QImage，Mat ，QByteArray转换

QImage 转为Mat

void QImageToMat(QImage image, cv::Mat& mat)
{
    switch (image.format())
    {
    case QImage::Format_ARGB32:
    case QImage::Format_RGB32:
    case QImage::Format_ARGB32_Premultiplied:
    {
        mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());
        std::vector<cv::Mat>channels;
        split(mat, channels);
        channels.pop_back();
        cv::merge(channels, mat);
    }

    break;
    case QImage::Format_RGB888:
        mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());
        //cv::cvtColor(mat, mat, CV_BGR2RGB);
        break;
    case QImage::Format_Indexed8:
        mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());
        break;
        
    }
}

void QByteArrayToMat(QByteArray array, cv::Mat& mat)
{
    QBuffer buffer(&array);
    buffer.open(QIODevice::ReadOnly);
    QImageReader reader(&buffer, "JPG");
    QImage image = reader.read();

    switch (image.format())
    {
    case QImage::Format_ARGB32:
    case QImage::Format_RGB32:
    case QImage::Format_ARGB32_Premultiplied:
    {
        mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());
        std::vector<cv::Mat>channels;
        split(mat, channels);
        channels.pop_back();
        cv::merge(channels, mat);
    }
    break;
    case QImage::Format_RGB888:
        mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());
        //cv::cvtColor(mat, mat, CV_BGR2RGB);
        break;
    case QImage::Format_Indexed8:
        mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());
        break;
        
    }
}

QByteArray转为Mat

void QByteArrayToMat(QByteArray array, cv::Mat& mat)
{
    QBuffer buffer(&array);
    buffer.open(QIODevice::ReadOnly);
    QImageReader reader(&buffer, "JPG");
    QImage image = reader.read();

    switch (image.format())
    {
    case QImage::Format_ARGB32:
    case QImage::Format_RGB32:
    case QImage::Format_ARGB32_Premultiplied:
    {
        mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());
        std::vector<cv::Mat>channels;
        split(mat, channels);
        channels.pop_back();
        cv::merge(channels, mat);
    }
    break;
    case QImage::Format_RGB888:
        mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());
        //cv::cvtColor(mat, mat, CV_BGR2RGB);
        break;
    case QImage::Format_Indexed8:
        mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());
        break;
        
    }
}