def to_world_canvas(world_point, canvas_extents, world_extents):
    """Transforms a point from world coord system to world canvas coord system."""
    x = int(world_point[0] / world_extents[0] * canvas_extents[0])
    y = int(canvas_extents[1] - 1 - world_point[1] / world_extents[1] * canvas_extents[1])
    return (x, y)