2023/09/20 day4 qt

做一个动态指针钟表

头文件

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QPainter>       //绘制事件类
#include <QPaintEvent>    //画家类
#include <QTime>
#include <QTimer>
#include <QTimerEvent>
QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();//重写绘制事件处理函数void paintEvent(QPaintEvent *event)override;private slots:void on_startbtn_clicked();void timeout_slot();
private:Ui::Widget *ui;//定义一个定时器的对象指针QTimer *timer;
};
#endif // WIDGET_H

源文件

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);//给定时器指针实例化对象timer = new  QTimer(this);connect(timer,&QTimer::timeout,this,&Widget::timeout_slot);
}Widget::~Widget()
{delete ui;
}void Widget::paintEvent(QPaintEvent *event)
{//定义一个画家类QPainter p1(this);//实例化一个画笔QPen pen1;   //无参构造pen1.setColor(QColor("red"));pen1.setStyle(Qt::SolidLine); //设置线形，默认实线pen1.setWidth(5); //设置粗细p1.setPen(pen1);//直径int side = qMin(this->width(),this->height());//设置起始坐标p1.translate(this->width()/2,this->height()/2); //ui界面中心//画个圆圈当作表盘p1.drawEllipse(QPoint(0,0),side/2,side/2);//绘制刻度线pen1.setColor(QColor("black"));pen1.setWidth(3);p1.setPen(pen1);for(int i=0;i<12;i++){p1.drawLine(0,-side/2+10,0,-side/2+20);p1.rotate(30);}//绘制时针、分针、秒针QTime curretTime = QTime::currentTime();//时针p1.setPen(Qt::NoPen);p1.setBrush(Qt::blue);p1.save();p1.rotate(30*(curretTime.hour()+curretTime.minute()/60));p1.drawConvexPolygon(QPolygon(QVector<QPoint>()<<QPoint(-2,-40)<<QPoint(2,-40)<<QPoint(4,0)<<QPoint(-4,0)));p1.restore();//分针p1.setBrush(Qt::black);p1.save();p1.rotate(6*(curretTime.minute() + curretTime.second() / 60));p1.drawConvexPolygon(QPolygon(QVector<QPoint>() << QPoint(-1, -50) << QPoint(1, -50) << QPoint(1, 100) << QPoint(-1, 100)));p1.restore();//秒针p1.setPen(Qt::red);p1.setBrush(Qt::red);p1.save();p1.rotate(6* curretTime.second());p1.drawConvexPolygon(QPolygon(QVector<QPoint>() << QPoint(-1, -70) << QPoint(1, -70) << QPoint(0, 160) << QPoint(-0, 160)));p1.restore();
}//启动定时器按钮对应的槽函数
void Widget::on_startbtn_clicked()
{timer->start(1000);
}void Widget::timeout_slot()
{update();
}

效果图