''' Purpose: support image mirroring transformation
'''

def mirror( nspot, nw, nh ) :
    ''' Returns the correspondent of nspot in its nw x ny image
        in the unmirrored original
    '''
    # we are trying to find where to look in the original image for our pixel location of interest
    # in the new image, we are reversing left and right
    # if we are nx from the left in the new image, we want to be nx from the right in the original image
    # this will be reversed for flip.py, you'll be reversing up and down
    nx, ny = nspot # unpack nx, ny
    # ox needs to be nx from the right hand side of the original image ( our image is nw pixels wide ), nw-1 is our right hand side
    ox = ( nw - 1 ) - nx
    oy = ny # since our y value is unchanged, oy = ny
    ospot = ( ox, oy ) # working backwards, now we know we're calculating ox and oy values
    return ospot

if ( __name__ == '__main__' ) :

    import url
    from manip import manip
    
    # get web image of interest
    link = "http://www.cs.virginia.edu/~cs1112/images/mandrill/full.png"

    original = url.get_image( link )

    new_image = manip( original, at=mirror ) # we want to use the same size and color, but only alter the location
                                # so we only have to specify one of the optional parameters for the manip() function
    new_image.show()