<MDSpinner>
    canvas.before:
        PushMatrix
        Rotate:
            angle: self._rotation_angle
            origin: self.center
    canvas:
        Color:
            rgba: self.color if self.color else self.theme_cls.primary_color
            a: self._alpha
        SmoothLine:
            cap: 'square'
            width: root.line_width
            circle:
                self.center_x, self.center_y, self.width / 2, \
                self._angle_start, self._angle_end
    canvas.after:
        PopMatrix