Re: Making espressivo longer

[Aaron Hill]

On 2019-01-22 5:30 pm, Andrew Bernard wrote:
> Hi Ben,
>
> Yes this is the code in the list archives that I was referring to in my
> initial mail. My question was actually not so much how to achieve this, 
> but
> whether a technique for this has been incorporated into lilypond more
> recently, similar to how hairpins can now be adjusted with the 
> shorten-pair
> technique common to other objects.
>
> The problem I have with this code is that, finding that it works, I 
> altered
> it to allow scaling in the vertical axis as well, but that is highly
> unsatisfactory as the line width gets scaled as well - perhaps why the 
> code
> omitted that feature to begin with.
>
> Espressivo marks are just hairpin-like objects, and I suppose I can 
> just
> revert to using hairpins, but it's a bit annoying as you have to make a
> separate voice for the hairpins to start and finish on non-existent 
> notes.

Would the following help you?

%%%%
\version "2.19.82"

#(define (assoc-list? arg) (and (list? arg) (every pair? arg)))
espressivoII = #(define-event-function (args) (assoc-list?)
  (define (make-espressivo-stencil thick width height gap)
    (let* ((inner (/ gap 2))
           (outer (+ width inner))
           (middle (/ height 2)))
      (ly:stencil-add
        (make-line-stencil thick (- inner) 0 (- outer) middle)
        (make-line-stencil thick (- outer) middle (- inner) height)
        (make-line-stencil thick inner 0 outer middle)
        (make-line-stencil thick outer middle inner height))))
  (let ((thick (ly:assoc-get 'thick args 0.12))
        (width (ly:assoc-get 'width args 1.7))
        (height (ly:assoc-get 'height args 0.9))
        (gap (ly:assoc-get 'gap args 0.35)))
    #{ \tweak stencil #(lambda (grob)
         (make-espressivo-stencil thick width height gap))
       \espressivo #}))

{ b'4 \espressivo
  b'4 \espressivoII #'()
  b'4 \espressivoII #'((width . 3.4))
  b'4 \espressivoII #'((thick . 0.24)(gap . 0.7)) }
%%%%

I followed the pattern of \shape and \shapeII for the naming, but I 
opted for an association list for the arguments.  It is more verbose, 
but it makes it easy to support default values for those that are not 
specified.

The MetaFont code for the 'scripts.espr' glyph was a little tedious to 
reverse engineer.  So, I tried my best to match the original glyph with 
the default values provided.  I am sure there could be some 
improvements.

NOTE: I could not find a predicate for an association list, so I 
provided one here.  If I overlooked something that already exists, then 
we should swap out the predicate for that one.

-- Aaron Hill

espressivo.cropped.png
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