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/*
* Copyright (C) 2020 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "BlockMarginCollapse.h"
#include "BlockFormattingContext.h"
#include "BlockFormattingGeometry.h"
#include "BlockFormattingQuirks.h"
#include "LayoutBox.h"
#include "LayoutElementBox.h"
#include "LayoutState.h"
#include "LayoutUnit.h"
#include "RenderStyleInlines.h"
namespace WebCore {
namespace Layout {
UsedVerticalMargin::PositiveAndNegativePair::Values BlockMarginCollapse::precomputedPositiveNegativeValues(const ElementBox& layoutBox, const BlockFormattingGeometry& formattingGeometry) const
{
if (formattingState().hasUsedVerticalMargin(layoutBox))
return formattingState().usedVerticalMargin(layoutBox).positiveAndNegativeValues.before;
auto horizontalConstraints = formattingGeometry.constraintsForInFlowContent(FormattingContext::containingBlock(layoutBox)).horizontal();
auto computedVerticalMargin = formattingGeometry.computedVerticalMargin(layoutBox, horizontalConstraints);
auto nonCollapsedMargin = UsedVerticalMargin::NonCollapsedValues { computedVerticalMargin.before.value_or(0), computedVerticalMargin.after.value_or(0) };
return precomputedPositiveNegativeMarginBefore(layoutBox, nonCollapsedMargin, formattingGeometry);
}
UsedVerticalMargin::PositiveAndNegativePair::Values BlockMarginCollapse::precomputedPositiveNegativeMarginBefore(const ElementBox& layoutBox, UsedVerticalMargin::NonCollapsedValues nonCollapsedValues, const BlockFormattingGeometry& formattingGeometry) const
{
auto firstChildCollapsedMarginBefore = [&]() -> UsedVerticalMargin::PositiveAndNegativePair::Values {
if (!marginBeforeCollapsesWithFirstInFlowChildMarginBefore(layoutBox))
return { };
return precomputedPositiveNegativeValues(downcast<ElementBox>(*layoutBox.firstInFlowChild()), formattingGeometry);
};
auto previouSiblingCollapsedMarginAfter = [&]() -> UsedVerticalMargin::PositiveAndNegativePair::Values {
if (!marginBeforeCollapsesWithPreviousSiblingMarginAfter(layoutBox))
return { };
auto& previousInFlowSibling = *layoutBox.previousInFlowSibling();
return formattingState().usedVerticalMargin(previousInFlowSibling).positiveAndNegativeValues.after;
};
// 1. Gather positive and negative margin values from first child if margins are adjoining.
// 2. Gather positive and negative margin values from previous inflow sibling if margins are adjoining.
// 3. Compute min/max positive and negative collapsed margin values using non-collpased computed margin before.
auto collapsedMarginBefore = computedPositiveAndNegativeMargin(firstChildCollapsedMarginBefore(), previouSiblingCollapsedMarginAfter());
auto shouldIgnoreCollapsedMargin = collapsedMarginBefore.isQuirk && inQuirksMode() && BlockFormattingQuirks::shouldIgnoreCollapsedQuirkMargin(layoutBox);
if (shouldIgnoreCollapsedMargin)
collapsedMarginBefore = { };
auto nonCollapsedBefore = UsedVerticalMargin::PositiveAndNegativePair::Values { };
if (nonCollapsedValues.before > 0)
nonCollapsedBefore = { nonCollapsedValues.before, { }, layoutBox.style().marginBefore().hasQuirk() };
else if (nonCollapsedValues.before < 0)
nonCollapsedBefore = { { }, nonCollapsedValues.before, layoutBox.style().marginBefore().hasQuirk() };
return computedPositiveAndNegativeMargin(collapsedMarginBefore, nonCollapsedBefore);
}
PrecomputedMarginBefore BlockMarginCollapse::precomputedMarginBefore(const ElementBox& layoutBox, UsedVerticalMargin::NonCollapsedValues usedNonCollapsedMargin, const BlockFormattingGeometry& formattingGeometry)
{
ASSERT(layoutBox.isBlockLevelBox());
// Don't pre-compute vertical margins for out of flow boxes.
ASSERT(layoutBox.isInFlow() || layoutBox.isFloatingPositioned());
ASSERT(!layoutBox.isReplacedBox());
auto positiveNegativeMarginBefore = precomputedPositiveNegativeMarginBefore(layoutBox, usedNonCollapsedMargin, formattingGeometry);
auto collapsedMarginBefore = marginValue(positiveNegativeMarginBefore);
return { usedNonCollapsedMargin.before, collapsedMarginBefore, positiveNegativeMarginBefore };
}
}
}
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