QT实现简单时钟效果

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();
 }

}

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