flutter_flutter/engine/platform/fonts/skia/FontCacheSkia.cpp

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#include <unicode/locid.h>
#include "sky/engine/platform/NotImplemented.h"
#include "sky/engine/platform/fonts/AlternateFontFamily.h"
#include "sky/engine/platform/fonts/FontCache.h"
#include "sky/engine/platform/fonts/FontDescription.h"
#include "sky/engine/platform/fonts/FontFaceCreationParams.h"
#include "sky/engine/platform/fonts/SimpleFontData.h"
#include "sky/engine/public/platform/Platform.h"
#include "sky/engine/public/platform/linux/WebSandboxSupport.h"
#include "sky/engine/wtf/Assertions.h"
#include "sky/engine/wtf/text/AtomicString.h"
#include "sky/engine/wtf/text/CString.h"
#include "third_party/skia/include/core/SkStream.h"
#include "third_party/skia/include/core/SkTypeface.h"
#include "third_party/skia/include/ports/SkFontMgr.h"

#if !OS(WIN) && !OS(ANDROID)
#include "third_party/skia/include/ports/SkFontConfigInterface.h"
#endif

#if !OS(WIN) && !OS(ANDROID) && !OS(IOS)
// TODO(bungeman) remove this temporary code ASAP.
// This namespace exists to ease transition of SkTypeface from using SkStream to SkStreamAsset.
namespace tmp {
// Like std::declval but only returns lvalue references, ok since it isn't used on rvalue references.
template<typename T> T& declvall();
// The return type of SkFontConfigInterface::openStream(const SkFontConfigInterface::FontIdentity&).
using StreamType = decltype(tmp::declvall<SkFontConfigInterface>().openStream(tmp::declvall<const SkFontConfigInterface::FontIdentity&>()));
}
static tmp::StreamType streamForFontconfigInterfaceId(int fontconfigInterfaceId)
{
    SkAutoTUnref<SkFontConfigInterface> fci(SkFontConfigInterface::RefGlobal());
    SkFontConfigInterface::FontIdentity fontIdentity;
    fontIdentity.fID = fontconfigInterfaceId;
    return fci->openStream(fontIdentity);
}
#endif

namespace blink {

static int toSkiaWeight(FontWeight weight)
{
    switch (weight) {
    case FontWeight100:
        return SkFontStyle::kThin_Weight;
    case FontWeight200:
        return SkFontStyle::kExtraLight_Weight;
    case FontWeight300:
        return SkFontStyle::kLight_Weight;
    case FontWeight400:
        return SkFontStyle::kNormal_Weight;
    case FontWeight500:
        return SkFontStyle::kMedium_Weight;
    case FontWeight600:
        return SkFontStyle::kSemiBold_Weight;
    case FontWeight700:
        return SkFontStyle::kBold_Weight;
    case FontWeight800:
        return SkFontStyle::kExtraBold_Weight;
    case FontWeight900:
        return SkFontStyle::kBlack_Weight;
    }
    ASSERT_NOT_REACHED();
    return SkFontStyle::kNormal_Weight;
}

static SkFontStyle::Slant toSkiaSlant(FontStyle style)
{
    switch (style) {
    case FontStyleNormal:
        return SkFontStyle::kUpright_Slant;
    case FontStyleItalic:
        return SkFontStyle::kItalic_Slant;
    }
    ASSERT_NOT_REACHED();
    return SkFontStyle::kUpright_Slant;
}

static int toSkiaWidth(FontStretch stretch)
{
    // Numeric values matching OS/2 & Windows Metrics usWidthClass table.
    // https://www.microsoft.com/typography/otspec/os2.htm
    return static_cast<int>(stretch);
}

static SkFontStyle toSkiaFontStyle(const FontDescription& fontDescription)
{
    return SkFontStyle(toSkiaWeight(fontDescription.weight()),
                       toSkiaWidth(fontDescription.stretch()),
                       toSkiaSlant(fontDescription.style()));
}

void FontCache::platformInit()
{
}

PassRefPtr<SimpleFontData> FontCache::fallbackOnStandardFontStyle(
    const FontDescription& fontDescription, UChar32 character)
{
    FontDescription substituteDescription(fontDescription);
    substituteDescription.setStyle(FontStyleNormal);
    substituteDescription.setWeight(FontWeightNormal);

    FontFaceCreationParams creationParams(substituteDescription.family().family());
    FontPlatformData* substitutePlatformData = getFontPlatformData(substituteDescription, creationParams);
    if (substitutePlatformData && substitutePlatformData->fontContainsCharacter(character)) {
        FontPlatformData platformData = FontPlatformData(*substitutePlatformData);
        platformData.setSyntheticBold(fontDescription.weight() >= FontWeight600);
        platformData.setSyntheticItalic(fontDescription.style() == FontStyleItalic);
        return fontDataFromFontPlatformData(&platformData, DoNotRetain);
    }

    return nullptr;
}

#if !OS(WIN) && !OS(ANDROID)
PassRefPtr<SimpleFontData> FontCache::fallbackFontForCharacter(const FontDescription& fontDescription, UChar32 c, const SimpleFontData*)
{
    // First try the specified font with standard style & weight.
    if (fontDescription.style() == FontStyleItalic
        || fontDescription.weight() >= FontWeight600) {
        RefPtr<SimpleFontData> fontData = fallbackOnStandardFontStyle(
            fontDescription, c);
        if (fontData)
            return fontData;
    }

    FontCache::PlatformFallbackFont fallbackFont;
    FontCache::getFontForCharacter(c, "", &fallbackFont);
    if (fallbackFont.name.isEmpty())
        return nullptr;

    FontFaceCreationParams creationParams;
    creationParams = FontFaceCreationParams(fallbackFont.filename, fallbackFont.fontconfigInterfaceId, fallbackFont.ttcIndex);

    // Changes weight and/or italic of given FontDescription depends on
    // the result of fontconfig so that keeping the correct font mapping
    // of the given character. See http://crbug.com/32109 for details.
    bool shouldSetSyntheticBold = false;
    bool shouldSetSyntheticItalic = false;
    FontDescription description(fontDescription);
    if (fallbackFont.isBold && description.weight() < FontWeightBold)
        description.setWeight(FontWeightBold);
    if (!fallbackFont.isBold && description.weight() >= FontWeightBold) {
        shouldSetSyntheticBold = true;
        description.setWeight(FontWeightNormal);
    }
    if (fallbackFont.isItalic && description.style() == FontStyleNormal)
        description.setStyle(FontStyleItalic);
    if (!fallbackFont.isItalic && description.style() == FontStyleItalic) {
        shouldSetSyntheticItalic = true;
        description.setStyle(FontStyleNormal);
    }

    FontPlatformData* substitutePlatformData = getFontPlatformData(description, creationParams);
    if (!substitutePlatformData)
        return nullptr;
    FontPlatformData platformData = FontPlatformData(*substitutePlatformData);
    platformData.setSyntheticBold(shouldSetSyntheticBold);
    platformData.setSyntheticItalic(shouldSetSyntheticItalic);
    return fontDataFromFontPlatformData(&platformData, DoNotRetain);
}

#endif // !OS(WIN) && !OS(ANDROID)

PassRefPtr<SimpleFontData> FontCache::getLastResortFallbackFont(const FontDescription& description, ShouldRetain shouldRetain)
{
    const FontFaceCreationParams fallbackCreationParams(getFallbackFontFamily(description));
    const FontPlatformData* fontPlatformData = getFontPlatformData(description, fallbackCreationParams);

    // We should at least have Sans or Arial which is the last resort fallback of SkFontHost ports.
    if (!fontPlatformData) {
        DEFINE_STATIC_LOCAL(const FontFaceCreationParams, sansCreationParams, (AtomicString("Sans", AtomicString::ConstructFromLiteral)));
        fontPlatformData = getFontPlatformData(description, sansCreationParams);
    }
    if (!fontPlatformData) {
        DEFINE_STATIC_LOCAL(const FontFaceCreationParams, arialCreationParams, (AtomicString("Arial", AtomicString::ConstructFromLiteral)));
        fontPlatformData = getFontPlatformData(description, arialCreationParams);
    }

    ASSERT(fontPlatformData);
    return fontDataFromFontPlatformData(fontPlatformData, shouldRetain);
}

PassRefPtr<SkTypeface> FontCache::createTypeface(const FontDescription& fontDescription, const FontFaceCreationParams& creationParams, CString& name)
{
#if !OS(WIN) && !OS(ANDROID) && !OS(IOS)
    if (creationParams.creationType() == CreateFontByFciIdAndTtcIndex) {
        // TODO(dro): crbug.com/381620 Use creationParams.ttcIndex() after
        // https://code.google.com/p/skia/issues/detail?id=1186 gets fixed.
        SkTypeface* typeface = nullptr;
        if (Platform::current()->sandboxSupport())
            typeface = SkTypeface::CreateFromStream(streamForFontconfigInterfaceId(creationParams.fontconfigInterfaceId()));
        else
            typeface = SkTypeface::CreateFromFile(creationParams.filename().data());

        if (typeface)
            return adoptRef(typeface);
        else
            return nullptr;
    }
#endif

    AtomicString family = creationParams.family();
    // If we're creating a fallback font (e.g. "-webkit-monospace"), convert the name into
    // the fallback name (like "monospace") that fontconfig understands.
    if (!family.length() || family.startsWith("-webkit-")) {
        name = getFallbackFontFamily(fontDescription).string().utf8();
    } else {
        // convert the name to utf8
        name = family.utf8();
    }

    SkFontStyle style = toSkiaFontStyle(fontDescription);
    RefPtr<SkFontMgr> fm = adoptRef(SkFontMgr::RefDefault());
    RefPtr<SkTypeface> typeface = adoptRef(fm->matchFamilyStyle(name.data(), style));
    if (typeface)
        return typeface.release();

    int legacyStyle = SkTypeface::kNormal;
    if (fontDescription.weight() >= FontWeight600)
        legacyStyle |= SkTypeface::kBold;
    if (fontDescription.style())
        legacyStyle |= SkTypeface::kItalic;

    // FIXME: Use fm, SkFontStyle and matchFamilyStyle instead of this legacy
    // API. To make this work, we need to understand the extra fallback behavior
    // in CreateFromName.
    return adoptRef(SkTypeface::CreateFromName(name.data(), static_cast<SkTypeface::Style>(legacyStyle)));
}

#if !OS(WIN)
FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontDescription, const FontFaceCreationParams& creationParams, float fontSize)
{
    CString name;
    RefPtr<SkTypeface> tf(createTypeface(fontDescription, creationParams, name));
    if (!tf)
        return 0;

    FontPlatformData* result = new FontPlatformData(tf,
        name.data(),
        fontSize,
        (fontDescription.weight() >= FontWeight600 && !tf->isBold()) || fontDescription.isSyntheticBold(),
        (fontDescription.style() && !tf->isItalic()) || fontDescription.isSyntheticItalic(),
        fontDescription.orientation(),
        fontDescription.useSubpixelPositioning());
    return result;
}
#endif // !OS(WIN)

} // namespace blink