C++ FontPlatformData类代码示例

static HB_Bool stringToGlyphs(HB_Font hbFont, const HB_UChar16* characters, hb_uint32 length, HB_Glyph* glyphs, hb_uint32* glyphsSize, HB_Bool isRTL)
{
    FontPlatformData* font = reinterpret_cast<FontPlatformData*>(hbFont->userData);
    SkPaint paint;

    font->setupPaint(&paint);
    paint.setTextEncoding(SkPaint::kUTF16_TextEncoding);

    unsigned codepoints = 0;
    for (hb_uint32 i = 0; i < length; i++) {
        if (!SkUTF16_IsHighSurrogate(characters[i]))
            codepoints++;
        if (codepoints > *glyphsSize)
            return 0;
    }

    int numGlyphs = paint.textToGlyphs(characters, length * sizeof(uint16_t), reinterpret_cast<uint16_t*>(glyphs));

    // HB_Glyph is 32-bit, but Skia outputs only 16-bit numbers. So our
    // |glyphs| array needs to be converted.
    for (int i = numGlyphs - 1; i >= 0; --i) {
        uint16_t value;
        // We use a memcpy to avoid breaking strict aliasing rules.
        memcpy(&value, reinterpret_cast<char*>(glyphs) + sizeof(uint16_t) * i, sizeof(uint16_t));
        glyphs[i] = value;
    }

    *glyphsSize = numGlyphs;
    return 1;
}

Font::Font(const FontPlatformData& platformData, bool isCustomFont, bool isLoading, bool isTextOrientationFallback)
    : m_maxCharWidth(-1)
    , m_avgCharWidth(-1)
    , m_platformData(platformData)
    , m_treatAsFixedPitch(false)
    , m_isCustomFont(isCustomFont)
    , m_isLoading(isLoading)
    , m_isTextOrientationFallback(isTextOrientationFallback)
    , m_isBrokenIdeographFallback(false)
    , m_mathData(nullptr)
#if ENABLE(OPENTYPE_VERTICAL)
    , m_verticalData(0)
#endif
    , m_hasVerticalGlyphs(false)
{
    platformInit();
    platformGlyphInit();
    platformCharWidthInit();
#if ENABLE(OPENTYPE_VERTICAL)
    if (platformData.orientation() == Vertical && !isTextOrientationFallback) {
        m_verticalData = platformData.verticalData();
        m_hasVerticalGlyphs = m_verticalData.get() && m_verticalData->hasVerticalMetrics();
    }
#endif
}

SimpleFontData::SimpleFontData(const FontPlatformData& f, bool customFont, bool loading, SVGFontData* svgFontData)
    : m_maxCharWidth(-1)
    , m_avgCharWidth(-1)
    , m_unitsPerEm(defaultUnitsPerEm)
    , m_platformData(f)
    , m_treatAsFixedPitch(false)
#if ENABLE(SVG_FONTS)
    , m_svgFontData(svgFontData)
#endif
    , m_isCustomFont(customFont)
    , m_isLoading(loading)
    , m_smallCapsFontData(0)
#if (PLATFORM(WKC))
    , m_lineSpacing(0)
#endif
{
#if !ENABLE(SVG_FONTS)
    UNUSED_PARAM(svgFontData);
#else
    if (SVGFontFaceElement* svgFontFaceElement = svgFontData ? svgFontData->svgFontFaceElement() : 0) {
        m_unitsPerEm = svgFontFaceElement->unitsPerEm();

        double scale = f.size();
        if (m_unitsPerEm)
            scale /= m_unitsPerEm;

        m_ascent = static_cast<int>(svgFontFaceElement->ascent() * scale);
        m_descent = static_cast<int>(svgFontFaceElement->descent() * scale);
        m_xHeight = static_cast<int>(svgFontFaceElement->xHeight() * scale);
        m_lineGap = 0.1f * f.size();
        m_lineSpacing = m_ascent + m_descent + m_lineGap;

        SVGFontElement* associatedFontElement = svgFontFaceElement->associatedFontElement();

        Vector<SVGGlyphIdentifier> spaceGlyphs;
        associatedFontElement->getGlyphIdentifiersForString(String(" ", 1), spaceGlyphs);
        m_spaceWidth = spaceGlyphs.isEmpty() ? m_xHeight : static_cast<float>(spaceGlyphs.first().horizontalAdvanceX * scale);

        Vector<SVGGlyphIdentifier> numeralZeroGlyphs;
        associatedFontElement->getGlyphIdentifiersForString(String("0", 1), numeralZeroGlyphs);
        m_avgCharWidth = numeralZeroGlyphs.isEmpty() ? m_spaceWidth : static_cast<float>(numeralZeroGlyphs.first().horizontalAdvanceX * scale);

        Vector<SVGGlyphIdentifier> letterWGlyphs;
        associatedFontElement->getGlyphIdentifiersForString(String("W", 1), letterWGlyphs);
        m_maxCharWidth = letterWGlyphs.isEmpty() ? m_ascent : static_cast<float>(letterWGlyphs.first().horizontalAdvanceX * scale);

        // FIXME: is there a way we can get the space glyph from the SVGGlyphIdentifier above?
        m_spaceGlyph = 0;
        determinePitch();
        m_adjustedSpaceWidth = roundf(m_spaceWidth);
        m_missingGlyphData.fontData = this;
        m_missingGlyphData.glyph = 0;
        return;
    }
#endif

    platformInit();
    platformGlyphInit();
    platformCharWidthInit();
}

static HB_Error getOutlinePoint(HB_Font hbFont, HB_Glyph glyph, int flags, hb_uint32 point, HB_Fixed* xPos, HB_Fixed* yPos, hb_uint32* resultingNumPoints)
{
    FontPlatformData* font = reinterpret_cast<FontPlatformData*>(hbFont->userData);
    SkPaint paint;

    if (flags & HB_ShaperFlag_UseDesignMetrics)
        return HB_Err_Invalid_Argument;  // This is requesting pre-hinted positions. We can't support this.

    font->setupPaint(&paint);
    paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
    uint16_t glyph16 = glyph;
    SkPath path;
    paint.getTextPath(&glyph16, sizeof(glyph16), 0, 0, &path);
    int numPoints = path.getPoints(0, 0);
    if (point >= static_cast<unsigned>(numPoints))
        return HB_Err_Invalid_SubTable;
    SkPoint* points = reinterpret_cast<SkPoint*>(fastMalloc(sizeof(SkPoint) * (point + 1)));
    if (!points)
        return HB_Err_Invalid_SubTable;
    // Skia does let us get a single point from the path.
    path.getPoints(points, point + 1);
    *xPos = SkiaScalarToHarfbuzzFixed(points[point].fX);
    *yPos = SkiaScalarToHarfbuzzFixed(points[point].fY);
    *resultingNumPoints = numPoints;
    fastFree(points);

    return HB_Err_Ok;
}

static void glyphsToAdvances(HB_Font hbFont, const HB_Glyph* glyphs, hb_uint32 numGlyphs, HB_Fixed* advances, int flags)
{
    FontPlatformData* font = reinterpret_cast<FontPlatformData*>(hbFont->userData);
    SkPaint paint;

    font->setupPaint(&paint);
    paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);

    OwnArrayPtr<uint16_t> glyphs16(new uint16_t[numGlyphs]);
    if (!glyphs16.get())
        return;
    for (unsigned i = 0; i < numGlyphs; ++i)
        glyphs16[i] = glyphs[i];
    paint.getTextWidths(glyphs16.get(), numGlyphs * sizeof(uint16_t), reinterpret_cast<SkScalar*>(advances));

    // The |advances| values which Skia outputs are SkScalars, which are floats
    // in Chromium. However, Harfbuzz wants them in 26.6 fixed point format.
    // These two formats are both 32-bits long.
    for (unsigned i = 0; i < numGlyphs; ++i) {
        float value;
        // We use a memcpy to avoid breaking strict aliasing rules.
        memcpy(&value, reinterpret_cast<char*>(advances) + sizeof(float) * i, sizeof(float));
        advances[i] = SkiaScalarToHarfbuzzFixed(value);
    }
}

FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomicString& family)
{
    // The CSS font matching algorithm (http://www.w3.org/TR/css3-fonts/#font-matching-algorithm)
    // says that we must find an exact match for font family, slant (italic or oblique can be used)
    // and font weight (we only match bold/non-bold here).
    RefPtr<FcPattern> pattern = adoptRef(FcPatternCreate());
    String familyNameString(getFamilyNameStringFromFontDescriptionAndFamily(fontDescription, family));
    if (!FcPatternAddString(pattern.get(), FC_FAMILY, reinterpret_cast<const FcChar8*>(familyNameString.utf8().data())))
        return 0;

    bool italic = fontDescription.italic();
    if (!FcPatternAddInteger(pattern.get(), FC_SLANT, italic ? FC_SLANT_ITALIC : FC_SLANT_ROMAN))
        return 0;
    if (!FcPatternAddInteger(pattern.get(), FC_WEIGHT, fontWeightToFontconfigWeight(fontDescription.weight())))
        return 0;
    if (!FcPatternAddDouble(pattern.get(), FC_PIXEL_SIZE, fontDescription.computedPixelSize()))
        return 0;

    // The strategy is originally from Skia (src/ports/SkFontHost_fontconfig.cpp):

    // Allow Fontconfig to do pre-match substitution. Unless we are accessing a "fallback"
    // family like "sans," this is the only time we allow Fontconfig to substitute one
    // family name for another (i.e. if the fonts are aliased to each other).
    FcConfigSubstitute(0, pattern.get(), FcMatchPattern);
    FcDefaultSubstitute(pattern.get());

    FcChar8* fontConfigFamilyNameAfterConfiguration;
    FcPatternGetString(pattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterConfiguration);
    String familyNameAfterConfiguration = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterConfiguration));

    FcResult fontConfigResult;
    RefPtr<FcPattern> resultPattern = adoptRef(FcFontMatch(0, pattern.get(), &fontConfigResult));
    if (!resultPattern) // No match.
        return 0;

    FcChar8* fontConfigFamilyNameAfterMatching;
    FcPatternGetString(resultPattern.get(), FC_FAMILY, 0, &fontConfigFamilyNameAfterMatching);
    String familyNameAfterMatching = String::fromUTF8(reinterpret_cast<char*>(fontConfigFamilyNameAfterMatching));

    // If Fontconfig gave use a different font family than the one we requested, we should ignore it
    // and allow WebCore to give us the next font on the CSS fallback list. The only exception is if
    // this family name is a commonly used generic family.
    if (!equalIgnoringCase(familyNameAfterConfiguration, familyNameAfterMatching)
            && !(equalIgnoringCase(familyNameString, "sans") || equalIgnoringCase(familyNameString, "sans-serif")
                 || equalIgnoringCase(familyNameString, "serif") || equalIgnoringCase(familyNameString, "monospace")
                 || equalIgnoringCase(familyNameString, "fantasy") || equalIgnoringCase(familyNameString, "cursive")))
        return 0;

    // Verify that this font has an encoding compatible with Fontconfig. Fontconfig currently
    // supports three encodings in FcFreeTypeCharIndex: Unicode, Symbol and AppleRoman.
    // If this font doesn't have one of these three encodings, don't select it.
    FontPlatformData* platformData = new FontPlatformData(resultPattern.get(), fontDescription);
    if (!platformData->hasCompatibleCharmap()) {
        delete platformData;
        return 0;
    }

    return platformData;
}

void paintSkiaText(GraphicsContext* context,
                   const FontPlatformData& data,
                   int numGlyphs,
                   const WORD* glyphs,
                   const int* advances,
                   const GOFFSET* offsets,
                   const SkPoint* origin)
{
    paintSkiaText(context, data.hfont(), data.typeface(), data.size(), data.lfQuality(),
                  numGlyphs, glyphs, advances, offsets, origin);
}

std::unique_ptr<FontPlatformData> FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomicString& family)
{
    FontPlatformData* ret = new FontPlatformData(fontDescription, family);

    if (!ret || !ret->font() || !ret->font()->font()) {
        delete ret;
        return nullptr;
    }

    return std::unique_ptr<FontPlatformData>(ret);
}

bool HarfBuzzShaper::shapeHarfBuzzRun()
{
    FontPlatformData* platformData = const_cast<FontPlatformData*>(&m_currentFontData->platformData());
    HarfBuzzFace* face = platformData->harfbuzzFace();
    if (!face)
        return false;
    hb_font_t* harfbuzzFont = face->createFont();
    hb_shape(harfbuzzFont, m_harfbuzzBuffer, m_features.size() > 0 ? m_features.data() : 0, m_features.size());
    hb_font_destroy(harfbuzzFont);
    m_harfbuzzRuns.append(HarfBuzzRun::create(m_numCharactersOfCurrentRun, m_run.direction(), m_harfbuzzBuffer));
    return true;
}

void paintSkiaText(GraphicsContext* context,
                   const FontPlatformData& data,
                   int numGlyphs,
                   const WORD* glyphs,
                   const int* advances,
                   const GOFFSET* offsets,
                   const SkPoint& origin,
                   const SkRect& textRect)
{
    paintSkiaText(context, data.hfont(), data.typeface(), data.size(), data.paintTextFlags(),
                  numGlyphs, glyphs, advances, offsets, origin, textRect);
}

bool HarfBuzzShaper::shapeHarfBuzzRuns(bool shouldSetDirection)
{
    HarfBuzzScopedPtr<hb_buffer_t> harfBuzzBuffer(hb_buffer_create(), hb_buffer_destroy);

    hb_buffer_set_unicode_funcs(harfBuzzBuffer.get(), hb_icu_get_unicode_funcs());

    for (unsigned i = 0; i < m_harfBuzzRuns.size(); ++i) {
        unsigned runIndex = m_run.rtl() ? m_harfBuzzRuns.size() - i - 1 : i;
        HarfBuzzRun* currentRun = m_harfBuzzRuns[runIndex].get();
        const SimpleFontData* currentFontData = currentRun->fontData();
        if (currentFontData->isSVGFont())
            return false;

        hb_buffer_set_script(harfBuzzBuffer.get(), currentRun->script());
        if (shouldSetDirection)
            hb_buffer_set_direction(harfBuzzBuffer.get(), currentRun->rtl() ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
        else
            // Leaving direction to HarfBuzz to guess is *really* bad, but will do for now.
            hb_buffer_guess_segment_properties(harfBuzzBuffer.get());

        // Add a space as pre-context to the buffer. This prevents showing dotted-circle
        // for combining marks at the beginning of runs.
        static const uint16_t preContext = ' ';
        hb_buffer_add_utf16(harfBuzzBuffer.get(), &preContext, 1, 1, 0);

        if (m_font->isSmallCaps() && u_islower(m_normalizedBuffer[currentRun->startIndex()])) {
            String upperText = String(m_normalizedBuffer.get() + currentRun->startIndex(), currentRun->numCharacters());
            upperText.makeUpper();
            currentFontData = m_font->glyphDataForCharacter(upperText[0], false, SmallCapsVariant).fontData;
            hb_buffer_add_utf16(harfBuzzBuffer.get(), upperText.characters(), currentRun->numCharacters(), 0, currentRun->numCharacters());
        } else
            hb_buffer_add_utf16(harfBuzzBuffer.get(), m_normalizedBuffer.get() + currentRun->startIndex(), currentRun->numCharacters(), 0, currentRun->numCharacters());

        FontPlatformData* platformData = const_cast<FontPlatformData*>(&currentFontData->platformData());
        HarfBuzzFace* face = platformData->harfBuzzFace();
        if (!face)
            return false;

        if (m_font->fontDescription().orientation() == Vertical)
            face->setScriptForVerticalGlyphSubstitution(harfBuzzBuffer.get());

        HarfBuzzScopedPtr<hb_font_t> harfBuzzFont(face->createFont(), hb_font_destroy);

        hb_shape(harfBuzzFont.get(), harfBuzzBuffer.get(), m_features.isEmpty() ? 0 : m_features.data(), m_features.size());

        currentRun->applyShapeResult(harfBuzzBuffer.get());
        setGlyphPositionsForHarfBuzzRun(currentRun, harfBuzzBuffer.get());

        hb_buffer_reset(harfBuzzBuffer.get());
    }

    return true;
}

FontPlatformData* FontCache::createFontPlatformData(const FontDescription& fontDescription, const AtomicString& family)
{
    bool isLucidaGrande = false;
    static AtomicString lucidaStr("Lucida Grande");
    if (equalIgnoringCase(family, lucidaStr))
        isLucidaGrande = true;

    bool useGDI = fontDescription.renderingMode() == AlternateRenderingMode && !isLucidaGrande;

    // The logical size constant is 32. We do this for subpixel precision when rendering using Uniscribe.
    // This masks rounding errors related to the HFONT metrics being  different from the CGFont metrics.
    // FIXME: We will eventually want subpixel precision for GDI mode, but the scaled rendering doesn't
    // look as nice. That may be solvable though.
#if PLATFORM(CG)
    bool canCreateCGFontWithLOGFONT = wkCanCreateCGFontWithLOGFONT();
#else
    bool canCreateCGFontWithLOGFONT = true;
#endif
    LONG weight = adjustedGDIFontWeight(toGDIFontWeight(fontDescription.weight()), family);
    HFONT hfont = createGDIFont(family, weight, fontDescription.italic(),
                                fontDescription.computedPixelSize() * (useGDI ? 1 : 32), useGDI && canCreateCGFontWithLOGFONT);

    if (!hfont)
        return 0;

    if (isLucidaGrande)
        useGDI = false; // Never use GDI for Lucida Grande.

    LOGFONT logFont;
    GetObject(hfont, sizeof(LOGFONT), &logFont);

    bool synthesizeBold = isGDIFontWeightBold(weight) && !isGDIFontWeightBold(logFont.lfWeight);
    bool synthesizeItalic = fontDescription.italic() && !logFont.lfItalic;

    FontPlatformData* result = new FontPlatformData(hfont, fontDescription.computedPixelSize(), synthesizeBold, synthesizeItalic, useGDI);

#if PLATFORM(CG)
    bool fontCreationFailed = !result->cgFont();
#elif PLATFORM(CAIRO)
    bool fontCreationFailed = !result->fontFace();
#endif

    if (fontCreationFailed) {
        // The creation of the CGFontRef failed for some reason.  We already asserted in debug builds, but to make
        // absolutely sure that we don't use this font, go ahead and return 0 so that we can fall back to the next
        // font.
        delete result;
        DeleteObject(hfont);
        return 0;
    }        

    return result;
}

Font::Font(const FontPlatformData& platformData, bool isCustomFont, bool isLoading, bool isTextOrientationFallback)
    : Font(platformData, std::unique_ptr<SVGData>(), isCustomFont, isLoading, isTextOrientationFallback)
{
    platformInit();
    platformGlyphInit();
    platformCharWidthInit();
#if ENABLE(OPENTYPE_VERTICAL)
    if (platformData.orientation() == Vertical && !isTextOrientationFallback) {
        m_verticalData = platformData.verticalData();
        m_hasVerticalGlyphs = m_verticalData.get() && m_verticalData->hasVerticalMetrics();
    }
#endif
}

PassRefPtr<Font>
Font::platformCreateScaledFont(const FontDescription& orig, float scaleFactor) const
{
    FontDescription d(orig);
    d.setComputedSize(orig.computedSize() * scaleFactor);
    d.setSpecifiedSize(orig.specifiedSize() * scaleFactor);
    FontPlatformData* ret = new FontPlatformData(d, m_platformData.font()->familyName().data());

    if (!ret || !ret->font() || !ret->font()->font()) {
        delete ret;
        return adoptRef((Font *)0);
    }

    return Font::create(*ret);
}

static int substituteWithVerticalGlyphs(const FontPlatformData& platformData, uint16_t* glyphs, unsigned bufferLength)
{
    HB_FaceRec_* hbFace = platformData.harfbuzzFace();
    if (!hbFace->gsub) {
        // if there is no GSUB table, treat it as not covered
        return 0Xffff;
    }

    HB_Buffer buffer;
    hb_buffer_new(&buffer);
    for (unsigned i = 0; i < bufferLength; ++i)
        hb_buffer_add_glyph(buffer, glyphs[i], 0, i);

    HB_UShort scriptIndex;
    HB_UShort featureIndex;

    HB_GSUB_Select_Script(hbFace->gsub, HB_MAKE_TAG('D', 'F', 'L', 'T'), &scriptIndex);
    HB_GSUB_Select_Feature(hbFace->gsub, HB_MAKE_TAG('v', 'e', 'r', 't'), scriptIndex, 0xffff, &featureIndex);
    HB_GSUB_Add_Feature(hbFace->gsub, featureIndex, 1);
    HB_GSUB_Select_Feature(hbFace->gsub, HB_MAKE_TAG('v', 'r', 't', '2'), scriptIndex, 0xffff, &featureIndex);
    HB_GSUB_Add_Feature(hbFace->gsub, featureIndex, 1);

    int error = HB_GSUB_Apply_String(hbFace->gsub, buffer);
    if (!error) {
        for (unsigned i = 0; i < bufferLength; ++i)
            glyphs[i] = static_cast<Glyph>(buffer->out_string[i].gindex);
    }
    return error;
}