案例
1、键盘按下w,s,a,d键分别为标签向上,下,左,右移动
鼠标按下获取本地坐标,全局坐标
鼠标双击获取本地坐标,全局坐标
鼠标移动获取本地坐标,全局坐标
让鼠标跟踪坐标,需要手动开启,标签会随着鼠标移动
widget.h代码
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE
class Widget : public QWidget
{
    Q_OBJECT
public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
protected:
    // 确保使用 override 关键字
    void keyPressEvent(QKeyEvent *event) override;             //声明键盘按下事件处理函数
    void keyReleaseEvent(QKeyEvent *event) override;            //声明键盘抬起事件处理函数
    void mousePressEvent(QMouseEvent *event) override;            //鼠标按下事件处理函数的声明
    void mouseReleaseEvent(QMouseEvent *event) override;          //鼠标抬起事件处理函数
    void mouseDoubleClickEvent(QMouseEvent *event) override;          //鼠标双击事件处理函数
    void mouseMoveEvent(QMouseEvent *event) override;            //鼠标移动事件的声明
private:
    Ui::Widget *ui;
};
#endif // WIDGET_H
 
widget.cpp代码
#include "widget.h"
#include "ui_widget.h"
#include <QtDebug>
#include <QKeyEvent>    //键盘事件
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    //如果需要让鼠标跟踪坐标,需要手动开启
    this->setMouseTracking(true);
}
Widget::~Widget()
{
    delete ui;
}
//重写键盘按下事件处理函数
void Widget::keyPressEvent(QKeyEvent *event)
{
//    static int num = 1;
//    qDebug() << "num = " << num++;
    //qDebug() << event->text() << "被按下,对应的键值为: " << event->key();
    //对用户按下的健进行判断
    switch(event->key())
    {
        //向上移动
        case 'W':
        case 'w':
        {
            //判断是否已经到界面外部了
            if(ui->label->y() <= -ui->label->height())
            {
                //将组件移动到界面的最下面
                ui->label->move(ui->label->x(),this->height());
            }
            //让组件向上移动10格
            ui->label->move(ui->label->x(),ui->label->y()-10);
        }
        break;
        //向下移动
        case 'S':
        case 's':
        {
            if(ui->label->y() >= this->height())
            {
                ui->label->move(ui->label->x(),-ui->label->height());
            }
            ui->label->move(ui->label->x(),ui->label->y()+10);
        }
        break;
        //向左移动
        case 'A':
        case 'a':
        {
            if(ui->label->x() <= -ui->label->width())
            {
                ui->label->move(this->width(),ui->label->y());
            }
            ui->label->move(ui->label->x()-10,ui->label->y());
        }
        break;
        //向右移动
        case 'D':
        case 'd':
        {
            if(ui->label->x() >= this->width())
            {
                ui->label->move(-ui->label->width(),ui->label->y());
            }
            ui->label->move(ui->label->x()+10,ui->label->y());
        }
        break;
    }
}
//键盘抬起事件处理函数的定义
void Widget::keyReleaseEvent(QKeyEvent *event)
{
    qDebug() << event->text() <<"被按下,对应的键值为:"<<event->key();
}
//鼠标按下事件处理函数
void Widget::mousePressEvent(QMouseEvent *event)
{
    //判断是哪个鼠标键按下
    if(event->button() == Qt::LeftButton)
    {
        qDebug() << "鼠标左键被按下了";
    }else if(event->button() == Qt::RightButton)
    {
        qDebug() << "鼠标右键被按下了";
    }else if(event->button() == Qt::MidButton)
    {
        qDebug() << "鼠标中键被按下了";
    }
}
//键盘抬起事件处理函数的定义
void Widget::mouseReleaseEvent(QMouseEvent *event)
{
    //判断是哪个鼠标键按下
    if(event->button() == Qt::LeftButton)
    {
        qDebug() << "鼠标左键被抬起,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::RightButton)
    {
        qDebug() << "鼠标右键被抬起,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::MiddleButton)
    {
        qDebug() << "鼠标中键被抬起,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }
}
//鼠标双击事件处理函数的定义
void Widget::mouseDoubleClickEvent(QMouseEvent *event)
{
    //判断是哪个鼠标键按下
    if(event->button() == Qt::LeftButton)
    {
        qDebug() << "鼠标左键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::RightButton)
    {
        qDebug() << "鼠标右键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::MiddleButton)
    {
        qDebug() << "鼠标中键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }
}
//鼠标移动事件的定义
void Widget::mouseMoveEvent(QMouseEvent *event)
{
    //判断是哪个鼠标键按下
    if(event->button() == Qt::LeftButton)
    {
        qDebug() << "鼠标左键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::RightButton)
    {
        qDebug() << "鼠标右键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }else if(event->button() == Qt::MiddleButton)
    {
        qDebug() << "鼠标中键被双击,本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    }
    qDebug() << "本地坐标:" << event->pos() << "鼠标左键被抬起,全局坐标:" << event->globalPos();
    ui->label->move(event->x()-ui->label->width()/2,event->y()-ui->label->height()/2);
}
 
运行效果


2、使用鼠标移动事件完成界面的移动
widget.h代码
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QPoint>   //点类
#include <QMouseEvent>  //鼠标事件
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE
class Widget : public QWidget
{
    Q_OBJECT
public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
    void mousePressEvent(QMouseEvent *event) override;        //鼠标点击事件
    void mouseMoveEvent(QMouseEvent *event) override;          //鼠标移动事件
private:
    Ui::Widget *ui;
    QPoint temp;           //辅助向量
};
#endif // WIDGET_H
 
widget.cpp代码
#include "widget.h"
#include "ui_widget.h"
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    //去除头部
    this->setWindowFlag(Qt::FramelessWindowHint);
}
Widget::~Widget()
{
    delete ui;
}
void Widget::mousePressEvent(QMouseEvent *event)    //鼠标点击事件
{
    temp = event->globalPos() - this->pos();    //得到中间向量
    //鼠标的当前位置        组件左上角的位置
}
void Widget::mouseMoveEvent(QMouseEvent *event)     //鼠标移动事件
{
    if(event->button() == Qt::LeftButton)
    {
        this->move(event->globalPos()- temp);   //组件移动位置
    }else if(event->button() == Qt::RightButton)
    {
        this->close();
    }
}
 
运行效果


知识梳理
QT的核心机制









对话框资源












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