| // 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 NGFragmentBuilder_h |
| #define NGFragmentBuilder_h |
| |
| #include "core/layout/ng/ng_fragment.h" |
| #include "core/layout/ng/ng_units.h" |
| |
| namespace blink { |
| |
| class CORE_EXPORT NGFragmentBuilder final |
| : public GarbageCollectedFinalized<NGFragmentBuilder> { |
| public: |
| NGFragmentBuilder(NGPhysicalFragmentBase::NGFragmentType); |
| |
| using WeakBoxList = HeapLinkedHashSet<WeakMember<NGBlockNode>>; |
| |
| NGFragmentBuilder& SetWritingMode(NGWritingMode); |
| NGFragmentBuilder& SetDirection(TextDirection); |
| |
| NGFragmentBuilder& SetInlineSize(LayoutUnit); |
| NGFragmentBuilder& SetBlockSize(LayoutUnit); |
| |
| NGFragmentBuilder& SetInlineOverflow(LayoutUnit); |
| NGFragmentBuilder& SetBlockOverflow(LayoutUnit); |
| |
| NGFragmentBuilder& AddChild(NGFragmentBase*, NGLogicalOffset); |
| |
| // Builder has non-trivial out-of-flow descendant methods. |
| // These methods are building blocks for implementation of |
| // out-of-flow descendants by layout algorithms. |
| // |
| // They are intended to be used by layout algorithm like this: |
| // |
| // Part 1: layout algorithm positions in-flow children. |
| // out-of-flow children, and out-of-flow descendants of fragments |
| // are stored inside builder. |
| // |
| // for (child : children) |
| // if (child->position == (Absolute or Fixed)) |
| // builder->AddOutOfFlowChildCandidate(child); |
| // else |
| // fragment = child->Layout() |
| // builder->AddChild(fragment) |
| // end |
| // |
| // Part 2: layout algorithm positions out-of-flow descendants. |
| // |
| // builder->SetInlineSize/SetBlockSize |
| // builder->GetAndClearOutOfFlowDescendantCandidates(oof_candidates) |
| // while (oof_candidates.size() > 0) |
| // { |
| // candidate = oof_candidates.shift() |
| // if (CanPosition(candidate)) |
| // fragment = candidate->Layout(); |
| // builder->AddChild(fragment); |
| // builder->GetAndClearOutOfFlowDescendantCandidates(child_oof_candidates) |
| // oof_candidates.prepend(child_oof_candidates) |
| // else |
| // builder->AddOutOfFlowDescendant(); |
| // } |
| NGFragmentBuilder& AddOutOfFlowChildCandidate(NGBlockNode*, NGLogicalOffset); |
| |
| void GetAndClearOutOfFlowDescendantCandidates(WeakBoxList*, |
| Vector<NGStaticPosition>*); |
| |
| NGFragmentBuilder& AddOutOfFlowDescendant(NGBlockNode*, |
| const NGStaticPosition&); |
| |
| // Sets MarginStrut for the resultant fragment. |
| NGFragmentBuilder& SetMarginStrutBlockStart(const NGMarginStrut& from); |
| NGFragmentBuilder& SetMarginStrutBlockEnd(const NGMarginStrut& from); |
| |
| // Offsets are not supposed to be set during fragment construction, so we |
| // do not provide a setter here. |
| |
| // Creates the fragment. Can only be called once. |
| NGPhysicalFragment* ToFragment(); |
| |
| DECLARE_VIRTUAL_TRACE(); |
| |
| private: |
| // Out-of-flow descendant placement information. |
| // The generated fragment must compute NGStaticPosition for all |
| // out-of-flow descendants. |
| // The resulting NGStaticPosition gets derived from: |
| // 1. The offset of fragment's child. |
| // 2. The static position of descendant wrt child. |
| // |
| // A child can be: |
| // 1. A descendant itself. In this case, descendant position is (0,0). |
| // 2. A fragment containing a descendant. |
| // |
| // child_offset is stored as NGLogicalOffset because physical offset cannot |
| // be computed until we know fragment's size. |
| struct OutOfFlowPlacement { |
| NGLogicalOffset child_offset; |
| NGStaticPosition descendant_position; |
| }; |
| |
| NGPhysicalFragmentBase::NGFragmentType type_; |
| NGWritingMode writing_mode_; |
| TextDirection direction_; |
| |
| NGLogicalSize size_; |
| NGLogicalSize overflow_; |
| |
| NGMarginStrut margin_strut_; |
| |
| HeapVector<Member<NGPhysicalFragmentBase>> children_; |
| Vector<NGLogicalOffset> offsets_; |
| |
| WeakBoxList out_of_flow_descendant_candidates_; |
| Vector<OutOfFlowPlacement> out_of_flow_candidate_placements_; |
| |
| WeakBoxList out_of_flow_descendants_; |
| Vector<NGStaticPosition> out_of_flow_positions_; |
| }; |
| |
| } // namespace blink |
| |
| #endif // NGFragmentBuilder |