QT 绘画功能的时钟

 .h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QPaintEvent>
#include <QDebug>     //信息调试类
#include <QPainter>
#include <QPixmap>        //图像引擎类
#include <QTime>
#include <QTimer>        //定时器类
#include <QDateTime>   //日期类
#include <QTimerEvent>
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

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

    void paintEvent(QPaintEvent *event);
    void timerEvent(QTimerEvent *e);
private slots:

private:
    Ui::Widget *ui;

    int timer_id;
    //给定时器实例化一个对象
    QTimer * timer;
    int hh=0,mm=0,ss=0;
};
#endif // WIDGET_H

 .cpp

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    timer_id=this->startTimer(1000);
    //给定时器实例化对象
    timer=new QTimer(this);

    // 设置窗口的大小和标题
      setFixedSize(500, 500);
      setWindowTitle("闹钟");

}

Widget::~Widget()
{
    delete ui;
}

//绘制事件处理函数
void Widget::paintEvent(QPaintEvent *event)
{
    //实例化一个画家
    QPainter painter(this);
   // 设置反锯齿渲染
     painter.setRenderHint(QPainter::Antialiasing, true);

    //实例化一个画笔
    QPen pen;
    pen.setColor(QColor("blue"));
    pen.setStyle(Qt::DashDotLine);    //设置线型

   //将画笔给画家安排上
    painter.setPen(pen);
    painter.translate(this->width()/2,this->height()/2);

    //给画家 偏移坐标系
    painter.rotate(0);              //旋转坐标系
    painter.setBrush(QBrush(QColor("skyblue")));

    //画个钟盘
    painter.drawEllipse(QPoint(0,0),200,200);

    //绘制矢量文字
    pen.setColor(QColor("red"));
    painter.setPen(pen);
    //给画家设置字体
    painter.setFont(QFont("隶书",15,13));

    //画小时格子
    for(int i=1;i<=12;i++)
    {
        //每转30度画一个时刻
        painter.rotate(30);
        painter.drawLine(0,-200,0,-175);
        painter.drawText(0,-170,QString("%1").arg(i));
    }
    //画分格子
    for(int i=0;i<=59;i++)
    {
        //pen.setColor(QColor("green"));
        painter.rotate(6);
        painter.drawLine(0,-200,0,-190);
     
    }

    //绘制矢量文字
    painter.translate(-this->width()/2,-this->height()/2);
    painter.drawText(this->rect(),Qt::AlignCenter,"啊啊，我饿了");

     //绘制指针
    QPainter p1(this);
    QPen  pen1;
    pen1.setWidth(5);
    p1.translate(this->width()/2,this->height()/2);
    pen1.setStyle(Qt::SolidLine);    //设置线型

    //1、绘制秒针

    p1.setPen(Qt::green);
    p1.setBrush(Qt::green);
    p1.rotate(ss*360/60);
    p1.drawLine(0,0,160,0);

    //2、绘制分针
    p1.setPen(Qt::red);
    p1.setBrush(Qt::red);
    p1.rotate(-ss*6);
    p1.rotate(mm*6+ss/10);
    p1.drawLine(0,0,140,0);
    p1.restore();

    //3、绘制时针
    p1.setPen(Qt::black);
    p1.setBrush(Qt::black);
    p1.rotate(-mm*6-ss*6/60);
    p1.rotate(hh*30.0+mm/2.0);
    p1.drawLine(0,0,110,0);

}

//定时器事件处理函数
void Widget::timerEvent(QTimerEvent *e)
{
    if(e->timerId() == timer_id)         //说明定时器1到位
    {
        QTime sys_t = QTime::currentTime();          //获取系统时间
        //将QTime类对象转换为字符串
        QString t = sys_t.toString("hh:mm:ss");
        QStringList list = t.split(":");

        hh = list[0].toUInt();
        mm = list[1].toUInt();
        ss = list[2].toUInt();
        update();

    }
}

 main函数

#include "widget.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}

文章来源地址https://uudwc.com/A/Gd3xd