def paintEvent(self, a0: QPaintEvent) -> None:
        super().paintEvent(a0)
        painter = QPainter(self)
        painter.save()
        painter.setRenderHint(QPainter.Antialiasing)
        pen2 = QPen()

        rect = QRectF(self.margin,
                      self.height() / 2,
                      self.width() - self.margin * 2,
                      self.height() / 2 - self.margin)
        rect2 = QRectF(3 * self.margin, 2 * self.margin,
                       self.width() - self.margin * 6, self.height())

        pen2.setWidth(6)
        painter.setPen(pen2)
        painter.drawArc(rect2, 0, 180 * 16)
        pen2.setWidth(3)
        pen2.setColor(Qt.white)
        painter.setPen(pen2)
        painter.drawArc(rect2, 0, 180 * 16)

        painter.fillRect(rect, Qt.white)
        pen2.setWidth(2)
        pen2.setColor(Qt.black)
        painter.setPen(pen2)
        painter.drawRect(rect)

        painter.restore()
 def drawValue(self, p: QPainter, baseRect: QRectF, value: float, delta: float):
     if value == self.m_min:
         return
     if self.m_barStyle == self.BarStyle.EXPAND:
         p.setBrush(self.palette().highlight())
         p.setPen(QPen(self.palette().shadow().color(), self.m_dataPenWidth))
         radius = (baseRect.height() / 2) / delta
         p.drawEllipse(baseRect.center(), radius, radius)
         return
     if self.m_barStyle == self.BarStyle.LINE:
         p.setPen(QPen(self.palette().highlight().color(), self.m_dataPenWidth))
         p.setBrush(Qt.NoBrush)
         if value == self.m_max:
             p.drawEllipse(baseRect.adjusted(self.m_outlinePenWidth / 2, self.m_outlinePenWidth / 2,
                                             -self.m_outlinePenWidth / 2, -self.m_outlinePenWidth / 2))
         else:
             arcLength = 360 / delta
             p.drawArc(baseRect.adjusted(self.m_outlinePenWidth / 2, self.m_outlinePenWidth / 2,
                                         -self.m_outlinePenWidth / 2, -self.m_outlinePenWidth / 2),
                       int(self.m_nullPosition * 16),
                       int(-arcLength * 16))
         return
     dataPath = QPainterPath()
     dataPath.setFillRule(Qt.WindingFill)
     if value == self.m_max:
         dataPath.addEllipse(baseRect)
     else:
         arcLength = 360 / delta
         dataPath.moveTo(baseRect.center())
         dataPath.arcTo(baseRect, self.m_nullPosition, -arcLength)
         dataPath.lineTo(baseRect.center())
     p.setBrush(self.palette().highlight())
     p.setPen(QPen(self.palette().shadow().color(), self.m_dataPenWidth))
     p.drawPath(dataPath)