Bresenham line doesn't terminate

I've implemented the Bresenham algorithm from Wikipedia in python but for some lines it doesn't work, like from 1,0 to 0,1 it doesn't stop and keep开发者_开发技巧s going on to make a super long line

def line(x0, y0, x1, y1):
    dx = x1 - x0
    dy = y1 - y0
    sx = x0 < x1 and 1 or -1
    sy = y0 < y1 and 1 or -1
    err = dx - dy

    points = []
    x, y = x0, y0
    while True:
        points += [(x, y)]
        if x == x1 and y == y1:
            break
        e2 = err * 2
        if e2 > -dy:
            err -= dy
            x += sx
        if e2 < dx:
            err += dx
            y += sy
    return points

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You are missing the call to abs in the initialization of dx and dy:

dx = abs(x1 - x0)
dy = abs(y1 - y0)

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You have a type in "if e2 > -dy:". The minus sign is wrong.