qfontsubset.cpp

奇趣公司比较新的qt/emd版本

      << quint16(0)

// quint16  unitsPerEm  Valid range is from 16 to 16384. This value should be a power of 2 for fonts that have TrueType outlines.
      << quint16(2048)
// qint64  created  Number of seconds since 12:00 midnight, January 1, 1904. 64-bit integer
      << head.created
// qint64  modified  Number of seconds since 12:00 midnight, January 1, 1904. 64-bit integer
      << head.modified
// qint16  xMin  For all glyph bounding boxes.
// qint16  yMin  For all glyph bounding boxes.
// qint16  xMax  For all glyph bounding boxes.
// qint16  yMax  For all glyph bounding boxes.
      << head.xMin
      << head.yMin
      << head.xMax
      << head.yMax
// quint16  macStyle  Bit 0: Bold (if set to 1);
// Bit 1: Italic (if set to 1)
// Bit 2: Underline (if set to 1)
// Bit 3: Outline (if set to 1)
// Bit 4: Shadow (if set to 1)
// Bit 5: Condensed (if set to 1)
// Bit 6: Extended (if set to 1)
// Bits 7-15: Reserved (set to 0).
      << head.macStyle
// quint16  lowestRecPPEM  Smallest readable size in pixels.
      << quint16(6) // just a wild guess
// qint16  fontDirectionHint   0: Fully mixed directional glyphs;
      << qint16(0)
// 1: Only strongly left to right;
// 2: Like 1 but also contains neutrals;
// -1: Only strongly right to left;
// -2: Like -1 but also contains neutrals. 1
// qint16  indexToLocFormat  0 for short offsets, 1 for long.
      << head.indexToLocFormat
// qint16  glyphDataFormat  0 for current format.
      << qint16(0);

    Q_ASSERT(s.offset() == head_size);
    return t;
}


static QTtfTable generateHhea(const qttf_hhea_table &hhea)
{
    const int hhea_size = 36;
    QTtfTable t;
    t.tag = MAKE_TAG('h', 'h', 'e', 'a');
    t.data.resize(hhea_size);

    QTtfStream s(t.data);
// qint32  Table version number  0x00010000 for version 1.0.
    s << qint32(0x00010000)
// qint16  Ascender  Typographic ascent.  (Distance from baseline of highest ascender)
      << hhea.ascender
// qint16  Descender  Typographic descent.  (Distance from baseline of lowest descender)
      << hhea.descender
// qint16  LineGap  Typographic line gap.
// Negative LineGap values are treated as zero
// in Windows 3.1, System 6, and
// System 7.
      << hhea.lineGap
// quint16  advanceWidthMax  Maximum advance width value in 'hmtx' table.
      << hhea.maxAdvanceWidth
// qint16  minLeftSideBearing  Minimum left sidebearing value in 'hmtx' table.
      << hhea.minLeftSideBearing
// qint16  minRightSideBearing  Minimum right sidebearing value; calculated as Min(aw - lsb - (xMax - xMin)).
      << hhea.minRightSideBearing
// qint16  xMaxExtent  Max(lsb + (xMax - xMin)).
      << hhea.xMaxExtent
// qint16  caretSlopeRise  Used to calculate the slope of the cursor (rise/run); 1 for vertical.
      << qint16(1)
// qint16  caretSlopeRun  0 for vertical.
      << qint16(0)
// qint16  caretOffset  The amount by which a slanted highlight on a glyph needs to be shifted to produce the best appearance. Set to 0 for non-slanted fonts
      << qint16(0)
// qint16  (reserved)  set to 0
      << qint16(0)
// qint16  (reserved)  set to 0
      << qint16(0)
// qint16  (reserved)  set to 0
      << qint16(0)
// qint16  (reserved)  set to 0
      << qint16(0)
// qint16  metricDataFormat  0 for current format.
      << qint16(0)
// quint16  numberOfHMetrics  Number of hMetric entries in 'hmtx' table
      << hhea.numberOfHMetrics;

    Q_ASSERT(s.offset() == hhea_size);
    return t;
}


static QTtfTable generateMaxp(const qttf_maxp_table &maxp)
{
    const int maxp_size = 32;
    QTtfTable t;
    t.tag = MAKE_TAG('m', 'a', 'x', 'p');
    t.data.resize(maxp_size);

    QTtfStream s(t.data);

// qint32  Table version number  0x00010000 for version 1.0.
    s << qint32(0x00010000)
// quint16  numGlyphs  The number of glyphs in the font.
      << maxp.numGlyphs
// quint16  maxPoints  Maximum points in a non-composite glyph.
      << maxp.maxPoints
// quint16  maxContours  Maximum contours in a non-composite glyph.
      << maxp.maxContours
// quint16  maxCompositePoints  Maximum points in a composite glyph.
      << maxp.maxCompositePoints
// quint16  maxCompositeContours  Maximum contours in a composite glyph.
      << maxp.maxCompositeContours
// quint16  maxZones  1 if instructions do not use the twilight zone (Z0), or 2 if instructions do use Z0; should be set to 2 in most cases.
      << quint16(1) // we do not embed instructions
// quint16  maxTwilightPoints  Maximum points used in Z0.
      << quint16(0)
// quint16  maxStorage  Number of Storage Area locations.
      << quint16(0)
// quint16  maxFunctionDefs  Number of FDEFs.
      << quint16(0)
// quint16  maxInstructionDefs  Number of IDEFs.
      << quint16(0)
// quint16  maxStackElements  Maximum stack depth2.
      << quint16(0)
// quint16  maxSizeOfInstructions  Maximum byte count for glyph instructions.
      << quint16(0)
// quint16  maxComponentElements  Maximum number of components referenced at "top level" for any composite glyph.
      << maxp.maxComponentElements
// quint16  maxComponentDepth  Maximum levels of recursion; 1 for simple components.
      << maxp.maxComponentDepth;

    Q_ASSERT(s.offset() == maxp_size);
    return t;
}

struct QTtfNameRecord {
    quint16 nameId;
    QString value;
};

static QTtfTable generateName(const QList<QTtfNameRecord> &name);

static QTtfTable generateName(const qttf_name_table &name)
{
    QList<QTtfNameRecord> list;
    QTtfNameRecord rec;
    rec.nameId = 0;
    rec.value = name.copyright;
    list.append(rec);
    rec.nameId = 1;
    rec.value = name.family;
    list.append(rec);
    rec.nameId = 2;
    rec.value = name.subfamily;
    list.append(rec);
    rec.nameId = 4;
    rec.value = name.family;
    if (name.subfamily != QLatin1String("Regular"))
        rec.value += QLatin1Char(' ') + name.subfamily;
    list.append(rec);
    rec.nameId = 6;
    rec.value = name.postscript_name;
    list.append(rec);

    return generateName(list);
}

// ####### should probably generate Macintosh/Roman name entries as well
static QTtfTable generateName(const QList<QTtfNameRecord> &name)
{
    const int char_size = 2;

    QTtfTable t;
    t.tag = MAKE_TAG('n', 'a', 'm', 'e');

    const int name_size = 6 + 12*name.size();
    int string_size = 0;
    for (int i = 0; i < name.size(); ++i) {
        string_size += name.at(i).value.length()*char_size;
    }
    t.data.resize(name_size + string_size);

    QTtfStream s(t.data);
// quint16  format  Format selector (=0).
    s << quint16(0)
// quint16  count  Number of name records.
      << quint16(name.size())
// quint16  stringOffset  Offset to start of string storage (from start of table).
      << quint16(name_size);
// NameRecord  nameRecord[count]  The name records where count is the number of records.
// (Variable)

    int off = 0;
    for (int i = 0; i < name.size(); ++i) {
        int len = name.at(i).value.length()*char_size;
// quint16  platformID  Platform ID.
// quint16  encodingID  Platform-specific encoding ID.
// quint16  languageID  Language ID.
        s << quint16(3)
          << quint16(1)
          << quint16(0x0409) // en_US
// quint16  nameId  Name ID.
          << name.at(i).nameId
// quint16  length  String length (in bytes).
          << quint16(len)
// quint16  offset  String offset from start of storage area (in bytes).
          << quint16(off);
        off += len;
    }
    for (int i = 0; i < name.size(); ++i) {
        const QString &n = name.at(i).value;
        const ushort *uc = n.utf16();
        for (int i = 0; i < n.length(); ++i) {
            s << quint16(*uc);
            ++uc;
        }
    }
    return t;
}


enum Flags {
    OffCurve = 0,
    OnCurve = (1 << 0),
    XShortVector = (1 << 1),
    YShortVector = (1 << 2),
    Repeat = (1 << 3),
    XSame = (1 << 4),
    XShortPositive = (1 << 4),
    YSame = (1 << 5),
    YShortPositive = (1 << 5)
};
struct TTF_POINT {
    qint16 x;
    qint16 y;
    quint8 flags;
};
Q_DECLARE_TYPEINFO(TTF_POINT, Q_PRIMITIVE_TYPE);

static void convertPath(const QPainterPath &path, QList<TTF_POINT> *points, QList<int> *endPoints, qreal ppem)
{
    int numElements = path.elementCount();
    for (int i = 0; i < numElements - 1; ++i) {
        const QPainterPath::Element &e = path.elementAt(i);
        TTF_POINT p;
        p.x = qRound(e.x * 2048. / ppem);
        p.y = qRound(-e.y * 2048. / ppem);

        switch(e.type) {
        case QPainterPath::MoveToElement:
            if (i != 0) {
                // see if start and end points of the last contour agree
                int start = endPoints->size() ? endPoints->at(endPoints->size()-1) - 1 : 0;
                int end = points->size() - 1;
                if (points->at(end).x == points->at(start).x
                    && points->at(end).y == points->at(start).y)
                    points->takeLast();
                endPoints->append(points->size() - 1);
            }
            // fall through
        case QPainterPath::LineToElement:
            p.flags = OnCurve;
            break;
        case QPainterPath::CurveToElement: {
            // cubic bezier curve, we need to reduce to a list of quadratic curves
            TTF_POINT list[3*16 + 4]; // we need max 16 subdivisions
            list[3] = points->at(points->size() - 1);
            list[2] = p;
            const QPainterPath::Element &e2 = path.elementAt(++i);
            list[1].x = qRound(e2.x * 2048. / ppem);
            list[1].y = qRound(-e2.y * 2048. / ppem);
            const QPainterPath::Element &e3 = path.elementAt(++i);
            list[0].x = qRound(e3.x * 2048. / ppem);
            list[0].y = qRound(-e3.y * 2048. / ppem);

            TTF_POINT *base = list;

            bool try_reduce = points->size() > 1
                              && points->at(points->size() - 1).flags == OnCurve
                              && points->at(points->size() - 2).flags == OffCurve;
//             qDebug("generating beziers:");
            while (base >= list) {
                const int split_limit = 3;
//                 {
//                     qDebug("iteration:");
//                     TTF_POINT *x = list;
//                     while (x <= base + 3) {
//                         qDebug() << "    " << QPoint(x->x, x->y);
//                         ++x;
//                     }
//                 }
                Q_ASSERT(base - list < 3*16 + 1);
                // first see if we can easily reduce the cubic to a quadratic bezier curve
                int i1_x = base[1].x + ((base[1].x - base[0].x) >> 1);
                int i1_y = base[1].y + ((base[1].y - base[0].y) >> 1);
                int i2_x = base[2].x + ((base[2].x - base[3].x) >> 1);
                int i2_y = base[2].y + ((base[2].y - base[3].y) >> 1);
//                 qDebug() << "checking: i1=" << QPoint(i1_x, i1_y) << " i2=" << QPoint(i2_x, i2_y);
                if (qAbs(i1_x - i2_x) <= split_limit && qAbs(i1_y - i2_y) <= split_limit) {
                    // got a quadratic bezier curve
                    TTF_POINT np;
                    np.x = (i1_x + i2_x) >> 1;
                    np.y = (i1_y + i2_y) >> 1;
                    if (try_reduce) {
                        // see if we can optimise out the last onCurve point
                        int mx = (points->at(points->size() - 2).x + base[2].x) >> 1;
                        int my = (points->at(points->size() - 2).y + base[2].y) >> 1;
                        if (qAbs(mx - base[3].x) <= split_limit && qAbs(my = base[3].y) <= split_limit)
                            points->takeLast();
                        try_reduce = false;
                    }
                    np.flags = OffCurve;
                    points->append(np);
//                     qDebug() << "   appending offcurve point " << QPoint(np.x, np.y);
                    base -= 3;
                } else {
                    // need to split
//                     qDebug() << "  -> splitting";
                    qint16 a, b, c, d;
                    base[6].x = base[3].x;
                    c = base[1].x;
                    d = base[2].x;
                    base[1].x = a = ( base[0].x + c ) >> 1;
                    base[5].x = b = ( base[3].x + d ) >> 1;
                    c = ( c + d ) >> 1;
                    base[2].x = a = ( a + c ) >> 1;
                    base[4].x = b = ( b + c ) >> 1;
                    base[3].x = ( a + b ) >> 1;

                    base[6].y = base[3].y;
                    c = base[1].y;
                    d = base[2].y;
                    base[1].y = a = ( base[0].y + c ) >> 1;
                    base[5].y = b = ( base[3].y + d ) >> 1;
                    c = ( c + d ) >> 1;
                    base[2].y = a = ( a + c ) >> 1;
                    base[4].y = b = ( b + c ) >> 1;
                    base[3].y = ( a + b ) >> 1;
                    base += 3;
                }
            }
            p = list[0];
            p.flags = OnCurve;
            break;