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* Copyright (C) 1999 Lars Knoll (
* (C) 1999 Antti Koivisto (
* Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 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
* 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.
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/editing/forward.h"
#include "third_party/blink/renderer/core/layout/api/line_layout_item.h"
#include "third_party/blink/renderer/core/layout/layout_box_model_object.h"
#include "third_party/blink/renderer/core/layout/line/inline_flow_box.h"
#include "third_party/blink/renderer/core/layout/line/line_box_list.h"
namespace blink {
class LayoutBlockFlow;
class NGPaintFragment;
// LayoutInline is the LayoutObject associated with display: inline.
// This is called an "inline box" in CSS 2.1.
// It is also the base class for content that behaves in similar way (like
// quotes and "display: ruby").
// Note that LayoutInline is always 'inline-level' but other LayoutObject
// can be 'inline-level', which is why it's stored as a boolean on LayoutObject
// (see LayoutObject::isInline()).
// For performance and memory consumption, this class ignores some inline-boxes
// during line layout because they don't impact layout (they still exist and are
// inserted into the layout tree). An example of this is
// <span><span>Text</span></span>
// where the 2 spans have the same size as the inner text-node so they can be
// ignored for layout purpose, generating a single inline-box instead of 3.
// One downside of this optimization is that we have extra work to do when
// asking for bounding rects (see generateLineBoxRects).
// This optimization is called "culled inline" in the code.
// LayoutInlines are expected to be laid out by their containing
// LayoutBlockFlow. See LayoutBlockFlow::layoutInlineChildren.
// LayoutInline enforces the following invariant:
// "All in-flow children of an inline box are inline."
// When a non-inline child is inserted, LayoutInline::addChild splits the inline
// and potentially enclosing inlines too. It then wraps layout objects into
// anonymous block-flow containers. This creates complexity in the code as:
// - a DOM node can have several associated LayoutObjects (we don't currently
// expose this information to the DOM code though).
// - more importantly, nodes that are parent/child in the DOM have no natural
// relationship anymore (see example below).
// In order to do a correct tree walk over this synthetic tree, a single linked
// list is stored called *continuation*. See splitFlow() about how it is
// populated during LayoutInline split.
// Continuations can only be a LayoutInline or an anonymous LayoutBlockFlow.
// That's why continuations are handled by LayoutBoxModelObject (common class
// between the 2). See LayoutBoxModelObject::continuation and setContinuation.
// Let's take the following example:
// <!DOCTYPE html>
// <b>Bold inline.<div>Bold block.</div>More bold inlines.</b>
// The generated layout tree is:
// LayoutBlockFlow {HTML}
// LayoutBlockFlow {BODY}
// LayoutBlockFlow (anonymous)
// LayoutInline {B}
// LayoutText {#text}
// text run: "Bold inline."
// LayoutBlockFlow (anonymous)
// LayoutBlockFlow {DIV}
// LayoutText {#text}
// text run: "Bold block."
// LayoutBlockFlow (anonymous)
// LayoutInline {B}
// LayoutText {#text}
// text run: "More bold inlines."
// The insertion of the <div> inside the <b> forces the latter to be split
// into 2 LayoutInlines and the insertion of anonymous LayoutBlockFlows. The 2
// LayoutInlines are done so that we can apply the correct (bold) style to both
// sides of the <div>. The continuation chain starts with the first
// LayoutInline {B}, continues to the middle anonymous LayoutBlockFlow and
// finishes with the last LayoutInline {B}.
// Note that the middle anonymous LayoutBlockFlow duplicates the content.
// TODO(jchaffraix): Find out why we made the decision to always insert the
// anonymous LayoutBlockFlows.
// This section was inspired by an older article by Dave Hyatt:
class CORE_EXPORT LayoutInline : public LayoutBoxModelObject {
explicit LayoutInline(Element*);
~LayoutInline() override;
static LayoutInline* CreateAnonymous(Document*);
// Create an anonymous inline box for ::first-line. The instance created by
// this function has IsFirstLineAnonymous() == true.
static LayoutInline* CreateAnonymousForFirstLine(Document*);
LayoutObject* FirstChild() const {
DCHECK_EQ(Children(), VirtualChildren());
return Children()->FirstChild();
LayoutObject* LastChild() const {
DCHECK_EQ(Children(), VirtualChildren());
return Children()->LastChild();
// If you have a LayoutInline, use firstChild or lastChild instead.
void SlowFirstChild() const = delete;
void SlowLastChild() const = delete;
void AddChild(LayoutObject* new_child,
LayoutObject* before_child = nullptr) override;
Element* GetNode() const {
return ToElement(LayoutBoxModelObject::GetNode());
// True if this is an anonymous inline box for ::first-line that wraps the
// whole inline formatting context.
virtual bool IsFirstLineAnonymous() const;
LayoutUnit MarginLeft() const final;
LayoutUnit MarginRight() const final;
LayoutUnit MarginTop() const final;
LayoutUnit MarginBottom() const final;
void AbsoluteRects(Vector<IntRect>&,
const LayoutPoint& accumulated_offset) const final;
FloatRect LocalBoundingBoxRectForAccessibility() const final;
LayoutRect LinesBoundingBox() const;
LayoutRect VisualOverflowRect() const final;
LayoutRect ReferenceBoxForClipPath() const;
InlineFlowBox* CreateAndAppendInlineFlowBox();
void DirtyLineBoxes(bool full_layout);
// LineBoxes() and FirstInlineFragment() are mutually exclusive,
// depends on IsInLayoutNGInlineFormattingContext().
const LineBoxList* LineBoxes() const {
return IsInLayoutNGInlineFormattingContext() ? &LineBoxList::Empty()
: &line_boxes_;
LineBoxList* MutableLineBoxes();
InlineFlowBox* FirstLineBox() const { return LineBoxes()->First(); }
InlineFlowBox* LastLineBox() const { return LineBoxes()->Last(); }
InlineBox* FirstLineBoxIncludingCulling() const {
return AlwaysCreateLineBoxes() ? FirstLineBox()
: CulledInlineFirstLineBox();
InlineBox* LastLineBoxIncludingCulling() const {
return AlwaysCreateLineBoxes() ? LastLineBox() : CulledInlineLastLineBox();
NGPaintFragment* FirstInlineFragment() const final;
void SetFirstInlineFragment(NGPaintFragment*) final;
// Return true if this inline doesn't occur on any lines, i.e. when it creates
// no fragments.
bool IsEmpty() const { return !FirstLineBox() && !FirstInlineFragment(); }
LayoutBoxModelObject* VirtualContinuation() const final {
return Continuation();
LayoutInline* InlineElementContinuation() const;
LayoutSize OffsetForInFlowPositionedInline(const LayoutBox& child) const;
void AddOutlineRects(Vector<LayoutRect>&,
const LayoutPoint& additional_offset,
NGOutlineType) const final;
// The following methods are called from the container if it has already added
// outline rects for line boxes and/or children of this LayoutInline.
void AddOutlineRectsForChildrenAndContinuations(
const LayoutPoint& additional_offset,
NGOutlineType) const;
void AddOutlineRectsForContinuations(Vector<LayoutRect>&,
const LayoutPoint& additional_offset,
NGOutlineType) const;
using LayoutBoxModelObject::Continuation;
using LayoutBoxModelObject::SetContinuation;
bool AlwaysCreateLineBoxes() const {
return AlwaysCreateLineBoxesForLayoutInline();
void SetAlwaysCreateLineBoxes(bool always_create_line_boxes = true) {
void UpdateAlwaysCreateLineBoxes(bool full_layout);
// True if this inline box should force creation of NGPhysicalBoxFragment.
bool ShouldCreateBoxFragment() const {
return AlwaysCreateLineBoxesForLayoutInline();
void SetShouldCreateBoxFragment(bool value = true) {
void UpdateShouldCreateBoxFragment();
LayoutRect LocalCaretRect(const InlineBox*,
LayoutUnit* extra_width_to_end_of_line) const final;
// When this LayoutInline doesn't generate line boxes of its own, regenerate
// the rects of the line boxes and hit test the rects.
// In LayoutNG, |parent_fragment| is non-null, and limits the regenerated
// rects to be from descendant fragments of |parent_fragment|.
// In legacy, |parent_fragment| is always null, and all rects are regenerated.
bool HitTestCulledInline(HitTestResult&,
const HitTestLocation& location_in_container,
const LayoutPoint& accumulated_offset,
const NGPaintFragment* parent_fragment = nullptr);
LayoutPoint FirstLineBoxTopLeft() const;
void MapLocalToAncestor(const LayoutBoxModelObject* ancestor,
MapCoordinatesFlags mode) const override;
const char* GetName() const override { return "LayoutInline"; }
LayoutRect DebugRect() const override;
void WillBeDestroyed() override;
void InLayoutNGInlineFormattingContextWillChange(bool) final;
void DeleteLineBoxes();
void StyleDidChange(StyleDifference, const ComputedStyle* old_style) override;
void ComputeSelfHitTestRects(Vector<LayoutRect>& rects,
const LayoutPoint& layer_offset) const override;
void InvalidateDisplayItemClients(PaintInvalidationReason) const override;
void AbsoluteQuadsForSelf(Vector<FloatQuad>& quads,
MapCoordinatesFlags mode = 0) const override;
LayoutSize OffsetFromContainerInternal(const LayoutObject*,
bool ignore_scroll_offset) const final;
FRIEND_TEST_ALL_PREFIXES(ParameterizedLayoutInlineTest, VisualRectInDocument);
LayoutObjectChildList* VirtualChildren() final { return Children(); }
const LayoutObjectChildList* VirtualChildren() const final {
return Children();
const LayoutObjectChildList* Children() const { return &children_; }
LayoutObjectChildList* Children() { return &children_; }
bool IsLayoutInline() const final { return true; }
// Compute the initial value of |ShouldCreateBoxFragment()| for this
// LayoutInline. It maybe flipped to true later for other conditions.
bool ComputeInitialShouldCreateBoxFragment() const;
bool ComputeInitialShouldCreateBoxFragment(const ComputedStyle& style) const;
LayoutRect CulledInlineVisualOverflowBoundingBox() const;
InlineBox* CulledInlineFirstLineBox() const;
InlineBox* CulledInlineLastLineBox() const;
// For visualOverflowRect() only, to get bounding box of visual overflow of
// line boxes.
LayoutRect LinesVisualOverflowBoundingBox() const;
template <typename GeneratorContext>
void GenerateLineBoxRects(GeneratorContext& yield) const;
template <typename GeneratorContext>
void GenerateCulledLineBoxRects(GeneratorContext& yield,
const LayoutInline* container) const;
void AddChildToContinuation(LayoutObject* new_child,
LayoutObject* before_child);
void AddChildIgnoringContinuation(LayoutObject* new_child,
LayoutObject* before_child = nullptr) final;
void MoveChildrenToIgnoringContinuation(LayoutInline* to,
LayoutObject* start_child);
void SplitInlines(LayoutBlockFlow* from_block,
LayoutBlockFlow* to_block,
LayoutBlockFlow* middle_block,
LayoutObject* before_child,
LayoutBoxModelObject* old_cont);
void SplitFlow(LayoutObject* before_child,
LayoutBlockFlow* new_block_box,
LayoutObject* new_child,
LayoutBoxModelObject* old_cont);
void UpdateLayout() final { NOTREACHED(); } // Do nothing for layout()
void Paint(const PaintInfo&) const final;
bool NodeAtPoint(HitTestResult&,
const HitTestLocation& location_in_container,
const LayoutPoint& accumulated_offset,
HitTestAction) final;
PaintLayerType LayerTypeRequired() const override;
LayoutUnit OffsetLeft(const Element*) const final;
LayoutUnit OffsetTop(const Element*) const final;
LayoutUnit OffsetWidth() const final { return LinesBoundingBox().Width(); }
LayoutUnit OffsetHeight() const final { return LinesBoundingBox().Height(); }
LayoutRect VisualRectInDocument() const override;
// This method differs from visualOverflowRect in that it doesn't include the
// rects for culled inline boxes, which aren't necessary for paint
// invalidation.
LayoutRect LocalVisualRectIgnoringVisibility() const override;
bool MapToVisualRectInAncestorSpaceInternal(
const LayoutBoxModelObject* ancestor,
VisualRectFlags = kDefaultVisualRectFlags) const final;
PositionWithAffinity PositionForPoint(const LayoutPoint&) const final;
IntRect BorderBoundingBox() const final {
IntRect bounding_box = EnclosingIntRect(LinesBoundingBox());
return IntRect(0, 0, bounding_box.Width(), bounding_box.Height());
virtual InlineFlowBox* CreateInlineFlowBox(); // Subclassed by SVG and Ruby
void DirtyLinesFromChangedChild(LayoutObject*, MarkingBehavior) final;
// TODO(leviw): This should probably be an int. We don't snap equivalent lines
// to different heights.
LayoutUnit LineHeight(
bool first_line,
LinePositionMode = kPositionOnContainingLine) const final;
LayoutUnit BaselinePosition(
bool first_line,
LinePositionMode = kPositionOnContainingLine) const final;
void ChildBecameNonInline(LayoutObject* child) final;
void UpdateHitTestResult(HitTestResult&, const LayoutPoint&) const final;
void ImageChanged(WrappedImagePtr, CanDeferInvalidation) final;
void AddAnnotatedRegions(Vector<AnnotatedRegionValue>&) final;
void UpdateFromStyle() final;
bool AnonymousHasStylePropagationOverride() final { return true; }
LayoutInline* Clone() const;
LayoutBoxModelObject* ContinuationBefore(LayoutObject* before_child);
LayoutObjectChildList children_;
union {
// All of the line boxes created for this inline flow. For example,
// <i>Hello<br>world.</i> will have two <i> line boxes.
// Valid only when !IsInLayoutNGInlineFormattingContext().
LineBoxList line_boxes_;
// The first fragment of inline boxes associated with this object.
// Valid only when IsInLayoutNGInlineFormattingContext().
NGPaintFragment* first_paint_fragment_;
inline LineBoxList* LayoutInline::MutableLineBoxes() {
return &line_boxes_;
inline NGPaintFragment* LayoutInline::FirstInlineFragment() const {
return IsInLayoutNGInlineFormattingContext() ? first_paint_fragment_
: nullptr;
DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutInline, IsLayoutInline());
} // namespace blink