| // 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. |
| |
| #include "core/layout/ng/ng_text_layout_algorithm.h" |
| |
| #include "core/layout/ng/ng_box_fragment.h" |
| #include "core/layout/ng/ng_break_token.h" |
| #include "core/layout/ng/ng_constraint_space.h" |
| #include "core/layout/ng/ng_fragment_builder.h" |
| #include "core/layout/ng/ng_inline_node.h" |
| #include "core/layout/ng/ng_layout_opportunity_iterator.h" |
| #include "core/layout/ng/ng_line_builder.h" |
| #include "core/layout/ng/ng_text_fragment.h" |
| #include "core/style/ComputedStyle.h" |
| #include "platform/text/TextBreakIterator.h" |
| |
| namespace blink { |
| |
| NGTextLayoutAlgorithm::NGTextLayoutAlgorithm( |
| NGInlineNode* inline_box, |
| NGConstraintSpace* constraint_space, |
| NGBreakToken* break_token) |
| : inline_box_(inline_box), |
| constraint_space_(constraint_space), |
| break_token_(break_token) { |
| DCHECK(inline_box_); |
| } |
| |
| RefPtr<NGLayoutResult> NGTextLayoutAlgorithm::Layout() { |
| ASSERT_NOT_REACHED(); |
| return nullptr; |
| } |
| |
| static bool IsHangable(UChar ch) { |
| return ch == ' '; |
| } |
| |
| void NGTextLayoutAlgorithm::LayoutInline(NGLineBuilder* line_builder) { |
| // TODO(kojii): Make this tickable. Each line is easy. Needs more thoughts |
| // for each fragment in a line. Bidi reordering is probably atomic. |
| // TODO(kojii): oof is not well-thought yet. The bottom static position may be |
| // in the next line, https://github.com/w3c/csswg-drafts/issues/609 |
| const String& text_content = inline_box_->Text(); |
| DCHECK(!text_content.isEmpty()); |
| // TODO(kojii): Give the locale to LazyLineBreakIterator. |
| LazyLineBreakIterator line_break_iterator(text_content); |
| unsigned current_offset = 0; |
| line_builder->SetStart(0, current_offset); |
| const unsigned end_offset = text_content.length(); |
| while (current_offset < end_offset) { |
| // Find the next break opportunity. |
| int tmp_next_breakable_offset = -1; |
| line_break_iterator.isBreakable(current_offset + 1, |
| tmp_next_breakable_offset); |
| current_offset = |
| tmp_next_breakable_offset >= 0 ? tmp_next_breakable_offset : end_offset; |
| DCHECK_LE(current_offset, end_offset); |
| |
| // Advance the break opportunity to the end of hangable characters; e.g., |
| // spaces. |
| // Unlike the ICU line breaker, LazyLineBreakIterator breaks before |
| // breakable spaces, and expect the line breaker to handle spaces |
| // differently. This logic computes in the ICU way; break after spaces, and |
| // handle spaces as hangable characters. |
| unsigned start_of_hangables = current_offset; |
| while (current_offset < end_offset && |
| IsHangable(text_content[current_offset])) |
| current_offset++; |
| |
| // Set the end to the next break opportunity. |
| line_builder->SetEnd(current_offset); |
| |
| // If there are more available spaces, mark the break opportunity and fetch |
| // more text. |
| // TODO(layout-ng): check if the height of the linebox can fit within |
| // the current opportunity. |
| if (line_builder->CanFitOnLine()) { |
| line_builder->SetBreakOpportunity(); |
| continue; |
| } |
| |
| // Compute hangable characters if exists. |
| if (current_offset != start_of_hangables) { |
| line_builder->SetStartOfHangables(start_of_hangables); |
| // If text before hangables can fit, include it in the current line. |
| if (line_builder->CanFitOnLine()) |
| line_builder->SetBreakOpportunity(); |
| } |
| |
| if (!line_builder->HasBreakOpportunity()) { |
| // The first word (break opportunity) did not fit on the line. |
| // Create a line including items that don't fit, allowing them to |
| // overflow. |
| line_builder->CreateLine(); |
| } else { |
| line_builder->CreateLineUpToLastBreakOpportunity(); |
| |
| // Items after the last break opportunity were sent to the next line. |
| // Set the break opportunity, or create a line if the word doesn't fit. |
| if (line_builder->HasItems()) { |
| if (!line_builder->CanFitOnLine()) |
| line_builder->CreateLine(); |
| else |
| line_builder->SetBreakOpportunity(); |
| } |
| } |
| } |
| |
| // If inline children ended with items left in the line builder, create a line |
| // for them. |
| if (line_builder->HasItems()) |
| line_builder->CreateLine(); |
| } |
| |
| } // namespace blink |