let bsize = (size as isize) + (EDGE_PRE as isize) + (EDGE_POST as isize);
let ref_x = (xpos as isize) + ((mvx >> 3) as isize) - (EDGE_PRE as isize);
let ref_y = (ypos as isize) + ((mvy >> 3) as isize) - (EDGE_PRE as isize);
let bsize = (size as isize) + (EDGE_PRE as isize) + (EDGE_POST as isize);
let ref_x = (xpos as isize) + ((mvx >> 3) as isize) - (EDGE_PRE as isize);
let ref_y = (ypos as isize) + ((mvy >> 3) as isize) - (EDGE_PRE as isize);