Source/WebCore/css/CSSSegmentedFontFace.cpp

/*
 * Copyright (C) 2008, 2013 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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#include "config.h"
#include "CSSSegmentedFontFace.h"

#include "CSSFontFace.h"
#include "CSSFontFaceSource.h"
#include "CSSFontSelector.h"
#include "Document.h"
#include "Font.h"
#include "FontCache.h"
#include "FontDescription.h"
#include "RuntimeEnabledFeatures.h"

namespace WebCore {

CSSSegmentedFontFace::CSSSegmentedFontFace()
{
}

CSSSegmentedFontFace::~CSSSegmentedFontFace()
{
    for (auto& face : m_fontFaces)
        face->removeClient(*this);
}

void CSSSegmentedFontFace::appendFontFace(Ref<CSSFontFace>&& fontFace)
{
    m_cache.clear();
    fontFace->addClient(*this);
    m_fontFaces.append(WTFMove(fontFace));
}

void CSSSegmentedFontFace::fontLoaded(CSSFontFace&)
{
    m_cache.clear();
}

class CSSFontAccessor final : public FontAccessor {
public:
    static Ref<CSSFontAccessor> create(CSSFontFace& fontFace, const FontDescription& fontDescription, bool syntheticBold, bool syntheticItalic)
    {
        return adoptRef(*new CSSFontAccessor(fontFace, fontDescription, syntheticBold, syntheticItalic));
    }

    const Font* font() const final
    {
        if (!m_result)
            m_result = m_fontFace->font(m_fontDescription, m_syntheticBold, m_syntheticItalic);
        return m_result.value().get();
    }

private:
    CSSFontAccessor(CSSFontFace& fontFace, const FontDescription& fontDescription, bool syntheticBold, bool syntheticItalic)
        : m_fontFace(fontFace)
        , m_fontDescription(fontDescription)
        , m_syntheticBold(syntheticBold)
        , m_syntheticItalic(syntheticItalic)
    {
    }

    bool isLoading() const final
    {
        return m_result && m_result.value() && m_result.value()->isLoading();
    }

    mutable std::optional<RefPtr<Font>> m_result; // Caches nullptr too
    mutable Ref<CSSFontFace> m_fontFace;
    FontDescription m_fontDescription;
    bool m_syntheticBold;
    bool m_syntheticItalic;
};

static void appendFontWithInvalidUnicodeRangeIfLoading(FontRanges& ranges, Ref<FontAccessor>&& fontAccessor, const Vector<CSSFontFace::UnicodeRange>& unicodeRanges)
{
    if (fontAccessor->isLoading()) {
        ranges.appendRange({ 0, 0, WTFMove(fontAccessor) });
        return;
    }

    if (unicodeRanges.isEmpty()) {
        ranges.appendRange({ 0, 0x7FFFFFFF, WTFMove(fontAccessor) });
        return;
    }

    for (auto& range : unicodeRanges)
        ranges.appendRange({ range.from, range.to, fontAccessor.copyRef() });
}

FontRanges CSSSegmentedFontFace::fontRanges(const FontDescription& fontDescription)
{
    FontTraitsMask desiredTraitsMask = fontDescription.traitsMask();

    auto addResult = m_cache.add(FontDescriptionKey(fontDescription), FontRanges());
    auto& result = addResult.iterator->value;

    if (addResult.isNewEntry) {
        for (auto& face : m_fontFaces) {
            if (face->allSourcesFailed())
                continue;

            FontTraitsMask traitsMask = face->traitsMask();
            bool syntheticBold = (fontDescription.fontSynthesis() & FontSynthesisWeight) && !(traitsMask & (FontWeight600Mask | FontWeight700Mask | FontWeight800Mask | FontWeight900Mask)) && (desiredTraitsMask & (FontWeight600Mask | FontWeight700Mask | FontWeight800Mask | FontWeight900Mask));
            bool syntheticItalic = (fontDescription.fontSynthesis() & FontSynthesisStyle) && !(traitsMask & FontStyleItalicMask) && (desiredTraitsMask & FontStyleItalicMask);

            // This doesn't trigger an unnecessary download because every element styled with this family will need font metrics in order to run layout.
            // Metrics used for layout come from FontRanges::fontForFirstRange(), which assumes that the first font is non-null.
            // We're kicking off this necessary first download now.
            auto fontAccessor = CSSFontAccessor::create(face, fontDescription, syntheticBold, syntheticItalic);
            if (result.isNull() && !fontAccessor->font())
                continue;
            appendFontWithInvalidUnicodeRangeIfLoading(result, WTFMove(fontAccessor), face->ranges());
        }
    }
    return result;
}

}