def place(self, center, radius):
        """Place Arcball, e.g. when window size changes.

        center : sequence[2]
            Window coordinates of trackball center.
        radius : float
            Radius of trackball in window coordinates.

        """
        self._radius = float(radius)
        self._center[0] = center[0]
        self._center[1] = center[1]
Place Arcball, e.g. when window size changes.

        center : sequence[2]
            Window coordinates of trackball center.
        radius : float
            Radius of trackball in window coordinates.

        
deploy/helpers/transformations.py