運行截圖如下：

邏輯很簡單，下面直接上代碼。

widget.h

#ifndef WIDGET_H #define WIDGET_H#include <QWidget>#include "qcustomplot.h"namespace Ui { class Widget; }class Widget : public QWidget {Q_OBJECTpublic:explicit Widget(QWidget *parent = 0);~Widget();public slots:void myMousePressEvent(QMouseEvent *event);void myMouseReleaseEvent(QMouseEvent *event);void myMouseMoveEvent(QMouseEvent *event);private:Ui::Widget *ui;QString m_myName;QVector<double> x,y;int m_point; };#endif // WIDGET_H

widget.cpp

#include "widget.h" #include "ui_widget.h"#include <QDebug> #include <math.h> #include <QTime>Widget::Widget(QWidget *parent) :QWidget(parent),x(100),y(100),m_point(-1),ui(new Ui::Widget) {ui->setupUi(this);m_myName="我的折線圖";for(int i=0;i<100;i++){x[i]=i;y[i]=1;}this->setWindowTitle("CSDN IT1995");ui->plot->addGraph();ui->plot->graph()->setData(x,y);ui->plot->graph()->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle, QPen(Qt::black, 1.5), QBrush(Qt::white), 9));ui->plot->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom);connect(ui->plot,SIGNAL(mousePress(QMouseEvent*)),this,SLOT(myMousePressEvent(QMouseEvent*)));connect(ui->plot,SIGNAL(mouseRelease(QMouseEvent*)),this,SLOT(myMouseReleaseEvent(QMouseEvent*)));connect(ui->plot,SIGNAL(mouseMove(QMouseEvent*)),this,SLOT(myMouseMoveEvent(QMouseEvent*))); }Widget::~Widget() {delete ui; }void Widget::myMousePressEvent(QMouseEvent *event) {qDebug()<<"mousePressEvent";int x_pos = event->pos().x();int y_pos = event->pos().y();float x_val = ui->plot->xAxis->pixelToCoord(x_pos);float y_val = ui->plot->yAxis->pixelToCoord(y_pos);for(int i=0;i<100;i++){if(fabs(x_val-x.at(i))<0.3&&fabs(y_val-y.at(i))<0.3){qDebug()<<"現在選擇的是第"<<i<<"個點";m_point=i;break;}}}void Widget::myMouseReleaseEvent(QMouseEvent *event) {ui->plot->setInteractions(QCP::iRangeDrag|QCP::iRangeZoom);m_point=-1; }void Widget::myMouseMoveEvent(QMouseEvent *event) {if(m_point==-1)return;ui->plot->setInteractions(QCP::iRangeZoom);int x_pos = event->pos().x();int y_pos = event->pos().y();float x_val = ui->plot->xAxis->pixelToCoord(x_pos);float y_val = ui->plot->yAxis->pixelToCoord(y_pos);x[m_point]=x_val;y[m_point]=y_val;ui->plot->graph()->setData(x, y);ui->plot->replot();}

main.cpp

#include "widget.h" #include <QApplication>int main(int argc, char *argv[]) {QApplication a(argc, argv);Widget w;w.show();return a.exec(); }

總結

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