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Flat ties

This snippet provides a function flared-tie to draw a tie that consist of straight lines. It is intended as a replacement for the default tie-drawing function (i.e., a replacement argument for the stencil property of the Tie grob).

The argument of flared-tie is a list of coordinate pairs that specify additional points between the first and last point to span up the tie’s lines. The first and last point are identical to the original tie’s start and end point, respectively. The X and Y coordinate values are multiples of the bounding box length and height of the original tie (also taking care of the tie’s direction); consequently, the first point has coordinates (0,0), and the last point (1,0).

The function flare-tie defines a shorthand for a flat tie. Further tweaking of the shape is possible by overriding Tie.details.height-limit or with \shape. It is also possible to change the custom definition on the fly.

#(define ((flared-tie coords) grob)
   (define (pair-to-list pair)
     (list (car pair) (cdr pair)))

   (define (normalize-coords goods x y dir)
     (map
      (lambda (coord)
        (cons (* x (car coord)) (* y dir (cdr coord))))
      goods))

   (define (my-c-p-s points thick)
     (make-connected-path-stencil points thick 1.0 1.0 #f #f))

   ;; Calling `ly:tie::print` and assigning its return value to a
   ;; variable in this outer `let` triggers LilyPond to position the
   ;; tie, allowing us to extract its extents.  We only proceed,
   ;; however, if the tie doesn't get discarded (for whatever reason).
   (let ((sten (ly:tie::print grob)))
     (if (grob::is-live? grob)
         (let* ((layout (ly:grob-layout grob))
                (line-thickness (ly:output-def-lookup layout
                                                      'line-thickness))
                (thickness (ly:grob-property grob 'thickness 0.1))
                (used-thick (* line-thickness thickness))
                (dir (ly:grob-property grob 'direction))
                (xex (ly:stencil-extent sten X))
                (yex (ly:stencil-extent sten Y))
                (lenx (interval-length xex))
                (leny (interval-length yex))
                (xtrans (car xex))
                (ytrans (if (> dir 0)(car yex) (cdr yex)))
                ;; Add last point.
                (coord-list (append coords '((1.0 . 0.0))))
                (uplist
                 (map pair-to-list
                      (normalize-coords coord-list lenx (* leny 2) dir))))
           (ly:stencil-translate
            (my-c-p-s uplist used-thick)
            (cons xtrans ytrans)))
         '())))

% Define a default tie shape consisting of three straight lines.
#(define flare-tie
   (flared-tie '((0.1 . 0.3) (0.9 . 0.3))))

\relative c' {
  a4~ a
  \once \override Tie.stencil = #flare-tie
  a4~ a \break

  <a c e a c e a c e>~ q
  \once \override Tie.stencil = #flare-tie
  q~ q\break

  <>^\markup \small \typewriter "height-limit = 14"
  \override Tie.details.height-limit = 14
  a'4~ a
  \once \override Tie.stencil = #flare-tie
  a4~ a \break

  <>^\markup \small \typewriter "height-limit = 0.5"
  \override Tie.details.height-limit = 0.5
  a4~ a
  \once \override Tie.stencil = #flare-tie
  a4~ a \break

  \revert Tie.details.height-limit

  <>^\markup \small \typewriter
             "\shape #'((0 . 0) (0 . -1) (0 . -1) (0 . 0))"
  \shape #'((0 . 0) (0 . -1) (0 . -1) (0 . 0)) Tie
  a4~ a
  \once \override Tie.stencil = #flare-tie
  \shape #'((0 . 0) (0 . -1) (0 . -1) (0 . 0)) Tie
  a4~ a \break

  <>^\markup \small \typewriter
             "#(flared-tie '((0.2 . 2) (0.5 . -3) (0.8 . 1))"
  \once \override Tie.stencil =
        #(flared-tie '((0.2 . 2) (0.5 . -3) (0.8 . 1)))
  a4~ a
  <>_\markup \small \typewriter
             "#(flared-tie '((0.5 . 2)))"
  \once \override Tie.stencil = #(flared-tie '((0.5 . 2)))
  a'4~ a
}