RenderBox.h

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2003, 2006, 2007, 2015 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#pragma once

#include "FrameView.h"
#include "RenderBoxModelObject.h"
#include "RenderOverflow.h"
#include "ScrollSnapOffsetsInfo.h"
#include "ScrollTypes.h"
#include "ShapeOutsideInfo.h"

namespace WebCore {

class LegacyInlineElementBox;
class RenderBlockFlow;
class RenderBoxFragmentInfo;
class RenderFragmentContainer;
struct PaintInfo;

enum SizeType { MainOrPreferredSize, MinSize, MaxSize };
enum AvailableLogicalHeightType { ExcludeMarginBorderPadding, IncludeMarginBorderPadding };
enum OverlayScrollbarSizeRelevancy { IgnoreOverlayScrollbarSize, IncludeOverlayScrollbarSize };

enum ShouldComputePreferred { ComputeActual, ComputePreferred };

enum class StretchingMode { Any, Explicit };

class RenderBox : public RenderBoxModelObject {
    WTF_MAKE_ISO_ALLOCATED(RenderBox);
public:
    virtual ~RenderBox();

    // hasAutoZIndex only returns true if the element is positioned or a flex-item since
    // position:static elements that are not flex-items get their z-index coerced to auto.
    bool requiresLayer() const override
    {
        return isDocumentElementRenderer() || isPositioned() || createsGroup() || hasNonVisibleOverflow()
            || hasTransformRelatedProperty() || hasHiddenBackface() || hasReflection() || style().specifiesColumns()
            || style().containsLayout() || !style().hasAutoUsedZIndex() || hasRunningAcceleratedAnimations();
    }

    bool requiresLayerWithScrollableArea() const;
    bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const final;
    
    // Returns false for the body renderer if its background is propagated to the root.
    bool paintsOwnBackground() const;

    LayoutUnit x() const { return m_frameRect.x(); }
    LayoutUnit y() const { return m_frameRect.y(); }
    LayoutUnit width() const { return m_frameRect.width(); }
    LayoutUnit height() const { return m_frameRect.height(); }

    // These represent your location relative to your container as a physical offset.
    // In layout related methods you almost always want the logical location (e.g. x() and y()).
    LayoutUnit top() const { return topLeftLocation().y(); }
    LayoutUnit left() const { return topLeftLocation().x(); }

    template<typename T> void setX(T x) { m_frameRect.setX(x); }
    template<typename T> void setY(T y) { m_frameRect.setY(y); }
    template<typename T> void setWidth(T width) { m_frameRect.setWidth(width); }
    template<typename T> void setHeight(T height) { m_frameRect.setHeight(height); }

    LayoutUnit logicalLeft() const { return style().isHorizontalWritingMode() ? x() : y(); }
    LayoutUnit logicalRight() const { return logicalLeft() + logicalWidth(); }
    LayoutUnit logicalTop() const { return style().isHorizontalWritingMode() ? y() : x(); }
    LayoutUnit logicalBottom() const { return logicalTop() + logicalHeight(); }
    LayoutUnit logicalWidth() const { return style().isHorizontalWritingMode() ? width() : height(); }
    LayoutUnit logicalHeight() const { return style().isHorizontalWritingMode() ? height() : width(); }

    enum class AllowIntrinsic { Yes, No };
    LayoutUnit constrainLogicalWidthInFragmentByMinMax(LayoutUnit, LayoutUnit, RenderBlock&, RenderFragmentContainer*, AllowIntrinsic = AllowIntrinsic::Yes) const;
    LayoutUnit constrainLogicalHeightByMinMax(LayoutUnit logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    LayoutUnit constrainContentBoxLogicalHeightByMinMax(LayoutUnit logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;

    void setLogicalLeft(LayoutUnit left)
    {
        if (style().isHorizontalWritingMode())
            setX(left);
        else
            setY(left);
    }
    void setLogicalTop(LayoutUnit top)
    {
        if (style().isHorizontalWritingMode())
            setY(top);
        else
            setX(top);
    }
    void setLogicalLocation(const LayoutPoint& location)
    {
        if (style().isHorizontalWritingMode())
            setLocation(location);
        else
            setLocation(location.transposedPoint());
    }
    void setLogicalWidth(LayoutUnit size)
    {
        if (style().isHorizontalWritingMode())
            setWidth(size);
        else
            setHeight(size);
    }
    void setLogicalHeight(LayoutUnit size)
    {
        if (style().isHorizontalWritingMode())
            setHeight(size);
        else
            setWidth(size);
    }
    void setLogicalSize(const LayoutSize& size)
    {
        if (style().isHorizontalWritingMode())
            setSize(size);
        else
            setSize(size.transposedSize());
    }

    LayoutPoint location() const { return m_frameRect.location(); }
    LayoutSize locationOffset() const { return LayoutSize(x(), y()); }
    LayoutSize size() const { return m_frameRect.size(); }
    LayoutSize logicalSize() const { return style().isHorizontalWritingMode() ? m_frameRect.size() : m_frameRect.size().transposedSize(); }

    void setLocation(const LayoutPoint& location) { m_frameRect.setLocation(location); }
    
    void setSize(const LayoutSize& size) { m_frameRect.setSize(size); }
    void move(LayoutUnit dx, LayoutUnit dy) { m_frameRect.move(dx, dy); }

    LayoutRect frameRect() const { return m_frameRect; }
    void setFrameRect(const LayoutRect& rect) { m_frameRect = rect; }

    LayoutRect marginBoxRect() const
    {
        auto marginLeft = computedCSSPadding(style().marginLeft());
        auto marginRight = computedCSSPadding(style().marginRight());
        auto marginTop = computedCSSPadding(style().marginTop());
        auto marginBottom = computedCSSPadding(style().marginBottom());
        return LayoutRect(-marginLeft, -marginTop, size().width() + marginLeft + marginRight, size().height() + marginTop + marginBottom);
    }
    LayoutRect borderBoxRect() const { return LayoutRect(LayoutPoint(), size()); }
    LayoutRect borderBoundingBox() const final { return borderBoxRect(); }
    LayoutSize borderBoxLogicalSize() const { return logicalSize(); }

    WEBCORE_EXPORT RoundedRect::Radii borderRadii() const;
    RoundedRect roundedBorderBoxRect() const;

    // The content area of the box (excludes padding - and intrinsic padding for table cells, etc... - and border).
    LayoutRect contentBoxRect() const;
    LayoutPoint contentBoxLocation() const;

    // https://www.w3.org/TR/css-transforms-1/#reference-box
    FloatRect referenceBoxRect(CSSBoxType) const final;

    // The content box in absolute coords. Ignores transforms.
    IntRect absoluteContentBox() const;
    // The content box converted to absolute coords (taking transforms into account).
    WEBCORE_EXPORT FloatQuad absoluteContentQuad() const;

    // This returns the content area of the box (excluding padding and border). The only difference with contentBoxRect is that computedCSSContentBoxRect
    // does include the intrinsic padding in the content box as this is what some callers expect (like getComputedStyle).
    LayoutRect computedCSSContentBoxRect() const { return LayoutRect(borderLeft() + computedCSSPaddingLeft(), borderTop() + computedCSSPaddingTop(), paddingBoxWidth() - computedCSSPaddingLeft() - computedCSSPaddingRight(), paddingBoxHeight() - computedCSSPaddingTop() - computedCSSPaddingBottom()); }

    // Bounds of the outline box in absolute coords. Respects transforms
    LayoutRect outlineBoundsForRepaint(const RenderLayerModelObject* /*repaintContainer*/, const RenderGeometryMap*) const final;
    void addFocusRingRects(Vector<LayoutRect>&, const LayoutPoint& additionalOffset, const RenderLayerModelObject* paintContainer = nullptr) override;
    
    FloatRect repaintRectInLocalCoordinates() const override { return borderBoxRect(); }
    FloatRect objectBoundingBox() const override { return borderBoxRect(); }

    // Note these functions are not equivalent of childrenOfType<RenderBox>
    RenderBox* parentBox() const;
    RenderBox* firstChildBox() const;
    RenderBox* lastChildBox() const;
    RenderBox* previousSiblingBox() const;
    RenderBox* nextSiblingBox() const;

    // Visual and layout overflow are in the coordinate space of the box.  This means that they aren't purely physical directions.
    // For horizontal-tb and vertical-lr they will match physical directions, but for horizontal-bt and vertical-rl, the top/bottom and left/right
    // respectively are flipped when compared to their physical counterparts.  For example minX is on the left in vertical-lr,
    // but it is on the right in vertical-rl.
    WEBCORE_EXPORT LayoutRect flippedClientBoxRect() const;
    LayoutRect layoutOverflowRect() const { return m_overflow ? m_overflow->layoutOverflowRect() : flippedClientBoxRect(); }
    LayoutUnit logicalLeftLayoutOverflow() const { return style().isHorizontalWritingMode() ? layoutOverflowRect().x() : layoutOverflowRect().y(); }
    LayoutUnit logicalRightLayoutOverflow() const { return style().isHorizontalWritingMode() ? layoutOverflowRect().maxX() : layoutOverflowRect().maxY(); }
    
    LayoutRect visualOverflowRect() const { return m_overflow ? m_overflow->visualOverflowRect() : borderBoxRect(); }
    LayoutUnit logicalLeftVisualOverflow() const { return style().isHorizontalWritingMode() ? visualOverflowRect().x() : visualOverflowRect().y(); }
    LayoutUnit logicalRightVisualOverflow() const { return style().isHorizontalWritingMode() ? visualOverflowRect().maxX() : visualOverflowRect().maxY(); }

    void addLayoutOverflow(const LayoutRect&);
    void addVisualOverflow(const LayoutRect&);
    void clearOverflow();
    
    virtual bool isTopLayoutOverflowAllowed() const { return !style().isLeftToRightDirection() && !isHorizontalWritingMode(); }
    virtual bool isLeftLayoutOverflowAllowed() const { return !style().isLeftToRightDirection() && isHorizontalWritingMode(); }
    
    void addVisualEffectOverflow();
    LayoutRect applyVisualEffectOverflow(const LayoutRect&) const;
    void addOverflowFromChild(const RenderBox* child) { addOverflowFromChild(child, child->locationOffset()); }
    void addOverflowFromChild(const RenderBox* child, const LayoutSize& delta);

    void applyTransform(TransformationMatrix&, const RenderStyle&, const FloatRect& boundingBox, OptionSet<RenderStyle::TransformOperationOption> = RenderStyle::allTransformOperations) const override;

    LayoutSize contentSize() const { return { contentWidth(), contentHeight() }; }
    LayoutUnit contentWidth() const { return std::max(0_lu, paddingBoxWidth() - paddingLeft() - paddingRight()); }
    LayoutUnit contentHeight() const { return std::max(0_lu, paddingBoxHeight() - paddingTop() - paddingBottom()); }
    LayoutSize contentLogicalSize() const { return style().isHorizontalWritingMode() ? contentSize() : contentSize().transposedSize(); }
    LayoutUnit contentLogicalWidth() const { return style().isHorizontalWritingMode() ? contentWidth() : contentHeight(); }
    LayoutUnit contentLogicalHeight() const { return style().isHorizontalWritingMode() ? contentHeight() : contentWidth(); }

    LayoutUnit paddingBoxWidth() const { return std::max(0_lu, width() - borderLeft() - borderRight() - verticalScrollbarWidth()); }
    LayoutUnit paddingBoxHeight() const { return std::max(0_lu, height() - borderTop() - borderBottom() - horizontalScrollbarHeight()); }
    LayoutRect paddingBoxRect() const;
    LayoutRect paddingBoxRectIncludingScrollbar() const { return LayoutRect(borderLeft(), borderTop(), width() - borderLeft() - borderRight(), height() - borderTop() - borderBottom()); }

    // IE extensions. Used to calculate offsetWidth/Height.  Overridden by inlines (RenderFlow)
    // to return the remaining width on a given line (and the height of a single line).
    LayoutUnit offsetWidth() const override { return width(); }
    LayoutUnit offsetHeight() const override { return height(); }

    // More IE extensions.  clientWidth and clientHeight represent the interior of an object
    // excluding border and scrollbar.  clientLeft/Top are just the borderLeftWidth and borderTopWidth.
    LayoutUnit clientLeft() const { return borderLeft(); }
    LayoutUnit clientTop() const { return borderTop(); }
    WEBCORE_EXPORT LayoutUnit clientWidth() const;
    WEBCORE_EXPORT LayoutUnit clientHeight() const;
    LayoutUnit clientLogicalWidth() const { return style().isHorizontalWritingMode() ? clientWidth() : clientHeight(); }
    LayoutUnit clientLogicalHeight() const { return style().isHorizontalWritingMode() ? clientHeight() : clientWidth(); }
    LayoutUnit clientLogicalBottom() const { return borderBefore() + clientLogicalHeight(); }
    LayoutRect clientBoxRect() const { return LayoutRect(clientLeft(), clientTop(), clientWidth(), clientHeight()); }

    // scrollWidth/scrollHeight will be the same as clientWidth/clientHeight unless the
    // object has overflow:hidden/scroll/auto specified and also has overflow.
    // scrollLeft/Top return the current scroll position.  These methods are virtual so that objects like
    // textareas can scroll shadow content (but pretend that they are the objects that are
    // scrolling).
    virtual int scrollLeft() const;
    virtual int scrollTop() const;
    virtual int scrollWidth() const;
    virtual int scrollHeight() const;
    virtual void setScrollLeft(int, const ScrollPositionChangeOptions&);
    virtual void setScrollTop(int, const ScrollPositionChangeOptions&);
    void setScrollPosition(const ScrollPosition&, const ScrollPositionChangeOptions&);

    const LayoutBoxExtent& marginBox() const { return m_marginBox; }
    LayoutUnit marginTop() const override { return m_marginBox.top(); }
    LayoutUnit marginBottom() const override { return m_marginBox.bottom(); }
    LayoutUnit marginLeft() const override { return m_marginBox.left(); }
    LayoutUnit marginRight() const override { return m_marginBox.right(); }
    void setMarginTop(LayoutUnit margin) { m_marginBox.setTop(margin); }
    void setMarginBottom(LayoutUnit margin) { m_marginBox.setBottom(margin); }
    void setMarginLeft(LayoutUnit margin) { m_marginBox.setLeft(margin); }
    void setMarginRight(LayoutUnit margin) { m_marginBox.setRight(margin); }

    LayoutUnit marginLogicalLeft(const RenderStyle* overrideStyle = nullptr) const { return m_marginBox.start((overrideStyle ? overrideStyle : &style())->writingMode()); }
    LayoutUnit marginLogicalRight(const RenderStyle* overrideStyle = nullptr) const { return m_marginBox.end((overrideStyle ? overrideStyle : &style())->writingMode()); }

    LayoutUnit marginBefore(const RenderStyle* overrideStyle = nullptr) const final { return m_marginBox.before((overrideStyle ? overrideStyle : &style())->writingMode()); }
    LayoutUnit marginAfter(const RenderStyle* overrideStyle = nullptr) const final { return m_marginBox.after((overrideStyle ? overrideStyle : &style())->writingMode()); }
    LayoutUnit marginStart(const RenderStyle* overrideStyle = nullptr) const final
    {
        const RenderStyle* styleToUse = overrideStyle ? overrideStyle : &style();
        return m_marginBox.start(styleToUse->writingMode(), styleToUse->direction());
    }
    LayoutUnit marginEnd(const RenderStyle* overrideStyle = nullptr) const final
    {
        const RenderStyle* styleToUse = overrideStyle ? overrideStyle : &style();
        return m_marginBox.end(styleToUse->writingMode(), styleToUse->direction());
    }
    void setMarginBefore(LayoutUnit value, const RenderStyle* overrideStyle = nullptr) { m_marginBox.setBefore(value, (overrideStyle ? overrideStyle : &style())->writingMode()); }
    void setMarginAfter(LayoutUnit value, const RenderStyle* overrideStyle = nullptr) { m_marginBox.setAfter(value, (overrideStyle ? overrideStyle : &style())->writingMode()); }
    void setMarginStart(LayoutUnit value, const RenderStyle* overrideStyle = nullptr)
    {
        const RenderStyle* styleToUse = overrideStyle ? overrideStyle : &style();
        m_marginBox.setStart(value, styleToUse->writingMode(), styleToUse->direction());
    }
    void setMarginEnd(LayoutUnit value, const RenderStyle* overrideStyle = nullptr)
    {
        const RenderStyle* styleToUse = overrideStyle ? overrideStyle : &style();
        m_marginBox.setEnd(value, styleToUse->writingMode(), styleToUse->direction());
    }

    virtual bool isSelfCollapsingBlock() const { return false; }
    virtual LayoutUnit collapsedMarginBefore() const { return marginBefore(); }
    virtual LayoutUnit collapsedMarginAfter() const { return marginAfter(); }

    void absoluteRects(Vector<IntRect>&, const LayoutPoint& accumulatedOffset) const override;
    void absoluteQuads(Vector<FloatQuad>&, bool* wasFixed) const override;
    
    int reflectionOffset() const;
    // Given a rect in the object's coordinate space, returns the corresponding rect in the reflection.
    LayoutRect reflectedRect(const LayoutRect&) const;

    void layout() override;
    bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation&, const LayoutPoint& accumulatedOffset, HitTestAction) override;
    bool hitTestVisualOverflow(const HitTestLocation&, const LayoutPoint& accumulatedOffset) const;
    bool hitTestClipPath(const HitTestLocation&, const LayoutPoint& accumulatedOffset) const;
    bool hitTestBorderRadius(const HitTestLocation&, const LayoutPoint& accumulatedOffset) const;

    LayoutUnit minPreferredLogicalWidth() const override;
    LayoutUnit maxPreferredLogicalWidth() const override;

    LayoutUnit overridingLogicalWidth() const;
    LayoutUnit overridingLogicalHeight() const;
    bool hasOverridingLogicalHeight() const;
    bool hasOverridingLogicalWidth() const;
    void setOverridingLogicalHeight(LayoutUnit);
    void setOverridingLogicalWidth(LayoutUnit);
    void clearOverridingContentSize();
    void clearOverridingLogicalHeight();
    void clearOverridingLogicalWidth();

    LayoutUnit overridingContentLogicalWidth() const { return std::max(LayoutUnit(), overridingLogicalWidth() - borderAndPaddingLogicalWidth() - scrollbarLogicalWidth()); }
    LayoutUnit overridingContentLogicalHeight() const { return std::max(LayoutUnit(), overridingLogicalHeight() - borderAndPaddingLogicalHeight() - scrollbarLogicalHeight()); }

    std::optional<LayoutUnit> overridingContainingBlockContentWidth() const override;
    std::optional<LayoutUnit> overridingContainingBlockContentHeight() const override;
    bool hasOverridingContainingBlockContentWidth() const override;
    bool hasOverridingContainingBlockContentHeight() const override;
    std::optional<LayoutUnit> overridingContainingBlockContentLogicalWidth() const;
    std::optional<LayoutUnit> overridingContainingBlockContentLogicalHeight() const;
    bool hasOverridingContainingBlockContentLogicalWidth() const;
    bool hasOverridingContainingBlockContentLogicalHeight() const;
    void setOverridingContainingBlockContentLogicalWidth(std::optional<LayoutUnit>);
    void setOverridingContainingBlockContentLogicalHeight(std::optional<LayoutUnit>);
    void clearOverridingContainingBlockContentSize();
    void clearOverridingContainingBlockContentLogicalHeight();

    // These are currently only used by Flexbox code. In some cases we must layout flex items with a different main size
    // (the size in the main direction) than the one specified by the item in order to compute the value of flex basis, i.e.,
    // the initial main size of the flex item before the free space is distributed.
    Length overridingLogicalHeightLength() const;
    Length overridingLogicalWidthLength() const;
    void setOverridingLogicalHeightLength(const Length&);
    void setOverridingLogicalWidthLength(const Length&);
    bool hasOverridingLogicalHeightLength() const;
    bool hasOverridingLogicalWidthLength() const;
    void clearOverridingLogicalHeightLength();
    void clearOverridingLogicalWidthLength();

    LayoutSize offsetFromContainer(RenderElement&, const LayoutPoint&, bool* offsetDependsOnPoint = nullptr) const override;
    
    LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(const Length& logicalWidth) const;
    LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(const Length& logicalWidth) const;

    LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit computedLogicalWidth, LengthType originalType) const;
    LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit computedLogicalWidth, LengthType originalType) const;

    template<typename T> LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(T computedLogicalWidth, LengthType originalType) const { return adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit(computedLogicalWidth), originalType); }
    template<typename T> LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(T computedLogicalWidth, LengthType originalType) const { return adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit(computedLogicalWidth), originalType); }

    // Overridden by fieldsets to subtract out the intrinsic border.
    virtual LayoutUnit adjustBorderBoxLogicalHeightForBoxSizing(LayoutUnit height) const;
    virtual LayoutUnit adjustContentBoxLogicalHeightForBoxSizing(std::optional<LayoutUnit> height) const;

    struct ComputedMarginValues {
        LayoutUnit m_before;
        LayoutUnit m_after;
        LayoutUnit m_start;
        LayoutUnit m_end;
    };
    struct LogicalExtentComputedValues {
        LayoutUnit m_extent;
        LayoutUnit m_position;
        ComputedMarginValues m_margins;
    };
    // Resolve auto margins in the inline direction of the containing block so that objects can be pushed to the start, middle or end
    // of the containing block.
    void computeInlineDirectionMargins(const RenderBlock& containingBlock, LayoutUnit containerWidth, LayoutUnit childWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const;

    // Used to resolve margins in the containing block's block-flow direction.
    void computeBlockDirectionMargins(const RenderBlock& containingBlock, LayoutUnit& marginBefore, LayoutUnit& marginAfter) const;
    void computeAndSetBlockDirectionMargins(const RenderBlock& containingBlock);

    enum RenderBoxFragmentInfoFlags { CacheRenderBoxFragmentInfo, DoNotCacheRenderBoxFragmentInfo };
    LayoutRect borderBoxRectInFragment(RenderFragmentContainer*, RenderBoxFragmentInfoFlags = CacheRenderBoxFragmentInfo) const;
    LayoutRect clientBoxRectInFragment(RenderFragmentContainer*) const;
    RenderFragmentContainer* clampToStartAndEndFragments(RenderFragmentContainer*) const;
    bool hasFragmentRangeInFragmentedFlow() const;
    virtual LayoutUnit offsetFromLogicalTopOfFirstPage() const;
    
    void positionLineBox(LegacyInlineElementBox&);

    virtual std::unique_ptr<LegacyInlineElementBox> createInlineBox();
    void dirtyLineBoxes(bool fullLayout);

    // For inline replaced elements, this function returns the inline box that owns us.  Enables
    // the replaced RenderObject to quickly determine what line it is contained on and to easily
    // iterate over structures on the line.
    LegacyInlineElementBox* inlineBoxWrapper() const { return m_inlineBoxWrapper; }
    void setInlineBoxWrapper(LegacyInlineElementBox*);
    void deleteLineBoxWrapper();

    LayoutRect clippedOverflowRect(const RenderLayerModelObject* repaintContainer, VisibleRectContext) const override;
    std::optional<LayoutRect> computeVisibleRectInContainer(const LayoutRect&, const RenderLayerModelObject* container, VisibleRectContext) const
override;
    void repaintDuringLayoutIfMoved(const LayoutRect&);
    virtual void repaintOverhangingFloats(bool paintAllDescendants);

    LayoutUnit containingBlockLogicalWidthForContent() const override;
    LayoutUnit containingBlockLogicalHeightForContent(AvailableLogicalHeightType) const;
    LayoutUnit containingBlockLogicalWidthForPositioned(const RenderBoxModelObject& containingBlock, RenderFragmentContainer* = nullptr, bool checkForPerpendicularWritingMode = true) const;
    LayoutUnit containingBlockLogicalHeightForPositioned(const RenderBoxModelObject& containingBlock, bool checkForPerpendicularWritingMode = true) const;
    LayoutUnit containingBlockLogicalWidthForContentInFragment(RenderFragmentContainer*) const;
    LayoutUnit containingBlockAvailableLineWidthInFragment(RenderFragmentContainer*) const;
    LayoutUnit perpendicularContainingBlockLogicalHeight() const;

    virtual void updateLogicalWidth();
    virtual void updateLogicalHeight();
    virtual LogicalExtentComputedValues computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop) const;

    void cacheIntrinsicContentLogicalHeightForFlexItem(LayoutUnit) const;
    
    // This function will compute the logical border-box height, without laying
    // out the box. This means that the result is only "correct" when the height
    // is explicitly specified. This function exists so that intrinsic width
    // calculations have a way to deal with children that have orthogonal writing modes.
    // When there is no explicit height, this function assumes a content height of
    // zero (and returns just border + padding).
    LayoutUnit computeLogicalHeightWithoutLayout() const;

    RenderBoxFragmentInfo* renderBoxFragmentInfo(RenderFragmentContainer*, RenderBoxFragmentInfoFlags = CacheRenderBoxFragmentInfo) const;
    void computeLogicalWidthInFragment(LogicalExtentComputedValues&, RenderFragmentContainer* = nullptr) const;

    bool stretchesToViewport() const
    {
        return document().inQuirksMode() && style().logicalHeight().isAuto() && !isFloatingOrOutOfFlowPositioned() && (isDocumentElementRenderer() || isBody()) && !shouldComputeLogicalHeightFromAspectRatio() && !isInline();
    }

    virtual LayoutSize intrinsicSize() const { return LayoutSize(); }
    LayoutUnit intrinsicLogicalWidth() const { return style().isHorizontalWritingMode() ? intrinsicSize().width() : intrinsicSize().height(); }
    LayoutUnit intrinsicLogicalHeight() const { return style().isHorizontalWritingMode() ? intrinsicSize().height() : intrinsicSize().width(); }

    // Whether or not the element shrinks to its intrinsic width (rather than filling the width
    // of a containing block).  HTML4 buttons, <select>s, <input>s, legends, and floating/compact elements do this.
    bool sizesLogicalWidthToFitContent(SizeType) const;

    bool hasStretchedLogicalHeight() const;
    bool hasStretchedLogicalWidth(StretchingMode = StretchingMode::Any) const;
    bool isStretchingColumnFlexItem() const;
    bool columnFlexItemHasStretchAlignment() const;
    
    LayoutUnit shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart, LayoutUnit childMarginEnd, const RenderBlock& cb, RenderFragmentContainer*) const;

    LayoutUnit computeLogicalWidthInFragmentUsing(SizeType, Length logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock, RenderFragmentContainer*) const;
    std::optional<LayoutUnit> computeLogicalHeightUsing(SizeType, const Length& height, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeContentLogicalHeight(SizeType, const Length& height, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeContentAndScrollbarLogicalHeightUsing(SizeType, const Length& height, std::optional<LayoutUnit> intrinsicContentHeight) const;
    LayoutUnit computeReplacedLogicalWidthUsing(SizeType, Length width) const;
    LayoutUnit computeReplacedLogicalWidthRespectingMinMaxWidth(LayoutUnit logicalWidth, ShouldComputePreferred  = ComputeActual) const;
    LayoutUnit computeReplacedLogicalHeightUsing(SizeType, Length height) const;
    LayoutUnit computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit logicalHeight) const;

    template<typename T> LayoutUnit computeReplacedLogicalWidthRespectingMinMaxWidth(T logicalWidth, ShouldComputePreferred shouldComputePreferred = ComputeActual) const { return computeReplacedLogicalWidthRespectingMinMaxWidth(LayoutUnit(logicalWidth), shouldComputePreferred); }
    template<typename T> LayoutUnit computeReplacedLogicalHeightRespectingMinMaxHeight(T logicalHeight) const { return computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit(logicalHeight)); }

    virtual LayoutUnit computeReplacedLogicalWidth(ShouldComputePreferred  = ComputeActual) const;
    virtual LayoutUnit computeReplacedLogicalHeight(std::optional<LayoutUnit> estimatedUsedWidth = std::nullopt) const;

    enum class UpdatePercentageHeightDescendants { Yes , No };
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Length& height, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;

    LayoutUnit availableLogicalWidth() const { return contentLogicalWidth(); }
    virtual LayoutUnit availableLogicalHeight(AvailableLogicalHeightType) const;
    LayoutUnit availableLogicalHeightUsing(const Length&, AvailableLogicalHeightType) const;
    
    // There are a few cases where we need to refer specifically to the available physical width and available physical height.
    // Relative positioning is one of those cases, since left/top offsets are physical.
    LayoutUnit availableWidth() const { return style().isHorizontalWritingMode() ? availableLogicalWidth() : availableLogicalHeight(IncludeMarginBorderPadding); }
    LayoutUnit availableHeight() const { return style().isHorizontalWritingMode() ? availableLogicalHeight(IncludeMarginBorderPadding) : availableLogicalWidth(); }

    WEBCORE_EXPORT virtual int verticalScrollbarWidth() const;
    WEBCORE_EXPORT int horizontalScrollbarHeight() const;
    int intrinsicScrollbarLogicalWidth() const;
    int scrollbarLogicalWidth() const { return style().isHorizontalWritingMode() ? verticalScrollbarWidth() : horizontalScrollbarHeight(); }
    int scrollbarLogicalHeight() const { return style().isHorizontalWritingMode() ? horizontalScrollbarHeight() : verticalScrollbarWidth(); }
    virtual bool scroll(ScrollDirection, ScrollGranularity, unsigned stepCount = 1, Element** stopElement = nullptr, RenderBox* startBox = nullptr, const IntPoint& wheelEventAbsolutePoint = IntPoint());
    virtual bool logicalScroll(ScrollLogicalDirection, ScrollGranularity, unsigned stepCount = 1, Element** stopElement = nullptr);
    WEBCORE_EXPORT bool canBeScrolledAndHasScrollableArea() const;
    virtual bool canBeProgramaticallyScrolled() const;
    virtual void autoscroll(const IntPoint&);
    bool canAutoscroll() const;
    IntSize calculateAutoscrollDirection(const IntPoint& windowPoint) const;
    static RenderBox* findAutoscrollable(RenderObject*);
    virtual void stopAutoscroll() { }
    virtual void panScroll(const IntPoint&);

    bool canUseOverlayScrollbars() const;
    bool hasAutoScrollbar(ScrollbarOrientation) const;
    bool hasAlwaysPresentScrollbar(ScrollbarOrientation) const;

    bool scrollsOverflow() const { return scrollsOverflowX() || scrollsOverflowY(); }
    bool scrollsOverflowX() const { return hasNonVisibleOverflow() && (style().overflowX() == Overflow::Scroll || style().overflowX() == Overflow::Auto); }
    bool scrollsOverflowY() const { return hasNonVisibleOverflow() && (style().overflowY() == Overflow::Scroll || style().overflowY() == Overflow::Auto); }

    bool hasHorizontalOverflow() const { return scrollWidth() != roundToInt(paddingBoxWidth()); }
    bool hasVerticalOverflow() const { return scrollHeight() != roundToInt(paddingBoxHeight()); }

    bool hasScrollableOverflowX() const { return scrollsOverflowX() && hasHorizontalOverflow(); }
    bool hasScrollableOverflowY() const { return scrollsOverflowY() && hasVerticalOverflow(); }

    LayoutBoxExtent scrollPaddingForViewportRect(const LayoutRect& viewportRect);

    bool usesCompositedScrolling() const;
    
    bool percentageLogicalHeightIsResolvable() const;
    bool hasUnsplittableScrollingOverflow() const;
    bool isUnsplittableForPagination() const;

    bool shouldTreatChildAsReplacedInTableCells() const;

    virtual LayoutRect overflowClipRect(const LayoutPoint& location, RenderFragmentContainer* = nullptr, OverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize, PaintPhase = PaintPhase::BlockBackground) const;
    virtual LayoutRect overflowClipRectForChildLayers(const LayoutPoint& location, RenderFragmentContainer* fragment, OverlayScrollbarSizeRelevancy relevancy) const { return overflowClipRect(location, fragment, relevancy); }
    LayoutRect clipRect(const LayoutPoint& location, RenderFragmentContainer*) const;
    virtual bool hasControlClip() const { return false; }
    virtual LayoutRect controlClipRect(const LayoutPoint&) const { return LayoutRect(); }
    bool pushContentsClip(PaintInfo&, const LayoutPoint& accumulatedOffset);
    void popContentsClip(PaintInfo&, PaintPhase originalPhase, const LayoutPoint& accumulatedOffset);

    virtual void paintObject(PaintInfo&, const LayoutPoint&) { ASSERT_NOT_REACHED(); }
    virtual void paintBoxDecorations(PaintInfo&, const LayoutPoint&);
    virtual void paintMask(PaintInfo&, const LayoutPoint&);
    virtual void paintClippingMask(PaintInfo&, const LayoutPoint&);
    void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;

    // Called when a positioned object moves but doesn't necessarily change size.  A simplified layout is attempted
    // that just updates the object's position. If the size does change, the object remains dirty.
    bool tryLayoutDoingPositionedMovementOnly()
    {
        LayoutUnit oldWidth = width();
        updateLogicalWidth();
        // If we shrink to fit our width may have changed, so we still need full layout.
        if (oldWidth != width())
            return false;
        updateLogicalHeight();
        return true;
    }

    LayoutRect maskClipRect(const LayoutPoint& paintOffset);

    VisiblePosition positionForPoint(const LayoutPoint&, const RenderFragmentContainer*) override;

    void removeFloatingOrPositionedChildFromBlockLists();
    
    RenderLayer* enclosingFloatPaintingLayer() const;
    
    virtual std::optional<LayoutUnit> firstLineBaseline() const { return std::optional<LayoutUnit>(); }
    virtual std::optional<LayoutUnit> inlineBlockBaseline(LineDirectionMode) const { return std::optional<LayoutUnit>(); } // Returns empty if we should skip this box when computing the baseline of an inline-block.

    bool shrinkToAvoidFloats() const;
    virtual bool avoidsFloats() const;

    virtual void markForPaginationRelayoutIfNeeded() { }
    
    LayoutUnit lineHeight(bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const override;
    LayoutUnit baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode = PositionOnContainingLine) const override;

    LayoutUnit offsetLeft() const override;
    LayoutUnit offsetTop() const override;

    LayoutPoint flipForWritingModeForChild(const RenderBox& child, const LayoutPoint&) const;
    LayoutUnit flipForWritingMode(LayoutUnit position) const; // The offset is in the block direction (y for horizontal writing modes, x for vertical writing modes).
    LayoutPoint flipForWritingMode(const LayoutPoint&) const;
    LayoutSize flipForWritingMode(const LayoutSize&) const;
    void flipForWritingMode(LayoutRect&) const;
    FloatPoint flipForWritingMode(const FloatPoint&) const;
    void flipForWritingMode(FloatRect&) const;
    // These represent your location relative to your container as a physical offset.
    // In layout related methods you almost always want the logical location (e.g. x() and y()).
    LayoutPoint topLeftLocation() const;
    LayoutSize topLeftLocationOffset() const;
    void applyTopLeftLocationOffset(LayoutPoint& point) const
    {
        // This is inlined for speed, since it is used by updateLayerPosition() during scrolling.
        if (!document().view()->hasFlippedBlockRenderers())
            point.move(m_frameRect.x(), m_frameRect.y());
        else
            applyTopLeftLocationOffsetWithFlipping(point);
    }

    LayoutRect logicalVisualOverflowRectForPropagation(const RenderStyle*) const;
    LayoutRect visualOverflowRectForPropagation(const RenderStyle*) const;
    LayoutRect logicalLayoutOverflowRectForPropagation(const RenderStyle*) const;
    LayoutRect layoutOverflowRectForPropagation(const RenderStyle*) const;

    bool hasRenderOverflow() const { return m_overflow; }    
    bool hasVisualOverflow() const { return m_overflow && !borderBoxRect().contains(m_overflow->visualOverflowRect()); }

    virtual bool needsPreferredWidthsRecalculation() const;
    virtual void computeIntrinsicRatioInformation(FloatSize& /* intrinsicSize */, double& /* intrinsicRatio */) const { }

    ScrollPosition scrollPosition() const;
    LayoutSize cachedSizeForOverflowClip() const;

    // Returns false if the rect has no intersection with the applied clip rect. When the context specifies edge-inclusive
    // intersection, this return value allows distinguishing between no intersection and zero-area intersection.
    bool applyCachedClipAndScrollPosition(LayoutRect&, const RenderLayerModelObject* container, VisibleRectContext) const;

    virtual bool hasRelativeDimensions() const;
    virtual bool hasRelativeLogicalHeight() const;
    virtual bool hasRelativeLogicalWidth() const;

    bool hasHorizontalLayoutOverflow() const
    {
        if (!m_overflow)
            return false;

        LayoutRect layoutOverflowRect = m_overflow->layoutOverflowRect();
        flipForWritingMode(layoutOverflowRect);
        return layoutOverflowRect.x() < x() || layoutOverflowRect.maxX() > x() + logicalWidth();
    }

    bool hasVerticalLayoutOverflow() const
    {
        if (!m_overflow)
            return false;

        LayoutRect layoutOverflowRect = m_overflow->layoutOverflowRect();
        flipForWritingMode(layoutOverflowRect);
        return layoutOverflowRect.y() < y() || layoutOverflowRect.maxY() > y() + logicalHeight();
    }

    virtual RenderPtr<RenderBox> createAnonymousBoxWithSameTypeAs(const RenderBox&) const
    {
        ASSERT_NOT_REACHED();
        return nullptr;
    }

    ShapeOutsideInfo* shapeOutsideInfo() const
    {
        return ShapeOutsideInfo::isEnabledFor(*this) ? ShapeOutsideInfo::info(*this) : nullptr;
    }

    void markShapeOutsideDependentsForLayout()
    {
        if (isFloating())
            removeFloatingOrPositionedChildFromBlockLists();
    }

    // True if this box can have a range in an outside fragmentation context.
    bool canHaveOutsideFragmentRange() const { return !isRenderFragmentedFlow(); }
    virtual bool needsLayoutAfterFragmentRangeChange() const { return false; }

    bool isGridItem() const { return parent() && parent()->isRenderGrid() && !isExcludedFromNormalLayout(); }
    bool isFlexItem() const { return parent() && parent()->isFlexibleBox() && !isExcludedFromNormalLayout(); }

    virtual void adjustBorderBoxRectForPainting(LayoutRect&) { };

    bool shouldComputeLogicalHeightFromAspectRatio() const;

protected:
    RenderBox(Element&, RenderStyle&&, BaseTypeFlags);
    RenderBox(Document&, RenderStyle&&, BaseTypeFlags);

    void styleWillChange(StyleDifference, const RenderStyle& newStyle) override;
    void styleDidChange(StyleDifference, const RenderStyle* oldStyle) override;
    void updateFromStyle() override;

    void willBeDestroyed() override;

    bool establishesIndependentFormattingContext() const override;

    virtual bool shouldResetLogicalHeightBeforeLayout() const { return false; }
    void resetLogicalHeightBeforeLayoutIfNeeded();

    virtual ItemPosition selfAlignmentNormalBehavior(const RenderBox* = nullptr) const { return ItemPosition::Stretch; }

    // Returns false if it could not cheaply compute the extent (e.g. fixed background), in which case the returned rect may be incorrect.
    bool getBackgroundPaintedExtent(const LayoutPoint& paintOffset, LayoutRect&) const;
    virtual bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const;
    bool computeBackgroundIsKnownToBeObscured(const LayoutPoint& paintOffset) override;

    void paintBackground(const PaintInfo&, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone);
    
    void paintFillLayer(const PaintInfo&, const Color&, const FillLayer&, const LayoutRect&, BackgroundBleedAvoidance, CompositeOperator, RenderElement* backgroundObject, BaseBackgroundColorUsage = BaseBackgroundColorUse);
    void paintFillLayers(const PaintInfo&, const Color&, const FillLayer&, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone, CompositeOperator = CompositeOperator::SourceOver, RenderElement* backgroundObject = nullptr);

    void paintMaskImages(const PaintInfo&, const LayoutRect&);

    BackgroundBleedAvoidance determineBackgroundBleedAvoidance(GraphicsContext&) const;
    bool backgroundHasOpaqueTopLayer() const;

    void computePositionedLogicalWidth(LogicalExtentComputedValues&, RenderFragmentContainer* = nullptr) const;

    LayoutUnit computeIntrinsicLogicalWidthUsing(Length logicalWidthLength, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    virtual std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsing(Length logicalHeightLength, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;
    
    virtual bool shouldComputeSizeAsReplaced() const { return isReplacedOrInlineBlock() && !isInlineBlockOrInlineTable(); }

    void mapLocalToContainer(const RenderLayerModelObject* ancestorContainer, TransformState&, OptionSet<MapCoordinatesMode>, bool* wasFixed) const override;
    const RenderObject* pushMappingToContainer(const RenderLayerModelObject*, RenderGeometryMap&) const override;
    void mapAbsoluteToLocalPoint(OptionSet<MapCoordinatesMode>, TransformState&) const override;

    void paintRootBoxFillLayers(const PaintInfo&);

    bool skipContainingBlockForPercentHeightCalculation(const RenderBox& containingBlock, bool isPerpendicularWritingMode) const;

    void incrementVisuallyNonEmptyPixelCountIfNeeded(const IntSize&);

    bool shouldIgnoreAspectRatio() const;
    bool shouldComputeLogicalWidthFromAspectRatio() const;
    LayoutUnit computeLogicalWidthFromAspectRatioInternal() const;
    LayoutUnit computeLogicalWidthFromAspectRatio(RenderFragmentContainer* = nullptr) const;
    std::pair<LayoutUnit, LayoutUnit> computeMinMaxLogicalWidthFromAspectRatio() const;

    static LayoutUnit blockSizeFromAspectRatio(LayoutUnit borderPaddingInlineSum, LayoutUnit borderPaddingBlockSum, double aspectRatio, BoxSizing boxSizing, LayoutUnit inlineSize)
    {
        if (boxSizing == BoxSizing::BorderBox)
            return LayoutUnit(inlineSize / aspectRatio);
        return LayoutUnit((inlineSize - borderPaddingInlineSum) / aspectRatio) + borderPaddingBlockSum;
    }

    void computePreferredLogicalWidths(const Length& minWidth, const Length& maxWidth, LayoutUnit borderAndPadding);

private:
    bool replacedMinMaxLogicalHeightComputesAsNone(SizeType) const;

    void updateShapeOutsideInfoAfterStyleChange(const RenderStyle&, const RenderStyle* oldStyle);

    void updateGridPositionAfterStyleChange(const RenderStyle&, const RenderStyle* oldStyle);

    bool scrollLayer(ScrollDirection, ScrollGranularity, unsigned stepCount, Element** stopElement);

    bool fixedElementLaysOutRelativeToFrame(const FrameView&) const;

    bool includeVerticalScrollbarSize() const;
    bool includeHorizontalScrollbarSize() const;

    bool isScrollableOrRubberbandableBox() const override;

    // Returns true if we did a full repaint.
    bool repaintLayerRectsForImage(WrappedImagePtr, const FillLayer& layers, bool drawingBackground);

    void computePositionedLogicalHeight(LogicalExtentComputedValues&) const;
    void computePositionedLogicalWidthUsing(SizeType, Length logicalWidth, const RenderBoxModelObject& containerBlock, TextDirection containerDirection,
                                            LayoutUnit containerLogicalWidth, LayoutUnit bordersPlusPadding,
                                            Length logicalLeft, Length logicalRight, Length marginLogicalLeft, Length marginLogicalRight,
                                            LogicalExtentComputedValues&) const;
    void computePositionedLogicalHeightUsing(SizeType, Length logicalHeightLength, const RenderBoxModelObject& containerBlock,
                                             LayoutUnit containerLogicalHeight, LayoutUnit bordersPlusPadding, LayoutUnit logicalHeight,
                                             Length logicalTop, Length logicalBottom, Length marginLogicalTop, Length marginLogicalBottom,
                                             LogicalExtentComputedValues&) const;

    void computePositionedLogicalHeightReplaced(LogicalExtentComputedValues&) const;
    void computePositionedLogicalWidthReplaced(LogicalExtentComputedValues&) const;

    LayoutUnit fillAvailableMeasure(LayoutUnit availableLogicalWidth) const;
    LayoutUnit fillAvailableMeasure(LayoutUnit availableLogicalWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const;

    virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const;
    virtual void computeIntrinsicKeywordLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
    {
        computeIntrinsicLogicalWidths(minLogicalWidth, maxLogicalWidth);
    }

    // This function calculates the minimum and maximum preferred widths for an object.
    // These values are used in shrink-to-fit layout systems.
    // These include tables, positioned objects, floats and flexible boxes.
    virtual void computePreferredLogicalWidths();

    LayoutRect frameRectForStickyPositioning() const override { return frameRect(); }

    LayoutRect computeVisibleRectUsingPaintOffset(const LayoutRect&) const;
    
    void applyTopLeftLocationOffsetWithFlipping(LayoutPoint&) const;

private:
    // The width/height of the contents + borders + padding.  The x/y location is relative to our container (which is not always our parent).
    LayoutRect m_frameRect;

protected:
    LayoutBoxExtent m_marginBox;

    // The preferred logical width of the element if it were to break its lines at every possible opportunity.
    LayoutUnit m_minPreferredLogicalWidth;
    
    // The preferred logical width of the element if it never breaks any lines at all.
    LayoutUnit m_maxPreferredLogicalWidth;

    // For inline replaced elements, the inline box that owns us.
    LegacyInlineElementBox* m_inlineBoxWrapper { nullptr };

    // Our overflow information.
    RefPtr<RenderOverflow> m_overflow;

private:
    // Used to store state between styleWillChange and styleDidChange
    static bool s_hadNonVisibleOverflow;
};

inline RenderBox* RenderBox::parentBox() const
{
    if (is<RenderBox>(parent()))
        return downcast<RenderBox>(parent());

    ASSERT(!parent());
    return nullptr;
}

inline RenderBox* RenderBox::firstChildBox() const
{
    if (is<RenderBox>(firstChild()))
        return downcast<RenderBox>(firstChild());

    ASSERT(!firstChild());
    return nullptr;
}

inline RenderBox* RenderBox::lastChildBox() const
{
    if (is<RenderBox>(lastChild()))
        return downcast<RenderBox>(lastChild());

    ASSERT(!lastChild());
    return nullptr;
}

inline RenderBox* RenderBox::previousSiblingBox() const
{
    if (is<RenderBox>(previousSibling()))
        return downcast<RenderBox>(previousSibling());

    ASSERT(!previousSibling());
    return nullptr;
}

inline RenderBox* RenderBox::nextSiblingBox() const
{
    if (is<RenderBox>(nextSibling()))
        return downcast<RenderBox>(nextSibling());

    ASSERT(!nextSibling());
    return nullptr;
}

inline void RenderBox::setInlineBoxWrapper(LegacyInlineElementBox* boxWrapper)
{
    if (boxWrapper) {
        ASSERT(!m_inlineBoxWrapper);
        // m_inlineBoxWrapper should already be 0. Deleting it is a safeguard against security issues.
        // Otherwise, there will two line box wrappers keeping the reference to this renderer, and
        // only one will be notified when the renderer is getting destroyed. The second line box wrapper
        // will keep a stale reference.
        if (UNLIKELY(m_inlineBoxWrapper != nullptr))
            deleteLineBoxWrapper();
    }

    m_inlineBoxWrapper = boxWrapper;
}

LayoutUnit synthesizedBaselineFromBorderBox(const RenderBox&, LineDirectionMode);

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderBox, isBox())