QT实现简易时钟

头文件

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QPaintEvent>
#include <QDebug>
#include <QPainter>
#include <QTimerEvent>
#include <QTimer>
#include <QTime>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();//绘画事件函数重写void paintEvent(QPaintEvent *event) override;private slots:void timeout_slot();private:Ui::Widget *ui;//定义一个定时器QTimer *timer;double h = 0;double m = 0;double s = 0;};
#endif // WIDGET_H

函数实现

#include "widget.h"
#include "ui_widget.h"Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);//启动定时器，每隔1000ms自动调用定时器事件处理函数timer = new QTimer(this);timer->start(1000);connect(timer, &QTimer::timeout, this, &Widget::timeout_slot);}Widget::~Widget()
{delete ui;
}void Widget::paintEvent(QPaintEvent *event)
{//实例化一个画家QPainter painter(this);painter.setRenderHint(QPainter::Antialiasing);//实例化一个画笔QPen pen;pen.setColor(QColor("black"));pen.setStyle(Qt::SolidLine);pen.setWidth(7);//表盘painter.setPen(pen);painter.translate(this->width()/2, this->height()/2);painter.drawEllipse(QPoint(0, 0), 200, 200);//刻度pen.setWidth(4);painter.setPen(pen);for(int i = 1; i <= 60; i++){painter.save();painter.rotate(i*6);if(!(i % 5)){painter.drawLine(0, -200, 0, -175);painter.drawText(-20, -170, 40, 40, Qt::AlignHCenter | Qt::AlignTop, QString::number(i/5));}else{painter.drawLine(0, -200, 0, -190);}painter.restore();}//时针painter.save();pen.setColor(QColor("red"));pen.setStyle(Qt::SolidLine);pen.setWidth(6);painter.setPen(pen);painter.rotate(30*h);painter.drawLine(0, 0, 0, -60);painter.restore();//分针painter.save();pen.setColor(QColor("green"));pen.setStyle(Qt::SolidLine);pen.setWidth(3);painter.setPen(pen);painter.rotate(6*m);painter.drawLine(0, 0, 0, -100);painter.restore();//秒针painter.save();pen.setColor(QColor("blue"));pen.setStyle(Qt::SolidLine);pen.setWidth(1);painter.setPen(pen);painter.rotate(6*(s+1));painter.drawLine(0, 0, 0, -160);painter.restore();update();
}void Widget::timeout_slot()
{QTime time = QTime::currentTime();h = time.hour();m = time.minute();s = time.second();}