def METHOD_NAME(self, action_state):
    pos = action_state.mouse_voxel_coordinates
    if pos is None:
        return
    patch_size = np.array((128, ) * 3, np.int64)
    spos = pos - patch_size // 2
    epos = spos + patch_size
    slice_expr = np.s_[int(spos[0]):int(epos[0]),
                       int(spos[1]):int(epos[1]),
                       int(spos[2]):int(epos[2])]
    gt_data = self.gt_vol[slice_expr][..., 0]
    boundary_mask = gt_data == 0
    boundary_mask[:, :, :-1] |= (gt_data[:, :, :-1] != gt_data[:, :, 1:])
    boundary_mask[:, :, 1:] |= (gt_data[:, :, :-1] != gt_data[:, :, 1:])
    boundary_mask[:, :-1, :] |= (gt_data[:, :-1, :] != gt_data[:, 1:, :])
    boundary_mask[:, 1:, :] |= (gt_data[:, :-1, :] != gt_data[:, 1:, :])
    boundary_mask[:-1, :, :] |= (gt_data[:-1, :, :] != gt_data[1:, :, :])
    boundary_mask[1:, :, :] |= (gt_data[:-1, :, :] != gt_data[1:, :, :])
    dist_transform = scipy.ndimage.morphology.distance_transform_edt(~boundary_mask)
    self.inf_results[slice_expr] = 1 + np.cast[np.uint8](
        np.minimum(dist_transform, 5) / 5.0 * 254)
    self.inf_volume.invalidate()