textspanner arrowed line

[Jonatan Liljedahl]

I'm trying to make an arrowed line textspanner, I'm almost there...
The problem is that the arrow is attached to the whole spanner including
the text. I wish to attach it only to the line, which means that it is
the Line_spanner::print function I should hook. But how do I do that?
How do I get to the TextSpanners line print function?

\version "2.5.18"
%TODO arrow on textspanner line
#(define (arr-callback callback)
   (define (arr-stencil grob)
     (let* ((s (callback grob))
            (sx (ly:stencil-extent s 0))
            (sy (ly:stencil-extent s 1))
            (arr (ly:make-stencil
             (list 'polygon ''(0 0.4 1.2 0 0 -0.4) 0.1)
             '(0 . -0.4)
             '(1.2 . 0.4))))
             
;        (set! s (ly:stencil-add s arr))
        (set! s (ly:stencil-combine-at-edge s 0 1 arr 0))
        s
       ))
   arr-stencil)

\relative c' {
    \override TextSpanner  #'edge-text = #'("bridge" . "board")
    \override TextSpanner  #'dash-fraction = #'()
    \override TextSpanner  #'style = #'line
%    \override TextSpanner  #'print-function = #(arr-callback
Line_spanner::print)
    \override TextSpanner  #'print-function = #(arr-callback
Text_spanner::print)
    a8\startTextSpan gis8 a2.
    c4 c c\stopTextSpan c
    
}
%%%%%%%%%%%%%%%%%%%%%%%%

/Jonatan    -=( http://kymatica.com )=-