Paste: useful image words?

USING: byte-arrays combinator images kernel locals
sequences ;
IN: images ! ?
:: crop ( image loc dim -- image' )
    loc first2 :> ( x y )
    dim first2 :> ( w h )
    y h y + [a,b) [ x swap w image pixel-row-slice-at ] map
    [ >byte-array ] map concat
    image clone
        swap >>bitmap
        dim >>dim ;

USING: cairo cairo.ffi combinators destructors images
images.normalization kernel ;
IN: cairo ! ?
: write-png ( image filename -- )
    [
        [
            clone BGRA reorder-components
            [ bitmap>> ] [ dim>> ] bi
            <image-surface> &cairo_surface_destroy
        ] dip
        cairo_surface_write_to_png
        dup CAIRO_STATUS_SUCCESS = not [ throw ] [ drop ] if
    ] with-destructors ;