'Update the cached drop shadow pixmap.'

def _updateShadowPixmap(self):

    rect_size = QSize(*CACHED_SHADOW_RECT_SIZE)
    (left, top, right, bottom) = self.getContentsMargins()
    pixmap_size = QSize(((rect_size.width() + left) + right), ((rect_size.height() + top) + bottom))
    shadow_rect = QRect(QPoint(left, top), rect_size)
    pixmap = QPixmap(pixmap_size)
    pixmap.fill(QColor(0, 0, 0, 0))
    rect_fill_color = self.palette().color(QPalette.Window)
    pixmap = render_drop_shadow_frame(pixmap, QRectF(shadow_rect), shadow_color=self.color, offset=self.offset, radius=self.radius, rect_fill_color=rect_fill_color)
    self._shadowPixmap = pixmap
