third_party/blink/renderer/core/layout/ng/layout_ng_block_flow.cc

// 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.

#include "third_party/blink/renderer/core/layout/ng/layout_ng_block_flow.h"

#include "third_party/blink/renderer/core/layout/layout_analyzer.h"
#include "third_party/blink/renderer/core/layout/min_max_size.h"
#include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_fragment_traversal.h"
#include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_node_data.h"
#include "third_party/blink/renderer/core/layout/ng/ng_box_fragment_builder.h"
#include "third_party/blink/renderer/core/layout/ng/ng_constraint_space.h"
#include "third_party/blink/renderer/core/layout/ng/ng_constraint_space_builder.h"
#include "third_party/blink/renderer/core/layout/ng/ng_length_utils.h"
#include "third_party/blink/renderer/core/layout/ng/ng_out_of_flow_layout_part.h"
#include "third_party/blink/renderer/core/layout/ng/ng_physical_box_fragment.h"
#include "third_party/blink/renderer/core/paint/paint_layer.h"

namespace blink {

LayoutNGBlockFlow::LayoutNGBlockFlow(Element* element)
    : LayoutNGMixin<LayoutBlockFlow>(element) {}

LayoutNGBlockFlow::~LayoutNGBlockFlow() = default;

bool LayoutNGBlockFlow::IsOfType(LayoutObjectType type) const {
  return type == kLayoutObjectNGBlockFlow ||
         LayoutNGMixin<LayoutBlockFlow>::IsOfType(type);
}

void LayoutNGBlockFlow::ComputeIntrinsicLogicalWidths(
    LayoutUnit& min_logical_width,
    LayoutUnit& max_logical_width) const {
  NGBlockNode node(const_cast<LayoutNGBlockFlow*>(this));
  if (!node.CanUseNewLayout()) {
    LayoutBlockFlow::ComputeIntrinsicLogicalWidths(min_logical_width,
                                                   max_logical_width);
    return;
  }
  MinMaxSizeInput input;
  // This function returns content-box plus scrollbar.
  input.size_type = NGMinMaxSizeType::kContentBoxSize;
  MinMaxSize sizes = node.ComputeMinMaxSize(StyleRef().GetWritingMode(), input);
  sizes += LayoutUnit(ScrollbarLogicalWidth());
  min_logical_width = sizes.min_size;
  max_logical_width = sizes.max_size;
}

void LayoutNGBlockFlow::UpdateBlockLayout(bool relayout_children) {
  LayoutAnalyzer::BlockScope analyzer(*this);

  // This block is an entry-point from the legacy engine to LayoutNG. This means
  // that we need to be at a formatting context boundary, since NG and legacy
  // don't cooperate on e.g. margin collapsing.
  DCHECK(CreatesNewFormattingContext());

  if (IsOutOfFlowPositioned()) {
    UpdateOutOfFlowBlockLayout();
    return;
  }

  NGConstraintSpace constraint_space =
      NGConstraintSpace::CreateFromLayoutObject(*this);

  scoped_refptr<NGLayoutResult> result =
      NGBlockNode(this).Layout(constraint_space);

  for (NGOutOfFlowPositionedDescendant descendant :
       result->OutOfFlowPositionedDescendants())
    descendant.node.UseOldOutOfFlowPositioning();

  const NGPhysicalBoxFragment* fragment =
      ToNGPhysicalBoxFragment(result->PhysicalFragment());

  // This object has already been positioned in legacy layout by our containing
  // block. Copy the position and place the fragment.
  //
  // TODO(kojii): This object is not positioned yet when the containing legacy
  // layout is not normal flow; e.g., table or flexbox. They lay out children to
  // determine the overall layout, then move children. In flexbox case,
  // LayoutLineItems() lays out children, which calls this function. Then later,
  // ApplyLineItemPosition() changes Location() of the children. See also
  // NGPhysicalFragment::IsPlacedByLayoutNG(). crbug.com/788590
  //
  // TODO(crbug.com/781241): LogicalLeft() is not calculated by the
  // containing block until after our layout.
  const LayoutBlock* containing_block = ContainingBlock();
  NGPhysicalOffset physical_offset;
  if (containing_block) {
    NGPhysicalSize containing_block_size(containing_block->Size().Width(),
                                         containing_block->Size().Height());
    NGLogicalOffset logical_offset(LogicalLeft(), LogicalTop());
    physical_offset = logical_offset.ConvertToPhysical(
        constraint_space.GetWritingMode(), constraint_space.Direction(),
        containing_block_size, fragment->Size());
  }
  result->SetOffset(physical_offset);
}

void LayoutNGBlockFlow::UpdateOutOfFlowBlockLayout() {
  LayoutBoxModelObject* css_container = ToLayoutBoxModelObject(Container());
  LayoutBox* container =
      css_container->IsBox() ? ToLayoutBox(css_container) : ContainingBlock();
  const ComputedStyle* container_style = container->Style();
  const ComputedStyle* parent_style = Parent()->Style();
  NGConstraintSpace constraint_space =
      NGConstraintSpace::CreateFromLayoutObject(*this);
  NGBlockNode container_node(container);
  NGBoxFragmentBuilder container_builder(
      container_node, scoped_refptr<const ComputedStyle>(container_style),
      container_style->GetWritingMode(), container_style->Direction());
  container_builder.SetIsNewFormattingContext(
      container_node.CreatesNewFormattingContext());

  // Compute ContainingBlock logical size.
  // OverrideContainingBlockContentLogicalWidth/Height are used by e.g. grid
  // layout. Override sizes are padding box size, not border box, so we must add
  // borders and scrollbars to compensate.
  NGBoxStrut borders_and_scrollbars =
      ComputeBorders(constraint_space, *container_style) +
      NGBlockNode(container).GetScrollbarSizes();

  // Calculate the border-box size of the object that's the containing block of
  // this out-of-flow positioned descendant. Note that this is not to be used as
  // the containing block size to resolve sizes and positions for the
  // descendant, since we're dealing with the border box here (not the padding
  // box, which is where the containing block is established). These sizes are
  // just used to do a fake/partial NG layout pass of the containing block (that
  // object is really managed by legacy layout).
  LayoutUnit container_border_box_logical_width;
  LayoutUnit container_border_box_logical_height;
  if (HasOverrideContainingBlockContentLogicalWidth()) {
    container_border_box_logical_width =
        OverrideContainingBlockContentLogicalWidth() +
        borders_and_scrollbars.InlineSum();
  } else {
    container_border_box_logical_width = container->LogicalWidth();
  }
  if (HasOverrideContainingBlockContentLogicalHeight()) {
    container_border_box_logical_height =
        OverrideContainingBlockContentLogicalHeight() +
        borders_and_scrollbars.BlockSum();
  } else {
    container_border_box_logical_height = container->LogicalHeight();
  }

  container_builder.SetInlineSize(container_border_box_logical_width);
  container_builder.SetBlockSize(container_border_box_logical_height);
  container_builder.SetBorders(
      ComputeBorders(constraint_space, *container_style));
  container_builder.SetPadding(
      ComputePadding(constraint_space, *container_style));

  // Calculate the actual size of the containing block for this out-of-flow
  // descendant. This is what's used to size and position us.
  LayoutUnit containing_block_logical_width =
      ContainingBlockLogicalWidthForPositioned(css_container);
  LayoutUnit containing_block_logical_height =
      ContainingBlockLogicalHeightForPositioned(css_container);

  // Determine static position.

  // static_inline and static_block are inline/block direction offsets
  // from physical origin. This is an unexpected blend of logical and
  // physical in a single variable.
  LayoutUnit static_inline;
  LayoutUnit static_block;

  Length logical_left;
  Length logical_right;
  Length logical_top;
  Length logical_bottom;

  ComputeInlineStaticDistance(logical_left, logical_right, this, css_container,
                              containing_block_logical_width);
  ComputeBlockStaticDistance(logical_top, logical_bottom, this, css_container);
  if (parent_style->IsLeftToRightDirection()) {
    if (!logical_left.IsAuto()) {
      static_inline =
          ValueForLength(logical_left, containing_block_logical_width);
    }
  } else {
    if (!logical_right.IsAuto()) {
      static_inline =
          ValueForLength(logical_right, containing_block_logical_width);
    }
  }
  if (!logical_top.IsAuto())
    static_block = ValueForLength(logical_top, containing_block_logical_height);

  // Legacy static position is relative to padding box. Convert to border
  // box. Also flip offsets as necessary to make them relative to to the
  // left/top edges.

  // First convert the static inline offset to a line-left offset, i.e. physical
  // left or top.
  LayoutUnit inline_left_or_top =
      parent_style->IsLeftToRightDirection()
          ? static_inline
          : containing_block_logical_width - static_inline;
  // Now make it relative to the left or top border edge of the containing
  // block.
  inline_left_or_top +=
      borders_and_scrollbars.LineLeft(container_style->Direction());

  // Make the static block offset relative to the start border edge of the
  // containing block.
  static_block += borders_and_scrollbars.block_start;
  // Then convert it to a physical top or left offset. Since we're already
  // border-box relative, flip it around the size of the border box, rather than
  // the size of the containing block (padding box).
  LayoutUnit block_top_or_left =
      container_style->IsFlippedBlocksWritingMode()
          ? container_border_box_logical_height - static_block
          : static_block;

  // Convert to physical direction. This can be done with a simple coordinate
  // flip because the distances are relative to physical top/left origin.
  NGPhysicalOffset static_location =
      container_style->IsHorizontalWritingMode()
          ? NGPhysicalOffset(inline_left_or_top, block_top_or_left)
          : NGPhysicalOffset(block_top_or_left, inline_left_or_top);
  NGStaticPosition static_position =
      NGStaticPosition::Create(container_style->GetWritingMode(),
                               parent_style->Direction(), static_location);

  // Set correct container for inline containing blocks.
  container_builder.AddOutOfFlowLegacyCandidate(
      NGBlockNode(this), static_position,
      css_container->IsBox() ? nullptr : css_container);

  // We really only want to lay out ourselves here, so we pass |this| to
  // Run(). Otherwise, NGOutOfFlowLayoutPart may also lay out other objects
  // it discovers that are part of the same containing block, but those
  // should get laid out by the actual containing block.
  NGOutOfFlowLayoutPart(
      &container_builder, css_container->CanContainAbsolutePositionObjects(),
      css_container->CanContainFixedPositionObjects(), borders_and_scrollbars,
      constraint_space, *container_style)
      .Run(/* only_layout */ this);
  scoped_refptr<NGLayoutResult> result = container_builder.ToBoxFragment();
  // These are the unpositioned OOF descendants of the current OOF block.
  for (NGOutOfFlowPositionedDescendant descendant :
       result->OutOfFlowPositionedDescendants())
    descendant.node.UseOldOutOfFlowPositioning();

  const NGPhysicalBoxFragment* fragment =
      ToNGPhysicalBoxFragment(result->PhysicalFragment());
  DCHECK_GT(fragment->Children().size(), 0u);
  // Copy sizes of all child fragments to Legacy.
  // There could be multiple fragments, when this node has descendants whose
  // container is this node's container.
  // Example: fixed descendant of fixed element.
  for (auto& child : fragment->Children()) {
    const NGPhysicalFragment* child_fragment = child.get();
    DCHECK(child_fragment->GetLayoutObject()->IsBox());
    LayoutBox* child_legacy_box =
        ToLayoutBox(child_fragment->GetLayoutObject());
    NGPhysicalOffset child_offset = child.Offset();
    if (container_style->IsFlippedBlocksWritingMode()) {
      child_legacy_box->SetX(container_border_box_logical_height -
                             child_offset.left - child_fragment->Size().width);
    } else {
      child_legacy_box->SetX(child_offset.left);
    }
    child_legacy_box->SetY(child_offset.top);
  }
  DCHECK_EQ(fragment->Children()[0]->GetLayoutObject(), this);
  SetIsLegacyInitiatedOutOfFlowLayout(true);
}

}  // namespace blink