Qt事件处理，提升组件类

1.相关说明

1.提升组件QLabel的类，以实现双击功能

2.监控键盘事件，实现上下左右移动

3.鼠标点击获取坐标

 2.相关界面

3.相关代码和操作

自定义类TMyLabel，父类为QLabel

tmylabel.h

#ifndef TMYLABEL_H
#define TMYLABEL_H
#include 
#include 
class TMyLabel : public QLabel
{
    Q_OBJECT
public:
    TMyLabel(QWidget *parent=nullptr);
signals:    // 信号
    void doubleClicked();
    // QWidget interface
protected:
    void mouseDoubleClickEvent(QMouseEvent *event) override;
    // QObject interface
public:
    bool event(QEvent *event) override;
};
#endif // TMYLABEL_H

tmylabel.cpp

#include "tmylabel.h"
#include 
TMyLabel::TMyLabel(QWidget *parent):QLabel(parent)
{
    setAttribute(Qt::WA_Hover, true);
}
// 双击label发射信号
void TMyLabel::mouseDoubleClickEvent(QMouseEvent *event)
{
    Q_UNUSED(event);
    // 当双击Label时，发送信号，主界面就能捕获到
    emit doubleClicked();
}
bool TMyLabel::event(QEvent *event)
{
    if(event->type() == QEvent::HoverEnter){
        QPalette plet = this->palette();
        plet.setColor(QPalette::WindowText, Qt::red);
        setPalette(plet);
    }else if(event->type() == QEvent::HoverLeave){
        QPalette plet = this->palette();
        plet.setColor(QPalette::WindowText, Qt::black);
        setPalette(plet);
    }
    return QLabel::event(event);
}

 提升labDoubeClick对象的类

填写自定义的TMyLabel类

widget.h

#ifndef WIDGET_H
#define WIDGET_H
#include 
QT_BEGIN_NAMESPACE
namespace Ui {
class Widget;
}
QT_END_NAMESPACE
class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
private:
    Ui::Widget *ui;
    // QWidget interface
protected:
    void mousePressEvent(QMouseEvent *event) override;
    void keyPressEvent(QKeyEvent *event) override;
    void paintEvent(QPaintEvent *event) override;
    // QWidget interface
protected:
    void closeEvent(QCloseEvent *event) override;
private:
    void do_doubleClick();
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include 
#include 
#include 
#include "tmylabel.h"
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    grabKeyboard(); // 抓取键盘输入
    connect(ui->labDoubleClick, &TMyLabel::doubleClicked, this, &Widget::do_doubleClick);
}
Widget::~Widget()
{
    delete ui;
}
// 鼠标左击
void Widget::mousePressEvent(QMouseEvent *event)
{
    if(event->button() != Qt::LeftButton){ // 鼠标左键按下生效
        return;
    }
    QPoint pt = event->pos();   // 相对widget的位置
    QPointF relaPt = event->position();
    QPointF winPt = event->scenePosition();
    QPointF globPt = event->globalPos(); // 相对屏幕位置
    QString str = QString::asprintf("pos()=(%d,%d)", pt.x(), pt.y());
    str += QString::asprintf("\npostion()=(%.0f,%.0f)", relaPt.x(), relaPt.y());
    str += QString::asprintf("\nscenePosition()=(%.0f,%.0f)", winPt.x(), winPt.y());
    str += QString::asprintf("\nglobalPos()=(%.0f,%.0f)", globPt.x(), globPt.y());
    ui->labMove->setText(str);
    ui->labMove->adjustSize();
    ui->labMove->move(event->pos());
    QWidget::mousePressEvent(event);
}
// 键盘 上下左右
void Widget::keyPressEvent(QKeyEvent *event)
{
    QPoint pt = ui->btnMove->pos();
    if((event->key() == Qt::Key_A) || (event->key() == Qt::Key_Left)){
        ui->btnMove->move(pt.x()-20, pt.y());
    }else if((event->key() == Qt::Key_D) || (event->key() == Qt::Key_Right)){
        ui->btnMove->move(pt.x()+20, pt.y());
    }else if((event->key() == Qt::Key_W) || (event->key() == Qt::Key_Up)){
        ui->btnMove->move(pt.x(), pt.y()-20);
    }else if((event->key() == Qt::Key_S) || (event->key() == Qt::Key_Down)){
        ui->btnMove->move(pt.x(), pt.y()+20);
    }
    QWidget::keyPressEvent(event);
}
void Widget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event);
    QPainter painter(this);
    painter.drawPixmap(0, 0, width(), height(), QPixmap(":/jpg/jpg/shenli.jpg"));
}
// 关闭窗口
void Widget::closeEvent(QCloseEvent *event)
{
    QMessageBox::StandardButton result = QMessageBox::question(this, "消息框", "确定退出吗？",QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel);
    if(result == QMessageBox::Yes){
        event->accept();
    } else {
        event->ignore();
    }
}
void Widget::do_doubleClick()
{
    ui->labDoubleClick->setText("标签被双击了");
    ui->labDoubleClick->adjustSize();
}