QCustomPlot鼠标点选折线上的

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     不多说直接上效果图：

图1：[attachment=15215]

 

图2：

 

实现思路参考qt Charts下例子：scatterinteractions。

void Dialog::initCustomplot(){    

     ///鼠标点击的有效距离，越小越准确。    

    ui->customplot->setSelectionTolerance(5);   

     ///设置用户交互

     ui->customplot->setInteractions(QCP::iRangeDrag     

                                                      | QCP::iRangeZoom                                     

                                                      | QCP::iMultiSelect                                     

                                                      | QCP::iSelectOther                                     

                                                      | QCP::iSelectItems                                     

                                                    /*| QCP::iSelectPlottables*/                                    

                                                      );

    ///set X Axis    

    ui->customplot->xAxis->setRange(0, 100);

    ///set Y Axis    

    ui->customplot->yAxis->setRange(-50, 50);    

    ui->customplot->yAxis->setAutoTickCount(2); ///设定自动显示的标签个数

    ///设置自动步长，方便区间控制    

    ui->customplot->yAxis->setAutoTickStep(false);    

    ui->customplot->yAxis->setTickStep(50.0);

    ///释放鼠标处理    

    connect(ui->customplot, SIGNAL(mouseRelease(QMouseEvent*)),  

               this, SLOT(slot_mouseRelese(QMouseEvent*)));
    ///添加文本标签

    m_pMousValue = new QCPItemText(ui->customplot);    

    ui->customplot->addItem(m_pMousValue);    

    m_pMousValue->setPositionAlignment(Qt::AlignTop|Qt::AlignHCenter);    

    m_pMousValue->position->setType(QCPItemPosition::ptAxisRectRatio);    

    m_pMousValue->position->setCoords(0.5, 0); // place position at center/top of axis rect    

    m_pMousValue->setText("Text Item Value");    m_pMousValue->setFont(QFont(font().family(), 16)); // make font a bit larger    

    m_pMousValue->setPen(QPen(Qt::red)); // show black border around text
        ///具体思路如下：两条折线图，一条实线的折线图，一条散点的折线图    

        ui->customplot->addGraph();   

         ui->customplot->graph(0)->setPen(QPen(Qt::red, 2));    

         ui->customplot->graph(0)->setSelectedPen(QPen(Qt::blue, 2));    

          ui->customplot->graph(0)->setLineStyle(QCPGraph::lsLine);    ///步骤2 新建一条散点图    

          

          QCPScatterStyle myScatter;    

          myScatter.setShape(QCPScatterStyle::ssDisc);    

          myScatter.setPen(QPen(Qt::blue));    

          myScatter.setBrush(QBrush(Qt::white));    

          myScatter.setSize(5);    

          ui->customplot->addGraph();    

          ui->customplot->graph(1)->setLineStyle(QCPGraph::lsNone);    

          ui->customplot->graph(1)->setScatterStyle(myScatter);

    QVector<double> dVctValue;    

     QVector<double> dVctKeys;    

     int dequlNum = qrand()%10*50;    

     if(dequlNum == 0){        dequlNum = 50;    }   

     int n = 50;    

     for(int i = 0; i < n; i++)    {

        dVctValue.append(qrand()%dequlNum);        

        dVctKeys.append(i*2);   

     }    

     ui->customplot->graph(0)->clearData();    

     ui->customplot->graph(0)->addData(dVctKeys, dVctValue);    

     ui->customplot->graph(0)->rescaleValueAxis();

}

 

void Dialog::slot_mouseRelese(QMouseEvent *event){    

    ///排除非左鼠标键    

    if (event->button() != Qt::LeftButton){        return;    }

    

    QPointF ChickedPoint = event->posF();    

     ///排除区间外鼠标点    

    if(!ui->customplot->viewport().contains(event->pos())){        return;    }

    QPointF closest(INT_MAX, INT_MAX);    

     qreal distance(INT_MAX);

     QCPDataMap* m_graphDataMap1 = ui->customplot->graph(0)->data();    

     QCPDataMapIterator itr(*m_graphDataMap1);     

     while(itr.hasNext()){        

           itr.next();

          qreal dPosX = ui->customplot->xAxis->coordToPixel(itr.key());    

          qreal dPosY = ui->customplot->yAxis->coordToPixel(itr.value().value); 

           QPointF currentPoint(dPosX, dPosY);

           qreal currentDistance = qSqrt((currentPoint.x()-ChickedPoint.x()) * (currentPoint.x()-ChickedPoint.x()) +  

                             (currentPoint.y()-ChickedPoint.y()) * (currentPoint.y()-ChickedPoint.y()));

        if(currentDistance < distance){ 

           distance = currentDistance; 

           closest  = currentPoint;

        } 

   }    

     ///可放开调试信息，观察鼠标点击到折线的距离。

    ///qDebug()<<"------pos-------"<<distance;    

    if(distance > ui->customplot->selectionTolerance()){        return;    }

     double dKey = ui->customplot->xAxis->pixelToCoord(closest.x()); 

     double dValue = ui->customplot->yAxis->pixelToCoord(closest.y());

    ///添加到散点折线图中

    ui->customplot->graph(1)->removeData(dKey);

    ui->customplot->graph(1)->addData(dKey, dValue);

    m_pMousValue->setText(QString("X: %1, Y: %2").arg(dKey).arg(dValue));

}

 本帖子原创作者：清澈的眼神@xiaoniede。转载注明原创作者地址。欢迎大家一起讨论技术问题。学习交流QQ群：498278174