131 lines
4.6 KiB
C++
131 lines
4.6 KiB
C++
/*
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* Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibWeb/Layout/LineBuilder.h>
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#include <LibWeb/Layout/TextNode.h>
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namespace Web::Layout {
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LineBuilder::LineBuilder(InlineFormattingContext& context)
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: m_context(context)
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{
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}
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LineBuilder::~LineBuilder()
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{
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update_last_line();
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}
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void LineBuilder::break_line()
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{
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update_last_line();
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m_context.containing_block().line_boxes().append(LineBox());
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begin_new_line();
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}
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void LineBuilder::begin_new_line()
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{
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m_current_y += m_max_height_on_current_line;
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auto space = m_context.available_space_for_line(m_current_y);
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m_available_width_for_current_line = space.right - space.left;
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m_max_height_on_current_line = 0;
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}
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void LineBuilder::append_box(Box& box)
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{
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m_context.containing_block().ensure_last_line_box().add_fragment(box, 0, 0, box.width(), box.height());
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m_max_height_on_current_line = max(m_max_height_on_current_line, box.height());
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}
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void LineBuilder::append_text_chunk(TextNode& text_node, size_t offset_in_node, size_t length_in_node, float width, float height)
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{
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m_context.containing_block().ensure_last_line_box().add_fragment(text_node, offset_in_node, length_in_node, width, height);
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m_max_height_on_current_line = max(m_max_height_on_current_line, height);
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}
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bool LineBuilder::should_break(LayoutMode layout_mode, float next_item_width, bool should_force_break)
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{
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if (layout_mode == LayoutMode::AllPossibleLineBreaks)
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return true;
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if (should_force_break)
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return true;
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if (layout_mode == LayoutMode::OnlyRequiredLineBreaks)
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return false;
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auto current_line_width = 0.0f;
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if (!m_context.containing_block().line_boxes().is_empty())
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current_line_width = m_context.containing_block().line_boxes().last().width();
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return (current_line_width + next_item_width) > m_available_width_for_current_line;
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}
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void LineBuilder::update_last_line()
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{
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if (m_context.containing_block().line_boxes().is_empty())
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return;
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auto& line_box = m_context.containing_block().line_boxes().last();
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auto text_align = m_context.containing_block().computed_values().text_align();
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float x_offset = m_context.available_space_for_line(m_current_y).left;
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float excess_horizontal_space = m_context.containing_block().width() - line_box.width();
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switch (text_align) {
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case CSS::TextAlign::Center:
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case CSS::TextAlign::LibwebCenter:
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x_offset += excess_horizontal_space / 2;
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break;
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case CSS::TextAlign::Right:
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x_offset += excess_horizontal_space;
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break;
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case CSS::TextAlign::Left:
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case CSS::TextAlign::Justify:
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default:
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break;
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}
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float excess_horizontal_space_including_whitespace = excess_horizontal_space;
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size_t whitespace_count = 0;
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if (text_align == CSS::TextAlign::Justify) {
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for (auto& fragment : line_box.fragments()) {
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if (fragment.is_justifiable_whitespace()) {
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++whitespace_count;
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excess_horizontal_space_including_whitespace += fragment.width();
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}
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}
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}
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float justified_space_width = whitespace_count > 0 ? (excess_horizontal_space_including_whitespace / static_cast<float>(whitespace_count)) : 0;
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for (size_t i = 0; i < line_box.fragments().size(); ++i) {
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auto& fragment = line_box.fragments()[i];
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// Vertically align everyone's bottom to the line.
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// FIXME: Support other kinds of vertical alignment.
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fragment.set_offset({ roundf(x_offset + fragment.offset().x()), m_current_y + (m_max_height_on_current_line - fragment.height()) });
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if (text_align == CSS::TextAlign::Justify
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&& fragment.is_justifiable_whitespace()
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&& fragment.width() != justified_space_width) {
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float diff = justified_space_width - fragment.width();
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fragment.set_width(justified_space_width);
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// Shift subsequent sibling fragments to the right to adjust for change in width.
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for (size_t j = i + 1; j < line_box.fragments().size(); ++j) {
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auto offset = line_box.fragments()[j].offset();
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offset.translate_by(diff, 0);
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line_box.fragments()[j].set_offset(offset);
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}
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}
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}
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if (!line_box.fragments().is_empty()) {
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float left_edge = line_box.fragments().first().offset().x();
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float right_edge = line_box.fragments().last().offset().x() + line_box.fragments().last().width();
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float final_line_box_width = right_edge - left_edge;
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line_box.m_width = final_line_box_width;
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}
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}
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}
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