RE: Notehead color on programmed pitch change

[Peter Gentry]

Thankyou  David but how is color  associated with NoteHead?

 

I hope these ramblings of a gnarled old scheme/Lily tyro can be of general interest....

 

I'm guessing that 'tweaks is some sort of switch to open up properties of the current music object.

 

In this case "pitch" is a property of  'NoteEvent and I'm guessing that color here is just NoteHead colour not NoteStem because NoteStem is not within the NoteEvent including 'pitch.

 

NoteStem color may be available in a tweak of another music object or possibly supplied by another bit of code (engraver??).

I do not know how code a "tweak" for stem color (apart from an override in the Lily .ly file) maybe you can't (anyway I don't want to).

 

Also AFSIU "ly:music-property" extracts various elements of the current music item (possibly contained in  a deeper Lily code), and allows user scheme to extract data from the current music object.

 

ly:music-set-property! does the reverse?

This part of my script kindly supplied by Thomas Morley

(if (ly:pitch? p)
(let ((new-pitch (naturalize-instrument-range p instrument)))
(ly:music-set-property! music 'pitch new-pitch)
(if (and (not (equal? p new-pitch)) (color? my-color))
(ly:music-set-property! music 'tweaks
(acons
'color my-color
(ly:music-property music 'tweaks))))))

In line 3 a pitch is written to the music event it may be the old pitch or a new pitch.

In line 4 further action is taken if the pitch has been changed, first the variable my-color (previously defined) is type checked

In line 5 'tweaks is inserted into the current music object.

lines 6 - 8 are a bit obscure somehow the current color is replaced by my-color but how?

 

Cannot find a definition for acons but it must be a variant of cons ("consists") it occurs 8 times in snippets and once in notation and is clearly the way to "tweak" associating the Lily 'color with the user supplied color my-color.

Rather confusingly the format of color has many guises (x11-color 'red), (1 0 0), simply 'red (no pun intended) and notehead colour can also be approached via a grob. The notehead grob must be somehow implied in the (make-music .....

Various different approaches to Notehead color are evident in the snippet repositry agin not much detailed explanation is to be found.

 

upline =

#(let ((m (make-articulation "stopped")))

(set! (ly:music-property m 'tweaks)

(acons 'font-size 3

(acons 'stencil (lambda (grob)

(grob-interpret-markup

grob

(make-draw-line-markup '(0 . 1))))

(ly:music-property m 'tweaks))))

m)

\relative c' {

a'4^\upline a( c d')_\upline

}

 

 

which results in

 

(make-music

'RelativeOctaveMusic

'element

(make-music

'SequentialMusic

'elements

(list (make-music

'NoteEvent

'articulations

(list (make-music

'ArticulationEvent

'direction

1

'tweaks

(list (cons (quote font-size) 3)

(cons (quote stencil) #<procedure #f (grob)>))

'articulation-type

"stopped"))

'duration

(ly:make-duration 2)

'pitch

(ly:make-pitch 0 5))

(make-music

'NoteEvent

'articulations

(list (make-music

'SlurEvent

'span-direction

-1))

'duration

(ly:make-duration 2)

'pitch

(ly:make-pitch 0 5))

(make-music

'NoteEvent

'pitch

(ly:make-pitch 1 0)

'duration

(ly:make-duration 2))

(make-music

'NoteEvent

'articulations

(list (make-music

'SlurEvent

'span-direction

1)

(make-music

'ArticulationEvent

'direction

-1

'tweaks

(list (cons (quote font-size) 3)

(cons (quote stencil) #<procedure #f (grob)>))

'articulation-type

"stopped"))

'duration

(ly:make-duration 2)

'pitch

(ly:make-pitch 2 1)))))

 

AFAICS tweaks are not documented properly anywhere - some of the possible tweaks are presented without detailed explanation in the notation and snippet manuals - is there another source of information?

 

 

---

From: David Nalesnik [mailto:address@hidden
Sent: Wednesday, May 27, 2015 5:51 PM
To: Peter Gentry
Cc: lilypond-user; Thomas Morley
Subject: Re: Notehead color on programmed pitch change

On Wed, May 27, 2015 at 4:15 AM, Peter Gentry <address@hidden> wrote:

[...]

(make-music
  'SequentialMusic
  'elements
  (list (make-music
          'NoteEvent
          'duration
          (ly:make-duration 0)
          'pitch
          (ly:make-pitch 0 0))
        (make-music
          'NoteEvent
          'tweaks
          (list (list (quote color) 1.0 0.0 0.0))

[...]

 

Still not sure how to interpret (list (list....... But as long as Lily does.....:)

We're simply creating a nested list: 

(list (quote color) 1.0 0.0 0.0)

==>

(color 1.0 0.0 0.0)

(list (list (quote color) 1.0 0.0 0.0))

==>

((color 1.0 0.0 0.0))

By the way, (quote color) is just "longhand" for 'color

Hope that helps,

David