Qt事件学习案例

视频链接

https://www.bilibili.com/video/BV18B4y1K7Cs?p=7&spm_id_from=pageDriver&vd_source=fa4ef8f26ae084f9b5f70a5f87e9e41b

Qt5跟着视频做即可，Qt6部分代码需要改动,改动的地方注释有写

素材

百度云

链接：https://pan.baidu.com/s/158jQbAmv0Y3JipAw-tl9ng 
提取码：subw

实现一个类似屏幕保护的效果（具体效果看视频）

代码

butterfly.h文件

#ifndef BUTTERFLY_H
#define BUTTERFLY_H#include <QWidget>class Butterfly : public QWidget
{Q_OBJECT
public:explicit Butterfly(QWidget *parent = nullptr);//封装void fly();//重载fly,处理方法很多，也可以直接加上默认参数，能实现功能就行void fly(int min,int max);signals:protected:void paintEvent(QPaintEvent *ev);void timerEvent(QTimerEvent *ev);void mousePressEvent(QMouseEvent* ev);void mouseMoveEvent(QMouseEvent* ev);void enterEvent(QEvent* ev);private:QPixmap m_pixmap;int m_indexPic = 1;//用于描述图片名字QPoint m_pt;
};#endif // BUTTERFLY_H

butterfly.cpp文件

#include "butterfly.h"
#include <QPaintEvent>
#include <QPainter>
#include <QMouseEvent>
#include <QRandomGenerator>
#include <QApplication>Butterfly::Butterfly(QWidget *parent): QWidget{parent}
{m_pixmap.load(":/1");setFixedSize(m_pixmap.size());//启动定时器startTimer(100);
}void Butterfly::fly()
{fly(10,30);
}void Butterfly::fly(int min, int max)
{m_indexPic++;if (m_indexPic > 2){m_indexPic = 1;}//构造图片路径QString name = QString(":/%1").arg(m_indexPic);m_pixmap.load(name);update();//蝴蝶移动的步长10 -29的随机数int stepX = QRandomGenerator::global()->bounded(min,max);int stepY = QRandomGenerator::global()->bounded(min,max);int curX = this->geometry().topLeft().x() + stepX;int curY = this->geometry().topLeft().y() + stepY;//Qt6没有视频中的方法，要换成这样写QRect screenRect=QGuiApplication::primaryScreen()->geometry();if (curX >= screenRect.right()){curX = screenRect.left();}if (curY >= screenRect.bottom()){curY = screenRect.top();}move(curX,curY);
}void Butterfly::paintEvent(QPaintEvent *ev)
{QPainter painter(this);painter.drawPixmap(rect(),m_pixmap);
}void Butterfly::timerEvent(QTimerEvent *ev)
{fly();
}void Butterfly::mousePressEvent(QMouseEvent *ev)
{if (ev->button() == Qt::LeftButton){m_pt = ev->globalPos() - this->geometry().topLeft();}
}void Butterfly::mouseMoveEvent(QMouseEvent *ev)
{/*ev>buttons 返回值是一些二进制值，每个二进制值对应鼠标的一个键位，* 如果两个二进制按位与返回1，则是同一个键位，否则不是*/if (ev->buttons() & Qt::LeftButton){this->move(ev->globalPos() - m_pt);}
}void Butterfly::enterEvent(QEvent *ev)
{fly(-200,200);
}

运行结果

部分代码解释：

QMouseEvent::buttons返回值是各种二进制数，每个二进制数对应的就是一个鼠标键位。如果两个二进制按位与返回1，则是同一个键位，否则不是