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：

 1 void SpectralProfileDialog::AddPressSlot()
 2 {
 3     //setModal(0);
 4     HyperProcess *ptr = (HyperProcess*)parentWidget();
 5     curFileName = ptr->curFileName;
 6     currentRow = ptr->curRow;
 7     currentCol = ptr->curCol;
 8 
 9     if(curFileName == "")
10     {
11         QMessageBox::information(this,"Message Error","Current Scene IS NULL!");
12         return;
13     }
14 
15     if(currentCol == -1 || currentRow == -1)
16     {
17         QMessageBox::information(this,"Message Error","please Select A Pixel");
18         return;
19     }
20 
21     cv::Mat curImg = GDALOpenCV::GDAL2Mat(curFileName);
22     if(currentCol > curImg.cols || currentRow > curImg.rows)
23         return;
24 
25     int count  = curImg.channels();
26 
27     std::vector<cv::Mat> curImgMat(count);
28     cv::split(curImg,curImgMat);
29 
30     QVector<QPointF> pixSpectralData(count);
31     double tmpMaxValue;
32     double tmpMinValue;
33     double maxValue = 0;
34     for(int c = 0;c<count;c++)
35     {
36         cv::minMaxIdx(curImgMat[c],&tmpMinValue,&tmpMaxValue);
37         if(maxValue < tmpMaxValue)
38             maxValue = tmpMaxValue;
39         pixSpectralData[c].setX(curImgMat[c].at<float>(currentCol,currentRow));
40         pixSpectralData[c].setY(c+1);
41     }
42 
43     float x_scale = 1.0*(ui->spectralGraphicsView->height()-1)/maxValue;
44     float y_scale = 1.0*(ui->spectralGraphicsView->width()-1)/count;
45 
46     QPen pen;
47     pen.setWidth(2);
48     QColor qc=QColor::fromHsl(rand()%360,rand()%256,rand()%200);
49     pen.setColor(QColor(qc.red(),qc.green(),qc.blue()));
50 
51     for(int c = 0;c<curImg.channels()-1;c++)
52     {
53         myScene->addLine(pixSpectralData[c].y()*y_scale,-1.0*(pixSpectralData[c].x()*x_scale),
54                          pixSpectralData[c+1].y()*y_scale,-1.0*(pixSpectralData[c+1].x()*x_scale),pen);
55     }
56     ui->spectralGraphicsView->setScene(myScene);
57 }

三、效果图