/* * Copyright (c) 2018-2020, Andreas Kling * Copyright (c) 2021, sin-ack * * SPDX-License-Identifier: BSD-2-Clause */ #include "TextLayout.h" namespace Gfx { enum class BlockType { Newline, Whitespace, Word }; struct Block { BlockType type; Utf8View characters; }; IntRect TextLayout::bounding_rect(TextWrapping wrapping, int line_spacing) const { auto lines = wrap_lines(TextElision::None, wrapping, line_spacing, FitWithinRect::No); if (!lines.size()) { return {}; } IntRect bounding_rect = { 0, 0, 0, static_cast((lines.size() * (m_font->glyph_height() + line_spacing)) - line_spacing) }; for (auto& line : lines) { auto line_width = m_font->width(line); if (line_width > bounding_rect.width()) bounding_rect.set_width(line_width); } return bounding_rect; } Vector TextLayout::wrap_lines(TextElision elision, TextWrapping wrapping, int line_spacing, FitWithinRect fit_within_rect) const { Vector blocks; Optional current_block_type; size_t block_start_offset = 0; size_t offset = 0; for (auto it = m_text.begin(); !it.done(); ++it) { offset = m_text.iterator_offset(it); switch (*it) { case '\t': case ' ': { if (current_block_type.has_value() && current_block_type.value() != BlockType::Whitespace) { blocks.append({ current_block_type.value(), m_text.substring_view(block_start_offset, offset - block_start_offset), }); current_block_type.clear(); } if (!current_block_type.has_value()) { current_block_type = BlockType::Whitespace; block_start_offset = offset; } continue; } case '\n': case '\r': { if (current_block_type.has_value()) { blocks.append({ current_block_type.value(), m_text.substring_view(block_start_offset, offset - block_start_offset), }); current_block_type.clear(); } blocks.append({ BlockType::Newline, Utf8View {} }); continue; } default: { if (current_block_type.has_value() && current_block_type.value() != BlockType::Word) { blocks.append({ current_block_type.value(), m_text.substring_view(block_start_offset, offset - block_start_offset), }); current_block_type.clear(); } if (!current_block_type.has_value()) { current_block_type = BlockType::Word; block_start_offset = offset; } } } } if (current_block_type.has_value()) { blocks.append({ current_block_type.value(), m_text.substring_view(block_start_offset, m_text.byte_length() - block_start_offset), }); } size_t max_lines_that_can_fit = 0; if (m_rect.height() >= m_font->glyph_height()) { // NOTE: If glyph height is 10 and line spacing is 1, we can fit a // single line into a 10px rect and a 20px rect, but 2 lines into a // 21px rect. max_lines_that_can_fit = 1 + (m_rect.height() - m_font->glyph_height()) / (m_font->glyph_height() + line_spacing); } if (max_lines_that_can_fit == 0) return {}; Vector lines; StringBuilder builder; size_t line_width = 0; size_t current_block = 0; bool did_not_finish = false; for (Block& block : blocks) { switch (block.type) { case BlockType::Newline: { lines.append(builder.to_string()); builder.clear(); line_width = 0; if (lines.size() == max_lines_that_can_fit && fit_within_rect == FitWithinRect::Yes) { did_not_finish = true; goto blocks_processed; } current_block++; continue; } case BlockType::Whitespace: case BlockType::Word: { size_t block_width = font().width(block.characters); // FIXME: This should look at the specific advance amount of the // last character, but we don't support that yet. if (current_block != blocks.size() - 1) { block_width += font().glyph_spacing(); } if (wrapping == TextWrapping::Wrap && line_width + block_width > static_cast(m_rect.width())) { lines.append(builder.to_string()); builder.clear(); line_width = 0; } if (lines.size() == max_lines_that_can_fit && fit_within_rect == FitWithinRect::Yes) { did_not_finish = true; goto blocks_processed; } builder.append(block.characters.as_string()); line_width += block_width; current_block++; } } } blocks_processed: if (!did_not_finish) { auto last_line = builder.to_string(); if (!last_line.is_empty()) lines.append(last_line); } switch (elision) { case TextElision::None: break; case TextElision::Right: { lines.at(lines.size() - 1) = elide_text_from_right(Utf8View { lines.at(lines.size() - 1) }, did_not_finish); break; } } return lines; } String TextLayout::elide_text_from_right(Utf8View text, bool force_elision) const { size_t text_width = m_font->width(text); if (force_elision || text_width > static_cast(m_rect.width())) { size_t ellipsis_width = m_font->width("..."); size_t current_width = ellipsis_width; size_t glyph_spacing = m_font->glyph_spacing(); // FIXME: This code will break when the font has glyphs with advance // amounts different from the actual width of the glyph // (which is the case with many TrueType fonts). if (ellipsis_width < text_width) { size_t offset = 0; for (auto it = text.begin(); !it.done(); ++it) { auto code_point = *it; int glyph_width = m_font->glyph_or_emoji_width(code_point); // NOTE: Glyph spacing should not be added after the last glyph on the line, // but since we are here because the last glyph does not actually fit on the line, // we don't have to worry about spacing. int width_with_this_glyph_included = current_width + glyph_width + glyph_spacing; if (width_with_this_glyph_included > m_rect.width()) break; current_width += glyph_width + glyph_spacing; offset = text.iterator_offset(it); } StringBuilder builder; builder.append(text.substring_view(0, offset).as_string()); builder.append("..."); return builder.to_string(); } } return text.as_string(); } }