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1 // Copyright 2016 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef NGFragmentBuilder_h | 5 #ifndef NGFragmentBuilder_h |
6 #define NGFragmentBuilder_h | 6 #define NGFragmentBuilder_h |
7 | 7 |
8 #include "core/layout/ng/ng_fragment.h" | 8 #include "core/layout/ng/ng_fragment.h" |
9 #include "core/layout/ng/ng_units.h" | 9 #include "core/layout/ng/ng_units.h" |
10 | 10 |
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21 NGFragmentBuilder& SetDirection(TextDirection); | 21 NGFragmentBuilder& SetDirection(TextDirection); |
22 | 22 |
23 NGFragmentBuilder& SetInlineSize(LayoutUnit); | 23 NGFragmentBuilder& SetInlineSize(LayoutUnit); |
24 NGFragmentBuilder& SetBlockSize(LayoutUnit); | 24 NGFragmentBuilder& SetBlockSize(LayoutUnit); |
25 | 25 |
26 NGFragmentBuilder& SetInlineOverflow(LayoutUnit); | 26 NGFragmentBuilder& SetInlineOverflow(LayoutUnit); |
27 NGFragmentBuilder& SetBlockOverflow(LayoutUnit); | 27 NGFragmentBuilder& SetBlockOverflow(LayoutUnit); |
28 | 28 |
29 NGFragmentBuilder& AddChild(NGFragmentBase*, NGLogicalOffset); | 29 NGFragmentBuilder& AddChild(NGFragmentBase*, NGLogicalOffset); |
30 | 30 |
31 NGFragmentBuilder& SetOutOfFlowDescendants(WeakBoxList&, | 31 // Builder has non-trivial out-of-flow descendant methods. |
32 Vector<NGLogicalOffset>&); | 32 // These methods are building blocks for implementation of |
| 33 // out-of-flow descendants by layout algorithms. |
| 34 // |
| 35 // They are intended to be used by layout algorithm like this: |
| 36 // |
| 37 // Part 1: layout algorithm positions in-flow children. |
| 38 // out-of-flow children, and out-of-flow descendants of fragments |
| 39 // are stored inside builder. |
| 40 // |
| 41 // for (child : children) |
| 42 // if (child->position == (Absolute or Fixed)) |
| 43 // builder->AddOutOfFlowChildCandidate(child); |
| 44 // else |
| 45 // fragment = child->Layout() |
| 46 // builder->AddChild(fragment) |
| 47 // end |
| 48 // |
| 49 // Part 2: layout algorithm positions out-of-flow descendants. |
| 50 // |
| 51 // builder->SetInlineSize/SetBlockSize |
| 52 // builder->GetAndClearOutOfFlowDescendantCandidates(oof_candidates) |
| 53 // while (oof_candidates.size() > 0) |
| 54 // { |
| 55 // candidate = oof_candidates.shift() |
| 56 // if (CanPosition(candidate)) |
| 57 // fragment = candidate->Layout(); |
| 58 // builder->AddChild(fragment); |
| 59 // builder->GetAndClearOutOfFlowDescendantCandidates(child_oof_candidates) |
| 60 // oof_candidates.prepend(child_oof_candidates) |
| 61 // else |
| 62 // builder->AddOutOfFlowDescendant(); |
| 63 // } |
| 64 NGFragmentBuilder& AddOutOfFlowChildCandidate(NGBlockNode*, NGLogicalOffset); |
| 65 |
| 66 void GetAndClearOutOfFlowDescendantCandidates(WeakBoxList*, |
| 67 Vector<NGStaticPosition>*); |
| 68 |
| 69 NGFragmentBuilder& AddOutOfFlowDescendant(NGBlockNode*, |
| 70 const NGStaticPosition&); |
33 | 71 |
34 // Sets MarginStrut for the resultant fragment. | 72 // Sets MarginStrut for the resultant fragment. |
35 NGFragmentBuilder& SetMarginStrutBlockStart(const NGMarginStrut& from); | 73 NGFragmentBuilder& SetMarginStrutBlockStart(const NGMarginStrut& from); |
36 NGFragmentBuilder& SetMarginStrutBlockEnd(const NGMarginStrut& from); | 74 NGFragmentBuilder& SetMarginStrutBlockEnd(const NGMarginStrut& from); |
37 | 75 |
38 // Offsets are not supposed to be set during fragment construction, so we | 76 // Offsets are not supposed to be set during fragment construction, so we |
39 // do not provide a setter here. | 77 // do not provide a setter here. |
40 | 78 |
41 // Creates the fragment. Can only be called once. | 79 // Creates the fragment. Can only be called once. |
42 NGPhysicalFragment* ToFragment(); | 80 NGPhysicalFragment* ToFragment(); |
43 | 81 |
44 DECLARE_VIRTUAL_TRACE(); | 82 DECLARE_VIRTUAL_TRACE(); |
45 | 83 |
46 private: | 84 private: |
| 85 // Out-of-flow descendant placement information. |
| 86 // The generated fragment must compute NGStaticPosition for all |
| 87 // out-of-flow descendants. |
| 88 // The resulting NGStaticPosition gets derived from: |
| 89 // 1. The offset of fragment's child. |
| 90 // 2. The static position of descendant wrt child. |
| 91 // |
| 92 // A child can be: |
| 93 // 1. A descendant itself. In this case, descendant position is (0,0). |
| 94 // 2. A fragment containing a descendant. |
| 95 // |
| 96 // child_offset is stored as NGLogicalOffset because physical offset cannot |
| 97 // be computed until we know fragment's size. |
| 98 struct OutOfFlowPlacement { |
| 99 NGLogicalOffset child_offset; |
| 100 NGStaticPosition descendant_position; |
| 101 }; |
| 102 |
47 NGPhysicalFragmentBase::NGFragmentType type_; | 103 NGPhysicalFragmentBase::NGFragmentType type_; |
48 NGWritingMode writing_mode_; | 104 NGWritingMode writing_mode_; |
49 TextDirection direction_; | 105 TextDirection direction_; |
50 | 106 |
51 NGLogicalSize size_; | 107 NGLogicalSize size_; |
52 NGLogicalSize overflow_; | 108 NGLogicalSize overflow_; |
53 | 109 |
54 NGMarginStrut margin_strut_; | 110 NGMarginStrut margin_strut_; |
55 | 111 |
56 HeapVector<Member<NGPhysicalFragmentBase>> children_; | 112 HeapVector<Member<NGPhysicalFragmentBase>> children_; |
57 Vector<NGLogicalOffset> offsets_; | 113 Vector<NGLogicalOffset> offsets_; |
| 114 |
| 115 WeakBoxList out_of_flow_descendant_candidates_; |
| 116 Vector<OutOfFlowPlacement> out_of_flow_candidate_placements_; |
| 117 |
58 WeakBoxList out_of_flow_descendants_; | 118 WeakBoxList out_of_flow_descendants_; |
59 Vector<NGLogicalOffset> out_of_flow_offsets_; | 119 Vector<NGStaticPosition> out_of_flow_positions_; |
60 }; | 120 }; |
61 | 121 |
62 } // namespace blink | 122 } // namespace blink |
63 | 123 |
64 #endif // NGFragmentBuilder | 124 #endif // NGFragmentBuilder |
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