Qt 绘制圆环，圆环外再绘制一个动态的椭圆。 - QTCN开发网

void RingWidget::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event);
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);

    QRadialGradient gradient(0, 0, height()/2);
    gradient.setColorAt(0, qRgb(3,139, 153));
    gradient.setColorAt(1.0, qRgb(169, 238, 125));
    painter.setBrush(gradient);

    int m_persent = 90;//绘制的环的比例
    int m_rotateAngle = 360*m_persent/100;
    int side = qMin(width(), height());
    QRectF ouRect(0, 0, side, side);//矩形长宽为窗口的长宽d
    QRectF inRect(20, 20, side-40, side-40);

    //画外圆
    painter.setPen(Qt::NoPen);
    //p.setBrush(QBrush(QColor(97, 117, 118)));
    painter.drawEllipse(ouRect);
    //画内圆
    //p.setBrush(QBrush(QColor(255, 107, 107)));
    painter.drawPie(ouRect, (90-m_rotateAngle)*16, m_rotateAngle*16);
    //画遮罩，遮罩颜色为窗口颜色
    painter.setBrush(palette().window().color());
    painter.drawEllipse(inRect);

    //画文字
    QFont f = QFont("Microsoft YaHei", 15, QFont::Bold);
    painter.setFont(f);
    painter.setPen(Qt::white);
    painter.drawText(inRect, Qt::AlignCenter, m_strDescribe);
}