mirror of
https://github.com/LadybirdBrowser/ladybird
synced 2026-04-26 01:35:08 +02:00
bfead0cb20
font_for_code_point() was the heaviest function in layout profiles of a YouTube page (216ms CPU out of 2900ms total). Every call walked the full cascade and ran a virtual contains_glyph() against each entry, even though the result is the same for most ASCII code points across a document. Add a 128-entry direct-mapped cache keyed by code point that stores the resolved Font pointer on first lookup. Subsequent ASCII lookups become a null check plus a load. No invalidation is needed: m_fonts is append-only, and the cascade returns the first matching font, so once an entry claims a code point, later appends cannot change the answer.
90 lines
2.5 KiB
C++
90 lines
2.5 KiB
C++
/*
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* Copyright (c) 2023, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGfx/FontCascadeList.h>
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namespace Gfx {
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void FontCascadeList::add(NonnullRefPtr<Font const> font)
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{
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m_fonts.append({ move(font), {} });
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}
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void FontCascadeList::add(NonnullRefPtr<Font const> font, Vector<UnicodeRange> unicode_ranges)
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{
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if (unicode_ranges.is_empty()) {
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m_fonts.append({ move(font), {} });
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return;
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}
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u32 lowest_code_point = 0xFFFFFFFF;
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u32 highest_code_point = 0;
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for (auto& range : unicode_ranges) {
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lowest_code_point = min(lowest_code_point, range.min_code_point());
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highest_code_point = max(highest_code_point, range.max_code_point());
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}
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m_fonts.append({ move(font),
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Entry::RangeData {
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{ lowest_code_point, highest_code_point },
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move(unicode_ranges),
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} });
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}
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void FontCascadeList::extend(FontCascadeList const& other)
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{
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m_fonts.extend(other.m_fonts);
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}
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Gfx::Font const& FontCascadeList::font_for_code_point(u32 code_point) const
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{
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if (code_point < m_ascii_cache.size()) {
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if (auto const* cached = m_ascii_cache[code_point])
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return *cached;
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}
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auto cache_and_return = [&](Font const& font) -> Font const& {
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if (code_point < m_ascii_cache.size())
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m_ascii_cache[code_point] = &font;
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return font;
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};
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for (auto const& entry : m_fonts) {
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if (entry.range_data.has_value()) {
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if (!entry.range_data->enclosing_range.contains(code_point))
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continue;
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for (auto const& range : entry.range_data->unicode_ranges) {
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if (range.contains(code_point) && entry.font->contains_glyph(code_point))
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return cache_and_return(*entry.font);
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}
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} else if (entry.font->contains_glyph(code_point)) {
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return cache_and_return(*entry.font);
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}
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}
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if (m_system_font_fallback_callback) {
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if (auto fallback = m_system_font_fallback_callback(code_point, first())) {
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m_fonts.append({ fallback.release_nonnull(), {} });
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return cache_and_return(*m_fonts.last().font);
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}
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}
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return cache_and_return(*m_last_resort_font);
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}
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bool FontCascadeList::equals(FontCascadeList const& other) const
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{
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if (m_fonts.size() != other.m_fonts.size())
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return false;
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for (size_t i = 0; i < m_fonts.size(); ++i) {
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if (m_fonts[i].font != other.m_fonts[i].font)
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return false;
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}
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return true;
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}
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}
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