Re: Directional NoteHead Stencil Support

[David Nalesnik]

On Sat, Mar 21, 2015 at 10:06 PM, David Nalesnik <address@hidden> wrote:

Hi Abraham,

On Sat, Mar 21, 2015 at 9:13 PM, tisimst <address@hidden> wrote:

David,

[...]

 

This works perfectly when there are NO rests, but I get this error when there is a rest in the NoteColumn:

In procedure ly:grob-array->list in _expression_ (ly:grob-array->list (ly:grob-object grob #)): Wrong type argument in position 1 (expecting Grob_array): ()

Glad I could help!

If there's a rest, then the note-heads array will be empty.  To make this work, just add a check that the note-heads list isn't the empty list '().

 Oh, shoot!  It's past my bedtime...

The error happens because you're applying ly:grob-array->list to that grob-array which is empty when there's a rest.  So the check has to be before the conversion to a list:

#(define (flipnotes grob)

   (let ((notes (ly:grob-object grob 'note-heads)))

     (if (ly:grob-array? notes)

         (for-each

          (lambda (note)

            (let* (;(pitch (ly:event-property (event-cause note) 'pitch)) ;; don't need this

                   (stem (ly:grob-object note 'stem))

                   (dir (ly:grob-property stem 'direction))

                   (offset (ly:grob-relative-coordinate note grob X)))

              (if (eq? dir DOWN)

                  (if (and (< offset 0.1) (> offset -0.1))

                      (ly:grob-set-property! note 'rotation '(180 0 0))

                      (ly:grob-set-property! note 'rotation '(0 0 0)))

                  (if (and (< offset 0.1) (> offset -0.1))

                      (ly:grob-set-property! note 'rotation '(0 0 0))

                      (ly:grob-set-property! note 'rotation '(180 0 0)))

                  )

              ))

          (ly:grob-array->list notes))

         ; alternate return?

         

         )))

--David