QT ＧＵＩ 简易时钟

//analogclock.h

 #include <QtGui>

 #include "analogclock.h"

 AnalogClock::AnalogClock(QWidget *parent)
     : QWidget(parent)
 {
     QTimer *timer = new QTimer(this);
     connect(timer, SIGNAL(timeout()), this, SLOT(update()));
  //时钟信号和更新绑定
     timer->start(1000);
  //设定时钟信号的发送时间间隔

     setWindowTitle(tr("Analog Clock"));
     resize(200, 200);
  //开始出现时大小
 }

 void AnalogClock::paintEvent(QPaintEvent *)
 {
     static const QPoint hourHand[3] = {
         QPoint(7, 8),
         QPoint(-7, 8),
         QPoint(0, -40)
     };
     static const QPoint minuteHand[3] = {
         QPoint(7, 8),
         QPoint(-7, 8),
         QPoint(0, -70)
     };
  static const QPoint secondHand[3] = {
         QPoint(7, 8),
   QPoint(-7, 8),
   QPoint(0, -90)
     };

     QColor hourColor(127, 0, 127);
     QColor minuteColor(0, 127, 127, 191);
  QColor secondColor(255, 0, 0, 100);

     int side = qMin(width(), height());
     QTime time = QTime::currentTime();

     QPainter painter(this);
     painter.setRenderHint(QPainter::Antialiasing);
  //反走样
     painter.translate(width() / 2, height() / 2);
  //转换坐标，坐标原点在width() / 2, height() / 2
     painter.scale(side / 200.0, side / 200.0);
  //放大倍数

     painter.setPen(Qt::NoPen);
     painter.setBrush(hourColor);

     painter.save();
  //Saves the current painter state (pushes the state onto a stack).
  //A save() must be followed by a corresponding restore(); the end() function unwinds the stack
     painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
  //Rotates the coordinate system the given angle clockwise
     painter.drawConvexPolygon(hourHand, 3);
  //画图形Draws the convex polygon defined by
  //the first pointCount points in the array points using the current pen.
     painter.restore();
  //Restores the current painter state (pops a saved state off the stack).

     painter.setPen(hourColor);

     for (int i = 0; i < 12; ++i) {
         painter.drawLine(88, 0, 96, 0);
         painter.rotate(30.0);
     }

     painter.setPen(Qt::NoPen);
     painter.setBrush(minuteColor);

     painter.save();
     painter.rotate(6.0 * (time.minute() + time.second() / 60.0));
     painter.drawConvexPolygon(minuteHand, 3);
     painter.restore();

     painter.setPen(minuteColor);

     for (int j = 0; j < 60; ++j) {
         if ((j % 5) != 0)
             painter.drawLine(92, 0, 96, 0);
         painter.rotate(6.0);
     }

  painter.setPen(Qt::NoPen);
  painter.setBrush(secondColor);
  painter.save();
  painter.rotate(6.0*time.second());
  painter.drawConvexPolygon(secondHand,3);
  painter.restore();

 }

//main.cpp

#include <QApplication>

 #include "analogclock.h"

 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     AnalogClock clock;
     clock.show();
     return app.exec();
 }