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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NGLayoutInputNode_h
#define NGLayoutInputNode_h
#include "base/optional.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/layout/layout_box.h"
#include "third_party/blink/renderer/core/layout/ng/geometry/ng_logical_size.h"
#include "third_party/blink/renderer/core/layout/ng/layout_box_utils.h"
#include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.h"
#include "third_party/blink/renderer/platform/geometry/layout_unit.h"
#include "third_party/blink/renderer/platform/text/writing_mode.h"
namespace blink {
class ComputedStyle;
class Document;
class LayoutObject;
class LayoutBox;
class NGBreakToken;
class NGConstraintSpace;
class NGInlineChildLayoutContext;
class NGLayoutResult;
class NGPaintFragment;
struct MinMaxSize;
struct NGLogicalSize;
struct NGPhysicalSize;
enum class NGMinMaxSizeType { kContentBoxSize, kBorderBoxSize };
// Input to the min/max inline size calculation algorithm for child nodes. Child
// nodes within the same formatting context need to know which floats are beside
// them.
struct MinMaxSizeInput {
// The min-max size calculation (un-intuitively) requires a percentage
// resolution size!
// This occurs when a replaced element has an intrinsic size. E.g.
// <div style="float: left; height: 100px">
// <img sr="intrinsic-ratio-1x1.png" style="height: 50%;" />
// </div>
// In the above example float ends up with a width of 50px.
// As we don't perform any tree walking, we need to pass the percentage
// resolution block-size for min/max down the min/max size calculation.
explicit MinMaxSizeInput(LayoutUnit percentage_resolution_block_size)
: percentage_resolution_block_size(percentage_resolution_block_size) {}
LayoutUnit float_left_inline_size;
LayoutUnit float_right_inline_size;
LayoutUnit percentage_resolution_block_size;
// Whether to return the size as a content-box size or border-box size.
NGMinMaxSizeType size_type = NGMinMaxSizeType::kBorderBoxSize;
// Represents the input to a layout algorithm for a given node. The layout
// engine should use the style, node type to determine which type of layout
// algorithm to use to produce fragments for this node.
class CORE_EXPORT NGLayoutInputNode {
enum NGLayoutInputNodeType {
// When adding new values, ensure type_ below has enough bits.
static NGLayoutInputNode Create(LayoutBox* box, NGLayoutInputNodeType type) {
// This function should create an instance of the subclass. This works
// because subclasses are not virtual and do not add fields.
return NGLayoutInputNode(box, type);
NGLayoutInputNode(std::nullptr_t) : box_(nullptr), type_(kBlock) {}
NGLayoutInputNodeType Type() const {
return static_cast<NGLayoutInputNodeType>(type_);
bool IsInline() const { return type_ == kInline; }
bool IsBlock() const { return type_ == kBlock; }
bool IsColumnSpanAll() const { return IsBlock() && box_->IsColumnSpanAll(); }
bool IsFloating() const { return IsBlock() && Style().IsFloating(); }
bool IsOutOfFlowPositioned() const {
return IsBlock() && Style().HasOutOfFlowPosition();
bool IsReplaced() const { return box_->IsLayoutReplaced(); }
bool IsAbsoluteContainer() const {
return box_->CanContainAbsolutePositionObjects();
bool IsFixedContainer() const {
return box_->CanContainFixedPositionObjects();
bool IsBody() const { return IsBlock() && box_->IsBody(); }
bool IsDocumentElement() const { return box_->IsDocumentElement(); }
bool IsFlexItem() const { return IsBlock() && box_->IsFlexItemIncludingNG(); }
bool ShouldBeConsideredAsReplaced() const {
return box_->ShouldBeConsideredAsReplaced();
bool IsListItem() const { return IsBlock() && box_->IsLayoutNGListItem(); }
bool IsListMarker() const {
return IsBlock() && box_->IsLayoutNGListMarker();
bool ListMarkerOccupiesWholeLine() const {
return ToLayoutNGListMarker(box_)->NeedsOccupyWholeLine();
bool IsTableCell() const { return IsBlock() && box_->IsTableCell(); }
bool IsFieldsetContainer() const {
return IsBlock() && box_->IsLayoutNGFieldset();
// Return true if this is the legend child of a fieldset that gets special
// treatment (i.e. placed over the block-start border).
bool IsRenderedLegend() const {
return IsBlock() && box_->IsRenderedLegend();
bool IsAnonymousBlock() const { return box_->IsAnonymousBlock(); }
// If the node is a quirky container for margin collapsing, see:
// NOTE: The spec appears to only somewhat match reality.
bool IsQuirkyContainer() const {
return box_->GetDocument().InQuirksMode() &&
(box_->IsBody() || box_->IsTableCell());
// In quirks mode, in-flow positioned BODY and root elements must completely
// fill the viewport. Return true if this is such a node.
bool IsQuirkyAndFillsViewport() const {
if (!GetDocument().InQuirksMode())
return false;
return (IsDocumentElement() || IsBody()) && !Style().HasOutOfFlowPosition();
bool CreatesNewFormattingContext() const {
return IsBlock() && box_->AvoidsFloats();
// Returns true if this node should pass its percentage resolution block-size
// to its children. Typically only quirks-mode, auto block-size, block nodes.
bool UseParentPercentageResolutionBlockSizeForChildren() const {
if (IsBlock() && box_->IsLayoutBlock()) {
return LayoutBoxUtils::SkipContainingBlockForPercentHeightCalculation(
return false;
// Performs layout on this input node, will return the layout result.
scoped_refptr<const NGLayoutResult> Layout(const NGConstraintSpace&,
const NGBreakToken*,
// Returns border box.
MinMaxSize ComputeMinMaxSize(WritingMode,
const MinMaxSizeInput&,
const NGConstraintSpace* = nullptr);
// Returns intrinsic sizing information for replaced elements.
// ComputeReplacedSize can use it to compute actual replaced size.
// Corresponds to Legacy's LayoutReplaced::IntrinsicSizingInfo.
void IntrinsicSize(base::Optional<LayoutUnit>* computed_inline_size,
base::Optional<LayoutUnit>* computed_block_size,
NGLogicalSize* aspect_ratio) const;
LayoutUnit IntrinsicPaddingBlockStart() const;
LayoutUnit IntrinsicPaddingBlockEnd() const;
// Returns the next sibling.
NGLayoutInputNode NextSibling();
Document& GetDocument() const { return box_->GetDocument(); }
NGPhysicalSize InitialContainingBlockSize() const;
// Returns the LayoutObject which is associated with this node.
LayoutBox* GetLayoutBox() const { return box_; }
const ComputedStyle& Style() const { return box_->StyleRef(); }
bool ShouldApplySizeContainment() const {
return box_->ShouldApplySizeContainment();
// Returns the first NGPaintFragment for this node. When block fragmentation
// occurs, there will be multiple NGPaintFragment for a node.
const NGPaintFragment* PaintFragment() const;
String ToString() const;
explicit operator bool() const { return box_ != nullptr; }
bool operator==(const NGLayoutInputNode& other) const {
return box_ == other.box_;
bool operator!=(const NGLayoutInputNode& other) const {
return !(*this == other);
#ifndef NDEBUG
void ShowNodeTree() const;
NGLayoutInputNode(LayoutBox* box, NGLayoutInputNodeType type)
: box_(box), type_(type) {}
LayoutBox* box_;
unsigned type_ : 1; // NGLayoutInputNodeType
} // namespace blink
#endif // NGLayoutInputNode_h