Source/WebCore/rendering/RenderBox.h

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2003-2025 Apple Inc. All rights reserved.
 * Copyright (C) 2025 Samuel Weinig <sam@webkit.org>
 *
 * 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 <WebCore/CSSPrimitiveNumeric.h>
#include <WebCore/FontBaseline.h>
#include <WebCore/LayoutRange.h>
#include <WebCore/LocalFrameView.h>
#include <WebCore/RenderBoxModelObject.h>
#include <WebCore/RenderOverflow.h>
#include <WebCore/ScrollSnapOffsetsInfo.h>
#include <WebCore/ScrollTypes.h>
#include <WebCore/ShapeOutsideInfo.h>
#include <WebCore/StyleUnevaluatedCalculation.h>
#include <wtf/TypeCasts.h>

namespace WebCore {

class LayoutRoundedRectRadii;
class RenderBlockFlow;
class RenderBoxFragmentInfo;
class RenderFragmentContainer;
class PositionedLayoutConstraints;
struct PaintInfo;

enum class AvailableLogicalHeightType : bool { ExcludeMarginBorderPadding, IncludeMarginBorderPadding };

enum class ShouldComputePreferred : bool { ComputeActual, ComputePreferred };

enum class StretchingMode { Normal, Explicit };

class RenderBox : public RenderBoxModelObject {
    WTF_MAKE_TZONE_ALLOCATED(RenderBox);
    WTF_OVERRIDE_DELETE_FOR_CHECKED_PTR(RenderBox);
public:
    virtual ~RenderBox();

    bool requiresLayer() const override;

    bool requiresLayerWithScrollableArea() const;
    bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const override;

    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); }

    inline LayoutUnit logicalLeft() const;
    inline LayoutUnit logicalRight() const;
    inline LayoutUnit logicalTop() const;
    inline LayoutUnit logicalBottom() const;
    inline LayoutUnit logicalWidth() const;
    inline LayoutUnit logicalHeight() const;

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

    inline void setLogicalLeft(LayoutUnit);
    inline void setLogicalTop(LayoutUnit);
    inline void setLogicalLocation(LayoutPoint);
    inline void setLogicalWidth(LayoutUnit);
    inline void setLogicalHeight(LayoutUnit);
    inline void setLogicalSize(LayoutSize);

    LayoutPoint location() const { return m_frameRect.location(); }
    LayoutSize locationOffset() const { return LayoutSize(x(), y()); }
    LayoutSize size() const { return m_frameRect.size(); }
    inline LayoutSize logicalSize() const;

    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; }

    inline LayoutRect marginBoxRect() const;
    LayoutRect borderBoxRect() const { return LayoutRect(LayoutPoint(), size()); }
    LayoutRect borderBoundingBox() const final { return borderBoxRect(); }
    inline LayoutSize borderBoxLogicalSize() const;

    // Don't use this; it doesn't make sense in a future world with corner-shape. Use BorderShape instead.
    WEBCORE_EXPORT LayoutRoundedRectRadii borderRadii() const;

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

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

    // 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).
    inline LayoutRect computedCSSContentBoxRect() const;

    // Bounds of the outline box in absolute coords. Respects transforms
    LayoutRect outlineBoundsForRepaint(const RenderLayerModelObject* /*repaintContainer*/, const RenderGeometryMap* = nullptr) const final;
    
    FloatRect repaintRectInLocalCoordinates(RepaintRectCalculation = RepaintRectCalculation::Fast) 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* firstInFlowChildBox() const;
    RenderBox* lastChildBox() const;
    RenderBox* lastInFlowChildBox() const;
    RenderBox* previousSiblingBox() const;
    RenderBox* previousInFlowSiblingBox() const;
    RenderBox* nextSiblingBox() const;
    RenderBox* nextInFlowSiblingBox() 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(); }
    inline LayoutUnit logicalLeftLayoutOverflow() const;
    inline LayoutUnit logicalRightLayoutOverflow() const;
    
    LayoutRect visualOverflowRect() const { return m_overflow ? m_overflow->visualOverflowRect() : borderBoxRect(); }
    inline LayoutUnit logicalLeftVisualOverflow() const;
    inline LayoutUnit logicalRightVisualOverflow() const;

    // RenderBox's basic implementation accounts for the writing mode (only).
    virtual LayoutOptionalOutsets allowedLayoutOverflow() const;
    void addLayoutOverflow(const LayoutRect&);
    void addVisualOverflow(const LayoutRect&);
    void clearOverflow();
    RenderOverflow& ensureOverflow();

    void addVisualEffectOverflow();
    LayoutRect applyVisualEffectOverflow(const LayoutRect&) const;

    enum class ComputeOverflowOptions {
        None,
        RecomputeFloats = 1 << 0,
        MarginsExtendContentArea = 1 << 1,
        MarginsExtendLayoutOverflow = 1 << 2,
    };
    virtual void addOverflowFromInFlowChildren(OptionSet<ComputeOverflowOptions> = { });
    void addOverflowFromContainedBox(const RenderBox& child, OptionSet<ComputeOverflowOptions> = { });
    void addOverflowFromFloatBox(const FloatingObject&);

    void applyTransform(TransformationMatrix&, const RenderStyle&, const FloatRect& boundingBox, OptionSet<Style::TransformResolverOption>) const override;

    inline LayoutSize contentBoxSize() const;
    inline LayoutUnit contentBoxWidth() const;
    inline LayoutUnit contentBoxHeight() const;
    inline LayoutSize contentBoxLogicalSize() const;
    inline LayoutUnit contentBoxLogicalWidth() const;
    inline LayoutUnit contentBoxLogicalHeight() const;
    inline LayoutUnit contentBoxLogicalWidth(LayoutUnit overridingBorderBoxWidth) const;
    inline LayoutUnit contentBoxLogicalHeight(LayoutUnit overridingBorderBoxHeight) const;

    inline LayoutUnit paddingBoxWidth() const;
    inline LayoutUnit paddingBoxHeight() const;
    LayoutRect paddingBoxRect() const;
    inline LayoutRect paddingBoxRectIncludingScrollbar() const;

    // 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.
    inline LayoutUnit clientLeft() const;
    inline LayoutUnit clientTop() const;
    WEBCORE_EXPORT LayoutUnit clientWidth() const;
    WEBCORE_EXPORT LayoutUnit clientHeight() const;
    inline LayoutUnit clientLogicalWidth() const;
    inline LayoutUnit clientLogicalHeight() const;
    inline LayoutUnit clientLogicalBottom() const;
    inline LayoutRect clientBoxRect() const;

    // 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&);
    virtual 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 WritingMode writingMode) const { return m_marginBox.logicalLeft(writingMode); }
    LayoutUnit marginLogicalRight(const WritingMode writingMode) const { return m_marginBox.logicalRight(writingMode); }
    LayoutUnit marginLogicalLeft() const { return marginLogicalLeft(writingMode()); }
    LayoutUnit marginLogicalRight() const { return marginLogicalRight(writingMode()); }

    LayoutUnit marginBefore(const WritingMode writingMode) const override { return m_marginBox.before(writingMode); }
    LayoutUnit marginAfter(const WritingMode writingMode) const override { return m_marginBox.after(writingMode); }
    LayoutUnit marginStart(const WritingMode writingMode) const override { return m_marginBox.start(writingMode); }
    LayoutUnit marginEnd(const WritingMode writingMode) const override { return m_marginBox.end(writingMode); }
    LayoutUnit marginBefore() const { return marginBefore(writingMode()); }
    LayoutUnit marginAfter() const { return marginAfter(writingMode()); }
    LayoutUnit marginStart() const { return marginStart(writingMode()); }
    LayoutUnit marginEnd() const { return marginEnd(writingMode()); }

    inline LayoutUnit marginBoxLogicalHeight(WritingMode) const;

    void setMarginBefore(LayoutUnit value, const WritingMode writingMode) { m_marginBox.setBefore(value, writingMode); }
    void setMarginAfter(LayoutUnit value, const WritingMode writingMode) { m_marginBox.setAfter(value, writingMode); }
    void setMarginStart(LayoutUnit value, const WritingMode writingMode) { m_marginBox.setStart(value, writingMode); }
    void setMarginEnd(LayoutUnit value, const WritingMode writingMode) { m_marginBox.setEnd(value, writingMode); }
    void setMarginBefore(LayoutUnit value) { setMarginBefore(value, writingMode()); }
    void setMarginAfter(LayoutUnit value) { setMarginAfter(value, writingMode()); }
    void setMarginStart(LayoutUnit value) { setMarginStart(value, writingMode()); }
    void setMarginEnd(LayoutUnit value) { setMarginEnd(value, writingMode()); }

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

    void boundingRects(Vector<LayoutRect>&, 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;

    virtual LayoutUnit minPreferredLogicalWidth() const;
    virtual LayoutUnit maxPreferredLogicalWidth() const;
    virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const = 0;

    std::optional<LayoutUnit> overridingBorderBoxLogicalWidth() const;
    std::optional<LayoutUnit> overridingBorderBoxLogicalHeight() const;
    void setOverridingBorderBoxLogicalHeight(LayoutUnit);
    void setOverridingBorderBoxLogicalWidth(LayoutUnit);
    void clearOverridingBorderBoxLogicalHeight();
    void clearOverridingBorderBoxLogicalWidth();
    void clearOverridingSize();

    // Grid item's containing block is not the grid container, but the grid area, for which we don't have a renderer.
    using GridAreaSize = std::optional<LayoutUnit>;
    std::optional<GridAreaSize> gridAreaContentWidth(WritingMode) const;
    std::optional<GridAreaSize> gridAreaContentHeight(WritingMode) const;
    std::optional<GridAreaSize> gridAreaContentLogicalWidth() const;
    std::optional<GridAreaSize> gridAreaContentLogicalHeight() const;
    void setGridAreaContentLogicalWidth(GridAreaSize);
    void setGridAreaContentLogicalHeight(GridAreaSize);
    void clearGridAreaContentSize();
    void clearGridAreaContentLogicalHeight();

    // 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.
    std::optional<Style::PreferredSize> overridingLogicalHeightForFlexBasisComputation() const;
    std::optional<Style::PreferredSize> overridingLogicalWidthForFlexBasisComputation() const;
    void setOverridingBorderBoxLogicalHeightForFlexBasisComputation(const Style::PreferredSize&);
    void setOverridingBorderBoxLogicalWidthForFlexBasisComputation(const Style::PreferredSize&);
    void clearOverridingLogicalHeightForFlexBasisComputation();
    void clearOverridingLogicalWidthForFlexBasisComputation();

    void markMarginAsTrimmed(Style::MarginTrimSide);
    void clearTrimmedMarginsMarkings();
    bool hasTrimmedMargin(std::optional<Style::MarginTrimSide>) const;

    LayoutSize offsetFromContainer(const RenderElement&, const LayoutPoint&, bool* offsetDependsOnPoint = nullptr) const override;
    
    LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(const Style::Length<CSS::Nonnegative, float>& logicalWidth) const;
    LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(const Style::Length<CSS::NonnegativeUnzoomed, float>& logicalWidth) const;
    LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit computedLogicalWidth) const;
    LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(const Style::Length<CSS::Nonnegative, float>& logicalWidth) const;
    LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(const Style::Length<CSS::NonnegativeUnzoomed, float>& logicalWidth) const;
    LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit computedLogicalWidth) const;

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

    struct ComputedMarginValues {
        LayoutUnit before;
        LayoutUnit after;
        LayoutUnit start;
        LayoutUnit end;
    };
    struct LogicalExtentComputedValues {
        LayoutUnit extent;
        LayoutUnit position;
        ComputedMarginValues 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, std::optional<LayoutUnit> availableSpaceAdjustedWithFloats, 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);

    RenderFragmentContainer* clampToStartAndEndFragments(RenderFragmentContainer*) const;
    bool hasFragmentRangeInFragmentedFlow() const;
    virtual LayoutUnit offsetFromLogicalTopOfFirstPage() const;

    RepaintRects localRectsForRepaint(RepaintOutlineBounds) const override;
    std::optional<RepaintRects> computeVisibleRectsInContainer(const RepaintRects&, const RenderLayerModelObject* container, VisibleRectContext) const override;
    void repaintDuringLayoutIfMoved(const LayoutRect&);
    virtual void repaintOverhangingFloats(bool paintAllDescendants);

    LayoutUnit containingBlockLogicalWidthForContent() const override;
    LayoutUnit containingBlockLogicalHeightForContent(AvailableLogicalHeightType) const;
    LayoutRange containingBlockRangeForPositioned(const RenderBoxModelObject& containingBlock, BoxAxis physicalAxis) const;
    LayoutUnit containingBlockAvailableLineWidth() const;
    LayoutUnit perpendicularContainingBlockLogicalHeight() const;

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

    void overrideLogicalHeightForSizeContainment();

    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;

    enum class RenderBoxFragmentInfoFlags : bool { CacheRenderBoxFragmentInfo, DoNotCacheRenderBoxFragmentInfo };
    RenderBoxFragmentInfo* renderBoxFragmentInfo(RenderFragmentContainer*, RenderBoxFragmentInfoFlags = RenderBoxFragmentInfoFlags::CacheRenderBoxFragmentInfo) const;
    void computeLogicalWidth(LogicalExtentComputedValues&) const;

    inline bool stretchesToViewport() const;

    virtual LayoutSize intrinsicSize() const { return LayoutSize(); }
    LayoutUnit intrinsicLogicalWidth() const;
    inline LayoutUnit intrinsicLogicalHeight() const;

    // 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 sizesPreferredLogicalWidthToFitContent() const;

    inline bool hasStretchedLogicalHeight(StretchingMode = StretchingMode::Normal) const;
    inline bool hasStretchedLogicalWidth(StretchingMode = StretchingMode::Normal) const;
    bool isStretchingColumnFlexItem() const;
    
    LayoutUnit shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart, LayoutUnit childMarginEnd, const RenderBlock& containingBlock) const;

    LayoutUnit computeLogicalWidthUsing(const Style::PreferredSize& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock) const;
    LayoutUnit computeLogicalWidthUsing(const Style::MinimumSize& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock) const;
    LayoutUnit computeLogicalWidthUsing(const Style::MaximumSize& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock) const;
    LayoutUnit computeLogicalWidthUsing(const Style::FlexBasis& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock) const;

    std::optional<LayoutUnit> computeLogicalHeightUsing(const Style::PreferredSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeLogicalHeightUsing(const Style::MinimumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeLogicalHeightUsing(const Style::MaximumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;

    std::optional<LayoutUnit> computeContentLogicalHeight(const Style::PreferredSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeContentLogicalHeight(const Style::MinimumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeContentLogicalHeight(const Style::MaximumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    std::optional<LayoutUnit> computeContentLogicalHeight(const Style::FlexBasis& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;

    enum class UpdatePercentageHeightDescendants : bool { No, Yes };
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::PreferredSize& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::MinimumSize& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::MaximumSize& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::FlexBasis& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::Percentage<CSS::Nonnegative, float>& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    std::optional<LayoutUnit> computePercentageLogicalHeight(const Style::UnevaluatedCalculation<CSS::LengthPercentage<CSS::NonnegativeUnzoomed, float>>& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    bool hasAutoHeightOrContainingBlockWithAutoHeight(UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;

    virtual LayoutUnit availableLogicalHeight(AvailableLogicalHeightType) const;
    LayoutUnit availableLogicalHeightUsing(const Style::PreferredSize&, AvailableLogicalHeightType) const;

    WEBCORE_EXPORT virtual int verticalScrollbarWidth() const;
    WEBCORE_EXPORT virtual int horizontalScrollbarHeight() const;
    int intrinsicScrollbarLogicalWidthIncludingGutter() const;
    inline int scrollbarLogicalWidth() const;
    inline int scrollbarLogicalHeight() const;
    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;

    inline bool scrollsOverflow() const;
    inline bool scrollsOverflowX() const;
    inline bool scrollsOverflowY() const;

    inline bool hasHorizontalOverflow() const;
    inline bool hasVerticalOverflow() const;

    inline bool hasScrollableOverflow() const;
    inline bool hasScrollableOverflowX() const;
    inline bool hasScrollableOverflowY() const;

    inline bool isScrollContainerX() const;
    inline bool isScrollContainerY() const;

    LayoutBoxExtent scrollPaddingForViewportRect(const LayoutRect& viewportRect);

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

    virtual LayoutRect overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy = OverlayScrollbarSizeRelevancy::IgnoreOverlayScrollbarSize, PaintPhase = PaintPhase::BlockBackground) const;
    virtual LayoutRect overflowClipRectForChildLayers(const LayoutPoint& location, OverlayScrollbarSizeRelevancy relevancy) const { return overflowClipRect(location, relevancy); }
    LayoutRect clipRect(const LayoutPoint& location) 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);

    ControlPart* ensureControlPart();
    ControlPart* ensureControlPartForRenderer();
    ControlPart* ensureControlPartForBorderOnly();
    ControlPart* ensureControlPartForDecorations();

    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 an out-of-flow box 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 tryLayoutDoingOutOfFlowMovementOnly()
    {
        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);

    PositionWithAffinity positionForPoint(const LayoutPoint&, HitTestSource, const RenderFragmentContainer*) override;

    void removeFloatingAndInvalidateForLayout();
    void removeFloatingOrOutOfFlowChildFromBlockLists();
    
    virtual std::optional<LayoutUnit> firstLineBaseline() const { return { }; }
    virtual std::optional<LayoutUnit> lastLineBaseline() const { return { }; }

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

    virtual void markForPaginationRelayoutIfNeeded() { }
    
    LayoutUnit lineHeight() const;

    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;
    FloatPoint flipForWritingMode(const FloatPoint&) const;

    void flipForWritingMode(LayoutRect&) const;
    void flipForWritingMode(FloatRect&) const;
    void flipForWritingMode(RepaintRects&) 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; // Defined in RenderBoxInlines.h
    LayoutSize topLeftLocationOffset() const; // Defined in RenderBoxInlines.h

    LayoutRect logicalVisualOverflowRectForPropagation(const WritingMode) const;
    LayoutRect visualOverflowRectForPropagation(const WritingMode) const;
    LayoutRect logicalLayoutOverflowRectForPropagation(const WritingMode) const;
    LayoutRect layoutOverflowRectForPropagation(const WritingMode) const;
    LayoutRect applyPaintGeometryTransformToRect(LayoutRect) const;
    LayoutRect convertRectToParentWritingMode(LayoutRect, const WritingMode parentWritingMode) const;

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

    virtual bool shouldInvalidatePreferredWidths() const;

    ScrollPosition scrollPosition() const;
    ScrollPosition constrainedScrollPosition() 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(RepaintRects&, const RenderLayerModelObject* container, VisibleRectContext) const final;

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

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

        auto layoutOverflowRect = m_overflow->layoutOverflowRect();
        auto paddingBoxRect = flippedClientBoxRect();
        return layoutOverflowRect.x() < paddingBoxRect.x() || layoutOverflowRect.maxX() > paddingBoxRect.maxX();
    }

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

        auto layoutOverflowRect = m_overflow->layoutOverflowRect();
        auto paddingBoxRect = flippedClientBoxRect();
        return layoutOverflowRect.y() < paddingBoxRect.y() || layoutOverflowRect.maxY() > paddingBoxRect.maxY();
    }

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

    // 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()->isRenderFlexibleBox() && !isExcludedFromNormalLayout(); }

    inline bool isColumnSpanner() const;

    virtual void adjustBorderBoxRectForPainting(LayoutRect&) { };

    bool shouldComputeLogicalHeightFromAspectRatio() const;

    bool shouldIgnoreLogicalMinMaxWidthSizes() const;
    bool shouldIgnoreLogicalMinMaxHeightSizes() const;

    // The explicit intrinsic inner size of contain-intrinsic-size
    std::optional<LayoutUnit> explicitIntrinsicInnerWidth() const;
    std::optional<LayoutUnit> explicitIntrinsicInnerHeight() const;
    inline std::optional<LayoutUnit> explicitIntrinsicInnerLogicalWidth() const;
    inline std::optional<LayoutUnit> explicitIntrinsicInnerLogicalHeight() const;

    void updateFloatPainterAfterSelfPaintingLayerChange();

    bool computeHasTransformRelatedProperty(const RenderStyle&) const;

    ShapeOutsideInfo* shapeOutsideInfo() const;

    LayoutUnit computeIntrinsicLogicalWidthUsing(CSS::Keyword::WebkitFillAvailable, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(CSS::Keyword::MinIntrinsic, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(CSS::Keyword::MaxContent, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(CSS::Keyword::MinContent, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(CSS::Keyword::FitContent, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(const Style::PreferredSize& logicalWidth, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(const Style::MinimumSize& logicalWidth, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(const Style::MaximumSize& logicalWidth, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;
    LayoutUnit computeIntrinsicLogicalWidthUsing(const Style::FlexBasis& logicalWidth, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;

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

    void invalidateAncestorBackgroundObscurationStatus();

    inline bool backgroundIsKnownToBeObscured(const LayoutPoint& paintOffset);

    virtual bool hasIntrinsicAspectRatio() const { return isBlockLevelReplacedOrAtomicInline() && (isImage() || isRenderVideo() || isRenderHTMLCanvas() || isRenderViewTransitionCapture()); }

protected:
    RenderBox(Type, Element&, RenderStyle&&, OptionSet<TypeFlag> = { }, TypeSpecificFlags = { });
    RenderBox(Type, Document&, RenderStyle&&, OptionSet<TypeFlag> = { }, TypeSpecificFlags = { });

    void styleWillChange(Style::Difference, const RenderStyle& newStyle) override;
    void styleDidChange(Style::Difference, const RenderStyle* oldStyle) override;
    void updateFromStyle() override;

    void willBeDestroyed() override;

    inline bool shouldTrimChildMargin(Style::MarginTrimSide, const RenderBox&) const;
    virtual bool isChildEligibleForMarginTrim(Style::MarginTrimSide, const RenderBox&) const { return false; }

    virtual bool shouldResetLogicalHeightBeforeLayout() const;
    void resetLogicalHeightBeforeLayoutIfNeeded();

    // 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;
    virtual bool computeBackgroundIsKnownToBeObscured(const LayoutPoint& paintOffset);

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

    void clipToPaddingBoxShape(GraphicsContext&, const LayoutPoint&, float deviceScaleFactor) const;
    void clipToContentBoxShape(GraphicsContext&, const LayoutPoint&, float deviceScaleFactor) const;

    BleedAvoidance determineBleedAvoidance(GraphicsContext&) const;
    bool backgroundHasOpaqueTopLayer() const;

    void computeOutOfFlowPositionedLogicalWidth(LogicalExtentComputedValues&) const;

    std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsing(const Style::PreferredSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;
    std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsing(const Style::MinimumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;
    std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsing(const Style::MaximumSize& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;
    std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsing(const Style::FlexBasis& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;

    LayoutRect localOutlineBoundsRepaintRect() const;

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

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

    void incrementVisuallyNonEmptyPixelCountIfNeeded(const IntSize&);

    std::optional<double> resolveAspectRatio() const;
    bool shouldIgnoreAspectRatio() const;
    bool isRenderReplacedWithIntrinsicRatio() const;
    bool shouldComputeLogicalWidthFromAspectRatio() const;
    LayoutUnit computeLogicalWidthFromAspectRatioInternal() const;
    LayoutUnit computeLogicalWidthFromAspectRatio() const;
    std::pair<LayoutUnit, LayoutUnit> computeMinMaxLogicalWidthFromAspectRatio() const;
    std::pair<LayoutUnit, LayoutUnit> computeMinMaxLogicalHeightFromAspectRatio() const;
    enum class ConstrainDimension { Width, Height };
    enum class MinimumSizeIsAutomaticContentBased : bool { No, Yes };
    void constrainLogicalMinMaxSizesByAspectRatio(LayoutUnit& minSize, LayoutUnit& maxSize, LayoutUnit computedSize, MinimumSizeIsAutomaticContentBased, ConstrainDimension) const;

    static LayoutUnit blockSizeFromAspectRatio(LayoutUnit borderPaddingInlineSum, LayoutUnit borderPaddingBlockSum, double aspectRatioValue, BoxSizing, LayoutUnit inlineSize, const Style::AspectRatio&, bool isRenderReplaced);

    void computePreferredLogicalWidths(const Style::MinimumSize& minLogicalWidth, const Style::MaximumSize& maxLogicalWidth, LayoutUnit borderAndPaddingLogicalWidth);

    bool isAspectRatioDegenerate(double aspectRatio) const { return !aspectRatio || isnan(aspectRatio); }

    bool overflowChangesMayAffectLayout() const final;

private:
    void addOverflowWithRendererOffset(const RenderBox&, LayoutSize, OptionSet<ComputeOverflowOptions> = { });

    void updateShapeOutsideInfoAfterStyleChange(const RenderStyle&, const RenderStyle* oldStyle, Style::Difference);

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

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

    bool fixedElementLaysOutRelativeToFrame(const LocalFrameView&) const;

    template<typename Function> LayoutUnit computeOrTrimInlineMargin(const RenderBlock& containingBlock, Style::MarginTrimSide marginSide, NOESCAPE const Function& computeInlineMargin) const;

    bool isScrollableOrRubberbandableBox() const override;

    // Returns true if we did a full repaint.
    template<typename Layers> bool repaintLayerRectsForImage(WrappedImagePtr, const Layers&, bool drawingBackground);

    void computeOutOfFlowPositionedLogicalHeight(LogicalExtentComputedValues&) const;

    template<typename SizeType> LayoutUnit computeOutOfFlowPositionedLogicalWidthUsing(const SizeType&, const PositionedLayoutConstraints&) const;

    LayoutUnit computeOutOfFlowPositionedLogicalHeightUsing(const Style::PreferredSize& logicalHeight, LayoutUnit computedHeight, const PositionedLayoutConstraints& blockConstraints) const;
    LayoutUnit computeOutOfFlowPositionedLogicalHeightUsing(const Style::MinimumSize& logicalHeight, LayoutUnit computedHeight, const PositionedLayoutConstraints& blockConstraints) const;
    LayoutUnit computeOutOfFlowPositionedLogicalHeightUsing(const Style::MaximumSize& logicalHeight, LayoutUnit computedHeight, const PositionedLayoutConstraints& blockConstraints) const;

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

    template<typename Keyword> void computeIntrinsicKeywordLogicalWidths(Keyword, LayoutUnit borderAndPadding, LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const;
    virtual void computeIntrinsicKeywordLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
    {
        computeIntrinsicLogicalWidths(minLogicalWidth, maxLogicalWidth);
    }

    template<typename SizeType> LayoutUnit computeLogicalWidthUsingGeneric(const SizeType& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock& containingBlock) const;
    template<typename SizeType> LayoutUnit computeIntrinsicLogicalWidthUsingGeneric(const SizeType& logicalWidth, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const;

    template<typename SizeType> std::optional<LayoutUnit> computeLogicalHeightUsingGeneric(const SizeType& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    template<typename SizeType> std::optional<LayoutUnit> computeIntrinsicLogicalContentHeightUsingGeneric(const SizeType& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const;
    template<typename SizeType> std::optional<LayoutUnit> computePercentageLogicalHeightGeneric(const SizeType& logicalHeight, UpdatePercentageHeightDescendants = UpdatePercentageHeightDescendants::Yes) const;
    template<typename SizeType> std::optional<LayoutUnit> computeContentLogicalHeightGeneric(const SizeType& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;
    template<typename SizeType> std::optional<LayoutUnit> computeContentAndScrollbarLogicalHeightUsing(const SizeType& logicalHeight, std::optional<LayoutUnit> intrinsicContentHeight) const;

    // 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();
    bool shouldComputePreferredLogicalWidthsFromStyle() const;

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

    RepaintRects computeVisibleRectsUsingPaintOffset(const RepaintRects&) const;
    
    LayoutPoint topLeftLocationWithFlipping() const;

    ShapeOutsideInfo& ensureShapeOutsideInfo();
    void removeShapeOutsideInfo();

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;

    // Our overflow information.
    std::unique_ptr<RenderOverflow> m_overflow;

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

inline bool isSkippedContentRoot(const RenderBox&);

inline RenderBox* RenderBox::parentBox() const
{
    if (auto* box = dynamicDowncast<RenderBox>(parent()))
        return box;

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

inline RenderBox* RenderBox::firstChildBox() const
{
    if (CheckedPtr box = dynamicDowncast<RenderBox>(firstChild()))
        return box.unsafeGet();

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

inline RenderBox* RenderBox::firstInFlowChildBox() const
{
    return dynamicDowncast<RenderBox>(firstInFlowChild());
}

inline RenderBox* RenderBox::lastChildBox() const
{
    if (CheckedPtr box = dynamicDowncast<RenderBox>(lastChild()))
        return box.unsafeGet();

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

inline RenderBox* RenderBox::lastInFlowChildBox() const 
{
    return dynamicDowncast<RenderBox>(lastInFlowChild());
}

inline RenderBox* RenderBox::previousSiblingBox() const
{
    if (CheckedPtr box = dynamicDowncast<RenderBox>(previousSibling()))
        return box.unsafeGet();

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

inline RenderBox* RenderBox::previousInFlowSiblingBox() const
{
    for (CheckedPtr curr = previousSiblingBox(); curr; curr = curr->previousSiblingBox()) {
        if (!curr->isFloatingOrOutOfFlowPositioned())
            return curr.unsafeGet();
    }
    return nullptr;
}

inline RenderBox* RenderBox::nextSiblingBox() const
{
    if (CheckedPtr box = dynamicDowncast<RenderBox>(nextSibling()))
        return box.unsafeGet();

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

inline RenderBox* RenderBox::nextInFlowSiblingBox() const
{
    for (CheckedPtr curr = nextSiblingBox(); curr; curr = curr->nextSiblingBox()) {
        if (!curr->isFloatingOrOutOfFlowPositioned())
            return curr.unsafeGet();
    }
    return nullptr;
}

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderBox, isRenderBox())