本文实例为大家分享了QT实现简单时钟效果的具体代码，供大家参考，具体内容如下
先上效果图：
预备知识：
一.钟表实现原理
设置定时器timer，每隔1000毫秒（即1s）发送timeout()信号到槽函数update（），重绘事件函数paintEvent(QPaintEventevent)
二.钟表的绘制方法
拆分钟表：表盘 数字 刻度线 指针
paintEvent(QPaintEventevent)
1.设置定时器，时间间隔为1000毫秒，并且将定时器时间与update函数关联为信号和槽，定时器每隔1秒发送一个信号
2.绘制时针分针秒针的形状。
// 时针、分针、秒针 - 多边形
static const QPoint hourHand[3] = {
QPoint(3, 8),
QPoint(-3, 8),
QPoint(0, -40)
};
static const QPoint minuteHand[3] = {
QPoint(3, 8),
QPoint(-3, 8),
QPoint(0, -65)
};
static const QPoint secondHand[3] = {
QPoint(3, 8),
QPoint(-3, 8),
QPoint(0, -80)
};
3.绘制时针和时刻度线
// 绘制时针
painter.setPen(Qt::NoPen);
painter.setBrush(hourColor);
painter.save();
painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
painter.drawConvexPolygon(hourHand, 3);
painter.restore();
painter.setPen(hourColor);
// 绘制时刻度线
for (int i = 0; i < 12; ++i)
{
painter.drawLine(88, 0, 96, 0);
painter.rotate(30.0);
}
QFont font = painter.font();
font.setBold(true);
painter.setFont(font);
下面是一些基础的绘图函数：
drawPoint() 绘制点
drawLine() 绘制线
drawRect() 绘制矩形
drawEllipse() 绘制椭圆（绘制圆也是此函数）
drawConvexPolygon() 绘制凸多边形
drawText（） 编制文本
特别的，我们还会经常用到
QPen：绘制几何图形的边缘，可绘制颜色，宽度，线的风格等
QBrush：用于几何图形的调色板与填充
则可借用setPen（）来当做画笔来使用。
setBrush（）来当做填充器使用来填充颜色。
setPen(color)；
然后我们的绘制将会用此颜色的画笔来绘制图形边缘。
setBrush(color)；
主要代码展示：
void Widget::drawhourhand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::blue);//画刷，填充
painter->setPen(Qt::Dense7Pattern);//画笔，制作廓线
painter->save();
painter->rotate(30.0*(time.hour()+time.minute()/60));//使得指针旋转到当前时间位置
painter->drawConvexPolygon(hourhand,4);;//绘制时针（凸多边形）
painter->restore();//与save连着用 绘制图形后复位坐标系
}
void Widget::drawminutehand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::white);
painter->setPen(Qt::Dense5Pattern);
painter->save();
painter->rotate(6.0*(time.minute()+time.second()/60.0));
painter->drawConvexPolygon(minutehand,4);
painter->restore();
}
void Widget::drawsecondhand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::red);
painter->setPen(Qt::Dense5Pattern);
painter->save();
painter->rotate(6*time.second());
painter->drawPolygon(minutehand,4);
painter->restore();
}
``
```cpp
#include "widget.h"
#include "ui_widget.h"
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
font.setPixelSize(10);
setFont(font);
setWindowTitle("THE CLOCK");
resize(1200,820);
}
Widget::~Widget()
{
delete ui;
}
const QPoint Widget::hourhand[4]={
QPoint(5,5),QPoint(0,13),QPoint(-5,5),QPoint(0,-40)
};
const QPoint Widget::minutehand[4]={
QPoint(3,5),QPoint(0,16),QPoint(-3,5),QPoint(0,-70)
};
const QPoint Widget::secondhand[4]={
QPoint(0,0),QPoint(0,0),QPoint(0,0),QPoint(0,0)
};
void Widget::drawhourhand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::blue);//画刷，填充
painter->setPen(Qt::Dense7Pattern);//画笔，制作廓线
painter->save();
painter->rotate(30.0*(time.hour()+time.minute()/60));//使得指针旋转到当前时间位置
painter->drawConvexPolygon(hourhand,4);;//绘制时针（凸多边形）
painter->restore();//与save连着用 绘制图形后复位坐标系
}
void Widget::drawminutehand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::white);
painter->setPen(Qt::Dense5Pattern);
painter->save();
painter->rotate(6.0*(time.minute()+time.second()/60.0));
painter->drawConvexPolygon(minutehand,4);
painter->restore();
}
void Widget::drawsecondhand(QPainter*painter)
{
QTime time=QTime::currentTime();
painter->setBrush(Qt::red);
painter->setPen(Qt::Dense5Pattern);
painter->save();
painter->rotate(6.0*time.second());
painter->drawPolygon(minutehand,4);
painter->restore();
}
void Widget::paintEvent(QPaintEvent*event)
{
QPainter painter(this);
QTimer*timer=new QTimer(this);
timer->start(1000);
connect(timer,SIGNAL(timeout()),this,SLOT(update()));
QPixmap map(":/new/prefix1/timg (1).jfif");
QRect q(0,0,1200,800);//截取这么大的面积
QRect q2(0,0,width(),height());//放到指定大小的框中
painter.drawPixmap(q2,map,q);
painter.setRenderHint(QPainter::Antialiasing,true);//反走样
int side=qMin(width(),height());
painter.setWindow(0,0,230,230);//原本截取放大的面积区域多大
painter.setViewport(96,0,side,side);//映射到新的区域面积多大
painter.translate(100,100);//重新设定坐标原点
drawhourhand(&painter);
drawminutehand(&painter);
drawsecondhand(&painter);
drawclockdial(&painter);
QString timeStr= QTime::currentTime().toString(); //绘制当前的电子时间
painter.setPen(Qt::white);
painter.drawText(-20,30,80,30,0,timeStr);
painter.setBrush(Qt::black);
painter.drawEllipse(QPoint(0,0),3,3);//中间画个小圆点
// QTransform Transform;
// Transform.rotate(90);
// painter.setTransform(Transform);
painter.drawText(-53,-30,QStringLiteral("老子利指导，杀人先看表"));
}
void Widget::drawclockdial(QPainter*painter)
{
hourhandpen.setColor(Qt::white);
hourhandpen.setWidth(2.0);//设置小时刻度线为粗黑
minutehandpen.setColor(Qt::white);
for(int i=1;i<=60;i++)
{
painter->save();
painter->rotate(6*i);
if(i%5==0)
{
painter->setPen(hourhandpen);
painter->drawLine(0,-98,0,-82);//原点变了
painter->drawText(-20,-82,40,40,Qt::AlignHCenter|Qt::AlignTop,QString::number(i/5));
}
else
{
painter->setPen(minutehandpen);
painter->drawLine(0,-98,0,-88);
}
painter->restore();
}
}
