/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 * Copyright (C) 2003, 2006, 2007 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.
 *
 */

#ifndef LayoutBox_h
#define LayoutBox_h

#include "core/CoreExport.h"
#include "core/layout/LayoutBoxModelObject.h"
#include "core/layout/OverflowModel.h"
#include "platform/scroll/ScrollTypes.h"
#include "wtf/Compiler.h"
#include "wtf/PtrUtil.h"
#include <memory>

namespace blink {

class LayoutBlockFlow;
class LayoutMultiColumnSpannerPlaceholder;
class ShapeOutsideInfo;

struct PaintInfo;

enum SizeType { MainOrPreferredSize, MinSize, MaxSize };
enum AvailableLogicalHeightType {
  ExcludeMarginBorderPadding,
  IncludeMarginBorderPadding
};
// When painting, overlay scrollbars do not take up space and should not affect
// clipping behavior. During hit testing, overlay scrollbars behave like regular
// scrollbars and should change how hit testing is clipped.
enum MarginDirection { BlockDirection, InlineDirection };
enum BackgroundRectType { BackgroundClipRect, BackgroundKnownOpaqueRect };

enum ShouldComputePreferred { ComputeActual, ComputePreferred };

using SnapAreaSet = HashSet<const LayoutBox*>;

struct LayoutBoxRareData {
  WTF_MAKE_NONCOPYABLE(LayoutBoxRareData);
  USING_FAST_MALLOC(LayoutBoxRareData);

 public:
  LayoutBoxRareData()
      : m_spannerPlaceholder(nullptr),
        m_overrideLogicalContentWidth(-1),
        m_overrideLogicalContentHeight(-1),
        m_hasOverrideContainingBlockContentLogicalWidth(false),
        m_hasOverrideContainingBlockContentLogicalHeight(false),
        m_percentHeightContainer(nullptr),
        m_snapContainer(nullptr),
        m_snapAreas(nullptr) {}

  // For spanners, the spanner placeholder that lays us out within the multicol
  // container.
  LayoutMultiColumnSpannerPlaceholder* m_spannerPlaceholder;

  LayoutUnit m_overrideLogicalContentWidth;
  LayoutUnit m_overrideLogicalContentHeight;

  bool m_hasOverrideContainingBlockContentLogicalWidth;
  bool m_hasOverrideContainingBlockContentLogicalHeight;
  LayoutUnit m_overrideContainingBlockContentLogicalWidth;
  LayoutUnit m_overrideContainingBlockContentLogicalHeight;

  LayoutUnit m_offsetToNextPage;

  LayoutUnit m_paginationStrut;

  LayoutBlock* m_percentHeightContainer;
  // For snap area, the owning snap container.
  LayoutBox* m_snapContainer;
  // For snap container, the descendant snap areas that contribute snap
  // points.
  std::unique_ptr<SnapAreaSet> m_snapAreas;

  SnapAreaSet& ensureSnapAreas() {
    if (!m_snapAreas)
      m_snapAreas = WTF::wrapUnique(new SnapAreaSet);

    return *m_snapAreas;
  }
};

// LayoutBox implements the full CSS box model.
//
// LayoutBoxModelObject only introduces some abstractions for LayoutInline and
// LayoutBox. The logic for the model is in LayoutBox, e.g. the storage for the
// rectangle and offset forming the CSS box (m_frameRect) and the getters for
// the different boxes.
//
// LayoutBox is also the uppermost class to support scrollbars, however the
// logic is delegated to PaintLayerScrollableArea.
// Per the CSS specification, scrollbars should "be inserted between the inner
// border edge and the outer padding edge".
// (see http://www.w3.org/TR/CSS21/visufx.html#overflow)
// Also the scrollbar width / height are removed from the content box. Taking
// the following example:
//
// <!DOCTYPE html>
// <style>
// ::-webkit-scrollbar {
//     /* Force non-overlay scrollbars */
//     width: 10px;
//     height: 20px;
// }
// </style>
// <div style="overflow:scroll; width: 100px; height: 100px">
//
// The <div>'s content box is not 100x100 as specified in the style but 90x80 as
// we remove the scrollbars from the box.
//
// The presence of scrollbars is determined by the 'overflow' property and can
// be conditioned on having layout overflow (see OverflowModel for more details
// on how we track overflow).
//
// There are 2 types of scrollbars:
// - non-overlay scrollbars take space from the content box.
// - overlay scrollbars don't and just overlay hang off from the border box,
//   potentially overlapping with the padding box's content.
// For more details on scrollbars, see PaintLayerScrollableArea.
//
//
// ***** THE BOX MODEL *****
// The CSS box model is based on a series of nested boxes:
// http://www.w3.org/TR/CSS21/box.html
//
//       |----------------------------------------------------|
//       |                                                    |
//       |                   margin-top                       |
//       |                                                    |
//       |     |-----------------------------------------|    |
//       |     |                                         |    |
//       |     |             border-top                  |    |
//       |     |                                         |    |
//       |     |    |--------------------------|----|    |    |
//       |     |    |                          |    |    |    |
//       |     |    |       padding-top        |####|    |    |
//       |     |    |                          |####|    |    |
//       |     |    |    |----------------|    |####|    |    |
//       |     |    |    |                |    |    |    |    |
//       | ML  | BL | PL |  content box   | PR | SW | BR | MR |
//       |     |    |    |                |    |    |    |    |
//       |     |    |    |----------------|    |    |    |    |
//       |     |    |                          |    |    |    |
//       |     |    |      padding-bottom      |    |    |    |
//       |     |    |--------------------------|----|    |    |
//       |     |    |                      ####|    |    |    |
//       |     |    |     scrollbar height ####| SC |    |    |
//       |     |    |                      ####|    |    |    |
//       |     |    |-------------------------------|    |    |
//       |     |                                         |    |
//       |     |           border-bottom                 |    |
//       |     |                                         |    |
//       |     |-----------------------------------------|    |
//       |                                                    |
//       |                 margin-bottom                      |
//       |                                                    |
//       |----------------------------------------------------|
//
// BL = border-left
// BR = border-right
// ML = margin-left
// MR = margin-right
// PL = padding-left
// PR = padding-right
// SC = scroll corner (contains UI for resizing (see the 'resize' property)
// SW = scrollbar width
//
// Those are just the boxes from the CSS model. Extra boxes are tracked by Blink
// (e.g. the overflows). Thus it is paramount to know which box a function is
// manipulating. Also of critical importance is the coordinate system used (see
// the COORDINATE SYSTEMS section in LayoutBoxModelObject).
class CORE_EXPORT LayoutBox : public LayoutBoxModelObject {
 public:
  explicit LayoutBox(ContainerNode*);

  PaintLayerType layerTypeRequired() const override;

  bool backgroundIsKnownToBeOpaqueInRect(
      const LayoutRect& localRect) const override;

  virtual bool backgroundShouldAlwaysBeClipped() const { return false; }

  // Use this with caution! No type checking is done!
  LayoutBox* firstChildBox() const;
  LayoutBox* firstInFlowChildBox() const;
  LayoutBox* lastChildBox() const;

  int pixelSnappedWidth() const { return m_frameRect.pixelSnappedWidth(); }
  int pixelSnappedHeight() const { return m_frameRect.pixelSnappedHeight(); }

  void setX(LayoutUnit x) {
    if (x == m_frameRect.x())
      return;
    m_frameRect.setX(x);
    locationChanged();
  }
  void setY(LayoutUnit y) {
    if (y == m_frameRect.y())
      return;
    m_frameRect.setY(y);
    locationChanged();
  }
  void setWidth(LayoutUnit width) {
    if (width == m_frameRect.width())
      return;
    m_frameRect.setWidth(width);
    sizeChanged();
  }
  void setHeight(LayoutUnit height) {
    if (height == m_frameRect.height())
      return;
    m_frameRect.setHeight(height);
    sizeChanged();
  }

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

  // Logical height of the object, including content overflowing the
  // border-after edge.
  virtual LayoutUnit logicalHeightWithVisibleOverflow() const;

  LayoutUnit constrainLogicalWidthByMinMax(LayoutUnit,
                                           LayoutUnit,
                                           LayoutBlock*) const;
  LayoutUnit constrainLogicalHeightByMinMax(
      LayoutUnit logicalHeight,
      LayoutUnit intrinsicContentHeight) const;
  LayoutUnit constrainContentBoxLogicalHeightByMinMax(
      LayoutUnit logicalHeight,
      LayoutUnit intrinsicContentHeight) const;

  int pixelSnappedLogicalHeight() const {
    return style()->isHorizontalWritingMode() ? pixelSnappedHeight()
                                              : pixelSnappedWidth();
  }
  int pixelSnappedLogicalWidth() const {
    return style()->isHorizontalWritingMode() ? pixelSnappedWidth()
                                              : pixelSnappedHeight();
  }

  LayoutUnit minimumLogicalHeightForEmptyLine() const {
    return borderAndPaddingLogicalHeight() + scrollbarLogicalHeight() +
           lineHeight(true,
                      isHorizontalWritingMode() ? HorizontalLine : VerticalLine,
                      PositionOfInteriorLineBoxes);
  }

  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);
  }

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

  void setLocation(const LayoutPoint& location) {
    if (location == m_frameRect.location())
      return;
    m_frameRect.setLocation(location);
    locationChanged();
  }

  // The ancestor box that this object's location and physicalLocation are
  // relative to.
  virtual LayoutBox* locationContainer() const;

  // FIXME: Currently scrollbars are using int geometry and positioned based on
  // pixelSnappedBorderBoxRect whose size may change when location changes
  // because of pixel snapping. This function is used to change location of the
  // LayoutBox outside of LayoutBox::layout(). Will remove when we use
  // LayoutUnits for scrollbars.
  void setLocationAndUpdateOverflowControlsIfNeeded(const LayoutPoint&);

  void setSize(const LayoutSize& size) {
    if (size == m_frameRect.size())
      return;
    m_frameRect.setSize(size);
    sizeChanged();
  }
  void move(LayoutUnit dx, LayoutUnit dy) {
    if (!dx && !dy)
      return;
    m_frameRect.move(dx, dy);
    locationChanged();
  }

  // This function is in the container's coordinate system, meaning
  // that it includes the logical top/left offset and the
  // inline-start/block-start margins.
  LayoutRect frameRect() const { return m_frameRect; }
  void setFrameRect(const LayoutRect& rect) {
    setLocation(rect.location());
    setSize(rect.size());
  }

  // Note that those functions have their origin at this box's CSS border box.
  // As such their location doesn't account for 'top'/'left'.
  LayoutRect borderBoxRect() const { return LayoutRect(LayoutPoint(), size()); }
  LayoutRect paddingBoxRect() const {
    return LayoutRect(LayoutUnit(borderLeft()), LayoutUnit(borderTop()),
                      clientWidth(), clientHeight());
  }
  IntRect pixelSnappedBorderBoxRect() const {
    return IntRect(IntPoint(), m_frameRect.pixelSnappedSize());
  }
  IntRect borderBoundingBox() const final {
    return pixelSnappedBorderBoxRect();
  }

  // The content area of the box (excludes padding - and intrinsic padding for
  // table cells, etc... - and border).
  DISABLE_CFI_PERF LayoutRect contentBoxRect() const {
    return LayoutRect(borderLeft() + paddingLeft(), borderTop() + paddingTop(),
                      contentWidth(), contentHeight());
  }
  LayoutSize contentBoxOffset() const {
    return LayoutSize(borderLeft() + paddingLeft(), borderTop() + paddingTop());
  }
  // The content box in absolute coords. Ignores transforms.
  IntRect absoluteContentBox() const;
  // The offset of the content box in absolute coords, ignoring transforms.
  IntSize absoluteContentBoxOffset() const;
  // The content box converted to absolute coords (taking transforms into
  // account).
  FloatQuad absoluteContentQuad() const;
  // The enclosing rectangle of the background with given opacity requirement.
  LayoutRect backgroundRect(BackgroundRectType) 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(),
        clientWidth() - computedCSSPaddingLeft() - computedCSSPaddingRight(),
        clientHeight() - computedCSSPaddingTop() - computedCSSPaddingBottom());
  }

  void addOutlineRects(Vector<LayoutRect>&,
                       const LayoutPoint& additionalOffset,
                       IncludeBlockVisualOverflowOrNot) const override;

  // Use this with caution! No type checking is done!
  LayoutBox* previousSiblingBox() const;
  LayoutBox* previousInFlowSiblingBox() const;
  LayoutBox* nextSiblingBox() const;
  LayoutBox* nextInFlowSiblingBox() const;
  LayoutBox* parentBox() const;

  // Return the previous sibling column set or spanner placeholder. Only to be
  // used on multicol container children.
  LayoutBox* previousSiblingMultiColumnBox() const;
  // Return the next sibling column set or spanner placeholder. Only to be used
  // on multicol container children.
  LayoutBox* nextSiblingMultiColumnBox() const;

  bool canResize() 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 vertical-rl, the
  // left/right 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.
  LayoutRect noOverflowRect() const;
  LayoutRect layoutOverflowRect() const {
    return m_overflow ? m_overflow->layoutOverflowRect() : noOverflowRect();
  }
  IntRect pixelSnappedLayoutOverflowRect() const {
    return pixelSnappedIntRect(layoutOverflowRect());
  }
  LayoutSize maxLayoutOverflow() const {
    return LayoutSize(layoutOverflowRect().maxX(), layoutOverflowRect().maxY());
  }
  LayoutUnit logicalLeftLayoutOverflow() const {
    return style()->isHorizontalWritingMode() ? layoutOverflowRect().x()
                                              : layoutOverflowRect().y();
  }
  LayoutUnit logicalRightLayoutOverflow() const {
    return style()->isHorizontalWritingMode() ? layoutOverflowRect().maxX()
                                              : layoutOverflowRect().maxY();
  }

  LayoutRect visualOverflowRect() const override;
  LayoutUnit logicalLeftVisualOverflow() const {
    return style()->isHorizontalWritingMode() ? visualOverflowRect().x()
                                              : visualOverflowRect().y();
  }
  LayoutUnit logicalRightVisualOverflow() const {
    return style()->isHorizontalWritingMode() ? visualOverflowRect().maxX()
                                              : visualOverflowRect().maxY();
  }

  LayoutRect selfVisualOverflowRect() const {
    return m_overflow ? m_overflow->selfVisualOverflowRect() : borderBoxRect();
  }
  LayoutRect contentsVisualOverflowRect() const {
    return m_overflow ? m_overflow->contentsVisualOverflowRect() : LayoutRect();
  }

  // These methods don't mean the box *actually* has top/left overflow. They
  // mean that *if* the box overflows, it will overflow to the top/left rather
  // than the bottom/right. This happens when child content is laid out
  // right-to-left (e.g. direction:rtl) or or bottom-to-top (e.g. direction:rtl
  // writing-mode:vertical-rl).
  virtual bool hasTopOverflow() const;
  virtual bool hasLeftOverflow() const;

  void addLayoutOverflow(const LayoutRect&);
  void addSelfVisualOverflow(const LayoutRect&);
  void addContentsVisualOverflow(const LayoutRect&);

  void addVisualEffectOverflow();
  LayoutRectOutsets computeVisualEffectOverflowOutsets() const;
  void addOverflowFromChild(LayoutBox* child) {
    addOverflowFromChild(child, child->locationOffset());
  }
  void addOverflowFromChild(LayoutBox* child, const LayoutSize& delta);
  void clearLayoutOverflow();
  void clearAllOverflows() { m_overflow.reset(); }

  void updateLayerTransformAfterLayout();

  DISABLE_CFI_PERF LayoutUnit contentWidth() const {
    return clientWidth() - paddingLeft() - paddingRight();
  }
  DISABLE_CFI_PERF LayoutUnit contentHeight() const {
    return clientHeight() - paddingTop() - paddingBottom();
  }
  LayoutSize contentSize() const {
    return LayoutSize(contentWidth(), contentHeight());
  }
  LayoutUnit contentLogicalWidth() const {
    return style()->isHorizontalWritingMode() ? contentWidth()
                                              : contentHeight();
  }
  LayoutUnit contentLogicalHeight() const {
    return style()->isHorizontalWritingMode() ? contentHeight()
                                              : contentWidth();
  }

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

  int pixelSnappedOffsetWidth(const Element*) const final;
  int pixelSnappedOffsetHeight(const Element*) const final;

  // More IE extensions.  clientWidth and clientHeight represent the interior of
  // an object excluding border and scrollbar. clientLeft/Top are just the
  // borderLeftWidth and borderTopWidth.
  DISABLE_CFI_PERF LayoutUnit clientLeft() const {
    return LayoutUnit(borderLeft() +
                      (shouldPlaceBlockDirectionScrollbarOnLogicalLeft()
                           ? verticalScrollbarWidth()
                           : 0));
  }
  DISABLE_CFI_PERF LayoutUnit clientTop() const {
    return LayoutUnit(borderTop());
  }
  LayoutUnit clientWidth() const;
  LayoutUnit clientHeight() const;
  DISABLE_CFI_PERF LayoutUnit clientLogicalWidth() const {
    return style()->isHorizontalWritingMode() ? clientWidth() : clientHeight();
  }
  DISABLE_CFI_PERF LayoutUnit clientLogicalHeight() const {
    return style()->isHorizontalWritingMode() ? clientHeight() : clientWidth();
  }
  DISABLE_CFI_PERF LayoutUnit clientLogicalBottom() const {
    return borderBefore() + clientLogicalHeight();
  }
  DISABLE_CFI_PERF LayoutRect clientBoxRect() const {
    return LayoutRect(clientLeft(), clientTop(), clientWidth(), clientHeight());
  }

  int pixelSnappedClientWidth() const;
  int pixelSnappedClientHeight() 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 LayoutUnit scrollLeft() const;
  virtual LayoutUnit scrollTop() const;
  virtual LayoutUnit scrollWidth() const;
  virtual LayoutUnit scrollHeight() const;
  int pixelSnappedScrollWidth() const;
  int pixelSnappedScrollHeight() const;
  virtual void setScrollLeft(LayoutUnit);
  virtual void setScrollTop(LayoutUnit);

  void scrollToPosition(const FloatPoint&,
                        ScrollBehavior = ScrollBehaviorInstant);
  void scrollByRecursively(const ScrollOffset& delta);
  // If makeVisibleInVisualViewport is set, the visual viewport will be scrolled
  // if required to make the rect visible.
  void scrollRectToVisible(const LayoutRect&,
                           const ScrollAlignment& alignX,
                           const ScrollAlignment& alignY,
                           ScrollType = ProgrammaticScroll,
                           bool makeVisibleInVisualViewport = true);

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

  LayoutUnit marginLogicalLeft() const {
    return m_marginBoxOutsets.logicalLeft(style()->getWritingMode());
  }
  LayoutUnit marginLogicalRight() const {
    return m_marginBoxOutsets.logicalRight(style()->getWritingMode());
  }

  LayoutUnit marginBefore(
      const ComputedStyle* overrideStyle = nullptr) const final {
    return m_marginBoxOutsets.before(
        (overrideStyle ? overrideStyle : style())->getWritingMode());
  }
  LayoutUnit marginAfter(
      const ComputedStyle* overrideStyle = nullptr) const final {
    return m_marginBoxOutsets.after(
        (overrideStyle ? overrideStyle : style())->getWritingMode());
  }
  LayoutUnit marginStart(
      const ComputedStyle* overrideStyle = nullptr) const final {
    const ComputedStyle* styleToUse = overrideStyle ? overrideStyle : style();
    return m_marginBoxOutsets.start(styleToUse->getWritingMode(),
                                    styleToUse->direction());
  }
  LayoutUnit marginEnd(
      const ComputedStyle* overrideStyle = nullptr) const final {
    const ComputedStyle* styleToUse = overrideStyle ? overrideStyle : style();
    return m_marginBoxOutsets.end(styleToUse->getWritingMode(),
                                  styleToUse->direction());
  }
  LayoutUnit marginOver() const final {
    return m_marginBoxOutsets.over(style()->getWritingMode());
  }
  LayoutUnit marginUnder() const final {
    return m_marginBoxOutsets.under(style()->getWritingMode());
  }
  void setMarginBefore(LayoutUnit value,
                       const ComputedStyle* overrideStyle = nullptr) {
    m_marginBoxOutsets.setBefore(
        (overrideStyle ? overrideStyle : style())->getWritingMode(), value);
  }
  void setMarginAfter(LayoutUnit value,
                      const ComputedStyle* overrideStyle = nullptr) {
    m_marginBoxOutsets.setAfter(
        (overrideStyle ? overrideStyle : style())->getWritingMode(), value);
  }
  void setMarginStart(LayoutUnit value,
                      const ComputedStyle* overrideStyle = nullptr) {
    const ComputedStyle* styleToUse = overrideStyle ? overrideStyle : style();
    m_marginBoxOutsets.setStart(styleToUse->getWritingMode(),
                                styleToUse->direction(), value);
  }
  void setMarginEnd(LayoutUnit value,
                    const ComputedStyle* overrideStyle = nullptr) {
    const ComputedStyle* styleToUse = overrideStyle ? overrideStyle : style();
    m_marginBoxOutsets.setEnd(styleToUse->getWritingMode(),
                              styleToUse->direction(), value);
  }

  // The following functions are used to implement collapsing margins.
  // All objects know their maximal positive and negative margins. The formula
  // for computing a collapsed margin is |maxPosMargin| - |maxNegmargin|.
  // For a non-collapsing box, such as a leaf element, this formula will simply
  // return the margin of the element.  Blocks override the maxMarginBefore and
  // maxMarginAfter methods.
  virtual bool isSelfCollapsingBlock() const { return false; }
  virtual LayoutUnit collapsedMarginBefore() const { return marginBefore(); }
  virtual LayoutUnit collapsedMarginAfter() const { return marginAfter(); }
  LayoutRectOutsets collapsedMarginBoxLogicalOutsets() const {
    return LayoutRectOutsets(collapsedMarginBefore(), LayoutUnit(),
                             collapsedMarginAfter(), LayoutUnit());
  }

  void absoluteRects(Vector<IntRect>&,
                     const LayoutPoint& accumulatedOffset) const override;
  void absoluteQuads(Vector<FloatQuad>&,
                     MapCoordinatesFlags mode = 0) const override;
  FloatRect localBoundingBoxRectForAccessibility() const final;

  void layout() override;
  void paint(const PaintInfo&, const LayoutPoint&) const override;
  bool nodeAtPoint(HitTestResult&,
                   const HitTestLocation& locationInContainer,
                   const LayoutPoint& accumulatedOffset,
                   HitTestAction) override;

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

  // FIXME: We should rename these back to overrideLogicalHeight/Width and have
  // them store the border-box height/width like the regular height/width
  // accessors on LayoutBox. Right now, these are different than contentHeight/
  // contentWidth because they still include the scrollbar height/width.
  LayoutUnit overrideLogicalContentWidth() const;
  LayoutUnit overrideLogicalContentHeight() const;
  bool hasOverrideLogicalContentHeight() const;
  bool hasOverrideLogicalContentWidth() const;
  void setOverrideLogicalContentHeight(LayoutUnit);
  void setOverrideLogicalContentWidth(LayoutUnit);
  void clearOverrideSize();
  void clearOverrideLogicalContentHeight();
  void clearOverrideLogicalContentWidth();

  LayoutUnit overrideContainingBlockContentLogicalWidth() const;
  LayoutUnit overrideContainingBlockContentLogicalHeight() const;
  bool hasOverrideContainingBlockLogicalWidth() const;
  bool hasOverrideContainingBlockLogicalHeight() const;
  void setOverrideContainingBlockContentLogicalWidth(LayoutUnit);
  void setOverrideContainingBlockContentLogicalHeight(LayoutUnit);
  void clearContainingBlockOverrideSize();
  void clearOverrideContainingBlockContentLogicalHeight();

  LayoutUnit extraInlineOffset() const;
  LayoutUnit extraBlockOffset() const;
  void setExtraInlineOffset(LayoutUnit inlineOffest);
  void setExtraBlockOffset(LayoutUnit blockOffest);
  void clearExtraInlineAndBlockOffests();

  LayoutSize offsetFromContainer(const LayoutObject*) const override;

  LayoutUnit adjustBorderBoxLogicalWidthForBoxSizing(float width) const;
  LayoutUnit adjustBorderBoxLogicalHeightForBoxSizing(float height) const;
  LayoutUnit adjustContentBoxLogicalWidthForBoxSizing(float width) const;
  LayoutUnit adjustContentBoxLogicalHeightForBoxSizing(float height) const;

  // ComputedMarginValues holds the actual values for margins. It ignores
  // margin collapsing as they are handled in LayoutBlockFlow.
  // The margins are stored in logical coordinates (see COORDINATE
  // SYSTEMS in LayoutBoxModel) for use during layout.
  struct ComputedMarginValues {
    DISALLOW_NEW();
    ComputedMarginValues() {}

    LayoutUnit m_before;
    LayoutUnit m_after;
    LayoutUnit m_start;
    LayoutUnit m_end;
  };

  // LogicalExtentComputedValues is used both for the
  // block-flow and inline-direction axis.
  struct LogicalExtentComputedValues {
    STACK_ALLOCATED();
    LogicalExtentComputedValues() {}

    // This is the dimension in the measured direction
    // (logical height or logical width).
    LayoutUnit m_extent;

    // This is the offset in the measured direction
    // (logical top or logical left).
    LayoutUnit m_position;

    // |m_margins| represents the margins in the measured direction.
    // Note that ComputedMarginValues has also the margins in
    // the orthogonal direction to have clearer names but they are
    // ignored in the code.
    ComputedMarginValues m_margins;
  };

  // Resolve auto margins in the chosen direction of the containing block so
  // that objects can be pushed to the start, middle or end of the containing
  // block.
  void computeMarginsForDirection(MarginDirection forDirection,
                                  const LayoutBlock* containingBlock,
                                  LayoutUnit containerWidth,
                                  LayoutUnit childWidth,
                                  LayoutUnit& marginStart,
                                  LayoutUnit& marginEnd,
                                  Length marginStartLength,
                                  Length marginStartEnd) const;

  // Used to resolve margins in the containing block's block-flow direction.
  void computeAndSetBlockDirectionMargins(const LayoutBlock* containingBlock);

  LayoutUnit offsetFromLogicalTopOfFirstPage() const;

  // The block offset from the logical top of this object to the end of the
  // first fragmentainer it lives in. If it only lives in one fragmentainer, 0
  // is returned.
  LayoutUnit offsetToNextPage() const {
    return m_rareData ? m_rareData->m_offsetToNextPage : LayoutUnit();
  }
  void setOffsetToNextPage(LayoutUnit);

  // Specify which page or column to associate with an offset, if said offset is
  // exactly at a page or column boundary.
  enum PageBoundaryRule { AssociateWithFormerPage, AssociateWithLatterPage };
  LayoutUnit pageLogicalHeightForOffset(LayoutUnit) const;
  bool isPageLogicalHeightKnown() const;
  LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit,
                                                 PageBoundaryRule) const;

  bool crossesPageBoundary(LayoutUnit offset, LayoutUnit logicalHeight) const;

  // Calculate the strut to insert in order fit content of size
  // |contentLogicalHeight|. |strutToNextPage| is the strut to add to |offset|
  // to merely get to the top of the next page or column. This is what will be
  // returned if the content can actually fit there. Otherwise, return the
  // distance to the next fragmentainer that can fit this piece of content.
  virtual LayoutUnit calculatePaginationStrutToFitContent(
      LayoutUnit offset,
      LayoutUnit strutToNextPage,
      LayoutUnit contentLogicalHeight) const;

  void positionLineBox(InlineBox*);
  void moveWithEdgeOfInlineContainerIfNecessary(bool isHorizontal);

  virtual InlineBox* createInlineBox();
  void dirtyLineBoxes(bool fullLayout);

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

  void setSpannerPlaceholder(LayoutMultiColumnSpannerPlaceholder&);
  void clearSpannerPlaceholder();
  LayoutMultiColumnSpannerPlaceholder* spannerPlaceholder() const final {
    return m_rareData ? m_rareData->m_spannerPlaceholder : 0;
  }

  // A pagination strut is the amount of space needed to push an in-flow block-
  // level object (or float) to the logical top of the next page or column. It
  // will be set both for forced breaks (e.g. page-break-before:always) and soft
  // breaks (when there's not enough space in the current page / column for the
  // object). The strut is baked into the logicalTop() of the object, so that
  // logicalTop() - paginationStrut() == the original position in the previous
  // column before deciding to break.
  //
  // Pagination struts are either set in front of a block-level box (here) or
  // before a line (RootInlineBox::paginationStrut()).
  LayoutUnit paginationStrut() const {
    return m_rareData ? m_rareData->m_paginationStrut : LayoutUnit();
  }
  void setPaginationStrut(LayoutUnit);
  void resetPaginationStrut() {
    if (m_rareData)
      m_rareData->m_paginationStrut = LayoutUnit();
  }

  // Is the specified break-before or break-after value supported on this
  // object? It needs to be in-flow all the way up to a fragmentation context
  // that supports the specified value.
  bool isBreakBetweenControllable(EBreak) const;

  // Is the specified break-inside value supported on this object? It needs to
  // be contained by a fragmentation context that supports the specified value.
  bool isBreakInsideControllable(EBreak) const;

  virtual EBreak breakAfter() const;
  virtual EBreak breakBefore() const;
  EBreak breakInside() const;

  // Join two adjacent break values specified on break-before and/or break-
  // after. avoid* values win over auto values, and forced break values win over
  // avoid* values. |firstValue| is specified on an element earlier in the flow
  // than |secondValue|. This method is used at class A break points [1], to
  // join the values of the previous break-after and the next break-before, to
  // figure out whether we may, must, or should not, break at that point. It is
  // also used when propagating break-before values from first children and
  // break-after values on last children to their container.
  //
  // [1] https://drafts.csswg.org/css-break/#possible-breaks
  static EBreak joinFragmentainerBreakValues(EBreak firstValue,
                                             EBreak secondValue);

  static bool isForcedFragmentainerBreakValue(EBreak);

  EBreak classABreakPointValue(EBreak previousBreakAfterValue) const;

  // Return true if we should insert a break in front of this box. The box needs
  // to start at a valid class A break point in order to allow a forced break.
  // To determine whether or not to break, we also need to know the break-after
  // value of the previous in-flow sibling.
  bool needsForcedBreakBefore(EBreak previousBreakAfterValue) const;

  bool paintedOutputOfObjectHasNoEffectRegardlessOfSize() const override;
  LayoutRect localVisualRect() const override;
  bool mapToVisualRectInAncestorSpace(
      const LayoutBoxModelObject* ancestor,
      LayoutRect&,
      VisualRectFlags = DefaultVisualRectFlags) const override;

  LayoutUnit containingBlockLogicalHeightForGetComputedStyle() const;

  LayoutUnit containingBlockLogicalWidthForContent() const override;
  LayoutUnit containingBlockLogicalHeightForContent(
      AvailableLogicalHeightType) const;

  LayoutUnit containingBlockAvailableLineWidth() const;
  LayoutUnit perpendicularContainingBlockLogicalHeight() const;

  virtual void updateLogicalWidth();
  void updateLogicalHeight();
  void computeLogicalHeight(LogicalExtentComputedValues&) const;
  virtual void computeLogicalHeight(LayoutUnit logicalHeight,
                                    LayoutUnit logicalTop,
                                    LogicalExtentComputedValues&) 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 flows.
  // When there is no explicit height, this function assumes a content height of
  // zero (and returns just border+padding).
  LayoutUnit computeLogicalHeightWithoutLayout() const;

  void computeLogicalWidth(LogicalExtentComputedValues&) const;

  bool stretchesToViewport() const {
    return document().inQuirksMode() && stretchesToViewportInQuirksMode();
  }

  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();
  }
  virtual LayoutUnit intrinsicContentLogicalHeight() const {
    return m_intrinsicContentLogicalHeight;
  }

  // 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(const Length& logicalWidth) const;

  LayoutUnit shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart,
                                             LayoutUnit childMarginEnd,
                                             const LayoutBlockFlow* cb) const;

  LayoutUnit computeLogicalWidthUsing(SizeType,
                                      const Length& logicalWidth,
                                      LayoutUnit availableLogicalWidth,
                                      const LayoutBlock* containingBlock) const;
  LayoutUnit computeLogicalHeightUsing(SizeType,
                                       const Length& height,
                                       LayoutUnit intrinsicContentHeight) const;
  LayoutUnit computeContentLogicalHeight(
      SizeType,
      const Length& height,
      LayoutUnit intrinsicContentHeight) const;
  LayoutUnit computeContentAndScrollbarLogicalHeightUsing(
      SizeType,
      const Length& height,
      LayoutUnit intrinsicContentHeight) const;
  LayoutUnit computeReplacedLogicalWidthUsing(SizeType,
                                              const Length& width) const;
  LayoutUnit computeReplacedLogicalWidthRespectingMinMaxWidth(
      LayoutUnit logicalWidth,
      ShouldComputePreferred = ComputeActual) const;
  LayoutUnit computeReplacedLogicalHeightUsing(SizeType,
                                               const Length& height) const;
  LayoutUnit computeReplacedLogicalHeightRespectingMinMaxHeight(
      LayoutUnit logicalHeight) const;

  virtual LayoutUnit computeReplacedLogicalWidth(
      ShouldComputePreferred = ComputeActual) const;
  virtual LayoutUnit computeReplacedLogicalHeight(
      LayoutUnit estimatedUsedWidth = LayoutUnit()) const;

  bool percentageLogicalHeightIsResolvable() const;
  LayoutUnit computePercentageLogicalHeight(const Length& height) const;

  // Block flows subclass availableWidth/Height to handle multi column layout
  // (shrinking the width/height available to children when laying out.)
  LayoutUnit availableLogicalWidth() const { return contentLogicalWidth(); }
  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();
  }

  int verticalScrollbarWidth() const;
  int horizontalScrollbarHeight() const;
  int scrollbarLogicalWidth() const {
    return style()->isHorizontalWritingMode() ? verticalScrollbarWidth()
                                              : horizontalScrollbarHeight();
  }
  int scrollbarLogicalHeight() const {
    return style()->isHorizontalWritingMode() ? horizontalScrollbarHeight()
                                              : verticalScrollbarWidth();
  }
  virtual ScrollResult scroll(ScrollGranularity, const FloatSize&);
  bool canBeScrolledAndHasScrollableArea() const;
  virtual bool canBeProgramaticallyScrolled() const;
  virtual void autoscroll(const IntPoint&);
  bool canAutoscroll() const;
  IntSize calculateAutoscrollDirection(const IntPoint& pointInRootFrame) const;
  static LayoutBox* findAutoscrollable(LayoutObject*);
  virtual void stopAutoscroll() {}

  DISABLE_CFI_PERF bool hasAutoVerticalScrollbar() const {
    return hasOverflowClip() && (style()->overflowY() == EOverflow::Auto ||
                                 style()->overflowY() == EOverflow::PagedY ||
                                 style()->overflowY() == EOverflow::Overlay);
  }
  DISABLE_CFI_PERF bool hasAutoHorizontalScrollbar() const {
    return hasOverflowClip() && (style()->overflowX() == EOverflow::Auto ||
                                 style()->overflowX() == EOverflow::Overlay);
  }
  DISABLE_CFI_PERF bool scrollsOverflow() const {
    return scrollsOverflowX() || scrollsOverflowY();
  }
  virtual bool shouldPlaceBlockDirectionScrollbarOnLogicalLeft() const {
    return style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft();
  }

  bool hasScrollableOverflowX() const {
    return scrollsOverflowX() &&
           pixelSnappedScrollWidth() != pixelSnappedClientWidth();
  }
  bool hasScrollableOverflowY() const {
    return scrollsOverflowY() &&
           pixelSnappedScrollHeight() != pixelSnappedClientHeight();
  }
  virtual bool scrollsOverflowX() const {
    return hasOverflowClip() && (style()->overflowX() == EOverflow::Scroll ||
                                 hasAutoHorizontalScrollbar());
  }
  virtual bool scrollsOverflowY() const {
    return hasOverflowClip() && (style()->overflowY() == EOverflow::Scroll ||
                                 hasAutoVerticalScrollbar());
  }

  // Elements such as the <input> field override this to specify that they are
  // scrollable outside the context of the CSS overflow style
  virtual bool isIntrinsicallyScrollable(
      ScrollbarOrientation orientation) const {
    return false;
  }

  bool hasUnsplittableScrollingOverflow() const;

  // Page / column breakability inside block-level objects.
  enum PaginationBreakability {
    AllowAnyBreaks,  // No restrictions on breaking. May examine children to
                     // find possible break points.
    ForbidBreaks,  // Forbid breaks inside this object. Content cannot be split
                   // nicely into smaller pieces.
    AvoidBreaks    // Preferably avoid breaks. If not possible, examine children
                   // to find possible break points.
  };
  virtual PaginationBreakability getPaginationBreakability() const;

  LayoutRect localCaretRect(
      InlineBox*,
      int caretOffset,
      LayoutUnit* extraWidthToEndOfLine = nullptr) override;

  virtual LayoutRect overflowClipRect(
      const LayoutPoint& location,
      OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize) const;
  LayoutRect clipRect(const LayoutPoint& location) const;
  virtual bool hasControlClip() const { return false; }
  virtual LayoutRect controlClipRect(const LayoutPoint&) const {
    return LayoutRect();
  }

  // Returns the combination of overflow clip, contain: paint clip and CSS clip
  // for this object, in local space.
  LayoutRect clippingRect() const;

  virtual void paintBoxDecorationBackground(const PaintInfo&,
                                            const LayoutPoint&) const;
  virtual void paintMask(const PaintInfo&, const LayoutPoint&) const;
  void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;
  ResourcePriority computeResourcePriority() const final;

  void logicalExtentAfterUpdatingLogicalWidth(const LayoutUnit& logicalTop,
                                              LogicalExtentComputedValues&);

  PositionWithAffinity positionForPoint(const LayoutPoint&) override;

  void removeFloatingOrPositionedChildFromBlockLists();

  PaintLayer* enclosingFloatPaintingLayer() const;

  virtual int firstLineBoxBaseline() const { return -1; }
  virtual int inlineBlockBaseline(LineDirectionMode) const {
    return -1;
  }  // Returns -1 if we should skip this box when computing the baseline of an
     // inline-block.

  virtual Node* nodeForHitTest() const { return node(); }

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

  void updateFragmentationInfoForChild(LayoutBox&);
  bool childNeedsRelayoutForPagination(const LayoutBox&) const;
  void markChildForPaginationRelayoutIfNeeded(LayoutBox&, SubtreeLayoutScope&);

  bool isWritingModeRoot() const {
    return !parent() ||
           parent()->style()->getWritingMode() != style()->getWritingMode();
  }
  bool isOrthogonalWritingModeRoot() const {
    return parent() &&
           parent()->isHorizontalWritingMode() != isHorizontalWritingMode();
  }
  void markOrthogonalWritingModeRoot();
  void unmarkOrthogonalWritingModeRoot();

  bool isDeprecatedFlexItem() const {
    return !isInline() && !isFloatingOrOutOfFlowPositioned() && parent() &&
           parent()->isDeprecatedFlexibleBox();
  }
  bool isFlexItemIncludingDeprecated() const {
    return !isInline() && !isFloatingOrOutOfFlowPositioned() && parent() &&
           parent()->isFlexibleBoxIncludingDeprecated();
  }
  bool isFlexItem() const {
    return !isInline() && !isFloatingOrOutOfFlowPositioned() && parent() &&
           parent()->isFlexibleBox();
  }

  bool isGridItem() const { return parent() && parent()->isLayoutGrid(); }

  LayoutUnit lineHeight(
      bool firstLine,
      LineDirectionMode,
      LinePositionMode = PositionOnContainingLine) const override;
  int baselinePosition(
      FontBaseline,
      bool firstLine,
      LineDirectionMode,
      LinePositionMode = PositionOnContainingLine) const override;

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

  LayoutPoint flipForWritingModeForChild(const LayoutBox* child,
                                         const LayoutPoint&) const;
  WARN_UNUSED_RESULT LayoutUnit flipForWritingMode(LayoutUnit position) const {
    // The offset is in the block direction (y for horizontal writing modes, x
    // for vertical writing modes).
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return position;
    return logicalHeight() - position;
  }
  WARN_UNUSED_RESULT LayoutPoint
  flipForWritingMode(const LayoutPoint& position) const {
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return position;
    return isHorizontalWritingMode()
               ? LayoutPoint(position.x(), m_frameRect.height() - position.y())
               : LayoutPoint(m_frameRect.width() - position.x(), position.y());
  }
  WARN_UNUSED_RESULT LayoutSize
  flipForWritingMode(const LayoutSize& offset) const {
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return offset;
    return LayoutSize(m_frameRect.width() - offset.width(), offset.height());
  }
  void flipForWritingMode(LayoutRect& rect) const {
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return;
    rect.setX(m_frameRect.width() - rect.maxX());
  }
  WARN_UNUSED_RESULT FloatPoint
  flipForWritingMode(const FloatPoint& position) const {
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return position;
    return FloatPoint(m_frameRect.width() - position.x(), position.y());
  }
  void flipForWritingMode(FloatRect& rect) const {
    if (!UNLIKELY(hasFlippedBlocksWritingMode()))
      return;
    rect.setX(m_frameRect.width() - rect.maxX());
  }

  // Passing |container| causes flipped-block flipping w.r.t. that container,
  // or containingBlock() otherwise.
  LayoutPoint physicalLocation(
      const LayoutBox* flippedBlocksContainer = nullptr) const;
  LayoutSize physicalLocationOffset() const {
    return toLayoutSize(physicalLocation());
  }

  LayoutRect logicalVisualOverflowRectForPropagation(
      const ComputedStyle&) const;
  LayoutRect visualOverflowRectForPropagation(const ComputedStyle&) const;
  LayoutRect logicalLayoutOverflowRectForPropagation(
      const ComputedStyle&) const;
  LayoutRect layoutOverflowRectForPropagation(const ComputedStyle&) const;

  bool hasOverflowModel() const { return m_overflow.get(); }
  bool hasSelfVisualOverflow() const {
    return m_overflow &&
           !borderBoxRect().contains(m_overflow->selfVisualOverflowRect());
  }
  bool hasVisualOverflow() const {
    return m_overflow && !borderBoxRect().contains(visualOverflowRect());
  }

  virtual bool needsPreferredWidthsRecalculation() const;

  // See README.md for an explanation of scroll origin.
  virtual IntSize originAdjustmentForScrollbars() const;
  IntSize scrolledContentOffset() const;

  // Maps a rect in scrolling contents space to box space and apply overflow
  // clip if needed. Returns true if no clipping applied or the rect actually
  // intersects the clipping region. If edgeInclusive is true, then this method
  // may return true even if the resulting rect has zero area.
  bool mapScrollingContentsRectToBoxSpace(
      LayoutRect&,
      VisualRectFlags = DefaultVisualRectFlags) const;

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

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

    LayoutRect layoutOverflowRect = m_overflow->layoutOverflowRect();
    LayoutRect noOverflowRect = this->noOverflowRect();
    return layoutOverflowRect.x() < noOverflowRect.x() ||
           layoutOverflowRect.maxX() > noOverflowRect.maxX();
  }

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

    LayoutRect layoutOverflowRect = m_overflow->layoutOverflowRect();
    LayoutRect noOverflowRect = this->noOverflowRect();
    return layoutOverflowRect.y() < noOverflowRect.y() ||
           layoutOverflowRect.maxY() > noOverflowRect.maxY();
  }

  virtual LayoutBox* createAnonymousBoxWithSameTypeAs(
      const LayoutObject*) const {
    NOTREACHED();
    return nullptr;
  }

  bool hasSameDirectionAs(const LayoutBox* object) const {
    return style()->direction() == object->style()->direction();
  }

  ShapeOutsideInfo* shapeOutsideInfo() const;

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

  void setIntrinsicContentLogicalHeight(
      LayoutUnit intrinsicContentLogicalHeight) const {
    m_intrinsicContentLogicalHeight = intrinsicContentLogicalHeight;
  }

  bool canRenderBorderImage() const;

  void mapLocalToAncestor(
      const LayoutBoxModelObject* ancestor,
      TransformState&,
      MapCoordinatesFlags = ApplyContainerFlip) const override;
  void mapAncestorToLocal(const LayoutBoxModelObject*,
                          TransformState&,
                          MapCoordinatesFlags) const override;

  void clearPreviousVisualRects() override;

  LayoutBlock* percentHeightContainer() const {
    return m_rareData ? m_rareData->m_percentHeightContainer : nullptr;
  }
  void setPercentHeightContainer(LayoutBlock*);
  void removeFromPercentHeightContainer();
  void clearPercentHeightDescendants();
  // For snap areas, returns the snap container that owns us.
  LayoutBox* snapContainer() const;
  void setSnapContainer(LayoutBox*);
  // For snap containers, returns all associated snap areas.
  SnapAreaSet* snapAreas() const;
  void clearSnapAreas();

  bool hitTestClippedOutByBorder(const HitTestLocation& locationInContainer,
                                 const LayoutPoint& borderBoxLocation) const;

  static bool mustInvalidateFillLayersPaintOnWidthChange(const FillLayer&);
  static bool mustInvalidateFillLayersPaintOnHeightChange(const FillLayer&);

  bool mustInvalidateBackgroundOrBorderPaintOnHeightChange() const;
  bool mustInvalidateBackgroundOrBorderPaintOnWidthChange() const;

  // Returns true if the box intersects the viewport visible to the user.
  bool intersectsVisibleViewport() const;

  bool hasNonCompositedScrollbars() const final;

  void ensureIsReadyForPaintInvalidation() override;

  virtual bool shouldClipOverflow() const;

 protected:
  void willBeDestroyed() override;

  void insertedIntoTree() override;
  void willBeRemovedFromTree() override;

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

  virtual ItemPosition selfAlignmentNormalBehavior() const {
    return ItemPositionStretch;
  }

  // Returns false if it could not cheaply compute the extent (e.g. fixed
  // background), in which case the returned rect may be incorrect.
  // FIXME: make this a const method once the LayoutBox reference in BoxPainter
  // is const.
  bool getBackgroundPaintedExtent(LayoutRect&) const;
  virtual bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect,
                                                 unsigned maxDepthToTest) const;
  bool computeBackgroundIsKnownToBeObscured() const override;

  virtual void computePositionedLogicalWidth(
      LogicalExtentComputedValues&) const;

  LayoutUnit computeIntrinsicLogicalWidthUsing(
      const Length& logicalWidthLength,
      LayoutUnit availableLogicalWidth,
      LayoutUnit borderAndPadding) const;
  virtual LayoutUnit computeIntrinsicLogicalContentHeightUsing(
      const Length& logicalHeightLength,
      LayoutUnit intrinsicContentHeight,
      LayoutUnit borderAndPadding) const;

  virtual bool shouldComputeSizeAsReplaced() const {
    return isAtomicInlineLevel() && !isInlineBlockOrInlineTable();
  }

  LayoutObject* splitAnonymousBoxesAroundChild(LayoutObject* beforeChild);

  virtual bool hitTestOverflowControl(HitTestResult&,
                                      const HitTestLocation&,
                                      const LayoutPoint&) {
    return false;
  }
  virtual bool hitTestChildren(HitTestResult&,
                               const HitTestLocation& locationInContainer,
                               const LayoutPoint& accumulatedOffset,
                               HitTestAction);
  void addLayerHitTestRects(LayerHitTestRects&,
                            const PaintLayer* currentCompositedLayer,
                            const LayoutPoint& layerOffset,
                            const LayoutRect& containerRect) const override;
  void computeSelfHitTestRects(Vector<LayoutRect>&,
                               const LayoutPoint& layerOffset) const override;

  PaintInvalidationReason invalidatePaintIfNeeded(
      const PaintInvalidationState&) override;
  PaintInvalidationReason invalidatePaintIfNeeded(
      const PaintInvalidatorContext&) const override;

  bool columnFlexItemHasStretchAlignment() const;
  bool isStretchingColumnFlexItem() const;
  bool hasStretchedLogicalWidth() const;

  void excludeScrollbars(
      LayoutRect&,
      OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize) const;

  LayoutUnit containingBlockLogicalWidthForPositioned(
      const LayoutBoxModelObject* containingBlock,
      bool checkForPerpendicularWritingMode = true) const;
  LayoutUnit containingBlockLogicalHeightForPositioned(
      const LayoutBoxModelObject* containingBlock,
      bool checkForPerpendicularWritingMode = true) const;

  static void computeBlockStaticDistance(
      Length& logicalTop,
      Length& logicalBottom,
      const LayoutBox* child,
      const LayoutBoxModelObject* containerBlock);
  static void computeInlineStaticDistance(
      Length& logicalLeft,
      Length& logicalRight,
      const LayoutBox* child,
      const LayoutBoxModelObject* containerBlock,
      LayoutUnit containerLogicalWidth);
  static void computeLogicalLeftPositionedOffset(
      LayoutUnit& logicalLeftPos,
      const LayoutBox* child,
      LayoutUnit logicalWidthValue,
      const LayoutBoxModelObject* containerBlock,
      LayoutUnit containerLogicalWidth);
  static void computeLogicalTopPositionedOffset(
      LayoutUnit& logicalTopPos,
      const LayoutBox* child,
      LayoutUnit logicalHeightValue,
      const LayoutBoxModelObject* containerBlock,
      LayoutUnit containerLogicalHeight);
  bool skipContainingBlockForPercentHeightCalculation(
      const LayoutBox* containingBlock) const;

 private:
  void updateShapeOutsideInfoAfterStyleChange(const ComputedStyle&,
                                              const ComputedStyle* oldStyle);
  void updateGridPositionAfterStyleChange(const ComputedStyle*);
  void updateScrollSnapMappingAfterStyleChange(const ComputedStyle*,
                                               const ComputedStyle* oldStyle);
  void clearScrollSnapMapping();
  void addScrollSnapMapping();

  bool autoWidthShouldFitContent() const;
  LayoutUnit shrinkToFitLogicalWidth(LayoutUnit availableLogicalWidth,
                                     LayoutUnit bordersPlusPadding) const;

  bool stretchesToViewportInQuirksMode() const;

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

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

  // Calculates the intrinsic(https://drafts.csswg.org/css-sizing-3/#intrinsic)
  // logical widths for this layout box.
  //
  // intrinsicWidth is defined as:
  //     intrinsic size of content (without our border and padding) +
  //     scrollbarWidth.
  //
  // preferredWidth is defined as:
  //     fixedWidth OR (intrinsicWidth plus border and padding).
  //     Note: fixedWidth includes border and padding and scrollbarWidth.
  virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth,
                                             LayoutUnit& maxLogicalWidth) const;

  // This function calculates the preferred widths for an object.
  //
  // This function is only expected to be called if
  // the boolean preferredLogicalWidthsDirty is true. It also MUST clear the
  // boolean before returning.
  //
  // See INTRINSIC SIZES / PREFERRED LOGICAL WIDTHS in LayoutObject.h for more
  // details about those widths.
  virtual void computePreferredLogicalWidths() {
    clearPreferredLogicalWidthsDirty();
  }

  LayoutBoxRareData& ensureRareData() {
    if (!m_rareData)
      m_rareData = WTF::makeUnique<LayoutBoxRareData>();
    return *m_rareData.get();
  }

  bool logicalHeightComputesAsNone(SizeType) const;

  bool isBox() const =
      delete;  // This will catch anyone doing an unnecessary check.

  void locationChanged();
  void sizeChanged();

  virtual bool isInSelfHitTestingPhase(HitTestAction hitTestAction) const {
    return hitTestAction == HitTestForeground;
  }

  void updateBackgroundAttachmentFixedStatusAfterStyleChange();

  // The CSS border box rect for this box.
  //
  // The rectangle is in this box's physical coordinates but with a
  // flipped block-flow direction (see the COORDINATE SYSTEMS section
  // in LayoutBoxModelObject). The location is the distance from this
  // object's border edge to the container's border edge (which is not
  // always the parent). Thus it includes any logical top/left along
  // with this box's margins.
  LayoutRect m_frameRect;

  // Our intrinsic height, used for min-height: min-content etc. Maintained by
  // updateLogicalHeight. This is logicalHeight() before it is clamped to
  // min/max.
  mutable LayoutUnit m_intrinsicContentLogicalHeight;

  void inflateVisualRectForFilter(LayoutRect&) const;
  void inflateVisualRectForFilterUnderContainer(
      LayoutRect&,
      const LayoutObject& container,
      const LayoutBoxModelObject* ancestorToStopAt) const;

  LayoutRectOutsets m_marginBoxOutsets;

  void addSnapArea(const LayoutBox&);
  void removeSnapArea(const LayoutBox&);

  LayoutRect debugRect() const override;

 protected:
  // The logical width of the element if it were to break its lines at every
  // possible opportunity.
  //
  // See LayoutObject::minPreferredLogicalWidth() for more details.
  LayoutUnit m_minPreferredLogicalWidth;

  // The logical width of the element if it never breaks any lines at all.
  //
  // See LayoutObject::maxPreferredLogicalWidth() for more details.
  LayoutUnit m_maxPreferredLogicalWidth;

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

 private:
  // The inline box containing this LayoutBox, for atomic inline elements.
  InlineBox* m_inlineBoxWrapper;

  std::unique_ptr<LayoutBoxRareData> m_rareData;
};

DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBox, isBox());

inline LayoutBox* LayoutBox::previousSiblingBox() const {
  return toLayoutBox(previousSibling());
}

inline LayoutBox* LayoutBox::previousInFlowSiblingBox() const {
  LayoutBox* previous = previousSiblingBox();
  while (previous && previous->isOutOfFlowPositioned())
    previous = previous->previousSiblingBox();
  return previous;
}

inline LayoutBox* LayoutBox::nextSiblingBox() const {
  return toLayoutBox(nextSibling());
}

inline LayoutBox* LayoutBox::nextInFlowSiblingBox() const {
  LayoutBox* next = nextSiblingBox();
  while (next && next->isOutOfFlowPositioned())
    next = next->nextSiblingBox();
  return next;
}

inline LayoutBox* LayoutBox::parentBox() const {
  return toLayoutBox(parent());
}

inline LayoutBox* LayoutBox::firstInFlowChildBox() const {
  LayoutBox* first = firstChildBox();
  return (first && first->isOutOfFlowPositioned())
             ? first->nextInFlowSiblingBox()
             : first;
}

inline LayoutBox* LayoutBox::firstChildBox() const {
  return toLayoutBox(slowFirstChild());
}

inline LayoutBox* LayoutBox::lastChildBox() const {
  return toLayoutBox(slowLastChild());
}

inline LayoutBox* LayoutBox::previousSiblingMultiColumnBox() const {
  ASSERT(isLayoutMultiColumnSpannerPlaceholder() || isLayoutMultiColumnSet());
  LayoutBox* previousBox = previousSiblingBox();
  if (previousBox->isLayoutFlowThread())
    return nullptr;
  return previousBox;
}

inline LayoutBox* LayoutBox::nextSiblingMultiColumnBox() const {
  ASSERT(isLayoutMultiColumnSpannerPlaceholder() || isLayoutMultiColumnSet());
  return nextSiblingBox();
}

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

  m_inlineBoxWrapper = boxWrapper;
}

inline bool LayoutBox::isForcedFragmentainerBreakValue(EBreak breakValue) {
  return breakValue == BreakColumn || breakValue == BreakLeft ||
         breakValue == BreakPage || breakValue == BreakRecto ||
         breakValue == BreakRight || breakValue == BreakVerso;
}

}  // namespace blink

#endif  // LayoutBox_h