QCustomPlot清除圖形清除不了，需要在qtcreator中設置qcustomWidget窗口背景色才能清除

Qt-QCustomplot畫靜態、動態曲線教程圖解

https://blog.csdn.net/qqwangfan/article/details/93897902

 

如上面加入QCustomplot源文件，在QtCreator中將QWidget提升爲QCustomPlot窗口後，在QCustomPlot上面畫了圖像，出現想清空圖像清空不了的情況。估計是QCustomPlot的一個bug，解決辦法如下：

因QCustomPlot默認背景色爲白色，如果代碼修改了QCustomPlot的背景色，則必須也同時在QtCreator中將QCustomPlotWidget

樣式表設置相應的背景色。見下圖，下面的代碼將窗口樣式表也修改爲透明後，就可以清除圖像了。

//在QCustomPlot上面，鼠標左鍵畫點，右鍵在點上點擊後清除點
// .h文件
#ifndef PLOTCURSE_H
#define PLOTCURSE_H

#include <QWidget>
#include <qlist.h>

namespace Ui {
class PlotCurse;
}



class PlotCurse : public QWidget
{
    Q_OBJECT

public:
    explicit PlotCurse(QWidget *parent = 0);
    ~PlotCurse();

private slots:
    void on_customW_mousePress(QMouseEvent *event);

private:
    void InitGrap();
    void UpdateGrap();
private:
    Ui::PlotCurse *ui;

    QVector<double> m_xVec;
    QVector<double> m_yVec;
};

#endif // PLOTCURSE_H



// .cpp文件
#include <qcursor.h>
#include <qpainter.h>
#include "plotcurse.h"
#include "ui_plotcurse.h"


const int g_pointSize = 8;
PlotCurse::PlotCurse(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::PlotCurse)
{
    ui->setupUi(this);

    InitGrap();
}

PlotCurse::~PlotCurse()
{
    delete ui;
}

void PlotCurse::InitGrap()
{
    QColor TextColor = QColor(255,255,0,90);
    QColor white = QColor(255,255,0);
    int TextWidth = 2;
    ui->customW->xAxis->setLabelColor(white);
    ui->customW->yAxis->setLabelColor(white);
    ui->customW->xAxis->setTickLabelColor(white);
    ui->customW->yAxis->setTickLabelColor(white);
    ui->customW->xAxis->setBasePen(QPen(TextColor,TextWidth));
    ui->customW->yAxis->setBasePen(QPen(TextColor,TextWidth));
    ui->customW->xAxis->setTickPen(QPen(TextColor,TextWidth));
    ui->customW->yAxis->setTickPen(QPen(TextColor,TextWidth));
    ui->customW->xAxis->setSubTickPen(QPen(TextColor,TextWidth));
    ui->customW->yAxis->setSubTickPen(QPen(TextColor,TextWidth));
// 此處修改了默認白色背景色爲透明，必須在QtCreator上也設置對應的customW窗口背景色，
// 後面清除圖像才能成功，否則會一直清除不到！！
    ui->customW->setBackground(Qt::transparent);  

    ui->customW->xAxis->setRange(0,1.0);
    ui->customW->yAxis->setRange(0,1.0);

   // ui->customW->plotLayout()->insertRow(0);
   // ui->customW->plotLayout()->addElement(0,0,new QCPTextElement(ui->customW,"point graph"));
   // ui->customW->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom|QCP::iSelectAxes|QCP::iSelectLegend|QCP::iSelectPlottables);;

}

void PlotCurse::UpdateGrap()
{
    ui->customW->clearGraphs();// 背景色會導致QCustomWidget窗口不會清除圖層。如發現沒有清除，可能是背景色問題

    ui->customW->addGraph();
    ui->customW->graph(0)->setPen(QPen(Qt::green));
    //ui->customW->graph(0)->setBrush(Qt::green);
    ui->customW->graph(0)->setLineStyle(QCPGraph::lsNone);
    ui->customW->graph(0)->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle,g_pointSize));//set points size
    ui->customW->graph(0)->addData(m_xVec,m_yVec);
    qDebug("xvec:%d, yvec:%d",m_xVec.size(),m_yVec.size());

   /* ui->customW->addGraph();
    ui->customW->graph(1)->setPen(QPen(Qt::white));
    ui->customW->graph(1)->addData(m_xVec,m_yVec,false);*/

    ui->customW->repaint();
    ui->customW->replot();

}


void PlotCurse::on_customW_mousePress(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton)
    {
        double px = event->x();
        double py = event->y();

        double cx = ui->customW->xAxis->pixelToCoord(px); // 將像素值轉爲座標值
        double cy = ui->customW->yAxis->pixelToCoord(py);
        m_xVec.push_back(cx);
        m_yVec.push_back(cy);
       // m_pointLs.push_back(QPointF(cx,cy));
        qDebug("px:%.2f,py:%.2f, cx:%.2f,cy:%.2f",px,py,cx,cy);

    }

    if(event->button() == Qt::RightButton)
    {
        double x = event->x(); // 此處取得的是像素值 //ui->customW->xAxis->pixelToCoord(event->x());
        double y = event->y();//ui->customW->yAxis->pixelToCoord(event->y());
        qDebug("x:%.2f,y:%.2f",x,y);

        for(int i=m_xVec.size()-1; i>=0; i--) // 從後往前刪
        {
            double cx = m_xVec[i];
            double cy = m_yVec[i];
            double px = ui->customW->xAxis->coordToPixel(cx); // 將座標轉回像素，方便與像素比較
            double py = ui->customW->yAxis->coordToPixel(cy);
            if(x< px + g_pointSize &&    // 判斷鼠標右鍵是否在 以點爲圓心，g_pointSize爲半徑的圓內
               x > px - g_pointSize &&
               y < py + g_pointSize &&
               y > py - g_pointSize)
            {
                m_xVec.remove(i);
                m_yVec.remove(i);

            }
        }
    }
    UpdateGrap();
}