qfontsubset.cpp

奇趣公司比较新的qt/emd版本

        }
        case QPainterPath::CurveToDataElement:
            Q_ASSERT(false);
            break;
        }
//         qDebug() << "   appending oncurve point " << QPoint(p.x, p.y);
        points->append(p);
    }
    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);
}

static void getBounds(const QList<TTF_POINT> &points, qint16 *xmin, qint16 *xmax, qint16 *ymin, qint16 *ymax)
{
    *xmin = points.at(0).x;
    *xmax = *xmin;
    *ymin = points.at(0).y;
    *ymax = *ymin;

    for (int i = 1; i < points.size(); ++i) {
        *xmin = qMin(*xmin, points.at(i).x);
        *xmax = qMax(*xmax, points.at(i).x);
        *ymin = qMin(*ymin, points.at(i).y);
        *ymax = qMax(*ymax, points.at(i).y);
    }
}

static int convertToRelative(QList<TTF_POINT> *points)
{
    // convert points to relative and setup flags
//     qDebug() << "relative points:";
    qint16 prev_x = 0;
    qint16 prev_y = 0;
    int point_array_size = 0;
    for (int i = 0; i < points->size(); ++i) {
        const int x = points->at(i).x;
        const int y = points->at(i).y;
        TTF_POINT rel;
        rel.x = x - prev_x;
        rel.y = y - prev_y;
        rel.flags = points->at(i).flags;
        Q_ASSERT(rel.flags < 2);
        if (!rel.x) {
            rel.flags |= XSame;
        } else if (rel.x > 0 && rel.x < 256) {
            rel.flags |= XShortVector|XShortPositive;
            point_array_size++;
        } else if (rel.x < 0 && rel.x > -256) {
            rel.flags |= XShortVector;
            rel.x = -rel.x;
            point_array_size++;
        } else {
            point_array_size += 2;
        }
        if (!rel.y) {
            rel.flags |= YSame;
        } else if (rel.y > 0 && rel.y < 256) {
            rel.flags |= YShortVector|YShortPositive;
            point_array_size++;
        } else if (rel.y < 0 && rel.y > -256) {
            rel.flags |= YShortVector;
            rel.y = -rel.y;
            point_array_size++;
        } else {
            point_array_size += 2;
        }
        (*points)[i] = rel;
// #define toString(x) ((rel.flags & x) ? #x : "")
//         qDebug() << "    " << QPoint(rel.x, rel.y) << "flags="
//                  << toString(OnCurve) << toString(XShortVector)
//                  << (rel.flags & XShortVector ? toString(XShortPositive) : toString(XSame))
//                  << toString(YShortVector)
//                  << (rel.flags & YShortVector ? toString(YShortPositive) : toString(YSame));

        prev_x = x;
        prev_y = y;
    }
    return point_array_size;
}

static void getGlyphData(QTtfGlyph *glyph, const QList<TTF_POINT> &points, const QList<int> &endPoints, int point_array_size)
{
    const int max_size = 5*sizeof(qint16) // header
                         + endPoints.size()*sizeof(quint16) // end points of contours
                         + sizeof(quint16) // instruction length == 0
                         + points.size()*(1) // flags
                         + point_array_size; // coordinates

    glyph->data.resize(max_size);

    QTtfStream s(glyph->data);
    s << qint16(endPoints.size())
      << glyph->xMin << glyph->yMin << glyph->xMax << glyph->yMax;

    for (int i = 0; i < endPoints.size(); ++i)
        s << quint16(endPoints.at(i));
    s << quint16(0); // instruction length

    // emit flags
    for (int i = 0; i < points.size(); ++i)
        s << quint8(points.at(i).flags);
    // emit points
    for (int i = 0; i < points.size(); ++i) {
        quint8 flags = points.at(i).flags;
        qint16 x = points.at(i).x;

        if (flags & XShortVector)
            s << quint8(x);
        else if (!(flags & XSame))
            s << qint16(x);
    }
    for (int i = 0; i < points.size(); ++i) {
        quint8 flags = points.at(i).flags;
        qint16 y = points.at(i).y;

        if (flags & YShortVector)
            s << quint8(y);
        else if (!(flags & YSame))
            s << qint16(y);
    }

//     qDebug() << "offset=" << s.offset() << "max_size=" << max_size << "point_array_size=" << point_array_size;
    Q_ASSERT(s.offset() == max_size);

    glyph->numContours = endPoints.size();
    glyph->numPoints = points.size();
}

static QTtfGlyph generateGlyph(int index, const QPainterPath &path, qreal advance, qreal lsb, qreal ppem)
{
    QList<TTF_POINT> points;
    QList<int> endPoints;
    QTtfGlyph glyph;
    glyph.index = index;
    glyph.advanceWidth = qRound(advance * 2048. / ppem);
    glyph.lsb = qRound(lsb * 2048. / ppem);

    if (!path.elementCount()) {
        //qDebug("glyph %d is empty", index);
        lsb = 0;
        glyph.xMin = glyph.xMax = glyph.yMin = glyph.yMax = 0;
        glyph.numContours = 0;
        glyph.numPoints = 0;
        return glyph;
    }

    convertPath(path, &points, &endPoints, ppem);

//     qDebug() << "number of contours=" << endPoints.size();
//     for (int i = 0; i < points.size(); ++i)
//         qDebug() << "  point[" << i << "] = " << QPoint(points.at(i).x, points.at(i).y) << " flags=" << points.at(i).flags;
//     qDebug() << "endPoints:";
//     for (int i = 0; i < endPoints.size(); ++i)
//         qDebug() << endPoints.at(i);

    getBounds(points, &glyph.xMin, &glyph.xMax, &glyph.yMin, &glyph.yMax);
    int point_array_size = convertToRelative(&points);
    getGlyphData(&glyph, points, endPoints, point_array_size);
    return glyph;
}

static bool operator <(const QTtfGlyph &g1, const QTtfGlyph &g2)
{
    return g1.index < g2.index;
}

static QList<QTtfTable> generateGlyphTables(qttf_font_tables &tables, const QList<QTtfGlyph> &_glyphs)
{
    const int max_size_small = 65536*2;
    QList<QTtfGlyph> glyphs = _glyphs;
    qSort(glyphs);

    Q_ASSERT(tables.maxp.numGlyphs == glyphs.at(glyphs.size()-1).index + 1);
    int nGlyphs = tables.maxp.numGlyphs;

    int glyf_size = 0;
    for (int i = 0; i < glyphs.size(); ++i)
        glyf_size += (glyphs.at(i).data.size() + 3) & ~3;

    tables.head.indexToLocFormat = glyf_size < max_size_small ? 0 : 1;
    tables.hhea.numberOfHMetrics = nGlyphs;

    QTtfTable glyf;
    glyf.tag = MAKE_TAG('g', 'l', 'y', 'f');

    QTtfTable loca;
    loca.tag = MAKE_TAG('l', 'o', 'c', 'a');
    loca.data.resize(glyf_size < max_size_small ? (nGlyphs+1)*sizeof(quint16) : (nGlyphs+1)*sizeof(quint32));
    QTtfStream ls(loca.data);

    QTtfTable hmtx;
    hmtx.tag = MAKE_TAG('h', 'm', 't', 'x');
    hmtx.data.resize(nGlyphs*4);
    QTtfStream hs(hmtx.data);

    int pos = 0;
    for (int i = 0; i < nGlyphs; ++i) {
        int gpos = glyf.data.size();
        quint16 advance = 0;
        qint16 lsb = 0;

        if (glyphs[pos].index == i) {
            // emit glyph
//             qDebug("emitting glyph %d: size=%d", i, glyphs.at(i).data.size());
            glyf.data += glyphs.at(pos).data;
            while (glyf.data.size() & 1)
                glyf.data.append('\0');
            advance = glyphs.at(pos).advanceWidth;
            lsb = glyphs.at(pos).lsb;
            ++pos;
        }
        if (glyf_size < max_size_small) {
            // use short loca format
            ls << quint16(gpos>>1);
        } else {
            // use long loca format
            ls << quint32(gpos);
        }
        hs << advance
           << lsb;
    }
    if (glyf_size < max_size_small) {
        // use short loca format
        ls << quint16(glyf.data.size()>>1);
    } else {
        // use long loca format
        ls << quint32(glyf.data.size());
    }

    Q_ASSERT(loca.data.size() == ls.offset());
    Q_ASSERT(hmtx.data.size() == hs.offset());

    QList<QTtfTable> list;
    list.append(glyf);
    list.append(loca);
    list.append(hmtx);
    return list;
}

static bool operator <(const QTtfTable &t1, const QTtfTable &t2)
{
    return t1.tag < t2.tag;
}

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

    qSort(tables);

    QByteArray font;
    const int header_size = sizeof(qint32) + 4*sizeof(quint16);
    const int directory_size = 4*sizeof(quint32)*tables.size();
    font.resize(header_size + directory_size);

    int log2 = 0;
    int pow = 1;
    int n = tables.size() >> 1;
    while (n) {
        ++log2;
        pow <<= 1;
        n >>= 1;
    }

    quint32 head_offset = 0;
    {
        QTtfStream f(font);
// Offset Table
// Type  Name  Description
//   qint32  sfnt version  0x00010000 for version 1.0.
//   quint16   numTables  Number of tables.
//   quint16   searchRange  (Maximum power of 2 <= numTables) x 16.
//   quint16   entrySelector  Log2(maximum power of 2 <= numTables).
//   quint16   rangeShift  NumTables x 16-searchRange.
        f << qint32(0x00010000)
          << quint16(tables.size())
          << quint16(16*pow)
          << quint16(log2)
          << quint16(16*(tables.size() - pow));

// Table Directory
// Type  Name  Description
//   quint32  tag  4 -byte identifier.
//   quint32  checkSum  CheckSum for this table.
//   quint32  offset  Offset from beginning of TrueType font file.
//   quint32  length  Length of this table.
        quint32 table_offset = header_size + directory_size;
        for (int i = 0; i < tables.size(); ++i) {
            const QTtfTable &t = tables.at(i);
            const quint32 size = (t.data.size() + 3) & ~3;
            if (t.tag == MAKE_TAG('h', 'e', 'a', 'd'))
                head_offset = table_offset;
            f << t.tag
              << checksum(t.data)
              << table_offset
              << t.data.size();
            table_offset += size;
#define TAG(x) char(t.tag >> 24) << char((t.tag >> 16) & 0xff) << char((t.tag >> 8) & 0xff) << char(t.tag & 0xff)
            //qDebug() << "table " << TAG(t.tag) << "has size " << t.data.size() << "stream at " << f.offset();
        }
    }
    for (int i = 0; i < tables.size(); ++i) {
        const QByteArray &t = tables.at(i).data;
        font += t;
        int s = t.size();
        while (s & 3) { font += '\0'; ++s; }
    }

    if (!head_offset) {
        qWarning("QFontSubset: Font misses 'head' table");
        return QByteArray();
    }

    // calculate the fonts checksum and qToBigEndian into 'head's checksum_adjust
    quint32 checksum_adjust = 0xB1B0AFBA - checksum(font);
    qToBigEndian(checksum_adjust, (uchar *)font.data() + head_offset + 8);

    return font;
}


/*
  PDF requires the following tables:

  head, hhea, loca, maxp, cvt , prep, glyf, hmtx, fpgm

  This means we don't have to add a os/2, post or name table. cvt , prep and fpgm could be empty
  if really required.
*/

QByteArray QFontSubset::toTruetype() const
{
    qttf_font_tables font;
    memset(&font, 0, sizeof(qttf_font_tables));

    qreal ppem = fontEngine->fontDef.pixelSize;
#define TO_TTF(x) qRound(x * 2048. / ppem)
    QList<QTtfGlyph> glyphs;

    QFontEngine::Properties properties = fontEngine->properties();
    // initialize some stuff needed in createWidthArray
    emSquare = 2048;
    widths.resize(nGlyphs());