Qt5 QGraphicsView -- 显示图片

废话不多说，在界面拖拽一个graphicsView,代码片如下：

1. 头文件中声明QGraphicsScene

#include <QtGui/qpixmap.h>

QGraphicsScene* originalScene;
originalScene = new QGraphicsScene(this);

2. 控件关联

ui.graphicsView->setScene(originalScene);

3.显示QImage

scene->clear();

QImage qimage = mat2qim(cvImage);    // cvImage(cv::Mat)
qimage = qimage.scaled(ui.graphicsView->width()-DIFF, ui.graphicsView->height()-DIFF, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

scene->addPixmap(QPixmap::fromImage(qimage));       
ui.graphicsView->show();

4. cv::Mat -> QImage 转换函数

QImage mat2qim(Mat & mat)
{
    cvtColor(mat, mat, COLOR_BGR2RGB);
    QImage qim((const unsigned char*)mat.data, mat.cols, mat.rows, mat.step, 
        QImage::Format_RGB888);
    return qim;
}

5. QImage -> cv::Mat 转换函数

Mat qim2mat(QImage & qim)
{
    Mat mat;
    switch(qim.format()){
        case QImage::Format_RGB888: 
            mat = Mat(qim.height(), qim.width(), 
                CV_8UC3,(void*)qim.constBits(),qim.bytesPerLine());
            break;
        case QImage::Format_ARGB32_Premultiplied:
            mat = Mat(qim.height(), qim.width(), 
                CV_8UC4,(void*)qim.constBits(),qim.bytesPerLine());
            break;
    }
    return mat;
}