C++ QT5中cv::Mat转化为QImage

/// 转化Mat为QImage
QImage scan::Mat2QImage(const cv::Mat& mat)
{
    QImage img;
    int chana = mat.channels();
    /// 依据通道数不同，改变不同的装换方式
    if (chana > 1) {
        //img = QImage(static_cast<uchar *>(mat.data),mat.cols,mat.rows,QImage::Format_RGB888);
        cv::cvtColor(mat, mat, CV_BGR2RGB);
        /// construct the QImage using the data of the mat, while do not copy the data
        img = QImage((const uchar*)(mat.data),
            mat.cols,
            mat.rows,
            mat.step,//TmpMat.cols*TmpMat.channels(),
            QImage::Format_RGB888);
    }
    else if (4 == chana) {
        cv::cvtColor(mat, mat, CV_BGR2RGB);
        /// construct the QImage using the data of the mat, while do not copy the data
        img = QImage((const uchar*)(mat.data),
            mat.cols,
            mat.rows,
            mat.step,//TmpMat.cols*TmpMat.channels(),
            QImage::Format_ARGB32);
    }
    else {
        /// 单通道，灰度图
        img = QImage(mat.cols, mat.rows, QImage::Format_Indexed8);
        uchar* matdata = mat.data;
        for (int row = 0; row < mat.rows; ++row) {
            uchar* rowdata = img.scanLine(row);
            memcpy(rowdata, matdata, mat.cols);
            matdata += mat.cols;
        }

        QVector<QRgb>  colorTable;

        for (int k = 0;k < 256;++k)
        {
            colorTable.push_back(qRgb(k, k, k));
        }

        img.setColorTable(colorTable);
    }
    img.bits();
    return img;
}