layout/generic/nsBlockReflowContext.h
author Brian Hackett <bhackett1024@gmail.com>
Wed, 14 Nov 2018 16:09:58 -1000
changeset 446931 1c7fc8389e012c987347efefca6b35f3948b742a
parent 388790 905239391e05483e8fb221378dd2092c5a0df8b7
child 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1507359 Part 2 - Bindings and internal changes to allow ReplayDebugger to control child pausing/resuming, r=mccr8.

/* -*- 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 "nsIFrame.h"
#include "mozilla/ReflowOutput.h"

class nsLineBox;
class nsPresContext;
namespace mozilla {
class BlockReflowInput;
} // namespace mozilla

/**
 * An encapsulation of the state and algorithm for reflowing block frames.
 */
class nsBlockReflowContext {
  using BlockReflowInput = mozilla::BlockReflowInput;
  using ReflowInput = mozilla::ReflowInput;
  using ReflowOutput = mozilla::ReflowOutput;

public:
  nsBlockReflowContext(nsPresContext* aPresContext,
                       const ReflowInput& aParentRI);
  ~nsBlockReflowContext() { }

  void ReflowBlock(const mozilla::LogicalRect& aSpace,
                   bool                        aApplyBStartMargin,
                   nsCollapsingMargin&         aPrevMargin,
                   nscoord                     aClearance,
                   bool                        aIsAdjacentWithBStart,
                   nsLineBox*                  aLine,
                   ReflowInput&          aReflowInput,
                   nsReflowStatus&             aReflowStatus,
                   BlockReflowInput&         aState);

  bool PlaceBlock(const ReflowInput& aReflowInput,
                  bool aForceFit,
                  nsLineBox* aLine,
                  nsCollapsingMargin& aBEndMarginResult /* out */,
                  nsOverflowAreas& aOverflowAreas,
                  const nsReflowStatus& aReflowStatus);

  nsCollapsingMargin& 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 state 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,
                                    nsCollapsingMargin* 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;
  nsCollapsingMargin mBStartMargin;
};

#endif /* nsBlockReflowContext_h___ */