PyQt QPainter 如何应用抗锯齿？

有一个绘制的千分表。尽管在 Painter 存在的任何地方都应用了抗锯齿，但红色部分仍然存在深度不规则（毛刺）。此外，沿着半圆的边界还有黑色区域。如何去除它？

from PySide6.QtGui import QPainter, QColor, QPolygon, QPen, QPaintEvent, QConicalGradient, QGradient, QBrush, QRegion, QResizeEvent
from PySide6.QtCore import Signal, QSize, QRect, QPoint, Qt
from PySide6.QtWidgets import QWidget, QSizePolicy, QLabel
from typing import List, Tuple
import numpy


class ArrowPointerIndicator(QWidget):

    def __init__(self,
                 chunks: List[Tuple[float, QColor]],
                 lineWidth: int = 5,
                 parent: QWidget = None) ->None:
        super().__init__(parent)
        self.__arrowColor: QColor = QColor(255, 0, 0)
        self.__gradient: QGradient = None
        self.setChunks(chunks)
        self.__arrow = QPolygon([
            QPoint(-2, -80),
            QPoint(0, -100),
            QPoint(2, -80),
            QPoint(2, 10),
            QPoint(-2, 10),
            QPoint(-2, -80)
        ])
        self.__minimum = -10.0
        self.__maximum = 10.0
        self.__lineWidth = lineWidth
        self.__value: float = 0.0

    def arrowColor(self) ->QColor:
        return self.__arrowColor

    def setArrowColor(self, arrowColor: QColor) ->QColor:
        if self.__arrowColor == arrowColor:
            return
        self.__arrowColor = arrowColor
        self.update()

    def setChunks(self, chunks: List[Tuple[float, QColor]]) ->None:
        weightsSum: float = sum(item[0] for item in chunks)
        chunks = [(item[0] / weightsSum / 2, item[1]) for item in chunks]
        self.__gradient = QConicalGradient()
        passedWeight = 0.25
        for weight, color in chunks:
            self.__gradient.setColorAt(passedWeight, color)
            self.__gradient.setColorAt(passedWeight + weight - 0.0000000001, color)
            passedWeight += weight
        self.__gradient.setCenter(QPoint(0, 0))
        self.__gradient.setAngle(-90)
        self.update()

    def paintEvent(self, event: QPaintEvent) ->None:
        super().paintEvent(event)
        drawSize = min(self.width() / 2, self.height())
        painter = QPainter(self)
        painter.translate(self.width() / 2, self.height())
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        self.__drawColorArc(drawSize, painter)
        self.__drawArrowPointer(drawSize, painter)

    def __drawColorArc(self, drawSize: int, painter: QPainter) ->None:
        drawingRect = QRect(-drawSize, -drawSize, 2 * drawSize, 2 * drawSize)
        excludeRect = QRect(-drawSize + self.__lineWidth, -drawSize + self.__lineWidth, 2 * (drawSize - self.__lineWidth), 2 * (drawSize - self.__lineWidth))
        painter.save()
        outerRegion = QRegion(drawingRect, QRegion.RegionType.Ellipse).subtracted(QRegion(excludeRect, QRegion.RegionType.Ellipse))
        painter.setClipRegion(outerRegion)
        painter.setBrush(QBrush(self.__gradient))
        painter.drawChord(drawingRect, 0, 180 * 16)
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        painter.restore()

    def __drawArrowPointer(self, drawSize: int, painter: QPainter) ->None:
        painter.save()
        painter.setBrush(self.__arrowColor)
        painter.scale(drawSize / 100.0, drawSize / 100.0)
        painter.drawConvexPolygon(self.__arrow)
        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
        painter.restore()


if __name__ == '__main__':
    from PySide6.QtWidgets import QApplication
    import sys
    app = QApplication(sys.argv)
    window = ArrowPointerIndicator(
            chunks=[
                (4, Qt.GlobalColor.white),
                (1, Qt.GlobalColor.red),
                (1, Qt.GlobalColor.white),
                (1, Qt.GlobalColor.red),
                (4, Qt.GlobalColor.white),
        ], lineWidth=1000000)
    window.show()
    sys.exit(app.exec())