03 Qt中是事件处理_哔哩哔哩_bilibili

 

1，新加mylabel文件，并 修改mylabe的基类QLabel

2 label提升为类

3，鼠标事件

myLabel.h

#ifndef MYLABEL_H
#define MYLABEL_H


#include <QLabel>

class myLabel : public QLabel
{
    Q_OBJECT
public:
    explicit myLabel(QWidget *parent = nullptr);


    void enterEvent(QEvent *);
    void leaveEvent(QEvent *);
    void mouseMoveEvent(QMouseEvent *ev);
    void mouseReleaseEvent(QMouseEvent *ev) override;
    void mousePressEvent(QMouseEvent *ev) override;
    void keyPressEvent(QKeyEvent *ev) override;

signals:

};

#endif // MYLABEL_H

myLabel.cpp

#include "mylabel.h"
#include <QDebug>
#include <QMouseEvent>

myLabel::myLabel(QWidget *parent) : QLabel(parent)
{
//    设置鼠标追踪
    this->setMouseTracking(true);
}


void myLabel::enterEvent(QEvent *)
{
    qDebug() << "enter------" << endl;

}


void myLabel::mouseMoveEvent(QMouseEvent *ev)
{
     if (ev->button() == Qt::RightButton)  // 瞬间的状态不能这样判断
//     if (ev->buttons() & Qt::LeftButton)
//    {
//        QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
//        qDebug() << "mouseMoveEvent---RightButton---" << str <<  endl;
//    }

//    设置鼠标追踪为true的情况下，只要一进区域就会获得坐标
      QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
      qDebug() << "mouseMoveEvent---RightButton---" << str <<  endl;
}
void myLabel::mouseReleaseEvent(QMouseEvent *ev)
{
     QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
     qDebug() << "mouseReleaseEvent------" << str <<  endl;
}
void myLabel::mousePressEvent(QMouseEvent *ev){

    if(ev->button() == Qt::RightButton)
    {
        QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
        qDebug() << "mousePressEvent---LeftButton---" << str <<  endl;
    }
    else if (ev->button() == Qt:: LeftButton)
    {
        QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
        qDebug() << "mousePressEvent---LeftButton---" << str <<  endl;

        QString strs = QString("坐标为x= %1, y = %2").arg(ev->globalX()).arg(ev->globalY());
        qDebug() << "mousePressEvent--globalX--LeftButton--globalY-" << strs <<  endl;


    }
//    else if (ev->button() == Qt::MidButton)
//    {
//        QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
//        qDebug() << "mousePressEvent---MidButton---" << str <<  endl;
//    }



    else if (ev->button() == Qt::MiddleButton)
    {
        QString str = QString("坐标为x= %1, y = %2").arg(ev->x()).arg(ev->y());
        qDebug() << "mousePressEvent---MidButton---" << str <<  endl;
    }

}

void myLabel::keyPressEvent(QKeyEvent *ev)
{
//   qDebug() <<  << endl;
}





void myLabel::leaveEvent(QEvent *){

     qDebug() << "Leave------" << endl;


}