Qt中在QLabel上画点，重写QLabel类

QT中label进行绘图

1.首先新建一个类，让这个类继承QLabel
2.在类中对鼠标点击事件及绘图事件进行重写
3.然后在UI框架下添加label控件，
4.右键label控件，添加重写的类，将其提升为刚刚写好的类

mylabel.h

#ifndef MYLABEL_H
#define MYLABEL_H#include <QObject>
#include <QLabel>
#include <QMouseEvent>
#include <QPainter>
#include <QPen>
#include <QPoint>class MyLabel : public QLabel{Q_OBJECTpublic:int labelWidth;int labelHeight;struct pointCoord{int x;int y;};std::vector<pointCoord> coordList;bool paintEnable = true;public:explicit MyLabel(QWidget *parent = 0);void enabelPaint(bool);void mousePressEvent(QMouseEvent *event);void paintEvent(QPaintEvent *event);//    void mouseReleaseEvent(QMouseEvent *event);//    void mouseMoveEvent(QMouseEvent *event);signals:void updatePoint(int x, int y, int labelWidth, int labelHeight);};#endif // MYLABEL_H

mylabel.cpp

#include "mylabel.h"#include <QMessageBox>#include <QString>#include <QDebug>MyLabel::MyLabel(QWidget *parent) : QLabel(parent){
;
}void MyLabel::enabelPaint(bool enable){if (enable){paintEnable = true;} else {paintEnable = false;}}void MyLabel::mousePressEvent(QMouseEvent *event){if (paintEnable){int x = event->position().x();int y = event->position().y();pointCoord coord;coord.x = x;coord.y = y;coordList.push_back(coord);labelWidth = this->width();labelHeight = this->height();emit updatePoint(x, y, labelWidth, labelHeight);update();}}void MyLabel::paintEvent(QPaintEvent *event){QLabel::paintEvent(event);QPainter painter(this);QPen pen;       //设置画笔，颜色、宽度pen.setColor(Qt::red);pen.setWidth(5);painter.setPen(pen);for (auto coord:coordList){painter.drawPoint(coord.x, coord.y);}}