Source/WebCore/layout/blockformatting/BlockFormattingContextGeometry.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2018 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 "BlockFormattingContext.h"

 #if ENABLE(LAYOUT_FORMATTING_CONTEXT)

 #include "FormattingContext.h"
 #include "InlineFormattingState.h"
 #include "LayoutChildIterator.h"
 #include "Logging.h"
 #include <wtf/text/TextStream.h>

 namespace WebCore {
 namespace Layout {

 HeightAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedHeight)
 {
     ASSERT(layoutBox.isInFlow() && !layoutBox.replaced());
     ASSERT(layoutBox.isOverflowVisible());

     auto compute = [&]() -> HeightAndMargin {

         // 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
         //
         // If 'margin-top', or 'margin-bottom' are 'auto', their used value is 0.
         // If 'height' is 'auto', the height depends on whether the element has any block-level children and whether it has padding or borders:
         // The element's height is the distance from its top content edge to the first applicable of the following:
         // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
         // 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin
         //    does not collapse with the element's bottom margin
         // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
         // 4. zero, otherwise
         // Only children in the normal flow are taken into account (i.e., floating boxes and absolutely positioned boxes are ignored,
         // and relatively positioned boxes are considered without their offset). Note that the child box may be an anonymous block box.

         auto& style = layoutBox.style();
         auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).contentBoxWidth();
         auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);

         auto nonCollapsedMargin = VerticalMargin::ComputedValues { computedValueIfNotAuto(style.marginBefore(), containingBlockWidth).value_or(0),
             computedValueIfNotAuto(style.marginAfter(), containingBlockWidth).value_or(0) };
         auto collapsedMargin = VerticalMargin::CollapsedValues { MarginCollapse::marginBefore(layoutState, layoutBox), MarginCollapse::marginAfter(layoutState, layoutBox) };
         auto borderAndPaddingTop = displayBox.borderTop() + displayBox.paddingTop().value_or(0);

         auto height = usedHeight ? usedHeight.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
         if (height)
             return { height.value(), { nonCollapsedMargin, collapsedMargin } };

         if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowChild())
             return { 0, { nonCollapsedMargin, collapsedMargin } };

         // 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
         if (layoutBox.establishesInlineFormattingContext()) {
             // This is temp and will be replaced by the correct display box once inline runs move over to the display tree.
             auto& inlineRuns = downcast<InlineFormattingState>(layoutState.establishedFormattingState(layoutBox)).inlineRuns();
             auto bottomEdge = inlineRuns.isEmpty() ? LayoutUnit() : inlineRuns.last().logicalBottom();
             return { bottomEdge, { nonCollapsedMargin, collapsedMargin } };
         }

         // 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin...
         auto* lastInFlowChild = downcast<Container>(layoutBox).lastInFlowChild();
         ASSERT(lastInFlowChild);
         if (!MarginCollapse::marginAfterCollapsesWithParentMarginAfter(layoutState, *lastInFlowChild)) {
             auto& lastInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*lastInFlowChild);
             return { lastInFlowDisplayBox.bottom() + lastInFlowDisplayBox.marginAfter() - borderAndPaddingTop, { nonCollapsedMargin, collapsedMargin } };
         }

         // 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
         auto* inFlowChild = lastInFlowChild;
         while (inFlowChild && MarginCollapse::marginBeforeCollapsesWithParentMarginAfter(layoutState, *inFlowChild))
             inFlowChild = inFlowChild->previousInFlowSibling();
         if (inFlowChild) {
             auto& inFlowDisplayBox = layoutState.displayBoxForLayoutBox(*inFlowChild);
             return { inFlowDisplayBox.top() + inFlowDisplayBox.borderBox().height() - borderAndPaddingTop, { nonCollapsedMargin, collapsedMargin } };
         }

         // 4. zero, otherwise
         return { 0, { nonCollapsedMargin, collapsedMargin } };
     };

     auto heightAndMargin = compute();

     LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.margin.usedValues().before << "px, " << heightAndMargin.margin.usedValues().after << "px) -> layoutBox(" << &layoutBox << ")");
     return heightAndMargin;
 }

 WidthAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
 {
     ASSERT(layoutBox.isInFlow() && !layoutBox.replaced());

     auto compute = [&]() {

         // 10.3.3 Block-level, non-replaced elements in normal flow
         //
         // The following constraints must hold among the used values of the other properties:
         // 'margin-left' + 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' + 'margin-right' = width of containing block
         //
         // 1. If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width'
         //    (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then
         //    any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
         //
         // 2. If all of the above have a computed value other than 'auto', the values are said to be "over-constrained" and one of the used values will
         //    have to be different from its computed value. If the 'direction' property of the containing block has the value 'ltr', the specified value
         //    of 'margin-right' is ignored and the value is calculated so as to make the equality true. If the value of 'direction' is 'rtl',
         //    this happens to 'margin-left' instead.
         //
         // 3. If there is exactly one value specified as 'auto', its used value follows from the equality.
         //
         // 4. If 'width' is set to 'auto', any other 'auto' values become '0' and 'width' follows from the resulting equality.
         //
         // 5. If both 'margin-left' and 'margin-right' are 'auto', their used values are equal. This horizontally centers the element with respect to the
         //    edges of the containing block.

         auto& style = layoutBox.style();
         auto* containingBlock = layoutBox.containingBlock();
         auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*containingBlock).contentBoxWidth();
         auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);

         auto width = computedValueIfNotAuto(usedWidth ? Length { usedWidth.value(), Fixed } : style.logicalWidth(), containingBlockWidth);
         auto marginStart = computedValueIfNotAuto(style.marginStart(), containingBlockWidth);
         auto marginEnd = computedValueIfNotAuto(style.marginEnd(), containingBlockWidth);
         auto nonComputedMarginStart = marginStart.value_or(0);
         auto nonComputedMarginEnd = marginEnd.value_or(0);
         auto borderLeft = displayBox.borderLeft();
         auto borderRight = displayBox.borderRight();
         auto paddingLeft = displayBox.paddingLeft().value_or(0);
         auto paddingRight = displayBox.paddingRight().value_or(0);

         // #1
         if (width) {
             auto horizontalSpaceForMargin = containingBlockWidth - (marginStart.value_or(0) + borderLeft + paddingLeft + *width + paddingRight + borderRight + marginEnd.value_or(0));
             if (horizontalSpaceForMargin < 0) {
                 marginStart = marginStart.value_or(0);
                 marginEnd = marginEnd.value_or(0);
             }
         }

         // #2
         if (width && marginStart && marginEnd) {
             if (containingBlock->style().isLeftToRightDirection())
                 marginEnd = containingBlockWidth - (*marginStart + borderLeft + paddingLeft  + *width + paddingRight + borderRight);
             else
                 marginStart = containingBlockWidth - (borderLeft + paddingLeft + *width + paddingRight + borderRight + *marginEnd);
         }

         // #3
         if (!marginStart && width && marginEnd)
             marginStart = containingBlockWidth - (borderLeft + paddingLeft  + *width + paddingRight + borderRight + *marginEnd);
         else if (marginStart && !width && marginEnd)
             width = containingBlockWidth - (*marginStart + borderLeft + paddingLeft + paddingRight + borderRight + *marginEnd);
         else if (marginStart && width && !marginEnd)
             marginEnd = containingBlockWidth - (*marginStart + borderLeft + paddingLeft + *width + paddingRight + borderRight);

         // #4
         if (!width) {
             marginStart = marginStart.value_or(0);
             marginEnd = marginEnd.value_or(0);
             width = containingBlockWidth - (*marginStart + borderLeft + paddingLeft + paddingRight + borderRight + *marginEnd);
         }

         // #5
         if (!marginStart && !marginEnd) {
             auto horizontalSpaceForMargin = containingBlockWidth - (borderLeft + paddingLeft  + *width + paddingRight + borderRight);
             marginStart = marginEnd = horizontalSpaceForMargin / 2;
         }

         ASSERT(width);
         ASSERT(marginStart);
         ASSERT(marginEnd);

         return WidthAndMargin { *width, { *marginStart, *marginEnd }, { nonComputedMarginStart, nonComputedMarginEnd } };
     };

     auto widthAndMargin = compute();
     LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow non-replaced -> width(" << widthAndMargin.width << "px) margin(" << widthAndMargin.margin.start << "px, " << widthAndMargin.margin.end << "px) -> layoutBox(" << &layoutBox << ")");
     return widthAndMargin;
 }

 WidthAndMargin BlockFormattingContext::Geometry::inFlowReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
 {
     ASSERT(layoutBox.isInFlow() && layoutBox.replaced());

     // 10.3.4 Block-level, replaced elements in normal flow
     //
     // 1. The used value of 'width' is determined as for inline replaced elements.
     // 2. Then the rules for non-replaced block-level elements are applied to determine the margins.

     // #1
     auto width = inlineReplacedWidthAndMargin(layoutState, layoutBox, usedWidth).width;
     // #2
     auto nonReplacedWidthAndMargin = inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, width);

     LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow replaced -> width(" << width << "px) margin(" << nonReplacedWidthAndMargin.margin.start << "px, " << nonReplacedWidthAndMargin.margin.end << "px) -> layoutBox(" << &layoutBox << ")");
     return { width, nonReplacedWidthAndMargin.margin, nonReplacedWidthAndMargin.nonComputedMargin };
 }

 Point BlockFormattingContext::Geometry::staticPosition(const LayoutState& layoutState, const Box& layoutBox)
 {
     // https://www.w3.org/TR/CSS22/visuren.html#block-formatting
     // In a block formatting context, boxes are laid out one after the other, vertically, beginning at the top of a containing block.
     // The vertical distance between two sibling boxes is determined by the 'margin' properties.
     // Vertical margins between adjacent block-level boxes in a block formatting context collapse.
     // In a block formatting context, each box's left outer edge touches the left edge of the containing block (for right-to-left formatting, right edges touch).

     LayoutUnit top;
     auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock());
     if (auto* previousInFlowSibling = layoutBox.previousInFlowSibling()) {
         auto& previousInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*previousInFlowSibling);
         top = previousInFlowDisplayBox.bottom() + previousInFlowDisplayBox.marginAfter();
     } else
         top = containingBlockDisplayBox.contentBoxTop();

     auto left = containingBlockDisplayBox.contentBoxLeft();
     LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position] -> static -> top(" << top << "px) left(" << left << "px) layoutBox(" << &layoutBox << ")");
     return { left, top };
 }

 HeightAndMargin BlockFormattingContext::Geometry::inFlowHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedHeight)
 {
     ASSERT(layoutBox.isInFlow());

     // 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block'
     // replaced elements in normal flow and floating replaced elements
     if (layoutBox.replaced())
         return inlineReplacedHeightAndMargin(layoutState, layoutBox, usedHeight);

     HeightAndMargin heightAndMargin;
     // TODO: Figure out the case for the document element. Let's just complicated-case it for now.
     if (layoutBox.isOverflowVisible() && !layoutBox.isDocumentBox())
         heightAndMargin = inFlowNonReplacedHeightAndMargin(layoutState, layoutBox, usedHeight);
     else {
         // 10.6.6 Complicated cases
         // Block-level, non-replaced elements in normal flow when 'overflow' does not compute to 'visible' (except if the 'overflow' property's value has been propagated to the viewport).
         heightAndMargin = complicatedCases(layoutState, layoutBox, usedHeight);
     }

     if (!Quirks::needsStretching(layoutState, layoutBox))
         return heightAndMargin;

     heightAndMargin = Quirks::stretchedHeight(layoutState, layoutBox, heightAndMargin);

     LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> streched to viewport -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.margin.usedValues().before << "px, " << heightAndMargin.margin.usedValues().after << "px) -> layoutBox(" << &layoutBox << ")");
     return heightAndMargin;
 }

 WidthAndMargin BlockFormattingContext::Geometry::inFlowWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
 {
     ASSERT(layoutBox.isInFlow());

     if (!layoutBox.replaced())
         return inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, usedWidth);
     return inFlowReplacedWidthAndMargin(layoutState, layoutBox, usedWidth);
 }

 bool BlockFormattingContext::Geometry::instrinsicWidthConstraintsNeedChildrenWidth(const Box& layoutBox)
 {
     if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowOrFloatingChild())
         return false;
     return layoutBox.style().width().isAuto();
 }

 FormattingContext::InstrinsicWidthConstraints BlockFormattingContext::Geometry::instrinsicWidthConstraints(const LayoutState& layoutState, const Box& layoutBox)
 {
     auto& style = layoutBox.style();
     if (auto width = fixedValue(style.logicalWidth()))
         return { *width, *width };

     // Minimum/maximum width can't be depending on the containing block's width.
     if (!style.logicalWidth().isAuto())
         return { };

     if (!is<Container>(layoutBox))
         return { };

     LayoutUnit minimumIntrinsicWidth;
     LayoutUnit maximumIntrinsicWidth;

     for (auto& child : childrenOfType<Box>(downcast<Container>(layoutBox))) {
         if (child.isOutOfFlowPositioned())
             continue;
         auto& formattingState = layoutState.formattingStateForBox(child);
         ASSERT(formattingState.isBlockFormattingState());
         auto childInstrinsicWidthConstraints = formattingState.instrinsicWidthConstraints(child);
         ASSERT(childInstrinsicWidthConstraints);

         auto& style = child.style();
         auto horizontalMarginBorderAndPadding = fixedValue(style.marginStart()).value_or(0)
             + LayoutUnit { style.borderLeftWidth() }
             + fixedValue(style.paddingLeft()).value_or(0)
             + fixedValue(style.paddingRight()).value_or(0)
             + LayoutUnit { style.borderRightWidth() }
             + fixedValue(style.marginEnd()).value_or(0);

         minimumIntrinsicWidth = std::max(minimumIntrinsicWidth, childInstrinsicWidthConstraints->minimum + horizontalMarginBorderAndPadding);
         maximumIntrinsicWidth = std::max(maximumIntrinsicWidth, childInstrinsicWidthConstraints->maximum + horizontalMarginBorderAndPadding);
     }

     return { minimumIntrinsicWidth, maximumIntrinsicWidth };
 }

 LayoutUnit BlockFormattingContext::Geometry::estimatedMarginBefore(const LayoutState& layoutState, const Box& layoutBox)
 {
     ASSERT(layoutBox.isBlockLevelBox());
     // Can't estimate vertical margins for out of flow boxes (and we shouldn't need to do it for float boxes).
     ASSERT(layoutBox.isInFlow());
     // Can't cross block formatting context boundary.
     ASSERT(!layoutBox.establishesBlockFormattingContext());

     // Let's just use the normal path for now.
     return MarginCollapse::marginBefore(layoutState, layoutBox);
 }

 LayoutUnit BlockFormattingContext::Geometry::estimatedMarginAfter(const LayoutState& layoutState, const Box& layoutBox)
 {
     ASSERT(layoutBox.isBlockLevelBox());
     // Can't estimate vertical margins for out of flow boxes (and we shouldn't need to do it for float boxes).
     ASSERT(layoutBox.isInFlow());
     // Can't cross block formatting context boundary.
     ASSERT(!layoutBox.establishesBlockFormattingContext());

     // Let's just use the normal path for now.
     return MarginCollapse::marginAfter(layoutState, layoutBox);
 }

 }
 }

 #endif
	/*
	* Copyright (C) 2018 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 "BlockFormattingContext.h"

	#if ENABLE(LAYOUT_FORMATTING_CONTEXT)

	#include "FormattingContext.h"
	#include "InlineFormattingState.h"
	#include "LayoutChildIterator.h"
	#include "Logging.h"
	#include <wtf/text/TextStream.h>

	namespace WebCore {
	namespace Layout {

	HeightAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedHeight)
	{
	ASSERT(layoutBox.isInFlow() && !layoutBox.replaced());
	ASSERT(layoutBox.isOverflowVisible());

	auto compute = [&]() -> HeightAndMargin {

	// 10.6.3 Block-level non-replaced elements in normal flow when 'overflow' computes to 'visible'
	//
	// If 'margin-top', or 'margin-bottom' are 'auto', their used value is 0.
	// If 'height' is 'auto', the height depends on whether the element has any block-level children and whether it has padding or borders:
	// The element's height is the distance from its top content edge to the first applicable of the following:
	// 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
	// 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin
	// does not collapse with the element's bottom margin
	// 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
	// 4. zero, otherwise
	// Only children in the normal flow are taken into account (i.e., floating boxes and absolutely positioned boxes are ignored,
	// and relatively positioned boxes are considered without their offset). Note that the child box may be an anonymous block box.

	auto& style = layoutBox.style();
	auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock()).contentBoxWidth();
	auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);

	auto nonCollapsedMargin = VerticalMargin::ComputedValues { computedValueIfNotAuto(style.marginBefore(), containingBlockWidth).value_or(0),
	computedValueIfNotAuto(style.marginAfter(), containingBlockWidth).value_or(0) };
	auto collapsedMargin = VerticalMargin::CollapsedValues { MarginCollapse::marginBefore(layoutState, layoutBox), MarginCollapse::marginAfter(layoutState, layoutBox) };
	auto borderAndPaddingTop = displayBox.borderTop() + displayBox.paddingTop().value_or(0);

	auto height = usedHeight ? usedHeight.value() : computedHeightValue(layoutState, layoutBox, HeightType::Normal);
	if (height)
	return { height.value(), { nonCollapsedMargin, collapsedMargin } };

	if (!is<Container>(layoutBox) \|\| !downcast<Container>(layoutBox).hasInFlowChild())
	return { 0, { nonCollapsedMargin, collapsedMargin } };

	// 1. the bottom edge of the last line box, if the box establishes a inline formatting context with one or more lines
	if (layoutBox.establishesInlineFormattingContext()) {
	// This is temp and will be replaced by the correct display box once inline runs move over to the display tree.
	auto& inlineRuns = downcast<InlineFormattingState>(layoutState.establishedFormattingState(layoutBox)).inlineRuns();
	auto bottomEdge = inlineRuns.isEmpty() ? LayoutUnit() : inlineRuns.last().logicalBottom();
	return { bottomEdge, { nonCollapsedMargin, collapsedMargin } };
	}

	// 2. the bottom edge of the bottom (possibly collapsed) margin of its last in-flow child, if the child's bottom margin...
	auto* lastInFlowChild = downcast<Container>(layoutBox).lastInFlowChild();
	ASSERT(lastInFlowChild);
	if (!MarginCollapse::marginAfterCollapsesWithParentMarginAfter(layoutState, *lastInFlowChild)) {
	auto& lastInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*lastInFlowChild);
	return { lastInFlowDisplayBox.bottom() + lastInFlowDisplayBox.marginAfter() - borderAndPaddingTop, { nonCollapsedMargin, collapsedMargin } };
	}

	// 3. the bottom border edge of the last in-flow child whose top margin doesn't collapse with the element's bottom margin
	auto* inFlowChild = lastInFlowChild;
	while (inFlowChild && MarginCollapse::marginBeforeCollapsesWithParentMarginAfter(layoutState, *inFlowChild))
	inFlowChild = inFlowChild->previousInFlowSibling();
	if (inFlowChild) {
	auto& inFlowDisplayBox = layoutState.displayBoxForLayoutBox(*inFlowChild);
	return { inFlowDisplayBox.top() + inFlowDisplayBox.borderBox().height() - borderAndPaddingTop, { nonCollapsedMargin, collapsedMargin } };
	}

	// 4. zero, otherwise
	return { 0, { nonCollapsedMargin, collapsedMargin } };
	};

	auto heightAndMargin = compute();

	LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.margin.usedValues().before << "px, " << heightAndMargin.margin.usedValues().after << "px) -> layoutBox(" << &layoutBox << ")");
	return heightAndMargin;
	}

	WidthAndMargin BlockFormattingContext::Geometry::inFlowNonReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
	{
	ASSERT(layoutBox.isInFlow() && !layoutBox.replaced());

	auto compute = [&]() {

	// 10.3.3 Block-level, non-replaced elements in normal flow
	//
	// The following constraints must hold among the used values of the other properties:
	// 'margin-left' + 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' + 'margin-right' = width of containing block
	//
	// 1. If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width'
	// (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then
	// any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
	//
	// 2. If all of the above have a computed value other than 'auto', the values are said to be "over-constrained" and one of the used values will
	// have to be different from its computed value. If the 'direction' property of the containing block has the value 'ltr', the specified value
	// of 'margin-right' is ignored and the value is calculated so as to make the equality true. If the value of 'direction' is 'rtl',
	// this happens to 'margin-left' instead.
	//
	// 3. If there is exactly one value specified as 'auto', its used value follows from the equality.
	//
	// 4. If 'width' is set to 'auto', any other 'auto' values become '0' and 'width' follows from the resulting equality.
	//
	// 5. If both 'margin-left' and 'margin-right' are 'auto', their used values are equal. This horizontally centers the element with respect to the
	// edges of the containing block.

	auto& style = layoutBox.style();
	auto* containingBlock = layoutBox.containingBlock();
	auto containingBlockWidth = layoutState.displayBoxForLayoutBox(*containingBlock).contentBoxWidth();
	auto& displayBox = layoutState.displayBoxForLayoutBox(layoutBox);

	auto width = computedValueIfNotAuto(usedWidth ? Length { usedWidth.value(), Fixed } : style.logicalWidth(), containingBlockWidth);
	auto marginStart = computedValueIfNotAuto(style.marginStart(), containingBlockWidth);
	auto marginEnd = computedValueIfNotAuto(style.marginEnd(), containingBlockWidth);
	auto nonComputedMarginStart = marginStart.value_or(0);
	auto nonComputedMarginEnd = marginEnd.value_or(0);
	auto borderLeft = displayBox.borderLeft();
	auto borderRight = displayBox.borderRight();
	auto paddingLeft = displayBox.paddingLeft().value_or(0);
	auto paddingRight = displayBox.paddingRight().value_or(0);

	// #1
	if (width) {
	auto horizontalSpaceForMargin = containingBlockWidth - (marginStart.value_or(0) + borderLeft + paddingLeft + *width + paddingRight + borderRight + marginEnd.value_or(0));
	if (horizontalSpaceForMargin < 0) {
	marginStart = marginStart.value_or(0);
	marginEnd = marginEnd.value_or(0);
	}
	}

	// #2
	if (width && marginStart && marginEnd) {
	if (containingBlock->style().isLeftToRightDirection())
	marginEnd = containingBlockWidth - (marginStart + borderLeft + paddingLeft + width + paddingRight + borderRight);
	else
	marginStart = containingBlockWidth - (borderLeft + paddingLeft + width + paddingRight + borderRight + marginEnd);
	}

	// #3
	if (!marginStart && width && marginEnd)
	marginStart = containingBlockWidth - (borderLeft + paddingLeft + width + paddingRight + borderRight + marginEnd);
	else if (marginStart && !width && marginEnd)
	width = containingBlockWidth - (marginStart + borderLeft + paddingLeft + paddingRight + borderRight + marginEnd);
	else if (marginStart && width && !marginEnd)
	marginEnd = containingBlockWidth - (marginStart + borderLeft + paddingLeft + width + paddingRight + borderRight);

	// #4
	if (!width) {
	marginStart = marginStart.value_or(0);
	marginEnd = marginEnd.value_or(0);
	width = containingBlockWidth - (marginStart + borderLeft + paddingLeft + paddingRight + borderRight + marginEnd);
	}

	// #5
	if (!marginStart && !marginEnd) {
	auto horizontalSpaceForMargin = containingBlockWidth - (borderLeft + paddingLeft + *width + paddingRight + borderRight);
	marginStart = marginEnd = horizontalSpaceForMargin / 2;
	}

	ASSERT(width);
	ASSERT(marginStart);
	ASSERT(marginEnd);

	return WidthAndMargin { width, { marginStart, *marginEnd }, { nonComputedMarginStart, nonComputedMarginEnd } };
	};

	auto widthAndMargin = compute();
	LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow non-replaced -> width(" << widthAndMargin.width << "px) margin(" << widthAndMargin.margin.start << "px, " << widthAndMargin.margin.end << "px) -> layoutBox(" << &layoutBox << ")");
	return widthAndMargin;
	}

	WidthAndMargin BlockFormattingContext::Geometry::inFlowReplacedWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
	{
	ASSERT(layoutBox.isInFlow() && layoutBox.replaced());

	// 10.3.4 Block-level, replaced elements in normal flow
	//
	// 1. The used value of 'width' is determined as for inline replaced elements.
	// 2. Then the rules for non-replaced block-level elements are applied to determine the margins.

	// #1
	auto width = inlineReplacedWidthAndMargin(layoutState, layoutBox, usedWidth).width;
	// #2
	auto nonReplacedWidthAndMargin = inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, width);

	LOG_WITH_STREAM(FormattingContextLayout, stream << "[Width][Margin] -> inflow replaced -> width(" << width << "px) margin(" << nonReplacedWidthAndMargin.margin.start << "px, " << nonReplacedWidthAndMargin.margin.end << "px) -> layoutBox(" << &layoutBox << ")");
	return { width, nonReplacedWidthAndMargin.margin, nonReplacedWidthAndMargin.nonComputedMargin };
	}

	Point BlockFormattingContext::Geometry::staticPosition(const LayoutState& layoutState, const Box& layoutBox)
	{
	// https://www.w3.org/TR/CSS22/visuren.html#block-formatting
	// In a block formatting context, boxes are laid out one after the other, vertically, beginning at the top of a containing block.
	// The vertical distance between two sibling boxes is determined by the 'margin' properties.
	// Vertical margins between adjacent block-level boxes in a block formatting context collapse.
	// In a block formatting context, each box's left outer edge touches the left edge of the containing block (for right-to-left formatting, right edges touch).

	LayoutUnit top;
	auto& containingBlockDisplayBox = layoutState.displayBoxForLayoutBox(*layoutBox.containingBlock());
	if (auto* previousInFlowSibling = layoutBox.previousInFlowSibling()) {
	auto& previousInFlowDisplayBox = layoutState.displayBoxForLayoutBox(*previousInFlowSibling);
	top = previousInFlowDisplayBox.bottom() + previousInFlowDisplayBox.marginAfter();
	} else
	top = containingBlockDisplayBox.contentBoxTop();

	auto left = containingBlockDisplayBox.contentBoxLeft();
	LOG_WITH_STREAM(FormattingContextLayout, stream << "[Position] -> static -> top(" << top << "px) left(" << left << "px) layoutBox(" << &layoutBox << ")");
	return { left, top };
	}

	HeightAndMargin BlockFormattingContext::Geometry::inFlowHeightAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedHeight)
	{
	ASSERT(layoutBox.isInFlow());

	// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block'
	// replaced elements in normal flow and floating replaced elements
	if (layoutBox.replaced())
	return inlineReplacedHeightAndMargin(layoutState, layoutBox, usedHeight);

	HeightAndMargin heightAndMargin;
	// TODO: Figure out the case for the document element. Let's just complicated-case it for now.
	if (layoutBox.isOverflowVisible() && !layoutBox.isDocumentBox())
	heightAndMargin = inFlowNonReplacedHeightAndMargin(layoutState, layoutBox, usedHeight);
	else {
	// 10.6.6 Complicated cases
	// Block-level, non-replaced elements in normal flow when 'overflow' does not compute to 'visible' (except if the 'overflow' property's value has been propagated to the viewport).
	heightAndMargin = complicatedCases(layoutState, layoutBox, usedHeight);
	}

	if (!Quirks::needsStretching(layoutState, layoutBox))
	return heightAndMargin;

	heightAndMargin = Quirks::stretchedHeight(layoutState, layoutBox, heightAndMargin);

	LOG_WITH_STREAM(FormattingContextLayout, stream << "[Height][Margin] -> inflow non-replaced -> streched to viewport -> height(" << heightAndMargin.height << "px) margin(" << heightAndMargin.margin.usedValues().before << "px, " << heightAndMargin.margin.usedValues().after << "px) -> layoutBox(" << &layoutBox << ")");
	return heightAndMargin;
	}

	WidthAndMargin BlockFormattingContext::Geometry::inFlowWidthAndMargin(const LayoutState& layoutState, const Box& layoutBox, Optional<LayoutUnit> usedWidth)
	{
	ASSERT(layoutBox.isInFlow());

	if (!layoutBox.replaced())
	return inFlowNonReplacedWidthAndMargin(layoutState, layoutBox, usedWidth);
	return inFlowReplacedWidthAndMargin(layoutState, layoutBox, usedWidth);
	}

	bool BlockFormattingContext::Geometry::instrinsicWidthConstraintsNeedChildrenWidth(const Box& layoutBox)
	{
	if (!is<Container>(layoutBox) \|\| !downcast<Container>(layoutBox).hasInFlowOrFloatingChild())
	return false;
	return layoutBox.style().width().isAuto();
	}

	FormattingContext::InstrinsicWidthConstraints BlockFormattingContext::Geometry::instrinsicWidthConstraints(const LayoutState& layoutState, const Box& layoutBox)
	{
	auto& style = layoutBox.style();
	if (auto width = fixedValue(style.logicalWidth()))
	return { width, width };

	// Minimum/maximum width can't be depending on the containing block's width.
	if (!style.logicalWidth().isAuto())
	return { };

	if (!is<Container>(layoutBox))
	return { };

	LayoutUnit minimumIntrinsicWidth;
	LayoutUnit maximumIntrinsicWidth;

	for (auto& child : childrenOfType<Box>(downcast<Container>(layoutBox))) {
	if (child.isOutOfFlowPositioned())
	continue;
	auto& formattingState = layoutState.formattingStateForBox(child);
	ASSERT(formattingState.isBlockFormattingState());
	auto childInstrinsicWidthConstraints = formattingState.instrinsicWidthConstraints(child);
	ASSERT(childInstrinsicWidthConstraints);

	auto& style = child.style();
	auto horizontalMarginBorderAndPadding = fixedValue(style.marginStart()).value_or(0)
	+ LayoutUnit { style.borderLeftWidth() }
	+ fixedValue(style.paddingLeft()).value_or(0)
	+ fixedValue(style.paddingRight()).value_or(0)
	+ LayoutUnit { style.borderRightWidth() }
	+ fixedValue(style.marginEnd()).value_or(0);

	minimumIntrinsicWidth = std::max(minimumIntrinsicWidth, childInstrinsicWidthConstraints->minimum + horizontalMarginBorderAndPadding);
	maximumIntrinsicWidth = std::max(maximumIntrinsicWidth, childInstrinsicWidthConstraints->maximum + horizontalMarginBorderAndPadding);
	}

	return { minimumIntrinsicWidth, maximumIntrinsicWidth };
	}

	LayoutUnit BlockFormattingContext::Geometry::estimatedMarginBefore(const LayoutState& layoutState, const Box& layoutBox)
	{
	ASSERT(layoutBox.isBlockLevelBox());
	// Can't estimate vertical margins for out of flow boxes (and we shouldn't need to do it for float boxes).
	ASSERT(layoutBox.isInFlow());
	// Can't cross block formatting context boundary.
	ASSERT(!layoutBox.establishesBlockFormattingContext());

	// Let's just use the normal path for now.
	return MarginCollapse::marginBefore(layoutState, layoutBox);
	}

	LayoutUnit BlockFormattingContext::Geometry::estimatedMarginAfter(const LayoutState& layoutState, const Box& layoutBox)
	{
	ASSERT(layoutBox.isBlockLevelBox());
	// Can't estimate vertical margins for out of flow boxes (and we shouldn't need to do it for float boxes).
	ASSERT(layoutBox.isInFlow());
	// Can't cross block formatting context boundary.
	ASSERT(!layoutBox.establishesBlockFormattingContext());

	// Let's just use the normal path for now.
	return MarginCollapse::marginAfter(layoutState, layoutBox);
	}

	}
	}

	#endif