Timer_Qt

今天写个简单的时钟的程序，秒钟、分钟，时钟能够自动的正确的显示现在的时间，但是不能够修改。这个程序非常简单需要的基本知识是：

1.Qpainter类

2.QTimer

步骤：

1.先新建一个widget

2.重新定义void paintEvent(QPainter *painter)

3.定义一个画图的函数 void draw(QPainter *painter)

main.cpp

#include

#include "timer.h"

#include
   

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    QTextCodec::setCodecForTr(QTextCodec::codecForLocale());

    Timer w;

    w.show();

    return a.exec();

}

timer.h

#ifndef TIMER_H

#define TIMER_H

#include 
   

namespace Ui {

    class Timer;

}

class Timer : public QWidget

{

    Q_OBJECT

public:

    explicit Timer(QWidget *parent = 0);

    ~Timer();

    void paintEvent(QPaintEvent *);

    void draw(QPainter *painter);

private:

    Ui::Timer *ui;

};

#endif // TIMER_H

timer.cpp

#include "timer.h"

#include "ui_timer.h"

#include
   

Timer::Timer(QWidget *parent) :

    QWidget(parent),

    ui(new Ui::Timer)

{

    ui->setupUi(this);

    QTimer *timer = new QTimer;//新建一个定时器来定时刷新图

    connect(timer,SIGNAL(timeout()),this,SLOT(update()));

 timer->start(1000);//每隔1秒钟重新绘制一下

    setWindowTitle(tr("深海的小鱼儿"));//定义widget的标题

    resize(200,200);//初始固定大小为200x200

}

Timer::~Timer()

{

    delete ui;

}

void Timer::paintEvent(QPaintEvent *)

{

    QPainter painter(this); //定义一个画笔

    painter.setRenderHint(QPainter::Antialiasing);//开启反转使你画的图比较光滑

    int side = qMin(width(), height());//取长宽的最小值来作为你放大和缩小的标准值（也就是说你的

    painter.translate(width() / 2, height() / 2);//长宽是一样的，这样缩放时不会变形。移到中心点，这时width/height=200

    painter.scale(side / 200.0, side / 200.0);

    draw(&painter);//开始画图

}

void Timer::draw(QPainter *painter)

{

    static const QPoint hourHand[3] = {

        QPoint(7, 8),

        QPoint(-7, 8),

        QPoint(0, -40)

    };//定义时针的图像

    static const QPoint minuteHand[3] = {

        QPoint(7, 8),

        QPoint(-7, 8),

        QPoint(0, -65)

    };//定义分针的图像

    static const QPoint secondHand[3] = {

        QPoint(7, 8),

        QPoint(-7, 8),

        QPoint(0, -85)

    };//定义秒针的图像

    QColor hourColor(127, 0, 127);//定义时针的颜色

    QColor minuteColor(0, 127, 127, 191);//定义分针的颜色

    QColor secondColor(0, 0,255);//定义秒针的颜色

    QTime time = QTime::currentTime();//取系统的时间

    painter->setPen(Qt::NoPen);//开始画秒针的在系统时间的位置

    painter->setBrush(secondColor);

    painter->save();

    painter->rotate(time.second()*6);//360/60=6

    painter->drawConvexPolygon(secondHand, 3);

    painter->restore();

    painter->setPen(Qt::NoPen);//开始画分针的在系统时间的位置

    painter->setBrush(hourColor);

    painter->save();

    painter->rotate(30.0 * ((time.hour() + time.minute() / 60.0)));

    painter->drawConvexPolygon(hourHand, 3);

    painter->restore();

    painter->setPen(hourColor);

    for (int i = 0; i < 12; ++i)

    {

        painter->drawLine(88, 0, 96, 0);

        painter->rotate(30.0);

    }

    painter->setPen(Qt::NoPen);//开始画时针的在系统时间的位置

    painter->setBrush(minuteColor);

    painter->save();

    painter->rotate(6.0 * (time.minute() + time.second() / 60.0));

    painter->drawConvexPolygon(minuteHand, 3);

    painter->restore();

    painter->setPen(minuteColor);

    for (int j = 0; j < 60; ++j)

    {

        if ((j % 5) != 0)

            painter->drawLine(92, 0, 96, 0);

        painter->rotate(6.0);

    }

}