digiclock.h

#ifndef DIGICLOCK_H
#define DIGICLOCK_H
​
#include <QLCDNumber>
​
class DigiClock : public QLCDNumber
{Q_OBJECT
public:DigiClock(QWidget* parent = 0);void mousePressEvent(QMouseEvent*);void mouseMoveEvent(QMouseEvent*);
public slots:void showTime();                   //显示当前的时间
private:QPoint dragPosition;              //保存鼠标点相对电子时钟窗体左上角的偏移值bool showColon;                    //用于显示时间时是否显示“：”
};
​
#endif // DIGICLOCK_H
​

digiclock.cpp

#include "digiclock.h"
#include <QTimer>
#include <QTime>
#include <QMouseEvent>
​
DigiClock::DigiClock(QWidget* parent):QLCDNumber(parent)
{QPalette p = palette();p.setColor(QPalette::Window, Qt::blue);setPalette(p);
​setWindowFlags(Qt::FramelessWindowHint);
​setWindowOpacity(0.5);
​QTimer* timer = new QTimer(this);connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));timer->start(1000);showTime();resize(150, 60);showColon = true;                                 //初始化
}
​
void DigiClock::showTime()
{QTime time = QTime::currentTime();QString text = time.toString("hh:mm");if (showColon){text[2] = ':';showColon = false;}else{text[2] = ' ';showColon = true;}display(text);
}
​
void DigiClock::mousePressEvent(QMouseEvent* event)
{if (event->button() == Qt::LeftButton){dragPosition = event->globalPos() - frameGeometry().topLeft();event->accept();}if (event->button() == Qt::RightButton){close();}
}
void DigiClock::mouseMoveEvent(QMouseEvent* event)
{if (event->buttons() & Qt::LeftButton){move(event->globalPos() - dragPosition);event->accept();}
}
​
​

main.cpp

#include <QApplication>
#include "digiclock.h"
​
int main(int argc, char* argv[])
{QApplication a(argc, argv);DigiClock clock;clock.show();
​return a.exec();
}
​