QT : 完成绘制时钟

1.头文件

#ifndef WIDGET_H
#define WIDGET_H
 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
 
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE
 
class Widget : public QWidget
{
    Q_OBJECT
 
public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
 
    //重写绘制事件事件处理函数
    void paintEvent(QPaintEvent *event) override;
private slots:
    void updateTime();
 
private:
    Ui::Widget *ui;
    QTimer *timer;
    QPixmap dial;
};
#endif // WIDGET_H

2.源文件

#include "widget.h"
#include "ui_widget.h"
 
Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setFixedSize(600,600);
    QTimer *timer = new QTimer(this);
    connect(timer,&QTimer::timeout,this,&Widget::updateTime);
    timer->start(1000);
    this->setStyleSheet("background-color:white;");
}
 
Widget::~Widget()
{
    delete ui;
}
 
void Widget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event);
    //实例化一个画家
    QPainter painter(this);
    //设置绘图器（QPainter）的渲染提示，开启抗锯齿效果
    painter.setRenderHint(QPainter::Antialiasing);
    //获取当前时间
    QTime currentTime = QTime::currentTime();
 
    int X=this->width()/2;
    int Y=this->height()/2;
    int radius=200;
    //绘制表盘
    painter.setPen(QPen(Qt::black,7));     //设置笔
    if(dial.isNull())
    {
        dial.load("E:\\clock.png");
    }
    if(!dial.isNull())
    {
            painter.drawPixmap(X-radius,Y-radius,radius*2,radius*2,dial);
    }
    //绘制时针
    painter.save();    // 保存当前的绘制状态
    painter.translate(X,Y);    // 将绘制的坐标原点移动到表盘的中心
    int hour = currentTime.hour();    // 获取当前的小时
    int minute = currentTime.minute();     // 获取当前的分钟
    double hourAngle = (hour%12 + minute/60.0)*30.0;  // 计算时针的角度，考虑分钟对时针的影响
    painter.rotate(-90);    // 将坐标系旋转，使12点位置对应0度
    painter.rotate(hourAngle);    // 旋转坐标系，使时针指向正确的位置
    painter.setPen(QPen(Qt::black,5));    //设置笔
    painter.drawLine(0,0,0,-radius*0.5);  // 绘制时针，起点是坐标原点 (0, 0)，终点是时针的末端位置
    painter.restore();       // 恢复之前保存的绘制状态，以便后续绘制
 
  
    //绘制分针
    painter.save();
    painter.translate(X,Y);
    double minuteAngle = minute*6.0;
    painter.rotate(-90);
    painter.rotate(minuteAngle);
    painter.setPen(QPen(Qt::red,3));        //设置笔
    painter.drawLine(0,0,0,-radius*0.7);
    painter.restore();
 
    //绘制秒针
    painter.save();
    painter.translate(X,Y);
    int second = currentTime.second();
    double secondAngle = second * 6.0;
    painter.rotate(-90);
    painter.rotate(secondAngle);
    painter.setPen(QPen(Qt::blue,2));      //设置笔
    painter.drawLine(0,0,0,-radius*0.9);
    painter.restore();
 
}
 
void Widget::updateTime()
{
    update();
}