Source/WebCore/layout/FormattingContext.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 "FormattingContext.h"

 #if ENABLE(LAYOUT_FORMATTING_CONTEXT)

 #include "DisplayBox.h"
 #include "FormattingState.h"
 #include "LayoutBox.h"
 #include "LayoutContainer.h"
 #include "LayoutContext.h"
 #include "LayoutDescendantIterator.h"
 #include "LayoutState.h"
 #include "Logging.h"
 #include <wtf/IsoMallocInlines.h>
 #include <wtf/text/TextStream.h>

 namespace WebCore {
 namespace Layout {

 WTF_MAKE_ISO_ALLOCATED_IMPL(FormattingContext);

 static UsedHorizontalValues::Constraints outOfFlowHorizontalConstraints(const Display::Box& containingBlockGeometry)
 {
     return UsedHorizontalValues::Constraints { containingBlockGeometry.paddingBoxLeft(), containingBlockGeometry.paddingBoxWidth() };
 }

 static UsedVerticalValues::Constraints outOfFlowVerticalConstraints(const Display::Box& containingBlockGeometry)
 {
     return UsedVerticalValues::Constraints { containingBlockGeometry.paddingBoxTop(), containingBlockGeometry.paddingBoxHeight() };
 }

 FormattingContext::FormattingContext(const Container& formattingContextRoot, FormattingState& formattingState)
     : m_root(makeWeakPtr(formattingContextRoot))
     , m_formattingState(formattingState)
 {
 #ifndef NDEBUG
     layoutState().registerFormattingContext(*this);
 #endif
 }

 FormattingContext::~FormattingContext()
 {
 #ifndef NDEBUG
     layoutState().deregisterFormattingContext(*this);
 #endif
 }

 LayoutState& FormattingContext::layoutState() const
 {
     return m_formattingState.layoutState();
 }

 void FormattingContext::computeOutOfFlowHorizontalGeometry(const Box& layoutBox)
 {
     auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
     auto containingBlockWidth = containingBlockGeometry.paddingBoxWidth();

     auto compute = [&](Optional<LayoutUnit> usedWidth) {
         auto usedHorizontalValues = UsedHorizontalValues { outOfFlowHorizontalConstraints(containingBlockGeometry), usedWidth, { } };
         auto usedVerticalValues = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), { } };
         return geometry().outOfFlowHorizontalGeometry(layoutBox, usedHorizontalValues, usedVerticalValues);
     };

     auto horizontalGeometry = compute({ });
     if (auto maxWidth = geometry().computedMaxWidth(layoutBox, containingBlockWidth)) {
         auto maxHorizontalGeometry = compute(maxWidth);
         if (horizontalGeometry.contentWidthAndMargin.contentWidth > maxHorizontalGeometry.contentWidthAndMargin.contentWidth)
             horizontalGeometry = maxHorizontalGeometry;
     }

     if (auto minWidth = geometry().computedMinWidth(layoutBox, containingBlockWidth)) {
         auto minHorizontalGeometry = compute(minWidth);
         if (horizontalGeometry.contentWidthAndMargin.contentWidth < minHorizontalGeometry.contentWidthAndMargin.contentWidth)
             horizontalGeometry = minHorizontalGeometry;
     }

     auto& displayBox = formattingState().displayBox(layoutBox);
     displayBox.setLeft(horizontalGeometry.left + horizontalGeometry.contentWidthAndMargin.usedMargin.start);
     displayBox.setContentBoxWidth(horizontalGeometry.contentWidthAndMargin.contentWidth);
     displayBox.setHorizontalMargin(horizontalGeometry.contentWidthAndMargin.usedMargin);
     displayBox.setHorizontalComputedMargin(horizontalGeometry.contentWidthAndMargin.computedMargin);
 }

 void FormattingContext::computeOutOfFlowVerticalGeometry(const Box& layoutBox)
 {
     auto compute = [&](auto usedHorizontalValues, auto usedVerticalValues) {
         return geometry().outOfFlowVerticalGeometry(layoutBox, usedHorizontalValues, usedVerticalValues);
     };
     auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
     auto containingBlockHeight = containingBlockGeometry.paddingBoxHeight();

     auto usedVerticalValuesForHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), { } };
     auto usedHorizontalValues = UsedHorizontalValues { outOfFlowHorizontalConstraints(containingBlockGeometry) };

     auto verticalGeometry = compute(usedHorizontalValues, usedVerticalValuesForHeight);
     if (auto maxHeight = geometry().computedMaxHeight(layoutBox, containingBlockHeight)) {
         auto usedValuesForMaxHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), maxHeight };
         auto maxVerticalGeometry = compute(usedHorizontalValues, usedValuesForMaxHeight);
         if (verticalGeometry.contentHeightAndMargin.contentHeight > maxVerticalGeometry.contentHeightAndMargin.contentHeight)
             verticalGeometry = maxVerticalGeometry;
     }

     if (auto minHeight = geometry().computedMinHeight(layoutBox, containingBlockHeight)) {
         auto usedValuesForMinHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), minHeight };
         auto minVerticalGeometry = compute(usedHorizontalValues, usedValuesForMinHeight);
         if (verticalGeometry.contentHeightAndMargin.contentHeight < minVerticalGeometry.contentHeightAndMargin.contentHeight)
             verticalGeometry = minVerticalGeometry;
     }

     auto& displayBox = formattingState().displayBox(layoutBox);
     auto nonCollapsedVerticalMargin = verticalGeometry.contentHeightAndMargin.nonCollapsedMargin;
     displayBox.setTop(verticalGeometry.top + nonCollapsedVerticalMargin.before);
     displayBox.setContentBoxHeight(verticalGeometry.contentHeightAndMargin.contentHeight);
     // Margins of absolutely positioned boxes do not collapse
     displayBox.setVerticalMargin({ nonCollapsedVerticalMargin, { } });
 }

 void FormattingContext::computeBorderAndPadding(const Box& layoutBox, Optional<UsedHorizontalValues> usedHorizontalValues)
 {
     if (!usedHorizontalValues)
         usedHorizontalValues = UsedHorizontalValues { UsedHorizontalValues::Constraints { geometryForBox(*layoutBox.containingBlock()) } };
     auto& displayBox = formattingState().displayBox(layoutBox);
     displayBox.setBorder(geometry().computedBorder(layoutBox));
     displayBox.setPadding(geometry().computedPadding(layoutBox, *usedHorizontalValues));
 }

 void FormattingContext::layoutOutOfFlowContent()
 {
     LOG_WITH_STREAM(FormattingContextLayout, stream << "Start: layout out-of-flow content -> context: " << &layoutState() << " root: " << &root());

     for (auto& outOfFlowBox : formattingState().outOfFlowBoxes()) {
         ASSERT(outOfFlowBox->establishesFormattingContext());

         computeBorderAndPadding(*outOfFlowBox);
         computeOutOfFlowHorizontalGeometry(*outOfFlowBox);
         if (is<Container>(*outOfFlowBox)) {
             auto& outOfFlowRootContainer = downcast<Container>(*outOfFlowBox);
             auto formattingContext = LayoutContext::createFormattingContext(outOfFlowRootContainer, layoutState());
             formattingContext->layoutInFlowContent();
             computeOutOfFlowVerticalGeometry(outOfFlowRootContainer);
             formattingContext->layoutOutOfFlowContent();
         } else
             computeOutOfFlowVerticalGeometry(*outOfFlowBox);
     }
     LOG_WITH_STREAM(FormattingContextLayout, stream << "End: layout out-of-flow content -> context: " << &layoutState() << " root: " << &root());
 }

 static LayoutUnit mapHorizontalPositionToAncestor(const FormattingContext& formattingContext, LayoutUnit horizontalPosition, const Container& containingBlock, const Container& ancestor)
 {
     // "horizontalPosition" is in the coordinate system of the "containingBlock". -> map from containingBlock to ancestor.
     if (&containingBlock == &ancestor)
         return horizontalPosition;
     ASSERT(containingBlock.isContainingBlockDescendantOf(ancestor));
     for (auto* container = &containingBlock; container && container != &ancestor; container = container->containingBlock())
         horizontalPosition += formattingContext.geometryForBox(*container).left();
     return horizontalPosition;
 }

 // FIXME: turn these into templates.
 LayoutUnit FormattingContext::mapTopToFormattingContextRoot(const Box& layoutBox) const
 {
     ASSERT(layoutBox.containingBlock());
     auto& formattingContextRoot = root();
     ASSERT(layoutBox.isContainingBlockDescendantOf(formattingContextRoot));
     auto top = geometryForBox(layoutBox).top();
     for (auto* container = layoutBox.containingBlock(); container && container != &formattingContextRoot; container = container->containingBlock())
         top += geometryForBox(*container).top();
     return top;
 }

 LayoutUnit FormattingContext::mapLeftToFormattingContextRoot(const Box& layoutBox) const
 {
     ASSERT(layoutBox.containingBlock());
     return mapHorizontalPositionToAncestor(*this, geometryForBox(layoutBox).left(), *layoutBox.containingBlock(), root());
 }

 LayoutUnit FormattingContext::mapRightToFormattingContextRoot(const Box& layoutBox) const
 {
     ASSERT(layoutBox.containingBlock());
     return mapHorizontalPositionToAncestor(*this, geometryForBox(layoutBox).right(), *layoutBox.containingBlock(), root());
 }

 const Display::Box& FormattingContext::geometryForBox(const Box& layoutBox, Optional<EscapeType> escapeType) const
 {
     UNUSED_PARAM(escapeType);
 #ifndef NDEBUG
     auto isOkToAccessDisplayBox = [&] {
         // 1. Highly common case of accessing the formatting root's display box itself. This is formatting context escaping in the strict sense, since
         // the formatting context root box lives in the parent formatting context.
         // This happens e.g. when a block level box box needs to stretch horizontally and checks its containing block for horizontal space (this should probably be limited to reading horizontal constraint values).
         if (&layoutBox == &root())
             return true;

         // 2. Special case when accessing the ICB's display box
         if (layoutBox.isInitialContainingBlock()) {
             // There has to be a valid reason to access the ICB.
             if (!escapeType)
                 return false;
             return *escapeType == EscapeType::AccessParentFormattingContext || *escapeType == EscapeType::AccessAncestorFormattingContext;
         }

         // 3. Most common case of accessing box/containing block display box within the same formatting context tree.
         if (&layoutBox.formattingContextRoot() == &root())
             return true;

         if (!escapeType)
             return false;

         // 4. Accessing child formatting context subtree is relatively rare. It happens when e.g a shrink to fit (out-of-flow block level) box checks the content width.
         // Checking the content width means to get display boxes from the established formatting context (we try to access display boxes in a child formatting context)
         if (*escapeType == EscapeType::AccessChildFormattingContext && &layoutBox.formattingContextRoot().formattingContextRoot() == &root())
             return true;

         // 5. Float box top/left values are mapped relative to the FloatState's root. Inline formatting contexts(A) inherit floats from parent
         // block formatting contexts(B). Floats in these inline formatting contexts(A) need to be mapped to the parent, block formatting context(B).
         if (*escapeType == EscapeType::AccessParentFormattingContext && &layoutBox.formattingContextRoot() == &root().formattingContextRoot())
             return true;

         // 6. Finding the first containing block with fixed height quirk. See Quirks::heightValueOfNearestContainingBlockWithFixedHeight
         if (*escapeType == EscapeType::AccessAncestorFormattingContext) {
             auto& targetFormattingRoot = layoutBox.formattingContextRoot();
             auto* ancestorFormattingContextRoot = &root().formattingContextRoot();
             while (true) {
                 if (&targetFormattingRoot == ancestorFormattingContextRoot)
                     return true;
                 if (ancestorFormattingContextRoot->isInitialContainingBlock())
                     return false;
                 ancestorFormattingContextRoot = &ancestorFormattingContextRoot->formattingContextRoot();
             }

         }
         return false;
     };
 #endif
     ASSERT(isOkToAccessDisplayBox());
     ASSERT(layoutState().hasDisplayBox(layoutBox));
     return layoutState().displayBoxForLayoutBox(layoutBox);
 }

 #ifndef NDEBUG
 void FormattingContext::validateGeometryConstraintsAfterLayout() const
 {
     auto& formattingContextRoot = root();
     // FIXME: add a descendantsOfType<> flavor that stops at nested formatting contexts
     for (auto& layoutBox : descendantsOfType<Box>(formattingContextRoot)) {
         if (&layoutBox.formattingContextRoot() != &formattingContextRoot)
             continue;
         auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
         auto& boxGeometry = geometryForBox(layoutBox);

         // 10.3.3 Block-level, non-replaced elements in normal flow
         // 10.3.7 Absolutely positioned, non-replaced elements
         if ((layoutBox.isBlockLevelBox() || layoutBox.isOutOfFlowPositioned()) && !layoutBox.replaced()) {
             // margin-left + border-left-width + padding-left + width + padding-right + border-right-width + margin-right = width of containing block
             auto containingBlockWidth = containingBlockGeometry.contentBoxWidth();
             ASSERT(boxGeometry.horizontalMarginBorderAndPadding() + boxGeometry.contentBoxWidth() == containingBlockWidth);
         }

         // 10.6.4 Absolutely positioned, non-replaced elements
         if (layoutBox.isOutOfFlowPositioned() && !layoutBox.replaced()) {
             // top + margin-top + border-top-width + padding-top + height + padding-bottom + border-bottom-width + margin-bottom + bottom = height of containing block
             auto containingBlockHeight = containingBlockGeometry.contentBoxHeight();
             ASSERT(boxGeometry.top() + boxGeometry.marginBefore() + boxGeometry.borderTop() + boxGeometry.paddingTop().valueOr(0) + boxGeometry.contentBoxHeight()
                 + boxGeometry.paddingBottom().valueOr(0) + boxGeometry.borderBottom() + boxGeometry.marginAfter() == containingBlockHeight);
         }
     }
 }
 #endif

 }
 }
 #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 "FormattingContext.h"

	#if ENABLE(LAYOUT_FORMATTING_CONTEXT)

	#include "DisplayBox.h"
	#include "FormattingState.h"
	#include "LayoutBox.h"
	#include "LayoutContainer.h"
	#include "LayoutContext.h"
	#include "LayoutDescendantIterator.h"
	#include "LayoutState.h"
	#include "Logging.h"
	#include <wtf/IsoMallocInlines.h>
	#include <wtf/text/TextStream.h>

	namespace WebCore {
	namespace Layout {

	WTF_MAKE_ISO_ALLOCATED_IMPL(FormattingContext);

	static UsedHorizontalValues::Constraints outOfFlowHorizontalConstraints(const Display::Box& containingBlockGeometry)
	{
	return UsedHorizontalValues::Constraints { containingBlockGeometry.paddingBoxLeft(), containingBlockGeometry.paddingBoxWidth() };
	}

	static UsedVerticalValues::Constraints outOfFlowVerticalConstraints(const Display::Box& containingBlockGeometry)
	{
	return UsedVerticalValues::Constraints { containingBlockGeometry.paddingBoxTop(), containingBlockGeometry.paddingBoxHeight() };
	}

	FormattingContext::FormattingContext(const Container& formattingContextRoot, FormattingState& formattingState)
	: m_root(makeWeakPtr(formattingContextRoot))
	, m_formattingState(formattingState)
	{
	#ifndef NDEBUG
	layoutState().registerFormattingContext(*this);
	#endif
	}

	FormattingContext::~FormattingContext()
	{
	#ifndef NDEBUG
	layoutState().deregisterFormattingContext(*this);
	#endif
	}

	LayoutState& FormattingContext::layoutState() const
	{
	return m_formattingState.layoutState();
	}

	void FormattingContext::computeOutOfFlowHorizontalGeometry(const Box& layoutBox)
	{
	auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
	auto containingBlockWidth = containingBlockGeometry.paddingBoxWidth();

	auto compute = [&](Optional<LayoutUnit> usedWidth) {
	auto usedHorizontalValues = UsedHorizontalValues { outOfFlowHorizontalConstraints(containingBlockGeometry), usedWidth, { } };
	auto usedVerticalValues = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), { } };
	return geometry().outOfFlowHorizontalGeometry(layoutBox, usedHorizontalValues, usedVerticalValues);
	};

	auto horizontalGeometry = compute({ });
	if (auto maxWidth = geometry().computedMaxWidth(layoutBox, containingBlockWidth)) {
	auto maxHorizontalGeometry = compute(maxWidth);
	if (horizontalGeometry.contentWidthAndMargin.contentWidth > maxHorizontalGeometry.contentWidthAndMargin.contentWidth)
	horizontalGeometry = maxHorizontalGeometry;
	}

	if (auto minWidth = geometry().computedMinWidth(layoutBox, containingBlockWidth)) {
	auto minHorizontalGeometry = compute(minWidth);
	if (horizontalGeometry.contentWidthAndMargin.contentWidth < minHorizontalGeometry.contentWidthAndMargin.contentWidth)
	horizontalGeometry = minHorizontalGeometry;
	}

	auto& displayBox = formattingState().displayBox(layoutBox);
	displayBox.setLeft(horizontalGeometry.left + horizontalGeometry.contentWidthAndMargin.usedMargin.start);
	displayBox.setContentBoxWidth(horizontalGeometry.contentWidthAndMargin.contentWidth);
	displayBox.setHorizontalMargin(horizontalGeometry.contentWidthAndMargin.usedMargin);
	displayBox.setHorizontalComputedMargin(horizontalGeometry.contentWidthAndMargin.computedMargin);
	}

	void FormattingContext::computeOutOfFlowVerticalGeometry(const Box& layoutBox)
	{
	auto compute = [&](auto usedHorizontalValues, auto usedVerticalValues) {
	return geometry().outOfFlowVerticalGeometry(layoutBox, usedHorizontalValues, usedVerticalValues);
	};
	auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
	auto containingBlockHeight = containingBlockGeometry.paddingBoxHeight();

	auto usedVerticalValuesForHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), { } };
	auto usedHorizontalValues = UsedHorizontalValues { outOfFlowHorizontalConstraints(containingBlockGeometry) };

	auto verticalGeometry = compute(usedHorizontalValues, usedVerticalValuesForHeight);
	if (auto maxHeight = geometry().computedMaxHeight(layoutBox, containingBlockHeight)) {
	auto usedValuesForMaxHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), maxHeight };
	auto maxVerticalGeometry = compute(usedHorizontalValues, usedValuesForMaxHeight);
	if (verticalGeometry.contentHeightAndMargin.contentHeight > maxVerticalGeometry.contentHeightAndMargin.contentHeight)
	verticalGeometry = maxVerticalGeometry;
	}

	if (auto minHeight = geometry().computedMinHeight(layoutBox, containingBlockHeight)) {
	auto usedValuesForMinHeight = UsedVerticalValues { outOfFlowVerticalConstraints(containingBlockGeometry), minHeight };
	auto minVerticalGeometry = compute(usedHorizontalValues, usedValuesForMinHeight);
	if (verticalGeometry.contentHeightAndMargin.contentHeight < minVerticalGeometry.contentHeightAndMargin.contentHeight)
	verticalGeometry = minVerticalGeometry;
	}

	auto& displayBox = formattingState().displayBox(layoutBox);
	auto nonCollapsedVerticalMargin = verticalGeometry.contentHeightAndMargin.nonCollapsedMargin;
	displayBox.setTop(verticalGeometry.top + nonCollapsedVerticalMargin.before);
	displayBox.setContentBoxHeight(verticalGeometry.contentHeightAndMargin.contentHeight);
	// Margins of absolutely positioned boxes do not collapse
	displayBox.setVerticalMargin({ nonCollapsedVerticalMargin, { } });
	}

	void FormattingContext::computeBorderAndPadding(const Box& layoutBox, Optional<UsedHorizontalValues> usedHorizontalValues)
	{
	if (!usedHorizontalValues)
	usedHorizontalValues = UsedHorizontalValues { UsedHorizontalValues::Constraints { geometryForBox(*layoutBox.containingBlock()) } };
	auto& displayBox = formattingState().displayBox(layoutBox);
	displayBox.setBorder(geometry().computedBorder(layoutBox));
	displayBox.setPadding(geometry().computedPadding(layoutBox, *usedHorizontalValues));
	}

	void FormattingContext::layoutOutOfFlowContent()
	{
	LOG_WITH_STREAM(FormattingContextLayout, stream << "Start: layout out-of-flow content -> context: " << &layoutState() << " root: " << &root());

	for (auto& outOfFlowBox : formattingState().outOfFlowBoxes()) {
	ASSERT(outOfFlowBox->establishesFormattingContext());

	computeBorderAndPadding(*outOfFlowBox);
	computeOutOfFlowHorizontalGeometry(*outOfFlowBox);
	if (is<Container>(*outOfFlowBox)) {
	auto& outOfFlowRootContainer = downcast<Container>(*outOfFlowBox);
	auto formattingContext = LayoutContext::createFormattingContext(outOfFlowRootContainer, layoutState());
	formattingContext->layoutInFlowContent();
	computeOutOfFlowVerticalGeometry(outOfFlowRootContainer);
	formattingContext->layoutOutOfFlowContent();
	} else
	computeOutOfFlowVerticalGeometry(*outOfFlowBox);
	}
	LOG_WITH_STREAM(FormattingContextLayout, stream << "End: layout out-of-flow content -> context: " << &layoutState() << " root: " << &root());
	}

	static LayoutUnit mapHorizontalPositionToAncestor(const FormattingContext& formattingContext, LayoutUnit horizontalPosition, const Container& containingBlock, const Container& ancestor)
	{
	// "horizontalPosition" is in the coordinate system of the "containingBlock". -> map from containingBlock to ancestor.
	if (&containingBlock == &ancestor)
	return horizontalPosition;
	ASSERT(containingBlock.isContainingBlockDescendantOf(ancestor));
	for (auto* container = &containingBlock; container && container != &ancestor; container = container->containingBlock())
	horizontalPosition += formattingContext.geometryForBox(*container).left();
	return horizontalPosition;
	}

	// FIXME: turn these into templates.
	LayoutUnit FormattingContext::mapTopToFormattingContextRoot(const Box& layoutBox) const
	{
	ASSERT(layoutBox.containingBlock());
	auto& formattingContextRoot = root();
	ASSERT(layoutBox.isContainingBlockDescendantOf(formattingContextRoot));
	auto top = geometryForBox(layoutBox).top();
	for (auto* container = layoutBox.containingBlock(); container && container != &formattingContextRoot; container = container->containingBlock())
	top += geometryForBox(*container).top();
	return top;
	}

	LayoutUnit FormattingContext::mapLeftToFormattingContextRoot(const Box& layoutBox) const
	{
	ASSERT(layoutBox.containingBlock());
	return mapHorizontalPositionToAncestor(this, geometryForBox(layoutBox).left(), layoutBox.containingBlock(), root());
	}

	LayoutUnit FormattingContext::mapRightToFormattingContextRoot(const Box& layoutBox) const
	{
	ASSERT(layoutBox.containingBlock());
	return mapHorizontalPositionToAncestor(this, geometryForBox(layoutBox).right(), layoutBox.containingBlock(), root());
	}

	const Display::Box& FormattingContext::geometryForBox(const Box& layoutBox, Optional<EscapeType> escapeType) const
	{
	UNUSED_PARAM(escapeType);
	#ifndef NDEBUG
	auto isOkToAccessDisplayBox = [&] {
	// 1. Highly common case of accessing the formatting root's display box itself. This is formatting context escaping in the strict sense, since
	// the formatting context root box lives in the parent formatting context.
	// This happens e.g. when a block level box box needs to stretch horizontally and checks its containing block for horizontal space (this should probably be limited to reading horizontal constraint values).
	if (&layoutBox == &root())
	return true;

	// 2. Special case when accessing the ICB's display box
	if (layoutBox.isInitialContainingBlock()) {
	// There has to be a valid reason to access the ICB.
	if (!escapeType)
	return false;
	return escapeType == EscapeType::AccessParentFormattingContext \|\| escapeType == EscapeType::AccessAncestorFormattingContext;
	}

	// 3. Most common case of accessing box/containing block display box within the same formatting context tree.
	if (&layoutBox.formattingContextRoot() == &root())
	return true;

	if (!escapeType)
	return false;

	// 4. Accessing child formatting context subtree is relatively rare. It happens when e.g a shrink to fit (out-of-flow block level) box checks the content width.
	// Checking the content width means to get display boxes from the established formatting context (we try to access display boxes in a child formatting context)
	if (*escapeType == EscapeType::AccessChildFormattingContext && &layoutBox.formattingContextRoot().formattingContextRoot() == &root())
	return true;

	// 5. Float box top/left values are mapped relative to the FloatState's root. Inline formatting contexts(A) inherit floats from parent
	// block formatting contexts(B). Floats in these inline formatting contexts(A) need to be mapped to the parent, block formatting context(B).
	if (*escapeType == EscapeType::AccessParentFormattingContext && &layoutBox.formattingContextRoot() == &root().formattingContextRoot())
	return true;

	// 6. Finding the first containing block with fixed height quirk. See Quirks::heightValueOfNearestContainingBlockWithFixedHeight
	if (*escapeType == EscapeType::AccessAncestorFormattingContext) {
	auto& targetFormattingRoot = layoutBox.formattingContextRoot();
	auto* ancestorFormattingContextRoot = &root().formattingContextRoot();
	while (true) {
	if (&targetFormattingRoot == ancestorFormattingContextRoot)
	return true;
	if (ancestorFormattingContextRoot->isInitialContainingBlock())
	return false;
	ancestorFormattingContextRoot = &ancestorFormattingContextRoot->formattingContextRoot();
	}

	}
	return false;
	};
	#endif
	ASSERT(isOkToAccessDisplayBox());
	ASSERT(layoutState().hasDisplayBox(layoutBox));
	return layoutState().displayBoxForLayoutBox(layoutBox);
	}

	#ifndef NDEBUG
	void FormattingContext::validateGeometryConstraintsAfterLayout() const
	{
	auto& formattingContextRoot = root();
	// FIXME: add a descendantsOfType<> flavor that stops at nested formatting contexts
	for (auto& layoutBox : descendantsOfType<Box>(formattingContextRoot)) {
	if (&layoutBox.formattingContextRoot() != &formattingContextRoot)
	continue;
	auto& containingBlockGeometry = geometryForBox(*layoutBox.containingBlock());
	auto& boxGeometry = geometryForBox(layoutBox);

	// 10.3.3 Block-level, non-replaced elements in normal flow
	// 10.3.7 Absolutely positioned, non-replaced elements
	if ((layoutBox.isBlockLevelBox() \|\| layoutBox.isOutOfFlowPositioned()) && !layoutBox.replaced()) {
	// margin-left + border-left-width + padding-left + width + padding-right + border-right-width + margin-right = width of containing block
	auto containingBlockWidth = containingBlockGeometry.contentBoxWidth();
	ASSERT(boxGeometry.horizontalMarginBorderAndPadding() + boxGeometry.contentBoxWidth() == containingBlockWidth);
	}

	// 10.6.4 Absolutely positioned, non-replaced elements
	if (layoutBox.isOutOfFlowPositioned() && !layoutBox.replaced()) {
	// top + margin-top + border-top-width + padding-top + height + padding-bottom + border-bottom-width + margin-bottom + bottom = height of containing block
	auto containingBlockHeight = containingBlockGeometry.contentBoxHeight();
	ASSERT(boxGeometry.top() + boxGeometry.marginBefore() + boxGeometry.borderTop() + boxGeometry.paddingTop().valueOr(0) + boxGeometry.contentBoxHeight()
	+ boxGeometry.paddingBottom().valueOr(0) + boxGeometry.borderBottom() + boxGeometry.marginAfter() == containingBlockHeight);
	}
	}
	}
	#endif

	}
	}
	#endif