A subclass of QtWidgets.QGraphicsDropShadowEffect which accounts for view scaling.

shadow_effect.py

from PySide6 import QtWidgets, QtCore


class SceneSpaceShadowEffect(QtWidgets.QGraphicsDropShadowEffect):
    """
    A drop shadow effect which takes the scene space size into account.
    """

    def __init__(self, parent=None):
        super().__init__(parent=parent)
        self._blur_radius = super().blurRadius()
        self._offset = super().offset()

    def blurRadius(self):
        return self._blur_radius

    def offset(self):
        return self._offset

    def setBlurRadius(self, value: float):
        self._blur_radius = value

    def setOffset(self, value: QtCore.QPointF):
        self._offset = value

    def draw(self, painter):
        super().setOffset(self._offset * painter.transform().m11())
        super().setBlurRadius(self._blur_radius * painter.transform().m11())
        super().draw(painter)