::WritingMode mWritingMode;

  ReflowOutput mMetrics;

  mozilla::CollapsingMargin mBStartMargin;

};

#endif /* nsBlockReflowContext_h___ */