【Qt编程】Qt 小时钟

时间:2021-07-08 09:08:52

Hello World! 学习编程语言的最简单最经典的小程序,当然Qt也不例外。在学习画图时,我觉得写个时钟小程序也是个比较好的开始。在之前的《Matlab及Java小时》一文中,我也从写时钟程序作为学习画图的开始。三者之间的不同点在于,matlab是通过while循环来进行重绘,Java和Qt事件来处理。实时显示时钟,都是通过改变指针与坐标轴的相对位置来实现的。前两者都是改变指针,而Qt是旋转坐标轴。具体代码如下:

1.widget.h文件

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;
protected:
    void paintEvent(QPaintEvent *event);//添加重绘事件
};

#endif // WIDGET_H

2.main.cpp

#include <QtGui/QApplication>
#include "widget.h"
#include<QTextCodec>
#include<QPainter>
#include<QtGui>
#include<QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTextCodec::setCodecForTr(QTextCodec::codecForLocale());
    Widget w;
    w.show();

    return a.exec();
}

3.widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include<QPainter>
#include<QtGui>
#include<QDebug>
#include<QFont>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    QTimer *timer = new QTimer(this);//创建一秒定时器
    connect(timer, SIGNAL(timeout()), this, SLOT(update()));//信号与槽关联
    timer->start(1000);
    setWindowTitle(tr("我的时钟--designed by TW"));

}

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

void Widget::paintEvent(QPaintEvent *event)
{
    int side = qMin(width(), height());//获取窗口的较短边的值
    QPainter painter(this);//指定画图设备
    painter.fillRect(rect(),Qt::yellow);//设置背景色
    painter.setRenderHint(QPainter::Antialiasing);//开启抗锯齿
    painter.translate(width() / 2, height() / 2);//将坐标移到窗口正中心
    painter.scale(side / 200.0, side / 200.0);//进行缩放

    QPen pen;//设置画笔的,宽度,样式,颜色
    pen.setWidth(2);
    pen.setStyle(Qt::SolidLine);
    pen.setColor(Qt::red);

    painter.setPen(pen);
    for (int i = 0; i < 12; ++i) //画表盘时针刻度
    {
        painter.drawLine(87, 0, 95, 0);
        painter.rotate(30);//将坐标进行顺时针选择30度
    }

    pen.setWidth(1);
    pen.setColor(Qt::black);
    painter.setPen(pen);

    for (int i = 0; i < 60; ++i) //画表盘时针刻度
    {
        if(i%5!=0)
          painter.drawLine(90, 0, 95, 0);
        painter.rotate(6);
    }

    pen.setColor(Qt::black);
    painter.setPen(pen);
    QFont font("Century");
    painter.setFont(font);
    //标时刻的数值
    painter.drawText(-6,-75,tr("12"));
    painter.drawText(-3,80,tr("6"));
    painter.drawText(75,5,tr("3"));
    painter.drawText(-80,5,tr("9"));

    painter.drawArc(-3,-3,6,6,0,360*16);//画中心小圆环
    /////////////////////////////////////
    QTime time = QTime::currentTime();//获取当前系统时间
//    qDebug()<<time.hour();
//    qDebug()<<time.minute();
//    qDebug()<<time.second();

    //画时针
    painter.save();//在旋转坐标系前,保存原来坐标系
    painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
    pen.setColor(Qt::green);
    pen.setWidth(4);
    painter.setPen(pen);
    painter.drawLine(0,0,0,-60);
    painter.restore();//在旋转坐标系后,恢复原来坐标系
    //画分针
    painter.save();
    painter.rotate(6.0 * (time.minute() + time.second() / 60.0));
    pen.setColor(Qt::blue);
    pen.setWidth(2);
    painter.setPen(pen);
    painter.drawLine(0,0,0,-80);
    painter.restore();
    //画秒针
    painter.save();
    painter.rotate(6.0 *time.second() );
    pen.setColor(Qt::red);
    pen.setWidth(1);
    painter.setPen(pen);
    //秒针形状由两条直线和一个小圆环组成
    painter.drawArc(-3,-66,6,6,0,360*16);
    painter.drawLine(0,20,0,-60);
    painter.drawLine(0,-66,0,-85);
    painter.restore();

}

运行结果如下图:

【Qt编程】Qt 小时钟

原文:http://blog.csdn.net/tengweitw/article/details/22308627

作者:nineheadedbird