Update the camera transform based on the new camera center.

def _update_camera(self, camera_center):
    """Update the camera transform based on the new camera center."""
    self._world_tl_to_world_camera_rel.offset = (
        -self._world_to_world_tl.fwd_pt(camera_center) *
        self._world_tl_to_world_camera_rel.scale)

    if self._feature_screen_px:
      camera_radius = (self._feature_screen_px / self._feature_screen_px.x *
                       self._feature_camera_width_world_units / 2)
      center = camera_center.bound(camera_radius,
                                   self._map_size - camera_radius)
      self._camera = point.Rect(
          (center - camera_radius).bound(self._map_size),
          (center + camera_radius).bound(self._map_size))