def cy2y(cy, e):
    """Transform from *y* index value to *y* index value, using the
    *e.css('ch')* (column height) as column measure."""
    if cy is None:
        y = 0
    else:
        if e.originTop:
            paddingY = e.pt
        else:
            paddingY = e.pb
        y = paddingY + cy * (e.css('ch', 0) + e.gh)
    return y
