Re: Directional NoteHead Stencil Support

[David Nalesnik]

Hi Abraham,

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

David,

You are a genius! I've almost got it, but I'm not sure how to handle rests. Here's my current function:

#(define (flipnotes grob)

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

     (for-each

       (lambda (note)

         (let* ((pitch (ly:event-property (event-cause note) 'pitch))

                (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)))

               )

           ))

       notes)))

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 '().

%%%%

#(define (flipnotes grob)

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

     (if (pair? 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)))

                  )

              ))

          notes)

         ; alternate return?

         

         )))

 

%%%%

If you get a rest, this function will return an unspecified value, so you might want to add another clause to the if-block if you need meaningful output.

Hope this helps!

David