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 <QLabel>
#include <QObject>
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 <QEvent>
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 <QWidget>
QT_BEGIN_NAMESPACE
namespace Ui {
class Widget;
}
QT_END_NAMESPACE
class Widget : public QWidget
{Q_OBJECTpublic: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 <QPainter>
#include <QMouseEvent>
#include <QMessageBox>
#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();
}