qt 仪表自定义控件

源码
qwidget（paintevent事件实现）废话不多说实现逻辑如下：

	QPainter p(this);
    p.setRenderHint(QPainter::Antialiasing);
    p.translate(width() / 2, height() / 2);
    int anglevalue = 0;
    QPen pen;
    pen.setColor(QColor("#646464A0"));
    pen.setWidth(4);
    p.setPen(pen);
    p.drawEllipse(QPoint(0,0),104,104);
    p.setPen(QColor("#636363"));
    p.drawEllipse(QPoint(0,0),105,105);

    p.setPen(QColor("#636363"));
    p.setBrush(Qt::black);
    p.drawEllipse(QPoint(0,0),100,100);

    p.setPen(QColor("#636363"));
    QLinearGradient lineargradient(0,-100,0,100);
    lineargradient.setColorAt(0,QColor("#FF005600"));
    lineargradient.setColorAt(0.5,QColor("#FF005600"));
    lineargradient.setColorAt(1,QColor("#00005600"));
    lineargradient.setSpread(QGradient::PadSpread);
    QBrush brush = QBrush(lineargradient);
    p.setBrush(brush);
    p.drawEllipse(QPoint(0,0),100,100);

    p.setPen(Qt::red);
    for (int i = 0; i < BigScale; ++i) {
    
        if (anglevalue < 60 || anglevalue > 120)
        {
    
            p.drawLine(85,0,100,0);
        }
        double angle = 360.00/BigScale;
        p.rotate(angle);
        anglevalue = anglevalue + angle;
    }

    anglevalue = 0;
    p.setPen(Qt::yellow);
    for (int i = 0; i < ModleScale; ++i) {
    
        if (anglevalue <= 60 || anglevalue >= 120)
        {
    
            if (i % 3 != 0)
                p.drawLine(90,0,100,0);
        }
        double angle = 360.00/ModleScale;
        p.rotate(angle);
        anglevalue = anglevalue + angle;
    }

    anglevalue = 0;
    p.setPen(Qt::white);
    for (int i = 0; i < SmallScale; ++i) {
    
        if (anglevalue < 60 || anglevalue > 120)
        {
    
            if (i % 5 != 0)
                p.drawLine(95,0,100,0);
        }
        double angle = 360.00/SmallScale;
        p.rotate(angle);
        anglevalue = anglevalue + angle;
    }

    anglevalue = 0;
    p.setPen(Qt::white);
    QStringList list;
    list<<"180"<<"210"<<"240"<<"270"<<"300"<<"330"<<"360"<<"30"<<"60"<<"90"<<"120"<<"150";
    for (int i = 0; i < ModleScale; ++i) {
    
        if (anglevalue >= 210 || anglevalue <= 150)
        {
    
            p.drawText(QRect(-8,-85,16,16),Qt::AlignHCenter,list[i]);
        }
        double angle = 360.00/ModleScale;
        p.rotate(angle);
        anglevalue = anglevalue + angle;
    }

    p.save();
    pen.setColor(Qt::gray);
    p.setPen(pen);
    QPoint points[3];
    points[0] = QPoint(-3,0);
    points[1] = QPoint(3,0);
    points[2] = QPoint(0,100);
    if (m_xangle < 30)
        m_xangle = 330;
    else if(m_xangle>330)
        m_xangle = 30;
    p.rotate(m_xangle);
    p.drawConvexPolygon(points,3);
    p.restore();

    QString val = QString("%1km/h").arg(m_xangle);
    pen.setColor(Qt::white);
    p.setPen(pen);
    p.setFont(QFont("微软雅黑",12,QFont::Bold,false));
    p.drawText(-50,40,100,40,Qt::AlignHCenter,val);

    //圆弧
    QConicalGradient conicalGradient(0,0,242);
    conicalGradient.setColorAt(0,QColor("#FFFF0000"));
    conicalGradient.setColorAt(0.5,QColor("#7DFF0000"));
    conicalGradient.setColorAt(0.75,QColor("#FF005600"));
    conicalGradient.setColorAt(1,QColor("#007D5600"));
    conicalGradient.setSpread(QGradient::PadSpread);
    pen = QPen(QBrush(conicalGradient),5);
    p.setPen(pen);
    QRect arcRect = QRect(-110,-110,220,220);
    double startAngle = 240 * 16;
    double spanAngle = -(m_xangle - 30) * 16;
    p.drawArc(arcRect,startAngle,spanAngle);
    qDebug()<<m_xangle;