QPainter绘制五角星

void Widget::paintEvent(QPaintEvent *event)

{

    QPainter painter(this);

    painter.setRenderHint(QPainter::Antialiasing);

    painter.setRenderHint(QPainter::TextAntialiasing);

    qreal R=100; //qreal == double

    const qreal  pi = 3.14159;

    qreal deg=pi*72/180;

    QPoint points[]

    {

        QPoint(R,0),

                QPoint(R*std::cos(deg),-R*std::sin(deg)),

                QPoint(R*std::cos(2*deg),-R*std::sin(2*deg)),

                QPoint(R*std::cos(3*deg),-R*std::sin(3*deg)),

                QPoint(R*std::cos(4*deg),-R*std::sin(4*deg)),

    };

    //设置字体

    QFont font;

    font.setPointSize(12);

    font.setBold(true);

    painter.setFont(font);

    //设置画笔

    QPen penline;

    penline.setWidth(2); //线宽

    penline.setColor(Qt::blue);//划线颜色

    penline.setStyle(Qt::SolidLine);//线的类型

    penline.setCapStyle(Qt::FlatCap); //线端点样式

    penline.setJoinStyle(Qt::BevelJoin); //线的连接点样式

    painter.setPen(penline);

    //设置画刷

    QBrush brush;

    brush.setStyle(Qt::SolidPattern);

    brush.setColor(Qt::yellow);

    painter.setBrush(brush);

    //设计绘制五角星的painterPATH 重复使用

    QPainterPath starPath;

    starPath.moveTo(points[0]);

    starPath.lineTo(points[2]);

    starPath.lineTo(points[4]);

    starPath.lineTo(points[1]);

    starPath.lineTo(points[3]);

    starPath.closeSubpath();//闭合路径，最后一个点与第一个点相连

    starPath.addText(points[0],font,"0");

    starPath.addText(points[1],font,"1");

    starPath.addText(points[2],font,"2");

    starPath.addText(points[3],font,"3");

    starPath.addText(points[4],font,"4");

    //绘图

    painter.save();

    painter.translate(100,120);

    painter.drawPath(starPath);

    painter.drawText(0,0,"1");

    painter.restore();

}