qfontsubset.cpp

奇趣公司比较新的qt/emd版本

    Q_ASSERT(!widths.isEmpty());

    QFontEngine::Properties properties = fontEngine->properties();

    QByteArray width;
    QPdf::ByteStream s(&width);
    QFixed scale = QFixed(1000)/emSquare;

    QFixed defWidth = widths[0];
    //qDebug("defWidth=%d, scale=%f", defWidth.toInt(), scale.toReal());
    for (int i = 0; i < nGlyphs(); ++i) {
        if (defWidth != widths[i])
            defWidth = 0;
    }
    if (defWidth > 0) {
        s << "/DW " << (defWidth*scale).toInt();
    } else {
        s << "/W [";
        for (int g = 0; g < nGlyphs();) {
            QFixed w = widths[g];
            int start = g;
            int startLinear = 0;
            ++g;
            while (g < nGlyphs()) {
                QFixed nw = widths[g];
                if (nw == w) {
                if (!startLinear)
                    startLinear = g - 1;
                } else {
                    if (startLinear > 0 && g - startLinear >= 10)
                        break;
                    startLinear = 0;
                }
                w = nw;
                ++g;
            }
            // qDebug("start=%x startLinear=%x g-1=%x",start,startLinear,g-1);
            if (g - startLinear < 10)
                startLinear = 0;
            int endnonlinear = startLinear ? startLinear : g;
            // qDebug("    startLinear=%x endnonlinear=%x", startLinear,endnonlinear);
            if (endnonlinear > start) {
                s << start << "[";
                for (int i = start; i < endnonlinear; ++i)
                    s << (widths[i]*scale).toInt();
                s << "]\n";
            }
            if (startLinear)
                s << startLinear << g - 1 << (widths[startLinear]*scale).toInt() << "\n";
        }
        s << "]\n";
    }
    return width;
}

static void checkRanges(QPdf::ByteStream &ts, QByteArray &ranges, int &nranges)
{
    if (++nranges > 100) {
        ts << nranges << "beginbfrange\n"
           << ranges << "endbfrange\n";
        ranges = QByteArray();
        nranges = 0;
    }
}

QVector<int> QFontSubset::getReverseMap() const
{
    QVector<int> reverseMap;
    reverseMap.resize(0x10000);
    for (uint i = 0; i < 0x10000; ++i)
        reverseMap[i] = 0;
    QGlyphLayout glyphs[10];
    for (uint uc = 0; uc < 0x10000; ++uc) {
        QChar ch(uc);
        int nglyphs = 10;
        fontEngine->stringToCMap(&ch, 1, glyphs, &nglyphs, QTextEngine::GlyphIndicesOnly);
        int idx = glyph_indices.indexOf(glyphs[0].glyph);
        if (idx >= 0 && !reverseMap.at(idx))
            reverseMap[idx] = uc;
    }
    return reverseMap;
}

QByteArray QFontSubset::createToUnicodeMap() const
{
    QVector<int> reverseMap = getReverseMap();

    QByteArray touc;
    QPdf::ByteStream ts(&touc);
    ts << "/CIDInit /ProcSet findresource begin\n"
        "12 dict begin\n"
        "begincmap\n"
        "/CIDSystemInfo << /Registry (Adobe) /Ordering (UCS) /Supplement 0 >> def\n"
        "/CMapName /Adobe-Identity-UCS def\n"
        "/CMapType 2 def\n"
        "1 begincodespacerange\n"
        "<0000> <FFFF>\n"
        "endcodespacerange\n";

    int nranges = 1;
    QByteArray ranges = "<0000> <0000> <0000>\n";
    QPdf::ByteStream s(&ranges);

    char buf[5];
    for (int g = 1; g < nGlyphs(); ) {
        int uc0 = reverseMap.at(g);
        if (!uc0) {
            ++g;
            continue;
        }
        int start = g;
        int startLinear = 0;
        ++g;
        while (g < nGlyphs()) {
            int uc = reverseMap[g];
            // cmaps can't have the high byte changing within one range, so we need to break on that as well
            if (!uc || (g>>8) != (start >> 8))
                break;
            if (uc == uc0 + 1) {
                if (!startLinear)
                    startLinear = g - 1;
            } else {
                if (startLinear > 0 && g - startLinear >= 10)
                    break;
                startLinear = 0;
            }
            uc0 = uc;
            ++g;
        }
        // qDebug("start=%x startLinear=%x g-1=%x",start,startLinear,g-1);
        if (g - startLinear < 10)
            startLinear = 0;
        int endnonlinear = startLinear ? startLinear : g;
        // qDebug("    startLinear=%x endnonlinear=%x", startLinear,endnonlinear);
        if (endnonlinear > start) {
            s << "<" << QPdf::toHex((ushort)start, buf) << "> <";
            s << QPdf::toHex((ushort)(endnonlinear - 1), buf) << "> ";
            if (endnonlinear == start + 1) {
                s << "<" << QPdf::toHex((ushort)reverseMap[start], buf) << ">\n";
            } else {
                s << "[";
                for (int i = start; i < endnonlinear; ++i) {
                    s << "<" << QPdf::toHex((ushort)reverseMap[i], buf) << "> ";
                }
                s << "]\n";
            }
            checkRanges(ts, ranges, nranges);
        }
        if (startLinear) {
            while (startLinear < g) {
                int len = g - startLinear;
                int uc_start = reverseMap[startLinear];
                int uc_end = uc_start + len - 1;
                if ((uc_end >> 8) != (uc_start >> 8))
                    len = 256 - (uc_start & 0xff);
                s << "<" << QPdf::toHex((ushort)startLinear, buf) << "> <";
                s << QPdf::toHex((ushort)(startLinear + len - 1), buf) << "> ";
                s << "<" << QPdf::toHex((ushort)reverseMap[startLinear], buf) << ">\n";
                checkRanges(ts, ranges, nranges);
                startLinear += len;
            }
        }
    }
    if (nranges) {
        ts << nranges << "beginbfrange\n"
           << ranges << "endbfrange\n";
    }
    ts << "endcmap\n"
        "CMapName currentdict /CMap defineresource pop\n"
        "end\n"
        "end\n";

    return touc;
}

int QFontSubset::addGlyph(int index)
{
    int idx = glyph_indices.indexOf(index);
    if (idx < 0) {
        idx = glyph_indices.size();
        glyph_indices.append(index);
    }
    return idx;
}


// ------------------------------ Truetype generation ----------------------------------------------

typedef qint16 F2DOT14;
typedef quint32 Tag;
typedef quint16 GlyphID;
typedef quint16 Offset;


class QTtfStream {
public:
    QTtfStream(QByteArray &ba) : data((uchar *)ba.data()) { start = data; }
    QTtfStream &operator <<(quint8 v) { *data = v; ++data; return *this; }
    QTtfStream &operator <<(quint16 v) { qToBigEndian(v, data); data += sizeof(v); return *this; }
    QTtfStream &operator <<(quint32 v) { qToBigEndian(v, data); data += sizeof(v); return *this; }
    QTtfStream &operator <<(qint8 v) { *data = quint8(v); ++data; return *this; }
    QTtfStream &operator <<(qint16 v) { qToBigEndian(v, data); data += sizeof(v); return *this; }
    QTtfStream &operator <<(qint32 v) { qToBigEndian(v, data); data += sizeof(v); return *this; }
    QTtfStream &operator <<(qint64 v) { qToBigEndian(v, data); data += sizeof(v); return *this; }

    int offset() const { return data - start; }
    void setOffset(int o) { data = start + o; }
    void align4() { while (offset() & 3) { *data = '\0'; ++data; } }
private:
    uchar *data;
    uchar *start;
};

struct QTtfTable {
    Tag tag;
    QByteArray data;
};
Q_DECLARE_TYPEINFO(QTtfTable, Q_MOVABLE_TYPE);


struct qttf_head_table {
    qint32 font_revision;
    quint16 flags;
    qint64 created;
    qint64 modified;
    qint16 xMin;
    qint16 yMin;
    qint16 xMax;
    qint16 yMax;
    quint16 macStyle;
    qint16 indexToLocFormat;
};


struct qttf_hhea_table {
    qint16 ascender;
    qint16 descender;
    qint16 lineGap;
    quint16 maxAdvanceWidth;
    qint16 minLeftSideBearing;
    qint16 minRightSideBearing;
    qint16 xMaxExtent;
    quint16 numberOfHMetrics;
};


struct qttf_maxp_table {
    quint16 numGlyphs;
    quint16 maxPoints;
    quint16 maxContours;
    quint16 maxCompositePoints;
    quint16 maxCompositeContours;
    quint16 maxComponentElements;
    quint16 maxComponentDepth;
};

struct qttf_name_table {
    QString copyright;
    QString family;
    QString subfamily;
    QString postscript_name;
};


static QTtfTable generateHead(const qttf_head_table &head);
static QTtfTable generateHhea(const qttf_hhea_table &hhea);
static QTtfTable generateMaxp(const qttf_maxp_table &maxp);
static QTtfTable generateName(const qttf_name_table &name);

struct qttf_font_tables
{
    qttf_head_table head;
    qttf_hhea_table hhea;
    qttf_maxp_table maxp;
};


struct QTtfGlyph {
    quint16 index;
    qint16 xMin;
    qint16 xMax;
    qint16 yMin;
    qint16 yMax;
    quint16 advanceWidth;
    qint16 lsb;
    quint16 numContours;
    quint16 numPoints;
    QByteArray data;
};
Q_DECLARE_TYPEINFO(QTtfGlyph, Q_MOVABLE_TYPE);

static QTtfGlyph generateGlyph(int index, const QPainterPath &path, qreal advance, qreal lsb, qreal ppem);
// generates glyf, loca and hmtx
static QList<QTtfTable> generateGlyphTables(qttf_font_tables &tables, const QList<QTtfGlyph> &_glyphs);

static QByteArray bindFont(const QList<QTtfTable>& _tables);


static quint32 checksum(const QByteArray &table)
{
    quint32 sum = 0;
    int offset = 0;
    const uchar *d = (uchar *)table.constData();
    while (offset <= table.size()-3) {
        sum += qFromBigEndian<quint32>(d + offset);
        offset += 4;
    }
    int shift = 24;
    quint32 x = 0;
    while (offset < table.size()) {
        x |= ((quint32)d[offset]) << shift;
        ++offset;
        shift -= 8;
    }
    sum += x;

    return sum;
}

static QTtfTable generateHead(const qttf_head_table &head)
{
    const int head_size = 54;
    QTtfTable t;
    t.tag = MAKE_TAG('h', 'e', 'a', 'd');
    t.data.resize(head_size);

    QTtfStream s(t.data);

// qint32  Table version number  0x00010000 for version 1.0.
// qint32  fontRevision  Set by font manufacturer.
    s << qint32(0x00010000)
      << head.font_revision
// quint32  checkSumAdjustment  To compute: set it to 0, sum the entire font as quint32, then store 0xB1B0AFBA - sum.
      << quint32(0)
// quint32  magicNumber  Set to 0x5F0F3CF5.
      << quint32(0x5F0F3CF5)
// quint16  flags  Bit 0: Baseline for font at y=0;
// Bit 1: Left sidebearing point at x=0;
// Bit 2: Instructions may depend on point size;
// Bit 3: Force ppem to integer values for all internal scaler math; may use fractional ppem sizes if this bit is clear;
// Bit 4: Instructions may alter advance width (the advance widths might not scale linearly);
// Bits 5-10: These should be set according to  Apple's specification . However, they are not implemented in OpenType.
// Bit 11: Font data is 'lossless,' as a result of having been compressed and decompressed with the Agfa MicroType Express engine.
// Bit 12: Font converted (produce compatible metrics)
// Bit 13: Font optimised for ClearType
// Bit 14: Reserved, set to 0
// Bit 15: Reserved, set to 0