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#include <qdebug.h>
#include <private/qfontengine_p.h>

#include "qbitmap.h"
#include "qpainter.h"
#include "qpainterpath.h"
#include "qvarlengtharray.h"
#include <private/qpdf_p.h>
#include <qmath.h>
#include <qendian.h>
#include <private/qharfbuzz_p.h>

QT_BEGIN_NAMESPACE

static inline bool qtransform_equals_no_translate(const QTransform &a, const QTransform &b)
{
    if (a.type() <= QTransform::TxTranslate && b.type() <= QTransform::TxTranslate) {
        return true;
    } else {
        // We always use paths for perspective text anyway, so no
        // point in checking the full matrix...
        Q_ASSERT(a.type() < QTransform::TxProject);
        Q_ASSERT(b.type() < QTransform::TxProject);

        return a.m11() == b.m11()
            && a.m12() == b.m12()
            && a.m21() == b.m21()
            && a.m22() == b.m22();
    }
}

// Harfbuzz helper functions

static HB_Bool hb_stringToGlyphs(HB_Font font, const HB_UChar16 *string, hb_uint32 length, HB_Glyph *glyphs, hb_uint32 *numGlyphs, HB_Bool rightToLeft)
{
    QFontEngine *fe = (QFontEngine *)font->userData;

    QVarLengthGlyphLayoutArray qglyphs(*numGlyphs);

    QTextEngine::ShaperFlags shaperFlags(QTextEngine::GlyphIndicesOnly);
    if (rightToLeft)
        shaperFlags |= QTextEngine::RightToLeft;

    int nGlyphs = *numGlyphs;
    bool result = fe->stringToCMap(reinterpret_cast<const QChar *>(string), length, &qglyphs, &nGlyphs, shaperFlags);
    *numGlyphs = nGlyphs;
    if (!result)
        return false;

    for (hb_uint32 i = 0; i < *numGlyphs; ++i)
        glyphs[i] = qglyphs.glyphs[i];

    return true;
}

static void hb_getAdvances(HB_Font font, const HB_Glyph *glyphs, hb_uint32 numGlyphs, HB_Fixed *advances, int flags)
{
    QFontEngine *fe = (QFontEngine *)font->userData;

    QVarLengthGlyphLayoutArray qglyphs(numGlyphs);

    for (hb_uint32 i = 0; i < numGlyphs; ++i)
        qglyphs.glyphs[i] = glyphs[i];

    fe->recalcAdvances(&qglyphs, flags & HB_ShaperFlag_UseDesignMetrics ? QFlags<QTextEngine::ShaperFlag>(QTextEngine::DesignMetrics) : QFlags<QTextEngine::ShaperFlag>(0));

    for (hb_uint32 i = 0; i < numGlyphs; ++i)
        advances[i] = qglyphs.advances_x[i].value();
}

static HB_Bool hb_canRender(HB_Font font, const HB_UChar16 *string, hb_uint32 length)
{
    QFontEngine *fe = (QFontEngine *)font->userData;
    return fe->canRender(reinterpret_cast<const QChar *>(string), length);
}

static void hb_getGlyphMetrics(HB_Font font, HB_Glyph glyph, HB_GlyphMetrics *metrics)
{
    QFontEngine *fe = (QFontEngine *)font->userData;
    glyph_metrics_t m = fe->boundingBox(glyph);
    metrics->x = m.x.value();
    metrics->y = m.y.value();
    metrics->width = m.width.value();
    metrics->height = m.height.value();
    metrics->xOffset = m.xoff.value();
    metrics->yOffset = m.yoff.value();
}

static HB_Fixed hb_getFontMetric(HB_Font font, HB_FontMetric metric)
{
    if (metric == HB_FontAscent) {
        QFontEngine *fe = (QFontEngine *)font->userData;
        return fe->ascent().value();
    }
    return 0;
}

HB_Error QFontEngine::getPointInOutline(HB_Glyph glyph, int flags, hb_uint32 point, HB_Fixed *xpos, HB_Fixed *ypos, hb_uint32 *nPoints)
{
    Q_UNUSED(glyph)
    Q_UNUSED(flags)
    Q_UNUSED(point)
    Q_UNUSED(xpos)
    Q_UNUSED(ypos)
    Q_UNUSED(nPoints)
    return HB_Err_Not_Covered;
}

static HB_Error hb_getPointInOutline(HB_Font font, HB_Glyph glyph, int flags, hb_uint32 point, HB_Fixed *xpos, HB_Fixed *ypos, hb_uint32 *nPoints)
{
    QFontEngine *fe = (QFontEngine *)font->userData;
    return fe->getPointInOutline(glyph, flags, point, xpos, ypos, nPoints);
}

static const HB_FontClass hb_fontClass = {
    hb_stringToGlyphs, hb_getAdvances, hb_canRender, hb_getPointInOutline,
    hb_getGlyphMetrics, hb_getFontMetric
};

static HB_Error hb_getSFntTable(void *font, HB_Tag tableTag, HB_Byte *buffer, HB_UInt *length)
{
    QFontEngine *fe = (QFontEngine *)font;
    if (!fe->getSfntTableData(tableTag, buffer, length))
        return HB_Err_Invalid_Argument;
    return HB_Err_Ok;
}

// QFontEngine

QFontEngine::QFontEngine()
    : QObject()
{
    ref = 0;
    cache_count = 0;
    fsType = 0;
    symbol = false;
    memset(&hbFont, 0, sizeof(hbFont));
    hbFont.klass = &hb_fontClass;
    hbFont.userData = this;

    hbFace = 0;
    glyphFormat = -1;
}

QFontEngine::~QFontEngine()
{
    for (QLinkedList<GlyphCacheEntry>::const_iterator it = m_glyphCaches.constBegin(),
            end = m_glyphCaches.constEnd(); it != end; ++it) {
        delete it->cache;
    }
    m_glyphCaches.clear();
    qHBFreeFace(hbFace);
}

QFixed QFontEngine::lineThickness() const
{
    // ad hoc algorithm
    int score = fontDef.weight * fontDef.pixelSize;
    int lw = score / 700;

    // looks better with thicker line for small pointsizes
    if (lw < 2 && score >= 1050) lw = 2;
    if (lw == 0) lw = 1;

    return lw;
}

QFixed QFontEngine::underlinePosition() const
{
    return ((lineThickness() * 2) + 3) / 6;
}

HB_Font QFontEngine::harfbuzzFont() const
{
    if (!hbFont.x_ppem) {
        QFixed emSquare = emSquareSize();
        hbFont.x_ppem = fontDef.pixelSize;
        hbFont.y_ppem = fontDef.pixelSize * fontDef.stretch / 100;
        hbFont.x_scale = (QFixed(hbFont.x_ppem * (1 << 16)) / emSquare).value();
        hbFont.y_scale = (QFixed(hbFont.y_ppem * (1 << 16)) / emSquare).value();
    }
    return &hbFont;
}

HB_Face QFontEngine::harfbuzzFace() const
{
    if (!hbFace) {
        hbFace = qHBNewFace(const_cast<QFontEngine *>(this), hb_getSFntTable);
        Q_CHECK_PTR(hbFace);
    }
    return hbFace;
}

glyph_metrics_t QFontEngine::boundingBox(glyph_t glyph, const QTransform &matrix)
{
    glyph_metrics_t metrics = boundingBox(glyph);

    if (matrix.type() > QTransform::TxTranslate) {
        return metrics.transformed(matrix);
    }
    return metrics;
}

QFixed QFontEngine::xHeight() const
{
    QGlyphLayoutArray<8> glyphs;
    int nglyphs = 7;
    QChar x((ushort)'x');
    stringToCMap(&x, 1, &glyphs, &nglyphs, QTextEngine::GlyphIndicesOnly);

    glyph_metrics_t bb = const_cast<QFontEngine *>(this)->boundingBox(glyphs.glyphs[0]);
    return bb.height;
}

QFixed QFontEngine::averageCharWidth() const
{
    QGlyphLayoutArray<8> glyphs;
    int nglyphs = 7;
    QChar x((ushort)'x');
    stringToCMap(&x, 1, &glyphs, &nglyphs, QTextEngine::GlyphIndicesOnly);

    glyph_metrics_t bb = const_cast<QFontEngine *>(this)->boundingBox(glyphs.glyphs[0]);
    return bb.xoff;
}


void QFontEngine::getGlyphPositions(const QGlyphLayout &glyphs, const QTransform &matrix, QTextItem::RenderFlags flags,
                                    QVarLengthArray<glyph_t> &glyphs_out, QVarLengthArray<QFixedPoint> &positions)
{
    QFixed xpos;
    QFixed ypos;

    const bool transform = matrix.m11() != 1.
                           || matrix.m12() != 0.
                           || matrix.m21() != 0.
                           || matrix.m22() != 1.;
    if (!transform) {
        xpos = QFixed::fromReal(matrix.dx());
        ypos = QFixed::fromReal(matrix.dy());
    }

    int current = 0;
    if (flags & QTextItem::RightToLeft) {
        int i = glyphs.numGlyphs;
        int totalKashidas = 0;
        while(i--) {
            xpos += glyphs.advances_x[i] + QFixed::fromFixed(glyphs.justifications[i].space_18d6);
            ypos += glyphs.advances_y[i];
            totalKashidas += glyphs.justifications[i].nKashidas;
        }
        positions.resize(glyphs.numGlyphs+totalKashidas);
        glyphs_out.resize(glyphs.numGlyphs+totalKashidas);

        i = 0;
        while(i < glyphs.numGlyphs) {
            if (glyphs.attributes[i].dontPrint) {
                ++i;
                continue;
            }
            xpos -= glyphs.advances_x[i];
            ypos -= glyphs.advances_y[i];

            QFixed gpos_x = xpos + glyphs.offsets[i].x;
            QFixed gpos_y = ypos + glyphs.offsets[i].y;
            if (transform) {
                QPointF gpos(gpos_x.toReal(), gpos_y.toReal());
                gpos = gpos * matrix;
                gpos_x = QFixed::fromReal(gpos.x());
                gpos_y = QFixed::fromReal(gpos.y());
            }
            positions[current].x = gpos_x;
            positions[current].y = gpos_y;
            glyphs_out[current] = glyphs.glyphs[i];
            ++current;
            if (glyphs.justifications[i].nKashidas) {
                QChar ch(0x640); // Kashida character
                QGlyphLayoutArray<8> g;
                int nglyphs = 7;
                stringToCMap(&ch, 1, &g, &nglyphs, 0);
                for (uint k = 0; k < glyphs.justifications[i].nKashidas; ++k) {
                    xpos -= g.advances_x[0];
                    ypos -= g.advances_y[0];

                    QFixed gpos_x = xpos + glyphs.offsets[i].x;
                    QFixed gpos_y = ypos + glyphs.offsets[i].y;
                    if (transform) {
                        QPointF gpos(gpos_x.toReal(), gpos_y.toReal());
                        gpos = gpos * matrix;
                        gpos_x = QFixed::fromReal(gpos.x());
                        gpos_y = QFixed::fromReal(gpos.y());
                    }
                    positions[current].x = gpos_x;
                    positions[current].y = gpos_y;
                    glyphs_out[current] = g.glyphs[0];
                    ++current;
                }
            } else {
                xpos -= QFixed::fromFixed(glyphs.justifications[i].space_18d6);
            }
            ++i;
        }
    } else {
        positions.resize(glyphs.numGlyphs);
        glyphs_out.resize(glyphs.numGlyphs);
        int i = 0;
        if (!transform) {
            while (i < glyphs.numGlyphs) {
                if (!glyphs.attributes[i].dontPrint) {
                    positions[current].x = xpos + glyphs.offsets[i].x;
                    positions[current].y = ypos + glyphs.offsets[i].y;
                    glyphs_out[current] = glyphs.glyphs[i];
                    xpos += glyphs.advances_x[i] + QFixed::fromFixed(glyphs.justifications[i].space_18d6);
                    ypos += glyphs.advances_y[i];
                    ++current;
                }
                ++i;
            }
        } else {
            while (i < glyphs.numGlyphs) {
                if (!glyphs.attributes[i].dontPrint) {
                    QFixed gpos_x = xpos + glyphs.offsets[i].x;
                    QFixed gpos_y = ypos + glyphs.offsets[i].y;
                    QPointF gpos(gpos_x.toReal(), gpos_y.toReal());
                    gpos = gpos * matrix;
                    positions[current].x = QFixed::fromReal(gpos.x());
                    positions[current].y = QFixed::fromReal(gpos.y());
                    glyphs_out[current] = glyphs.glyphs[i];
                    xpos += glyphs.advances_x[i] + QFixed::fromFixed(glyphs.justifications[i].space_18d6);
                    ypos += glyphs.advances_y[i];
                    ++current;
                }
                ++i;
            }
        }
    }
    positions.resize(current);
    glyphs_out.resize(current);
    Q_ASSERT(positions.size() == glyphs_out.size());
}


glyph_metrics_t QFontEngine::tightBoundingBox(const QGlyphLayout &glyphs)
{
    glyph_metrics_t overall;

    QFixed ymax = 0;
    QFixed xmax = 0;
    for (int i = 0; i < glyphs.numGlyphs; i++) {
        glyph_metrics_t bb = boundingBox(glyphs.glyphs[i]);
        QFixed x = overall.xoff + glyphs.offsets[i].x + bb.x;
        QFixed y = overall.yoff + glyphs.offsets[i].y + bb.y;
        overall.x = qMin(overall.x, x);
        overall.y = qMin(overall.y, y);
        xmax = qMax(xmax, x + bb.width);
        ymax = qMax(ymax, y + bb.height);
        overall.xoff += bb.xoff;
        overall.yoff += bb.yoff;
    }
    overall.height = qMax(overall.height, ymax - overall.y);
    overall.width = xmax - overall.x;

    return overall;
}


void QFontEngine::addOutlineToPath(qreal x, qreal y, const QGlyphLayout &glyphs, QPainterPath *path,
                                   QTextItem::RenderFlags flags)
{
    if (!glyphs.numGlyphs)
        return;

    QVarLengthArray<QFixedPoint> positions;
    QVarLengthArray<glyph_t> positioned_glyphs;
    QTransform matrix = QTransform::fromTranslate(x, y);
    getGlyphPositions(glyphs, matrix, flags, positioned_glyphs, positions);
    addGlyphsToPath(positioned_glyphs.data(), positions.data(), positioned_glyphs.size(), path, flags);
}

#define GRID(x, y) grid[(y)*(w+1) + (x)]
#define SET(x, y) (*(image_data + (y)*bpl + ((x) >> 3)) & (0x80 >> ((x) & 7)))

enum { EdgeRight = 0x1,
       EdgeDown = 0x2,
       EdgeLeft = 0x4,
       EdgeUp = 0x8
};

static void collectSingleContour(qreal x0, qreal y0, uint *grid, int x, int y, int w, int h, QPainterPath *path)
{
    Q_UNUSED(h);

    path->moveTo(x + x0, y + y0);
    while (GRID(x, y)) {
        if (GRID(x, y) & EdgeRight) {
            while (GRID(x, y) & EdgeRight) {
                GRID(x, y) &= ~EdgeRight;
                ++x;
            }
            Q_ASSERT(x <= w);
            path->lineTo(x + x0, y + y0);
            continue;
        }
        if (GRID(x, y) & EdgeDown) {
            while (GRID(x, y) & EdgeDown) {
                GRID(x, y) &= ~EdgeDown;
                ++y;
            }
            Q_ASSERT(y <= h);
            path->lineTo(x + x0, y + y0);
            continue;
        }
        if (GRID(x, y) & EdgeLeft) {
            while (GRID(x, y) & EdgeLeft) {
                GRID(x, y) &= ~EdgeLeft;
                --x;
            }
            Q_ASSERT(x >= 0);
            path->lineTo(x + x0, y + y0);
            continue;
        }
        if (GRID(x, y) & EdgeUp) {
            while (GRID(x, y) & EdgeUp) {
                GRID(x, y) &= ~EdgeUp;
                --y;
            }
            Q_ASSERT(y >= 0);
            path->lineTo(x + x0, y + y0);
            continue;
        }
    }
    path->closeSubpath();
}

void qt_addBitmapToPath(qreal x0, qreal y0, const uchar *image_data, int bpl, int w, int h, QPainterPath *path)
{
    uint *grid = new uint[(w+1)*(h+1)];
    // set up edges
    for (int y = 0; y <= h; ++y) {
        for (int x = 0; x <= w; ++x) {
            bool topLeft = (x == 0)|(y == 0) ? false : SET(x - 1, y - 1);
            bool topRight = (x == w)|(y == 0) ? false : SET(x, y - 1);
            bool bottomLeft = (x == 0)|(y == h) ? false : SET(x - 1, y);
            bool bottomRight = (x == w)|(y == h) ? false : SET(x, y);

            GRID(x, y) = 0;
            if ((!topRight) & bottomRight)
                GRID(x, y) |= EdgeRight;
            if ((!bottomRight) & bottomLeft)
                GRID(x, y) |= EdgeDown;
            if ((!bottomLeft) & topLeft)
                GRID(x, y) |= EdgeLeft;
            if ((!topLeft) & topRight)
                GRID(x, y) |= EdgeUp;
        }
    }

    // collect edges
    for (int y = 0; y < h; ++y) {
        for (int x = 0; x < w; ++x) {
            if (!GRID(x, y))
                continue;
            // found start of a contour, follow it
            collectSingleContour(x0, y0, grid, x, y, w, h, path);
        }
    }
    delete [] grid;
}

#undef GRID
#undef SET


void QFontEngine::addBitmapFontToPath(qreal x, qreal y, const QGlyphLayout &glyphs,
                                      QPainterPath *path, QTextItem::RenderFlags flags)
{
// TODO what to do with 'flags' ??
    Q_UNUSED(flags);
    QFixed advanceX = QFixed::fromReal(x);
    QFixed advanceY = QFixed::fromReal(y);
    for (int i=0; i < glyphs.numGlyphs; ++i) {
        glyph_metrics_t metrics = boundingBox(glyphs.glyphs[i]);
        if (metrics.width.value() == 0 || metrics.height.value() == 0) {
            advanceX += glyphs.advances_x[i];
            advanceY += glyphs.advances_y[i];
            continue;
        }
        const QImage alphaMask = alphaMapForGlyph(glyphs.glyphs[i]);

        const int w = alphaMask.width();
        const int h = alphaMask.height();
        const int srcBpl = alphaMask.bytesPerLine();
        QImage bitmap;
        if (alphaMask.depth() == 1) {
            bitmap = alphaMask;
        } else {
            bitmap = QImage(w, h, QImage::Format_Mono);
            const uchar *imageData = alphaMask.bits();
            const int destBpl = bitmap.bytesPerLine();
            uchar *bitmapData = bitmap.bits();

            for (int yi = 0; yi < h; ++yi) {
                const uchar *src = imageData + yi*srcBpl;
                uchar *dst = bitmapData + yi*destBpl;
                for (int xi = 0; xi < w; ++xi) {
                    const int byte = xi / 8;
                    const int bit = xi % 8;
                    if (bit == 0)
                        dst[byte] = 0;
                    if (src[xi])
                        dst[byte] |= 128 >> bit;
                }
            }
        }
        const uchar *bitmap_data = bitmap.bits();
        QFixedPoint offset = glyphs.offsets[i];
        advanceX += offset.x;
        advanceY += offset.y;
        qt_addBitmapToPath((advanceX + metrics.x).toReal(), (advanceY + metrics.y).toReal(), bitmap_data, bitmap.bytesPerLine(), w, h, path);
        advanceX += glyphs.advances_x[i];
        advanceY += glyphs.advances_y[i];
    }
}

void QFontEngine::addGlyphsToPath(glyph_t *glyphs, QFixedPoint *positions, int nGlyphs,
                                  QPainterPath *path, QTextItem::RenderFlags flags)
{
    qreal x = positions[0].x.toReal();
    qreal y = positions[0].y.toReal();
    QVarLengthGlyphLayoutArray g(nGlyphs);

    for (int i = 0; i < nGlyphs; ++i) {
        g.glyphs[i] = glyphs[i];
        if (i < nGlyphs - 1) {
            g.advances_x[i] = positions[i+1].x - positions[i].x;
            g.advances_y[i] = positions[i+1].y - positions[i].y;
        } else {
            g.advances_x[i] = QFixed::fromReal(maxCharWidth());
            g.advances_y[i] = 0;
        }
    }

    addBitmapFontToPath(x, y, g, path, flags);
}

QImage QFontEngine::alphaMapForGlyph(glyph_t glyph, const QTransform &t)
{
    QImage i = alphaMapForGlyph(glyph);
    if (t.type() > QTransform::TxTranslate)
        i = i.transformed(t);
    Q_ASSERT(i.depth() <= 8); // To verify that transformed didn't change the format...
    return i;
}

QImage QFontEngine::alphaRGBMapForGlyph(glyph_t glyph, int /* margin */, const QTransform &t)
{
    QImage alphaMask = alphaMapForGlyph(glyph, t);
    QImage rgbMask(alphaMask.width(), alphaMask.height(), QImage::Format_RGB32);

    for (int y=0; y<alphaMask.height(); ++y) {
        uint *dst = (uint *) rgbMask.scanLine(y);
        uchar *src = (uchar *) alphaMask.scanLine(y);
        for (int x=0; x<alphaMask.width(); ++x)
            dst[x] = qRgb(src[x], src[x], src[x]);
    }

    return rgbMask;
}

QImage QFontEngine::alphaMapForGlyph(glyph_t glyph)
{
    glyph_metrics_t gm = boundingBox(glyph);
    int glyph_x = qFloor(gm.x.toReal());
    int glyph_y = qFloor(gm.y.toReal());
    int glyph_width = qCeil((gm.x + gm.width).toReal()) -  glyph_x;
    int glyph_height = qCeil((gm.y + gm.height).toReal()) - glyph_y;

    if (glyph_width <= 0 || glyph_height <= 0)
        return QImage();
    QFixedPoint pt;
    pt.x = 0;
    pt.y = -glyph_y; // the baseline
    QPainterPath path;
    QImage im(glyph_width + qAbs(glyph_x) + 4, glyph_height, QImage::Format_ARGB32_Premultiplied);
    im.fill(Qt::transparent);
    QPainter p(&im);
    p.setRenderHint(QPainter::Antialiasing);
    addGlyphsToPath(&glyph, &pt, 1, &path, 0);
    p.setPen(Qt::NoPen);
    p.setBrush(Qt::black);
    p.drawPath(path);
    p.end();

    QImage indexed(im.width(), im.height(), QImage::Format_Indexed8);
    QVector<QRgb> colors(256);
    for (int i=0; i<256; ++i)
        colors[i] = qRgba(0, 0, 0, i);
    indexed.setColorTable(colors);

    for (int y=0; y<im.height(); ++y) {
        uchar *dst = (uchar *) indexed.scanLine(y);
        uint *src = (uint *) im.scanLine(y);
        for (int x=0; x<im.width(); ++x)
            dst[x] = qAlpha(src[x]);
    }

    return indexed;
}

void QFontEngine::removeGlyphFromCache(glyph_t)
{
}

QFontEngine::Properties QFontEngine::properties() const
{
    Properties p;
#ifndef QT_NO_PRINTER
    QByteArray psname = QPdf::stripSpecialCharacters(fontDef.family.toUtf8());
#else
    QByteArray psname = fontDef.family.toUtf8();
#endif
    psname += '-';
    psname += QByteArray::number(fontDef.style);
    psname += '-';
    psname += QByteArray::number(fontDef.weight);

    p.postscriptName = psname;
    p.ascent = ascent();
    p.descent = descent();
    p.leading = leading();
    p.emSquare = p.ascent;
    p.boundingBox = QRectF(0, -p.ascent.toReal(), maxCharWidth(), (p.ascent + p.descent).toReal());
    p.italicAngle = 0;
    p.capHeight = p.ascent;
    p.lineWidth = lineThickness();
    return p;
}

void QFontEngine::getUnscaledGlyph(glyph_t glyph, QPainterPath *path, glyph_metrics_t *metrics)
{
    *metrics = boundingBox(glyph);
    QFixedPoint p;
    p.x = 0;
    p.y = 0;
    addGlyphsToPath(&glyph, &p, 1, path, QFlag(0));
}

QByteArray QFontEngine::getSfntTable(uint tag) const
{
    QByteArray table;
    uint len = 0;
    if (!getSfntTableData(tag, 0, &len))
        return table;
    if (!len)
        return table;
    table.resize(len);
    if (!getSfntTableData(tag, reinterpret_cast<uchar *>(table.data()), &len))
        return QByteArray();
    return table;
}

void QFontEngine::setGlyphCache(void *key, QFontEngineGlyphCache *data)
{
    Q_ASSERT(data);

    GlyphCacheEntry entry = { key, data };
    if (m_glyphCaches.contains(entry))
        return;

    // Limit the glyph caches to 4. This covers all 90 degree rotations and limits
    // memory use when there is continous or random rotation
    if (m_glyphCaches.size() == 4)
        delete m_glyphCaches.takeLast().cache;

    m_glyphCaches.push_front(entry);

}

QFontEngineGlyphCache *QFontEngine::glyphCache(void *key, QFontEngineGlyphCache::Type type, const QTransform &transform) const
{
    for (QLinkedList<GlyphCacheEntry>::const_iterator it = m_glyphCaches.constBegin(), end = m_glyphCaches.constEnd(); it != end; ++it) {
        QFontEngineGlyphCache *c = it->cache;
        if (key == it->context
            && type == c->cacheType()
            && qtransform_equals_no_translate(c->m_transform, transform)) {
            return c;
        }
    }
    return 0;
}

#if defined(Q_WS_WIN) || defined(Q_WS_X11) || defined(Q_WS_QWS) || defined(Q_OS_SYMBIAN)
static inline QFixed kerning(int left, int right, const QFontEngine::KernPair *pairs, int numPairs)
{
    uint left_right = (left << 16) + right;

    left = 0, right = numPairs - 1;
    while (left <= right) {
        int middle = left + ( ( right - left ) >> 1 );

        if(pairs[middle].left_right == left_right)
            return pairs[middle].adjust;

        if (pairs[middle].left_right < left_right)
            left = middle + 1;
        else
            right = middle - 1;
    }
    return 0;
}

void QFontEngine::doKerning(QGlyphLayout *glyphs, QTextEngine::ShaperFlags flags) const
{
    int numPairs = kerning_pairs.size();
    if(!numPairs)
        return;

    const KernPair *pairs = kerning_pairs.constData();

    if(flags & QTextEngine::DesignMetrics) {
        for(int i = 0; i < glyphs->numGlyphs - 1; ++i)
            glyphs->advances_x[i] += kerning(glyphs->glyphs[i], glyphs->glyphs[i+1] , pairs, numPairs);
    } else {
        for(int i = 0; i < glyphs->numGlyphs - 1; ++i)
            glyphs->advances_x[i] += qRound(kerning(glyphs->glyphs[i], glyphs->glyphs[i+1] , pairs, numPairs));
    }
}

void QFontEngine::loadKerningPairs(QFixed scalingFactor)
{
    kerning_pairs.clear();

    QByteArray tab = getSfntTable(MAKE_TAG('k', 'e', 'r', 'n'));
    if (tab.isEmpty())
        return;

    const uchar *table = reinterpret_cast<const uchar *>(tab.constData());

    unsigned short version = qFromBigEndian<quint16>(table);
    if (version != 0) {
//        qDebug("wrong version");
       return;
    }

    unsigned short numTables = qFromBigEndian<quint16>(table + 2);
    {
        int offset = 4;
        for(int i = 0; i < numTables; ++i) {
            if (offset + 6 > tab.size()) {
//                qDebug("offset out of bounds");
                goto end;
            }
            const uchar *header = table + offset;

            ushort version = qFromBigEndian<quint16>(header);
            ushort length = qFromBigEndian<quint16>(header+2);
            ushort coverage = qFromBigEndian<quint16>(header+4);
//            qDebug("subtable: version=%d, coverage=%x",version, coverage);
            if(version == 0 && coverage == 0x0001) {
                if (offset + length > tab.size()) {
//                    qDebug("length ouf ot bounds");
                    goto end;
                }
                const uchar *data = table + offset + 6;

                ushort nPairs = qFromBigEndian<quint16>(data);
                if(nPairs * 6 + 8 > length - 6) {
//                    qDebug("corrupt table!");
                    // corrupt table
                    goto end;
                }

                int off = 8;
                for(int i = 0; i < nPairs; ++i) {
                    QFontEngine::KernPair p;
                    p.left_right = (((uint)qFromBigEndian<quint16>(data+off)) << 16) + qFromBigEndian<quint16>(data+off+2);
                    p.adjust = QFixed(((int)(short)qFromBigEndian<quint16>(data+off+4))) / scalingFactor;
                    kerning_pairs.append(p);
                    off += 6;
                }
            }
            offset += length;
        }
    }
end:
    qSort(kerning_pairs);
//    for (int i = 0; i < kerning_pairs.count(); ++i)
//        qDebug() << 'i' << i << "left_right" << hex << kerning_pairs.at(i).left_right;
}

#else
void QFontEngine::doKerning(QGlyphLayout *, QTextEngine::ShaperFlags) const
{
}
#endif

int QFontEngine::glyphCount() const
{
    QByteArray maxpTable = getSfntTable(MAKE_TAG('m', 'a', 'x', 'p'));
    if (maxpTable.size() < 6)
        return 0;
    return qFromBigEndian<quint16>(reinterpret_cast<const uchar *>(maxpTable.constData() + 4));
}

const uchar *QFontEngine::getCMap(const uchar *table, uint tableSize, bool *isSymbolFont, int *cmapSize)
{
    const uchar *header = table;
    if (tableSize < 4)
        return 0;

    const uchar *endPtr = table + tableSize;

    // version check
    if (qFromBigEndian<quint16>(header) != 0)
        return 0;

    unsigned short numTables = qFromBigEndian<quint16>(header + 2);
    const uchar *maps = table + 4;
    if (maps + 8 * numTables > endPtr)
        return 0;

    enum {
        Invalid,
        Symbol,
        AppleRoman,
        Unicode11,
        Unicode,
        MicrosoftUnicode,
        MicrosoftUnicodeExtended
    };

    int symbolTable = -1;
    int tableToUse = -1;
    int score = Invalid;
    for (int n = 0; n < numTables; ++n) {
        const quint16 platformId = qFromBigEndian<quint16>(maps + 8 * n);
        const quint16 platformSpecificId = qFromBigEndian<quint16>(maps + 8 * n + 2);
        switch (platformId) {
        case 0: // Unicode
            if (score < Unicode &&
                (platformSpecificId == 0 ||
                 platformSpecificId == 2 ||
                 platformSpecificId == 3)) {
                tableToUse = n;
                score = Unicode;
            } else if (score < Unicode11 && platformSpecificId == 1) {
                tableToUse = n;
                score = Unicode11;
            }
            break;
        case 1: // Apple
            if (score < AppleRoman && platformSpecificId == 0) { // Apple Roman
                tableToUse = n;
                score = AppleRoman;
            }
            break;
        case 3: // Microsoft
            switch (platformSpecificId) {
            case 0:
                symbolTable = n;
                if (score < Symbol) {
                    tableToUse = n;
                    score = Symbol;
                }
                break;
            case 1:
                if (score < MicrosoftUnicode) {
                    tableToUse = n;
                    score = MicrosoftUnicode;
                }
                break;
            case 0xa:
                if (score < MicrosoftUnicodeExtended) {
                    tableToUse = n;
                    score = MicrosoftUnicodeExtended;
                }
                break;
            default:
                break;
            }
        default:
            break;
        }
    }
    if(tableToUse < 0)
        return 0;

resolveTable:
    *isSymbolFont = (score == Symbol);

    unsigned int unicode_table = qFromBigEndian<quint32>(maps + 8*tableToUse + 4);

    if (!unicode_table || unicode_table + 8 > tableSize)
        return 0;

    // get the header of the unicode table
    header = table + unicode_table;

    unsigned short format = qFromBigEndian<quint16>(header);
    unsigned int length;
    if(format < 8)
        length = qFromBigEndian<quint16>(header + 2);
    else
        length = qFromBigEndian<quint32>(header + 4);

    if (table + unicode_table + length > endPtr)
        return 0;
    *cmapSize = length;

    // To support symbol fonts that contain a unicode table for the symbol area
    // we check the cmap tables and fall back to symbol font unless that would
    // involve losing information from the unicode table
    if (symbolTable > -1 && ((score == Unicode) || (score == Unicode11))) {
        const uchar *selectedTable = table + unicode_table;

        // Check that none of the latin1 range are in the unicode table
        bool unicodeTableHasLatin1 = false;
        for (int uc=0x00; uc<0x100; ++uc) {
            if (getTrueTypeGlyphIndex(selectedTable, uc) != 0) {
                unicodeTableHasLatin1 = true;
                break;
            }
        }

        // Check that at least one symbol char is in the unicode table
        bool unicodeTableHasSymbols = false;
        if (!unicodeTableHasLatin1) {
            for (int uc=0xf000; uc<0xf100; ++uc) {
                if (getTrueTypeGlyphIndex(selectedTable, uc) != 0) {
                    unicodeTableHasSymbols = true;
                    break;
                }
            }
        }

        // Fall back to symbol table
        if (!unicodeTableHasLatin1 && unicodeTableHasSymbols) {
            tableToUse = symbolTable;
            score = Symbol;
            goto resolveTable;
        }
    }

    return table + unicode_table;
}

quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
{
    unsigned short format = qFromBigEndian<quint16>(cmap);
    if (format == 0) {
        if (unicode < 256)
            return (int) *(cmap+6+unicode);
    } else if (format == 4) {
        /* some fonts come with invalid cmap tables, where the last segment
           specified end = start = rangeoffset = 0xffff, delta = 0x0001
           Since 0xffff is never a valid Unicode char anyway, we just get rid of the issue
           by returning 0 for 0xffff
        */
        if(unicode >= 0xffff)
            return 0;
        quint16 segCountX2 = qFromBigEndian<quint16>(cmap + 6);
        const unsigned char *ends = cmap + 14;
        int i = 0;
        for (; i < segCountX2/2 && qFromBigEndian<quint16>(ends + 2*i) < unicode; i++) {}

        const unsigned char *idx = ends + segCountX2 + 2 + 2*i;
        quint16 startIndex = qFromBigEndian<quint16>(idx);

        if (startIndex > unicode)
            return 0;

        idx += segCountX2;
        qint16 idDelta = (qint16)qFromBigEndian<quint16>(idx);
        idx += segCountX2;
        quint16 idRangeoffset_t = (quint16)qFromBigEndian<quint16>(idx);

        quint16 glyphIndex;
        if (idRangeoffset_t) {
            quint16 id = qFromBigEndian<quint16>(idRangeoffset_t + 2*(unicode - startIndex) + idx);
            if (id)
                glyphIndex = (idDelta + id) % 0x10000;
            else
                glyphIndex = 0;
        } else {
            glyphIndex = (idDelta + unicode) % 0x10000;
        }
        return glyphIndex;
    } else if (format == 6) {
        quint16 tableSize = qFromBigEndian<quint16>(cmap + 2);

        quint16 firstCode6 = qFromBigEndian<quint16>(cmap + 6);
        if (unicode < firstCode6)
            return 0;

        quint16 entryCount6 = qFromBigEndian<quint16>(cmap + 8);
        if (entryCount6 * 2 + 10 > tableSize)
            return 0;

        quint16 sentinel6 = firstCode6 + entryCount6;
        if (unicode >= sentinel6)
            return 0;

        quint16 entryIndex6 = unicode - firstCode6;
        return qFromBigEndian<quint16>(cmap + 10 + (entryIndex6 * 2));
    } else if (format == 12) {
        quint32 nGroups = qFromBigEndian<quint32>(cmap + 12);

        cmap += 16; // move to start of groups

        int left = 0, right = nGroups - 1;
        while (left <= right) {
            int middle = left + ( ( right - left ) >> 1 );

            quint32 startCharCode = qFromBigEndian<quint32>(cmap + 12*middle);
            if(unicode < startCharCode)
                right = middle - 1;
            else {
                quint32 endCharCode = qFromBigEndian<quint32>(cmap + 12*middle + 4);
                if(unicode <= endCharCode)
                    return qFromBigEndian<quint32>(cmap + 12*middle + 8) + unicode - startCharCode;
                left = middle + 1;
            }
        }
    } else {
        qDebug("cmap table of format %d not implemented", format);
    }

    return 0;
}

Q_GLOBAL_STATIC_WITH_INITIALIZER(QVector<QRgb>, qt_grayPalette, {
    x->resize(256);
    QRgb *it = x->data();
    for (int i = 0; i < x->size(); ++i, ++it)
        *it = 0xff000000 | i | (i<<8) | (i<<16);
})

const QVector<QRgb> &QFontEngine::grayPalette()
{
    return *qt_grayPalette();
}

// ------------------------------------------------------------------
// The box font engine
// ------------------------------------------------------------------

QFontEngineBox::QFontEngineBox(int size)
    : _size(size)
{
    cache_cost = sizeof(QFontEngineBox);
}

QFontEngineBox::~QFontEngineBox()
{
}

bool QFontEngineBox::stringToCMap(const QChar *, int len, QGlyphLayout *glyphs, int *nglyphs, QTextEngine::ShaperFlags) const
{
    if (*nglyphs < len) {
        *nglyphs = len;
        return false;
    }

    for (int i = 0; i < len; i++) {
        glyphs->glyphs[i] = 0;
        glyphs->advances_x[i] = _size;
        glyphs->advances_y[i] = 0;
    }

    *nglyphs = len;
    glyphs->numGlyphs = len;
    return true;
}

void QFontEngineBox::recalcAdvances(QGlyphLayout *glyphs, QTextEngine::ShaperFlags) const
{
    for (int i = 0; i < glyphs->numGlyphs; i++) {
        glyphs->advances_x[i] = _size;
        glyphs->advances_y[i] = 0;
    }
}

void QFontEngineBox::addOutlineToPath(qreal x, qreal y, const QGlyphLayout &glyphs, QPainterPath *path, QTextItem::RenderFlags flags)
{
    if (!glyphs.numGlyphs)
        return;

    QVarLengthArray<QFixedPoint> positions;
    QVarLengthArray<glyph_t> positioned_glyphs;
    QTransform matrix = QTransform::fromTranslate(x, y - _size);
    getGlyphPositions(glyphs, matrix, flags, positioned_glyphs, positions);

    QSize s(_size - 3, _size - 3);
    for (int k = 0; k < positions.size(); k++)
        path->addRect(QRectF(positions[k].toPointF(), s));
}

glyph_metrics_t QFontEngineBox::boundingBox(const QGlyphLayout &glyphs)
{
    glyph_metrics_t overall;
    overall.width = _size*glyphs.numGlyphs;
    overall.height = _size;
    overall.xoff = overall.width;
    return overall;
}

#if defined(Q_WS_QWS)
void QFontEngineBox::draw(QPaintEngine *p, qreal x, qreal y, const QTextItemInt &ti)
{
    if (!ti.glyphs.numGlyphs)
        return;

    // any fixes here should probably also be done in QPaintEnginePrivate::drawBoxTextItem
    QSize s(_size - 3, _size - 3);

    QVarLengthArray<QFixedPoint> positions;
    QVarLengthArray<glyph_t> glyphs;
    QTransform matrix = QTransform::fromTranslate(x, y - _size);
    ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);
    if (glyphs.size() == 0)
        return;


    QPainter *painter = p->painter();
    painter->save();
    painter->setBrush(Qt::NoBrush);
    QPen pen = painter->pen();
    pen.setWidthF(lineThickness().toReal());
    painter->setPen(pen);
    for (int k = 0; k < positions.size(); k++)
        painter->drawRect(QRectF(positions[k].toPointF(), s));
    painter->restore();
}
#endif

glyph_metrics_t QFontEngineBox::boundingBox(glyph_t)
{
    return glyph_metrics_t(0, -_size, _size, _size, _size, 0);
}



QFixed QFontEngineBox::ascent() const
{
    return _size;
}

QFixed QFontEngineBox::descent() const
{
    return 0;
}

QFixed QFontEngineBox::leading() const
{
    QFixed l = _size * QFixed::fromReal(qreal(0.15));
    return l.ceil();
}

qreal QFontEngineBox::maxCharWidth() const
{
    return _size;
}

#ifdef Q_WS_X11
int QFontEngineBox::cmap() const
{
    return -1;
}
#endif

const char *QFontEngineBox::name() const
{
    return "null";
}

bool QFontEngineBox::canRender(const QChar *, int)
{
    return true;
}

QFontEngine::Type QFontEngineBox::type() const
{
    return Box;
}

QImage QFontEngineBox::alphaMapForGlyph(glyph_t)
{
    QImage image(_size, _size, QImage::Format_Indexed8);
    QVector<QRgb> colors(256);
    for (int i=0; i<256; ++i)
        colors[i] = qRgba(0, 0, 0, i);
    image.setColorTable(colors);
    image.fill(0);

    // can't use qpainter for index8; so use setPixel to draw our rectangle.
    for (int i=2; i <= _size-3; ++i) {
        image.setPixel(i, 2, 255);
        image.setPixel(i, _size-3, 255);
        image.setPixel(2, i, 255);
        image.setPixel(_size-3, i, 255);
    }
    return image;
}

// ------------------------------------------------------------------
// Multi engine
// ------------------------------------------------------------------

static inline uchar highByte(glyph_t glyph)
{ return glyph >> 24; }

// strip high byte from glyph
static inline glyph_t stripped(glyph_t glyph)
{ return glyph & 0x00ffffff; }

QFontEngineMulti::QFontEngineMulti(int engineCount)
{
    engines.fill(0, engineCount);
    cache_cost = 0;
}

QFontEngineMulti::~QFontEngineMulti()
{
    for (int i = 0; i < engines.size(); ++i) {
        QFontEngine *fontEngine = engines.at(i);
        if (fontEngine) {
            fontEngine->ref.deref();
            if (fontEngine->cache_count == 0 && fontEngine->ref == 0)
                delete fontEngine;
        }
    }
}

bool QFontEngineMulti::stringToCMap(const QChar *str, int len,
                                    QGlyphLayout *glyphs, int *nglyphs,
                                    QTextEngine::ShaperFlags flags) const
{
    int ng = *nglyphs;
    if (!engine(0)->stringToCMap(str, len, glyphs, &ng, flags))
        return false;

    int glyph_pos = 0;
    for (int i = 0; i < len; ++i) {
        bool surrogate = (str[i].unicode() >= 0xd800 && str[i].unicode() < 0xdc00 && i < len-1
                          && str[i+1].unicode() >= 0xdc00 && str[i+1].unicode() < 0xe000);

        if (glyphs->glyphs[glyph_pos] == 0 && str[i].category() != QChar::Separator_Line) {
            QGlyphLayoutInstance tmp = glyphs->instance(glyph_pos);
            for (int x = 1; x < engines.size(); ++x) {
                QFontEngine *engine = engines.at(x);
                if (!engine) {
                    const_cast<QFontEngineMulti *>(this)->loadEngine(x);
                    engine = engines.at(x);
                }
                Q_ASSERT(engine != 0);
                if (engine->type() == Box)
                    continue;
                glyphs->advances_x[glyph_pos] = glyphs->advances_y[glyph_pos] = 0;
                glyphs->offsets[glyph_pos] = QFixedPoint();
                int num = 2;
                QGlyphLayout offs = glyphs->mid(glyph_pos, num);
                engine->stringToCMap(str + i, surrogate ? 2 : 1, &offs, &num, flags);
                Q_ASSERT(num == 1); // surrogates only give 1 glyph
                if (glyphs->glyphs[glyph_pos]) {
                    // set the high byte to indicate which engine the glyph came from
                    glyphs->glyphs[glyph_pos] |= (x << 24);
                    break;
                }
            }
            // ensure we use metrics from the 1st font when we use the fallback image.
            if (!glyphs->glyphs[glyph_pos]) {
                glyphs->setInstance(glyph_pos, tmp);
            }
        }
        if (surrogate)
            ++i;
        ++glyph_pos;
    }

    *nglyphs = ng;
    glyphs->numGlyphs = ng;
    return true;
}

glyph_metrics_t QFontEngineMulti::boundingBox(const QGlyphLayout &glyphs)
{
    if (glyphs.numGlyphs <= 0)
        return glyph_metrics_t();

    glyph_metrics_t overall;

    int which = highByte(glyphs.glyphs[0]);
    int start = 0;
    int end, i;
    for (end = 0; end < glyphs.numGlyphs; ++end) {
        const int e = highByte(glyphs.glyphs[end]);
        if (e == which)
            continue;

        // set the high byte to zero
        for (i = start; i < end; ++i)
            glyphs.glyphs[i] = stripped(glyphs.glyphs[i]);

        // merge the bounding box for this run
        const glyph_metrics_t gm = engine(which)->boundingBox(glyphs.mid(start, end - start));

        overall.x = qMin(overall.x, gm.x);
        overall.y = qMin(overall.y, gm.y);
        overall.width = overall.xoff + gm.width;
        overall.height = qMax(overall.height + overall.y, gm.height + gm.y) -
                         qMin(overall.y, gm.y);
        overall.xoff += gm.xoff;
        overall.yoff += gm.yoff;

        // reset the high byte for all glyphs
        const int hi = which << 24;
        for (i = start; i < end; ++i)
            glyphs.glyphs[i] = hi | glyphs.glyphs[i];

        // change engine
        start = end;
        which = e;
    }

    // set the high byte to zero
    for (i = start; i < end; ++i)
        glyphs.glyphs[i] = stripped(glyphs.glyphs[i]);

    // merge the bounding box for this run
    const glyph_metrics_t gm = engine(which)->boundingBox(glyphs.mid(start, end - start));

    overall.x = qMin(overall.x, gm.x);
    overall.y = qMin(overall.y, gm.y);
    overall.width = overall.xoff + gm.width;
    overall.height = qMax(overall.height + overall.y, gm.height + gm.y) -
                     qMin(overall.y, gm.y);
    overall.xoff += gm.xoff;
    overall.yoff += gm.yoff;

    // reset the high byte for all glyphs
    const int hi = which << 24;
    for (i = start; i < end; ++i)
        glyphs.glyphs[i] = hi | glyphs.glyphs[i];

    return overall;
}

void QFontEngineMulti::addOutlineToPath(qreal x, qreal y, const QGlyphLayout &glyphs,
                                        QPainterPath *path, QTextItem::RenderFlags flags)
{
    if (glyphs.numGlyphs <= 0)
        return;

    int which = highByte(glyphs.glyphs[0]);
    int start = 0;
    int end, i;
    if (flags & QTextItem::RightToLeft) {
        for (int gl = 0; gl < glyphs.numGlyphs; gl++) {
            x += glyphs.advances_x[gl].toReal();
            y += glyphs.advances_y[gl].toReal();
        }
    }
    for (end = 0; end < glyphs.numGlyphs; ++end) {
        const int e = highByte(glyphs.glyphs[end]);
        if (e == which)
            continue;

        if (flags & QTextItem::RightToLeft) {
            for (i = start; i < end; ++i) {
                x -= glyphs.advances_x[i].toReal();
                y -= glyphs.advances_y[i].toReal();
            }
        }

        // set the high byte to zero
        for (i = start; i < end; ++i)
            glyphs.glyphs[i] = stripped(glyphs.glyphs[i]);
        engine(which)->addOutlineToPath(x, y, glyphs.mid(start, end - start), path, flags);
        // reset the high byte for all glyphs and update x and y
        const int hi = which << 24;
        for (i = start; i < end; ++i)
            glyphs.glyphs[i] = hi | glyphs.glyphs[i];

        if (!(flags & QTextItem::RightToLeft)) {
            for (i = start; i < end; ++i) {
                x += glyphs.advances_x[i].toReal();
                y += glyphs.advances_y[i].toReal();
            }
        }

        // change engine
        start = end;
        which = e;
    }

    if (flags & QTextItem::RightToLeft) {
        for (i = start; i < end; ++i) {
            x -= glyphs.advances_x[i].toReal();
            y -= glyphs.advances_y[i].toReal();
        }
    }

    // set the high byte to zero
    for (i = start; i < end; ++i)
        glyphs.glyphs[i] = stripped(glyphs.glyphs[i]);

    engine(which)->addOutlineToPath(x, y, glyphs.mid(start, end - start), path, flags);

    // reset the high byte for all glyphs
    const int hi = which << 24;
    for (i = start; i < end; ++i)
        glyphs.glyphs[i] = hi | glyphs.glyphs[i];
}

void QFontEngineMulti::recalcAdvances(QGlyphLayout *glyphs, QTextEngine::ShaperFlags flags) const
{
    if (glyphs->numGlyphs <= 0)
        return;

    int which = highByte(glyphs->glyphs[0]);
    int start = 0;
    int end, i;
    for (end = 0; end < glyphs->numGlyphs; ++end) {
        const int e = highByte(glyphs->glyphs[end]);
        if (e == which)
            continue;

        // set the high byte to zero
        for (i = start; i < end; ++i)
            glyphs->glyphs[i] = stripped(glyphs->glyphs[i]);

        QGlyphLayout offs = glyphs->mid(start, end - start);
        engine(which)->recalcAdvances(&offs, flags);

        // reset the high byte for all glyphs and update x and y
        const int hi = which << 24;
        for (i = start; i < end; ++i)
            glyphs->glyphs[i] = hi | glyphs->glyphs[i];

        // change engine
        start = end;
        which = e;
    }

    // set the high byte to zero
    for (i = start; i < end; ++i)
        glyphs->glyphs[i] = stripped(glyphs->glyphs[i]);

    QGlyphLayout offs = glyphs->mid(start, end - start);
    engine(which)->recalcAdvances(&offs, flags);

    // reset the high byte for all glyphs
    const int hi = which << 24;
    for (i = start; i < end; ++i)
        glyphs->glyphs[i] = hi | glyphs->glyphs[i];
}

void QFontEngineMulti::doKerning(QGlyphLayout *glyphs, QTextEngine::ShaperFlags flags) const
{
    if (glyphs->numGlyphs <= 0)
        return;

    int which = highByte(glyphs->glyphs[0]);
    int start = 0;
    int end, i;
    for (end = 0; end < glyphs->numGlyphs; ++end) {
        const int e = highByte(glyphs->glyphs[end]);
        if (e == which)
            continue;

        // set the high byte to zero
        for (i = start; i < end; ++i)
            glyphs->glyphs[i] = stripped(glyphs->glyphs[i]);

        QGlyphLayout offs = glyphs->mid(start, end - start);
        engine(which)->doKerning(&offs, flags);

        // reset the high byte for all glyphs and update x and y
        const int hi = which << 24;
        for (i = start; i < end; ++i)
            glyphs->glyphs[i] = hi | glyphs->glyphs[i];

        // change engine
        start = end;
        which = e;
    }

    // set the high byte to zero
    for (i = start; i < end; ++i)
        glyphs->glyphs[i] = stripped(glyphs->glyphs[i]);

    QGlyphLayout offs = glyphs->mid(start, end - start);
    engine(which)->doKerning(&offs, flags);

    // reset the high byte for all glyphs
    const int hi = which << 24;
    for (i = start; i < end; ++i)
        glyphs->glyphs[i] = hi | glyphs->glyphs[i];
}

glyph_metrics_t QFontEngineMulti::boundingBox(glyph_t glyph)
{
    const int which = highByte(glyph);
    Q_ASSERT(which < engines.size());
    return engine(which)->boundingBox(stripped(glyph));
}

QFixed QFontEngineMulti::ascent() const
{ return engine(0)->ascent(); }

QFixed QFontEngineMulti::descent() const
{ return engine(0)->descent(); }

QFixed QFontEngineMulti::leading() const
{
    return engine(0)->leading();
}

QFixed QFontEngineMulti::xHeight() const
{
    return engine(0)->xHeight();
}

QFixed QFontEngineMulti::averageCharWidth() const
{
    return engine(0)->averageCharWidth();
}

QFixed QFontEngineMulti::lineThickness() const
{
    return engine(0)->lineThickness();
}

QFixed QFontEngineMulti::underlinePosition() const
{
    return engine(0)->underlinePosition();
}

qreal QFontEngineMulti::maxCharWidth() const
{
    return engine(0)->maxCharWidth();
}

qreal QFontEngineMulti::minLeftBearing() const
{
    return engine(0)->minLeftBearing();
}

qreal QFontEngineMulti::minRightBearing() const
{
    return engine(0)->minRightBearing();
}

bool QFontEngineMulti::canRender(const QChar *string, int len)
{
    if (engine(0)->canRender(string, len))
        return true;

    QVarLengthGlyphLayoutArray glyphs(len);
    int nglyphs = len;
    if (stringToCMap(string, len, &glyphs, &nglyphs, QTextEngine::GlyphIndicesOnly) == false) {
        glyphs.resize(nglyphs);
        stringToCMap(string, len, &glyphs, &nglyphs, QTextEngine::GlyphIndicesOnly);
    }

    bool allExist = true;
    for (int i = 0; i < nglyphs; i++) {
        if (!glyphs.glyphs[i]) {
            allExist = false;
            break;
        }
    }

    return allExist;
}

QImage QFontEngineMulti::alphaMapForGlyph(glyph_t)
{
    Q_ASSERT(false);
    return QImage();
}


QT_END_NAMESPACE