| // 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 NGLayoutAlgorithm_h |
| #define NGLayoutAlgorithm_h |
| |
| #include "base/optional.h" |
| #include "third_party/blink/renderer/core/core_export.h" |
| #include "third_party/blink/renderer/core/layout/min_max_size.h" |
| #include "third_party/blink/renderer/core/layout/ng/ng_constraint_space.h" |
| #include "third_party/blink/renderer/platform/wtf/allocator.h" |
| |
| namespace blink { |
| |
| class ComputedStyle; |
| class NGLayoutResult; |
| struct MinMaxSizeInput; |
| |
| // Base class for all LayoutNG algorithms. |
| template <typename NGInputNodeType, |
| typename NGBoxFragmentBuilderType, |
| typename NGBreakTokenType> |
| class CORE_EXPORT NGLayoutAlgorithm { |
| STACK_ALLOCATED(); |
| public: |
| NGLayoutAlgorithm(NGInputNodeType node, |
| scoped_refptr<const ComputedStyle> style, |
| const NGConstraintSpace& space, |
| TextDirection direction, |
| const NGBreakTokenType* break_token) |
| : node_(node), |
| constraint_space_(space), |
| break_token_(break_token), |
| container_builder_(node, style, space.GetWritingMode(), direction) {} |
| |
| NGLayoutAlgorithm(NGInputNodeType node, |
| const NGConstraintSpace& space, |
| const NGBreakTokenType* break_token) |
| : NGLayoutAlgorithm(node, |
| &node.Style(), |
| space, |
| space.Direction(), |
| break_token) {} |
| |
| virtual ~NGLayoutAlgorithm() = default; |
| |
| // Actual layout function. Lays out the children and descendants within the |
| // constraints given by the NGConstraintSpace. Returns a layout result with |
| // the resulting layout information. |
| // TODO(layout-dev): attempt to make this function const. |
| virtual scoped_refptr<NGLayoutResult> Layout() = 0; |
| |
| // Computes the min-content and max-content intrinsic sizes for the given box. |
| // The result will not take any min-width, max-width or width properties into |
| // account. If the return value is empty, the caller is expected to synthesize |
| // this value from the overflow rect returned from Layout called with an |
| // available width of 0 and LayoutUnit::max(), respectively. |
| virtual base::Optional<MinMaxSize> ComputeMinMaxSize( |
| const MinMaxSizeInput&) const { |
| return base::nullopt; |
| } |
| |
| protected: |
| const NGConstraintSpace& ConstraintSpace() const { return constraint_space_; } |
| |
| const ComputedStyle& Style() const { return node_.Style(); } |
| |
| NGBfcOffset ContainerBfcOffset() const { |
| DCHECK(container_builder_.BfcBlockOffset()); |
| return {container_builder_.BfcLineOffset(), |
| container_builder_.BfcBlockOffset().value()}; |
| } |
| |
| NGInputNodeType Node() const { return node_; } |
| |
| const NGBreakTokenType* BreakToken() const { return break_token_.get(); } |
| |
| NGInputNodeType node_; |
| const NGConstraintSpace& constraint_space_; |
| |
| // The break token from which we are currently resuming layout. |
| scoped_refptr<const NGBreakTokenType> break_token_; |
| |
| NGBoxFragmentBuilderType container_builder_; |
| }; |
| |
| } // namespace blink |
| |
| #endif // NGLayoutAlgorithm_h |