New snippet from a previous discussion on the list

(... aaand the LSR is down again...)

diff --git a/input/new/coloring-notes-depending-on-their-pitch.ly b/input/new/coloring-notes-depending-on-their-pitch.ly
new file mode 100644 (file)
index 0000000..dd29c94
--- /dev/null
+++ b/input/new/coloring-notes-depending-on-their-pitch.ly
@@ -0,0 +1,52 @@
+\version "2.11.61"
+\header {
+  lsrtags = "pitches,editorial-annotations,really-cool"
+  texidoc = "
+It is possible to color note heads depending on their pitch and/or their names:
+the function used in this example even makes it possible to distinguish enharmonics.
+"
+  doctitle = "Coloring notes depending on their pitch"
+}
+
+%LSR Thanks a LOT to Damian leGassick, Steven Weber and Jay Anderson for this snippet
+
+%Association list of pitches to colors.
+#(define color-mapping
+ (list
+   (cons (ly:make-pitch 0 0 0) (x11-color 'red))
+   (cons (ly:make-pitch 0 0 1/2) (x11-color 'green))
+   (cons (ly:make-pitch 0 1 -1/2) (x11-color 'green))
+   (cons (ly:make-pitch 0 2 0) (x11-color 'red))
+   (cons (ly:make-pitch 0 2 1/2) (x11-color 'green))
+   (cons (ly:make-pitch 0 3 -1/2) (x11-color 'red))
+   (cons (ly:make-pitch 0 3 0) (x11-color 'green))
+   (cons (ly:make-pitch 0 4 1/2) (x11-color 'red))
+   (cons (ly:make-pitch 0 5 0) (x11-color 'green))
+   (cons (ly:make-pitch 0 5 -1/2) (x11-color 'red))
+   (cons (ly:make-pitch 0 6 1/2) (x11-color 'red))
+   (cons (ly:make-pitch 0 1 0) (x11-color 'blue))
+   (cons (ly:make-pitch 0 3 1/2) (x11-color 'blue))
+   (cons (ly:make-pitch 0 4 -1/2) (x11-color 'blue))
+   (cons (ly:make-pitch 0 5 1/2) (x11-color 'blue))
+   (cons (ly:make-pitch 0 6 -1/2) (x11-color 'blue))
+   ))
+
+%Compare pitch and alteration (not octave).
+#(define (pitch-equals? p1 p2)
+ (and (= (ly:pitch-alteration p1) (ly:pitch-alteration p2))
+      (= (ly:pitch-notename p1) (ly:pitch-notename p2))))
+
+#(define (pitch-to-color pitch)
+ (let ((color (assoc pitch color-mapping pitch-equals?)))
+   (if color (cdr color))))
+
+#(define (color-notehead grob)
+ (pitch-to-color (ly:event-property (ly:grob-property grob 'cause) 'pitch)))
+
+
+\score {
+ \new Staff \relative c' {
+   \override NoteHead #'color = #color-notehead
+   c8 b d dis ees f g aes
+ }
+}