mirror of
https://github.com/LadybirdBrowser/ladybird
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120 lines
4.0 KiB
C++
120 lines
4.0 KiB
C++
/*
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* Copyright (c) 2023-2024, 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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#pragma once
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#include <AK/Array.h>
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#include <AK/Function.h>
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#include <AK/RefCounted.h>
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#include <LibGfx/Font/Font.h>
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#include <LibGfx/Font/UnicodeRange.h>
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namespace Gfx {
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class FontCascadeList : public RefCounted<FontCascadeList> {
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public:
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using SystemFontFallbackCallback = Function<RefPtr<Font const>(u32, Font const&)>;
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static NonnullRefPtr<FontCascadeList> create()
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{
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return adopt_ref(*new FontCascadeList());
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}
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size_t size() const { return m_fonts.size(); }
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bool is_empty() const { return m_fonts.is_empty() && m_pending_faces.is_empty() && !m_last_resort_font; }
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Font const& first() const { return !m_fonts.is_empty() ? *m_fonts.first().font : *m_last_resort_font; }
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template<typename Callback>
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void for_each_font_entry(Callback callback) const
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{
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for (auto const& font : m_fonts)
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callback(font);
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}
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void add(NonnullRefPtr<Font const> font);
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void add(NonnullRefPtr<Font const> font, Vector<UnicodeRange> unicode_ranges);
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// Register an unloaded face covering `unicode_ranges`. The cascade invokes
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// `start_load` the first time a rendered codepoint falls within one of the ranges.
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void add_pending_face(Vector<UnicodeRange> unicode_ranges, Function<void()> start_load);
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void extend(FontCascadeList const& other);
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// A pending-face fetch should only be initiated for codepoints that are actually
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// being shaped into glyph runs. Callers that merely probe the cascade (e.g. the
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// U+0020 check in "first available font" metrics) pass No so that probing does
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// not kick off downloads for subset faces that happen to cover the probe point.
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enum class TriggerPendingLoads : u8 {
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No,
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Yes,
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};
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Gfx::Font const& font_for_code_point(u32 code_point, TriggerPendingLoads = TriggerPendingLoads::No) const;
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bool equals(FontCascadeList const& other) const;
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struct Entry {
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NonnullRefPtr<Font const> font;
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struct RangeData {
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// The enclosing range is the union of all Unicode ranges. Used for fast skipping.
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UnicodeRange enclosing_range;
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Vector<UnicodeRange> unicode_ranges;
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};
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Optional<RangeData> range_data;
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};
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class PendingFace : public RefCounted<PendingFace> {
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public:
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PendingFace(UnicodeRange enclosing, Vector<UnicodeRange> ranges, Function<void()> start_load)
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: m_enclosing_range(enclosing)
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, m_unicode_ranges(move(ranges))
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, m_start_load(move(start_load))
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{
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}
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bool covers(u32 code_point) const
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{
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if (!m_enclosing_range.contains(code_point))
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return false;
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for (auto const& range : m_unicode_ranges) {
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if (range.contains(code_point))
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return true;
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}
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return false;
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}
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void start_load() { m_start_load(); }
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private:
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UnicodeRange m_enclosing_range;
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Vector<UnicodeRange> m_unicode_ranges;
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Function<void()> m_start_load;
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};
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void set_last_resort_font(NonnullRefPtr<Font> font) { m_last_resort_font = move(font); }
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void set_system_font_fallback_callback(SystemFontFallbackCallback callback) { m_system_font_fallback_callback = move(callback); }
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Font const& first_text_face() const
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{
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for (auto const& entry : m_fonts)
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if (!entry.font->is_emoji_font())
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return *entry.font;
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return first();
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}
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private:
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RefPtr<Font const> m_last_resort_font;
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mutable Vector<Entry> m_fonts;
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mutable Vector<NonnullRefPtr<PendingFace>> m_pending_faces;
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SystemFontFallbackCallback m_system_font_fallback_callback;
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// OPTIMIZATION: Cache of resolved fonts for ASCII code points. Since m_fonts only grows and the cascade returns
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// the first matching font, a cached hit can never become stale.
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mutable Array<Font const*, 128> m_ascii_cache {};
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};
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}
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