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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 */
/* 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;
nsBlockReflowContext(nsPresContext* aPresContext,
const ReflowInput& aParentRI);
~nsBlockReflowContext() = default;
void ReflowBlock(const mozilla::LogicalRect& aSpace, bool aApplyBStartMargin,
nsCollapsingMargin& aPrevMargin, nscoord aClearance,
nsLineBox* aLine, ReflowInput& aReflowInput,
nsReflowStatus& aReflowStatus, BlockReflowState& aState);
bool PlaceBlock(const ReflowInput& aReflowInput, bool aForceFit,
nsLineBox* aLine,
nsCollapsingMargin& aBEndMarginResult /* out */,
mozilla::OverflowAreas& 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 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,
nsCollapsingMargin* aMargin,
nsIFrame* aClearanceFrame,
bool* aMayNeedRetry,
bool* aIsEmpty = nullptr);
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___ */