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// Copyright 2019 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/ng_simplified_layout_algorithm.h"
#include "third_party/blink/renderer/core/layout/ng/ng_block_break_token.h"
#include "third_party/blink/renderer/core/layout/ng/ng_block_layout_algorithm_utils.h"
#include "third_party/blink/renderer/core/layout/ng/ng_box_fragment.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_fragment.h"
#include "third_party/blink/renderer/core/layout/ng/ng_layout_result.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/layout/ng/ng_space_utils.h"
#include "third_party/blink/renderer/core/paint/paint_layer.h"
namespace blink {
NGSimplifiedLayoutAlgorithm::NGSimplifiedLayoutAlgorithm(
const NGLayoutAlgorithmParams& params,
const NGLayoutResult& result)
: NGLayoutAlgorithm(params),
previous_result_(result),
writing_mode_(Style().GetWritingMode()),
direction_(Style().Direction()) {
// Currently this only supports block-flow layout due to the static-position
// calculations. If support for other layout types is added this logic will
// need to be changed.
bool is_block_flow = Node().IsBlockFlow();
const NGPhysicalBoxFragment& physical_fragment =
To<NGPhysicalBoxFragment>(result.PhysicalFragment());
container_builder_.SetInitialFragmentGeometry(params.fragment_geometry);
container_builder_.SetIsNewFormattingContext(
physical_fragment.IsFormattingContextRoot());
if (is_block_flow) {
container_builder_.SetIsInlineFormattingContext(
Node().IsInlineFormattingContextRoot());
container_builder_.SetStyleVariant(physical_fragment.StyleVariant());
if (result.SubtreeModifiedMarginStrut())
container_builder_.SetSubtreeModifiedMarginStrut();
container_builder_.SetEndMarginStrut(result.EndMarginStrut());
// Ensure that the parent layout hasn't asked us to move our BFC position.
DCHECK_EQ(ConstraintSpace().BfcOffset(),
previous_result_.GetConstraintSpaceForCaching().BfcOffset());
container_builder_.SetBfcLineOffset(result.BfcLineOffset());
if (result.BfcBlockOffset())
container_builder_.SetBfcBlockOffset(*result.BfcBlockOffset());
if (result.LinesUntilClamp())
container_builder_.SetLinesUntilClamp(result.LinesUntilClamp());
NGExclusionSpace exclusion_space = result.ExclusionSpace();
container_builder_.SetExclusionSpace(std::move(exclusion_space));
if (result.IsSelfCollapsing())
container_builder_.SetIsSelfCollapsing();
if (result.IsPushedByFloats())
container_builder_.SetIsPushedByFloats();
container_builder_.SetAdjoiningObjectTypes(result.AdjoiningObjectTypes());
container_builder_.SetUnpositionedListMarker(
result.UnpositionedListMarker());
if (physical_fragment.LastBaseline())
container_builder_.SetLastBaseline(*physical_fragment.LastBaseline());
} else {
// Only block-flow layout sets the following fields.
DCHECK(physical_fragment.IsFormattingContextRoot());
DCHECK(!Node().IsInlineFormattingContextRoot());
DCHECK_EQ(physical_fragment.StyleVariant(), NGStyleVariant::kStandard);
DCHECK(!result.SubtreeModifiedMarginStrut());
DCHECK(result.EndMarginStrut().IsEmpty());
DCHECK_EQ(ConstraintSpace().BfcOffset(), NGBfcOffset());
DCHECK_EQ(result.BfcLineOffset(), LayoutUnit());
DCHECK_EQ(result.BfcBlockOffset().value_or(LayoutUnit()), LayoutUnit());
DCHECK(!result.LinesUntilClamp());
DCHECK(result.ExclusionSpace().IsEmpty());
DCHECK(!result.IsSelfCollapsing());
DCHECK(!result.IsPushedByFloats());
DCHECK_EQ(result.AdjoiningObjectTypes(), kAdjoiningNone);
DCHECK(!result.UnpositionedListMarker());
DCHECK(!physical_fragment.LastBaseline());
if (physical_fragment.IsFieldsetContainer())
container_builder_.SetIsFieldsetContainer();
if (physical_fragment.IsMathMLFraction())
container_builder_.SetIsMathMLFraction();
container_builder_.SetCustomLayoutData(result.CustomLayoutData());
}
if (physical_fragment.IsHiddenForPaint())
container_builder_.SetIsHiddenForPaint(true);
if (physical_fragment.Baseline())
container_builder_.SetBaseline(*physical_fragment.Baseline());
container_builder_.SetIntrinsicBlockSize(result.IntrinsicBlockSize());
container_builder_.SetOverflowBlockSize(result.OverflowBlockSize());
LayoutUnit new_block_size = ComputeBlockSizeForFragment(
ConstraintSpace(), Style(),
container_builder_.Borders() + container_builder_.Padding(),
result.IntrinsicBlockSize(),
container_builder_.InitialBorderBoxSize().inline_size);
// Only block-flow is allowed to change its block-size during "simplified"
// layout, all other layout types must remain the same size.
if (is_block_flow) {
container_builder_.SetBlockSize(new_block_size);
} else {
LayoutUnit old_block_size =
NGFragment(writing_mode_, physical_fragment).BlockSize();
DCHECK_EQ(old_block_size, new_block_size);
container_builder_.SetBlockSize(old_block_size);
}
// We need the previous physical container size to calculate the position of
// any child fragments.
previous_physical_container_size_ = physical_fragment.Size();
}
scoped_refptr<const NGLayoutResult> NGSimplifiedLayoutAlgorithm::Layout() {
// Since simplified layout's |Layout()| function deals with laying out
// children, we can early out if we are display-locked.
if (Node().LayoutBlockedByDisplayLock(DisplayLockLifecycleTarget::kChildren))
return container_builder_.ToBoxFragment();
const auto& previous_fragment =
To<NGPhysicalBoxFragment>(previous_result_.PhysicalFragment());
for (const auto& child_link : previous_fragment.Children()) {
const auto& child_fragment =
*To<NGPhysicalContainerFragment>(child_link.get());
// We'll add OOF-positioned candidates below.
if (child_fragment.IsOutOfFlowPositioned())
continue;
// We don't need to relayout list-markers, or line-box fragments.
if (child_fragment.IsListMarker() || child_fragment.IsLineBox()) {
AddChildFragment(child_link, child_fragment);
continue;
}
// Add the (potentially updated) layout result.
scoped_refptr<const NGLayoutResult> result =
NGBlockNode(ToLayoutBox(child_fragment.GetMutableLayoutObject()))
.SimplifiedLayout(child_fragment);
// The child may have failed "simplified" layout! (Due to adding/removing
// scrollbars). In this case we also return a nullptr, indicating a full
// layout is required.
if (!result)
return nullptr;
AddChildFragment(child_link, result->PhysicalFragment());
}
// Iterate through all our OOF-positioned children and add them as candidates.
for (NGLayoutInputNode child = Node().FirstChild(); child;
child = child.NextSibling()) {
if (!child.IsOutOfFlowPositioned())
continue;
// TODO(ikilpatrick): Accessing the static-position from the layer isn't
// ideal. We should save this on the physical fragment which initially
// calculated it.
const auto* layer = child.GetLayoutBox()->Layer();
NGLogicalStaticPosition position = layer->GetStaticPosition();
container_builder_.AddOutOfFlowChildCandidate(
To<NGBlockNode>(child), position.offset, position.inline_edge,
position.block_edge, /* needs_block_offset_adjustment */ false);
}
// We add both items and line-box fragments for existing mechanisms to work.
// We may revisit this in future. See also |NGBoxFragmentBuilder::AddResult|.
if (RuntimeEnabledFeatures::LayoutNGFragmentItemEnabled()) {
if (const NGFragmentItems* previous_items = previous_fragment.Items()) {
auto* items_builder = container_builder_.ItemsBuilder();
DCHECK(items_builder);
items_builder->AddPreviousItems(*previous_items, writing_mode_,
direction_,
previous_physical_container_size_);
}
}
NGOutOfFlowLayoutPart(
Node(), ConstraintSpace(),
container_builder_.Borders() + container_builder_.Scrollbar(),
&container_builder_)
.Run();
// The block size may have been changed. This may affect the inline block
// baseline if it is from the logical bottom margin edge.
DCHECK_EQ(previous_fragment.LastBaseline().has_value(),
container_builder_.LastBaseline().has_value());
if (container_builder_.LastBaseline())
container_builder_.SetLastBaselineToBlockEndMarginEdgeIfNeeded();
return container_builder_.ToBoxFragment();
}
NOINLINE scoped_refptr<const NGLayoutResult>
NGSimplifiedLayoutAlgorithm::LayoutWithItemsBuilder() {
NGFragmentItemsBuilder items_builder;
container_builder_.SetItemsBuilder(&items_builder);
scoped_refptr<const NGLayoutResult> result = Layout();
// Ensure stack-allocated |NGFragmentItemsBuilder| is not used anymore.
// TODO(kojii): Revisit when the storage of |NGFragmentItemsBuilder| is
// finalized.
container_builder_.SetItemsBuilder(nullptr);
return result;
}
void NGSimplifiedLayoutAlgorithm::AddChildFragment(
const NGLink& old_fragment,
const NGPhysicalContainerFragment& new_fragment) {
DCHECK_EQ(old_fragment->Size(), new_fragment.Size());
// Determine the previous position in the logical coordinate system.
LogicalOffset child_offset = old_fragment.Offset().ConvertToLogical(
writing_mode_, direction_, previous_physical_container_size_,
new_fragment.Size());
// Add the new fragment to the builder.
container_builder_.AddChild(new_fragment, child_offset);
}
} // namespace blink
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