Qt绘制简单时钟

painter.setBrush(Qt::red); //设置画刷，填充颜色(红色)
painter.setPen(Qt::red);  //设置画笔，外围轮廓颜色(红色）

painter.setRenderHint(QPainter::Antialiasing,true);

painter.save();  //保存属性
painter.restore(); //属性恢复

class Dialog : public QDialog
{
 Q_OBJECT

public:
 Dialog(QWidget *parent = nullptr);
 ~Dialog();

 void Dialog::paintEvent(QPaintEvent *); //函数声明

private:
 Ui::Dialog *ui;
};

#include <QPainter>
#include <QPoint>
#include <QTime>
#include <QTimer>
#include <QPixmap>
#include <math.h>

QPoint sec[4]={QPoint(0,-80),QPoint(2,0),QPoint(0,8),QPoint(-2,0)};
QPoint min[4]={QPoint(0,-62),QPoint(4,0),QPoint(0,10),QPoint(-4,0)};
QPoint hour[4]={QPoint(0,-48),QPoint(5,0),QPoint(0,11),QPoint(-5,0)};

Dialog::Dialog(QWidget *parent)
 : QDialog(parent)
 , ui(new Ui::Dialog)
{
 ui->setupUi(this);
 resize(300,300);

 QTimer * timer = new QTimer(this);
 timer->start(1000); //确定刷新时间（此处为1000毫秒=1秒）
 connect(timer,SIGNAL(timeout()),this,SLOT(update())); //update()为自动刷新界面，使指针可以不停转动
}

void Dialog::paintEvent(QPaintEvent *){
 QPainter painter(this);

 //时钟背景
 QRect q1(20,20,0.5*512,0.5*512);
 QRect q2(0,0,512,512);
 QPixmap map(":/b/ClockBack/clockback.png");
 painter.drawPixmap(q1,map,q2);

 QTime time=QTime::currentTime(); //调用系统时间

 //表盘
 painter.setRenderHint(QPainter::Antialiasing,true); //抗锯齿，平滑化
 painter.setPen(QPen(Qt::white,6,Qt::SolidLine));  //调色
 painter.translate(50,50);
 painter.drawEllipse(0,0,198,198);

 //指针属性
 painter.translate(99,99);

 //秒针
 painter.setRenderHint(QPainter::Antialiasing,true);
 painter.setBrush(Qt::red); //设置画刷，填充颜色
 painter.setPen(Qt::red);  //设置画笔，外围轮廓颜色
 painter.save();    //保存属性
 painter.rotate(6.0*time.second());
 painter.drawPolygon(sec,4); //绘制指针（绘制几何图形函数）
 painter.restore();   //属性恢复

 //分针（同秒针）
 painter.setRenderHint(QPainter::Antialiasing,true);
 painter.setBrush(Qt::white);
 painter.setPen(Qt::white);
 painter.save();
 painter.rotate(6.0*time.minute()+time.second()/60.0);
 painter.drawPolygon(min,4);
 painter.restore();

 //时针（同秒针）
 painter.setRenderHint(QPainter::Antialiasing,true);
 painter.setBrush(Qt::black);
 painter.setPen(Qt::black);
 painter.save();
 painter.rotate(30.0*time.hour()+time.minute()/60.0);
 painter.drawPolygon(hour,4);
 painter.restore();

 //表盘刻度
 //长刻度（整点刻度）
 for(int i=1;i<=12;i++){
  painter.rotate(30);
  painter.drawLine(0,-100,0,-85);
 }
 
 //短刻度
 for(int i=1;i<=60;i++){
  painter.rotate(6);
  painter.drawLine(0,-94,0,-90);
 }
}