KisPaintDeviceSP KisShearVisitor::yShear(KisPaintDeviceSP src, qreal shearY, KoUpdater *progress)
{
    int start = progress->progress();

    KisPaintDeviceSP dst = KisPaintDeviceSP(new KisPaintDevice(src->colorSpace()));
    KoMixColorsOp * mixOp = src->colorSpace()->mixColorsOp();

    dst->setX(src->x());
    dst->setY(src->y());

    QRect r = src->exactBounds();

    qreal displacement;
    qint32 displacementInt;
    qreal weight;

    for (qint32 x = r.left(); x <= r.right(); x++) {

        //calculate displacement
        displacement = x * shearY;

        displacementInt = (qint32)(floor(displacement));
        weight = displacement - displacementInt;

        qint16 pixelWeights[2];

        pixelWeights[0] = static_cast<quint8>(weight * 255 + 0.5);
        pixelWeights[1] = 255 - pixelWeights[0];

        KisVLineConstIteratorPixel srcIt = src->createVLineIterator(x, r.y(), r.height() + 1);
        KisVLineIteratorPixel leftSrcIt = src->createVLineIterator(x, r.y() - 1, r.height() + 1);
        KisVLineIteratorPixel dstIt = dst->createVLineIterator(x, r.y() + displacementInt, r.height() + 1);

        while (!srcIt.isDone()) {

            const quint8 *pixelPtrs[2];

            pixelPtrs[0] = leftSrcIt.rawData();
            pixelPtrs[1] = srcIt.rawData();

            mixOp->mixColors(pixelPtrs, pixelWeights, 2, dstIt.rawData());

            ++srcIt;
            ++leftSrcIt;
            ++dstIt;
        }
        progress->setProgress(start + x);
    }
    return dst;
}