4. 绘制光谱曲线QGraphicsView类

一、前言

Qt的QGraphicsView类具有强大的视图功能，与其一起使用的还有QGraphicsScene类和QGraphicsItem类。大体思路就是通过构建场景类，然后向场景对象中增加各种图元，最后利用QGraphicsView类对场景进行显示。

二、绘制光谱曲线

实现功能主要有：

1 传递点击图像行列号，然后绘制曲线，代码如下：

void SpectralProfileDialog::AddPressSlot()
{
    //setModal(0);
    HyperProcess *ptr = (HyperProcess*)parentWidget();
    curFileName = ptr->curFileName;
    currentRow = ptr->curRow;
    currentCol = ptr->curCol;

    if(curFileName == "")
    {
        QMessageBox::information(this,"Message Error","Current Scene IS NULL!");
        return;
    }

    if(currentCol == -1 || currentRow == -1)
    {
        QMessageBox::information(this,"Message Error","please Select A Pixel");
        return;
    }

    cv::Mat curImg = GDALOpenCV::GDAL2Mat(curFileName);
    if(currentCol > curImg.cols || currentRow > curImg.rows)
        return;

    int count  = curImg.channels();

    std::vector<cv::Mat> curImgMat(count);
    cv::split(curImg,curImgMat);

    QVector<QPointF> pixSpectralData(count);
    double tmpMaxValue;
    double tmpMinValue;
    double maxValue = 0;
    for(int c = 0;c<count;c++)
    {
        cv::minMaxIdx(curImgMat[c],&tmpMinValue,&tmpMaxValue);
        if(maxValue < tmpMaxValue)
            maxValue = tmpMaxValue;
        pixSpectralData[c].setX(curImgMat[c].at<float>(currentCol,currentRow));
        pixSpectralData[c].setY(c+1);
    }

    float x_scale = 1.0*(ui->spectralGraphicsView->height()-1)/maxValue;
    float y_scale = 1.0*(ui->spectralGraphicsView->width()-1)/count;

    QPen pen;
    pen.setWidth(2);
    QColor qc=QColor::fromHsl(rand()%360,rand()%256,rand()%200);
    pen.setColor(QColor(qc.red(),qc.green(),qc.blue()));

    for(int c = 0;c<curImg.channels()-1;c++)
    {
        myScene->addLine(pixSpectralData[c].y()*y_scale,-1.0*(pixSpectralData[c].x()*x_scale),
                         pixSpectralData[c+1].y()*y_scale,-1.0*(pixSpectralData[c+1].x()*x_scale),pen);
    }
    ui->spectralGraphicsView->setScene(myScene);
}

三、效果图