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| 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 | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "core/layout/ng/ng_text_layout_algorithm.h" | |
| 6 | |
| 7 #include "core/layout/ng/ng_box_fragment.h" | |
| 8 #include "core/layout/ng/ng_break_token.h" | |
| 9 #include "core/layout/ng/ng_constraint_space.h" | |
| 10 #include "core/layout/ng/ng_fragment_builder.h" | |
| 11 #include "core/layout/ng/ng_inline_node.h" | |
| 12 #include "core/layout/ng/ng_layout_opportunity_iterator.h" | |
| 13 #include "core/layout/ng/ng_line_builder.h" | |
| 14 #include "core/layout/ng/ng_text_fragment.h" | |
| 15 #include "core/style/ComputedStyle.h" | |
| 16 #include "platform/text/TextBreakIterator.h" | |
| 17 | |
| 18 namespace blink { | |
| 19 | |
| 20 NGTextLayoutAlgorithm::NGTextLayoutAlgorithm( | |
| 21 NGInlineNode* inline_box, | |
| 22 NGBreakToken* break_token) | |
| 23 : inline_box_(inline_box), | |
| 24 break_token_(break_token) { | |
| 25 DCHECK(inline_box_); | |
| 26 } | |
| 27 | |
| 28 RefPtr<NGLayoutResult> NGTextLayoutAlgorithm::Layout() { | |
| 29 NOTREACHED(); | |
| 30 return nullptr; | |
| 31 } | |
| 32 | |
| 33 static bool IsHangable(UChar ch) { | |
| 34 return ch == ' '; | |
| 35 } | |
| 36 | |
| 37 void NGTextLayoutAlgorithm::LayoutInline(NGLineBuilder* line_builder) { | |
| 38 // TODO(kojii): Make this tickable. Each line is easy. Needs more thoughts | |
| 39 // for each fragment in a line. Bidi reordering is probably atomic. | |
| 40 // TODO(kojii): oof is not well-thought yet. The bottom static position may be | |
| 41 // in the next line, https://github.com/w3c/csswg-drafts/issues/609 | |
| 42 const String& text_content = inline_box_->Text(); | |
| 43 DCHECK(!text_content.isEmpty()); | |
| 44 // TODO(kojii): Give the locale to LazyLineBreakIterator. | |
| 45 LazyLineBreakIterator line_break_iterator(text_content); | |
| 46 unsigned current_offset = 0; | |
| 47 line_builder->SetStart(0, current_offset); | |
| 48 const unsigned end_offset = text_content.length(); | |
| 49 while (current_offset < end_offset) { | |
| 50 // Find the next break opportunity. | |
| 51 int tmp_next_breakable_offset = -1; | |
| 52 line_break_iterator.isBreakable(current_offset + 1, | |
| 53 tmp_next_breakable_offset); | |
| 54 current_offset = | |
| 55 tmp_next_breakable_offset >= 0 ? tmp_next_breakable_offset : end_offset; | |
| 56 DCHECK_LE(current_offset, end_offset); | |
| 57 | |
| 58 // Advance the break opportunity to the end of hangable characters; e.g., | |
| 59 // spaces. | |
| 60 // Unlike the ICU line breaker, LazyLineBreakIterator breaks before | |
| 61 // breakable spaces, and expect the line breaker to handle spaces | |
| 62 // differently. This logic computes in the ICU way; break after spaces, and | |
| 63 // handle spaces as hangable characters. | |
| 64 unsigned start_of_hangables = current_offset; | |
| 65 while (current_offset < end_offset && | |
| 66 IsHangable(text_content[current_offset])) | |
| 67 current_offset++; | |
| 68 | |
| 69 // Set the end to the next break opportunity. | |
| 70 line_builder->SetEnd(current_offset); | |
| 71 | |
| 72 // If there are more available spaces, mark the break opportunity and fetch | |
| 73 // more text. | |
| 74 // TODO(layout-ng): check if the height of the linebox can fit within | |
| 75 // the current opportunity. | |
| 76 if (line_builder->CanFitOnLine()) { | |
| 77 line_builder->SetBreakOpportunity(); | |
| 78 continue; | |
| 79 } | |
| 80 | |
| 81 // Compute hangable characters if exists. | |
| 82 if (current_offset != start_of_hangables) { | |
| 83 line_builder->SetStartOfHangables(start_of_hangables); | |
| 84 // If text before hangables can fit, include it in the current line. | |
| 85 if (line_builder->CanFitOnLine()) | |
| 86 line_builder->SetBreakOpportunity(); | |
| 87 } | |
| 88 | |
| 89 if (!line_builder->HasBreakOpportunity()) { | |
| 90 // The first word (break opportunity) did not fit on the line. | |
| 91 // Create a line including items that don't fit, allowing them to | |
| 92 // overflow. | |
| 93 line_builder->CreateLine(); | |
| 94 } else { | |
| 95 line_builder->CreateLineUpToLastBreakOpportunity(); | |
| 96 | |
| 97 // Items after the last break opportunity were sent to the next line. | |
| 98 // Set the break opportunity, or create a line if the word doesn't fit. | |
| 99 if (line_builder->HasItems()) { | |
| 100 if (!line_builder->CanFitOnLine()) | |
| 101 line_builder->CreateLine(); | |
| 102 else | |
| 103 line_builder->SetBreakOpportunity(); | |
| 104 } | |
| 105 } | |
| 106 } | |
| 107 | |
| 108 // If inline children ended with items left in the line builder, create a line | |
| 109 // for them. | |
| 110 if (line_builder->HasItems()) | |
| 111 line_builder->CreateLine(); | |
| 112 } | |
| 113 | |
| 114 } // namespace blink | |
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Chromium Code Reviews
Issue 2772503004:
[LayoutNG] Add NGInlineBreakToken and back of NGInlineLayoutAlgorithm (Closed)
