\version "2.19.23"

#(define (key-signature::special-print alt-color-list)
   (lambda (grob)
     (let* ((inter (/ (ly:staff-symbol-staff-space grob) 2.0))
            (mol empty-stencil)
            (c0s (ly:grob-property grob 'c0-position))
            (is-cancellation? (grob::has-interface grob 'key-cancellation-interface))
            (pos empty-interval)
            (overlapping-pos empty-interval)
            (padding-pairs (ly:grob-property grob 'padding-pairs))
            (fm (ly:grob-default-font grob))
            (alist (ly:grob-property grob 'glyph-name-alist)))
       (let loop ((s (ly:grob-property grob 'alteration-alist))
                  (stil mol)
                  (last-glyph-name #f))
         (if (pair? s)
             (let* ((alt (if is-cancellation? 0 (cdar s)))
                    (glyph-name (ly:assoc-get alt alist)))
               (if (not (string? glyph-name))
                   (begin
                    (ly:warning "No glyph found for alteration: ~a" alt)
                    (loop (cdr s) stil last-glyph-name))
                   (let ((acc (ly:font-get-glyph fm glyph-name)))
                     (if (equal? acc empty-stencil)
                         (begin 
                          (ly:warning "alteration not found")
                          (loop (cdr s) stil last-glyph-name))
                         (let ((column empty-stencil)
                               (pos empty-interval))
                           (let inner ((pos-list
                                        (key-signature-interface::alteration-positions
                                         (car s) c0s grob)))
                             (if (pair? pos-list)
                                 (let* ((p (car pos-list))
                                        (color (assoc-get p alt-color-list))
                                        (acc
                                         (if (color? color)
                                             (stencil-with-color acc color)
                                             acc)))
                                   (set! pos (add-point pos p))
                                   (set! column
                                         (ly:stencil-add column
                                           (ly:stencil-translate-axis acc (* p inter) Y)))
                                   (inner (cdr pos-list))))
                             (let* ((padding (ly:grob-property grob 'padding 0.0))
                                    (handle (assoc (cons glyph-name last-glyph-name) padding-pairs))
                                    (padding
                                     (cond
                                      ((pair? handle) (cdr handle))
                                      ((and
                                        (string=? glyph-name "accidentals.natural")
                                        (not (interval-empty?
                                              (interval-intersection overlapping-pos pos))))
                                       (+ padding 0.3))
                                      (else padding))))
                         
                               (set! pos (interval-widen pos 4))
                               (set! overlapping-pos (coord-translate pos 2))
                               (loop (cdr s)
                                 (ly:stencil-combine-at-edge
                                  stil
                                  X
                                  LEFT
                                  column
                                  padding)
                                 glyph-name))))))))
             (ly:stencil-aligned-to stil X LEFT))))))

music =
{
  \key ces \major
  ces'1
  \key a \major
  a'1
  \key g \major
  g'1
  
  \override Staff.KeySignature.flat-positions = #'((-5 . 5))
  \override Staff.KeyCancellation.flat-positions = #'((-5 . 5))
  \clef bass \key es \major es g bes d
  \clef treble \bar "||" \key es \major es g bes d

  \override Staff.KeySignature.sharp-positions = #'(2)
  \bar "||" \key b \major b fis b2
  \override Staff.KeySignature.padding-pairs = #'((("accidentals.flat" . "accidentals.sharp") . 2)) 
  \set Staff.keyAlterations = #`(((0 . 6) . ,FLAT)
                                 ((0 . 5) . ,FLAT)
                                 ((0 . 3) . ,SHARP))
  c4 d e fis
  aes4 bes c'1
}

%% DEFAULT:

{
  \music
}

%% WITH OVERRIDES:

{
  \override Staff.KeySignature.stencil =
  #(key-signature::special-print `((4 . ,green) (-3 . ,red) (1 . ,blue)))

  \override Staff.KeyCancellation.stencil =
  #(key-signature::special-print `((-3 . ,magenta) (1 . ,cyan)))

  \music
}