参考网上的代码，

直接附上源码

clock.cpp

#include"clock.h"

#include<QTime>

#include<QTimer>

#include<QPainter>

#include<QDebug>

CLOCK::CLOCK(QWidget*parent)

:QWidget(parent)

{

QTimer*timer=newQTimer(this);

timer->start(1000);//一秒钟

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

QFontfont;

font.setPointSize(10);//字体大小设置为10

setFont(font);

}

CLOCK::~CLOCK()

{

}

voidCLOCK::paintEvent(QPaintEvent*/*event*/)

{

//下面三个数组用来定义表针的三个顶点，以便后面的填充

staticconstQPointhourHand[3]={

QPoint(3,8),

QPoint(-3,8),

QPoint(0,-40)

};

staticconstQPointminuteHand[3]={

QPoint(3,8),

QPoint(-3,8),

QPoint(0,-70)

};

staticconstQPointsecondHand[3]={

QPoint(3,8),

QPoint(-3,8),

QPoint(0,-90)

};//秒针

//填充表针的颜色

QColorhourColor(127,0,127);//分针颜色(第四个表示不透明度)

QColorminuteColor(0,127,127,191);

QColorsecondColor(127,127,0,127);

intside=qMin(width(),height());//绘制的范围(宽、高中最小值)

QTimetime=QTime::currentTime();//获取当前的时间

QPainterpainter(this);//声明用来绘图用的painter

painter.setRenderHint(QPainter::Antialiasing);//绘制的图像反锯齿

painter.translate(width()/2,height()/2);//重新定位坐标起始点，把坐标原点放到窗体的中央

painter.scale(side/300.0,side/300.0);//设定画布的边界,用窗体宽高的最小值来计算时钟的大小，防止窗体拉伸导致的时钟变形以及显示不全

painter.setPen(Qt::red);//填充时针，不需要边线所以NoPen

QStringtimeStr=QTime::currentTime().toString();//绘制当前的时间

painter.drawText(-40,30,80,30,Qt::AlignHCenter|Qt::AlignTop,timeStr);

painter.setPen(Qt::NoPen);//填充时针，不需要边线所以NoPen

painter.setBrush(hourColor);//画刷颜色设定

painter.save();//保存painter的状态，保存的是当前的坐标状态，如果不保存，画完之后坐标以改变不方便画下一个

painter.rotate(30.0*((time.hour()+time.minute()/60.0)));//将painter（的”视角“）根据时间参数转移(30°*(小时+分钟/60))

painter.drawConvexPolygon(hourHand,3);//填充时针的区域

painter.restore();

painter.setPen(hourColor);//下面画表示小时的刻度，此时要用到画笔（因为要划线）

for(inti=0;i<12;++i){

painter.drawLine(0,-88,0,-96);//写上刻度数字

if(i==0)painter.drawText(-10,-88,20,20,Qt::AlignHCenter|Qt::AlignTop,QString::number(12));

elsepainter.drawText(-10,-88,20,20,Qt::AlignHCenter|Qt::AlignTop,QString::number(i));

painter.rotate(30.0);

}

//后面的跟前面的类似，分别绘制了分针和秒针，及相应的刻度

painter.setPen(Qt::NoPen);

painter.setBrush(minuteColor);

painter.save();

painter.rotate(6.0*(time.minute()+time.second()/60.0));//设旋转(角度=6°*(分钟+秒/60))

painter.drawConvexPolygon(minuteHand,3);//填充分针部分

painter.restore();

painter.setPen(minuteColor);

for(intj=0;j<60;++j){//循环60次，绘制表盘（其实可以从1开始，到59，提高一点效率）

if((j%5)!=0)//判断是否能被5整除(能被5整除表示是正点刻度，暂不绘制)

painter.drawLine(0,-92,0,-96);//不是正点刻度，绘制长4个像素的直线

painter.rotate(6.0);//循环60次，每次旋转6度，所以不用save和restore

}

painter.setPen(Qt::NoPen);//填充分针，不需要边线所以NoPen

painter.setBrush(secondColor);

painter.save();//设置画刷颜色

painter.rotate(6.0*time.second());//设置旋转(6°*秒)

painter.drawConvexPolygon(secondHand,3);//设置填充

painter.restore();//恢复保存前状态

painter.setBrush(Qt::black);//画上中心原点

painter.drawEllipse(QPoint(0,0),2,2);

painter.setBrush(Qt::NoBrush);//画上外圆圈

painter.setPen(Qt::black);

painter.drawEllipse(QPoint(0,0),97,97);

}

voidCLOCK::draw(QPainter*painter)

{

QPenthickPen(palette().foreground(),1.5);//设置刻度线为粗黑

QPenthinPen(palette().foreground(),0.5);//设置刻度线为灰

QTimetime=QTime::currentTime();

painter->translate(100,100);//重新设定坐标原点

painter->setRenderHint(QPainter::Antialiasing);//消锯齿

painter->setBrush(Qt::red);

painter->setPen(Qt::red);

painter->save();//保存坐标系，防止坐标系跑偏了

painter->rotate(6.0*time.second());//注意是6.0，不是6

//painter->drawConvexPolygon(sed,4);

painter->restore();//复位之前的坐标系

painter->setBrush(Qt::blue);

painter->setPen(Qt::blue);

painter->save();

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

//painter->drawConvexPolygon(min,4);

painter->restore();

painter->setBrush(Qt::black);

painter->setPen(Qt::black);

painter->save();

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

//painter->drawConvexPolygon(hour,4);

painter->restore();

////painter->drawLine(0,-98,0,-88);

//for(inti=0;i<</FONT>12;i++)

//{

//painter->rotate(30);//坐标轴旋转30度

//painter->drawLine(0,-98,0,-88);

//}

/*画刻度还有数字*/

for(inti=1;i>=60;++i){

painter->save();

painter->rotate(6*i);//坐标轴旋转6度

if(i%5==0){

painter->setPen(thickPen);

painter->drawLine(0,-98,0,-82);

painter->drawText(-20,-82,40,40,

Qt::AlignHCenter|Qt::AlignTop,

QString::number(i/5));

}else{

painter->setPen(thinPen);

painter->drawLine(0,-98,0,-88);

}

//painter->rotate(-DegreesPerMinute);

painter->restore();

}

}

clock.h

#ifndef_CLOCK_H_

#define_CLOCK_H_

#include<QWidget>

classCLOCK:publicQWidget

{

public:

CLOCK(QWidget*parent=0);

~CLOCK();

voidpaintEvent(QPaintEvent*/*event*/);

voiddraw(QPainter*painter);

};

#endif//CLOCK_H

解释，update槽函数，每当定时器时间到了1秒后，给出定时器溢出信号，触发update槽函数，该函数自动调用

paintEvent(QPaintEvent*/*event*/)

，paintEvent是一个虚函数，我只知道是继承自QWidget。我们将其重写，画出时钟，每秒溢出后，update槽函数都会调用一次这个函数。这个时钟类可以直接使用。