2 ;;;; beam.scm -- Beam scheme stuff
4 ;;;; source file of the GNU LilyPond music typesetter
6 ;;;; (c) 2000--2005 Jan Nieuwenhuizen <janneke@gnu.org>
10 ;; width in staff space.
12 (define (beam-flag-width-function type)
15 ((eq? type 1) 1.65) ;; FIXME: check what this should be and why
18 ;; There are several ways to calculate the direction of a beam
20 ;; * majority: number count of up or down notes
21 ;; * mean : mean centre distance of all notes
22 ;; * median : mean centre distance weighted per note
24 ;; [Ross] states that the majority of the notes dictates the
25 ;; direction (and not the mean of "center distance")
27 ;; But is that because it really looks better, or because he wants
28 ;; to provide some real simple hands-on rules?
30 ;; We have our doubts, so we simply provide all sensible alternatives.
34 ;; DOCME: what goes into this func, what comes out.
35 (define (dir-compare up down)
38 ;; arguments are in the form (up . down)
39 (define-public (beam-dir-majority count total)
40 (dir-compare (car count) (cdr count)))
42 (define-public (beam-dir-majority-median count total)
43 "First try majority. If that doesn't work, try median."
44 (let ((maj (dir-compare (car count) (cdr count))))
47 (beam-dir-median count total))))
49 (define-public (beam-dir-mean count total)
50 (dir-compare (car total) (cdr total)))
52 (define-public (beam-dir-median count total)
53 (if (and (> (car count) 0)
55 (dir-compare (/ (car total) (car count)) (/ (cdr total) (cdr count)))
56 (dir-compare (car count) (cdr count))))
58 (define ((check-beam-quant posl posr) beam)
59 "Check whether BEAM has POSL and POSR quants. POSL are (POSITION
60 . QUANT) pairs, where QUANT is -1 (hang), 0 (center), 1 (sit) or -2/ 2 (inter)
63 (let* ((posns (ly:grob-property beam 'positions))
64 (thick (ly:grob-property beam 'thickness))
65 (layout (ly:grob-layout beam))
66 (lthick (ly:output-def-lookup layout 'linethickness))
67 (staff-thick lthick) ; fixme.
68 (quant->coord (lambda (p q)
71 (+ p (- (* 0.5 q thick) (* 0.5 q lthick))))))
72 (want-l (quant->coord (car posl) (cdr posl)))
73 (want-r (quant->coord (car posr) (cdr posr)))
74 (almost-equal (lambda (x y) (< (abs (- x y)) 1e-3))))
76 (if (or (not (almost-equal want-l (car posns)))
77 (not (almost-equal want-r (cdr posns))))
79 (ly:warning (_ "Error in beam quanting. Expected (~S,~S) found ~S.")
81 (set! (ly:grob-property beam 'quant-score)
82 (format "(~S,~S)" want-l want-r)))
83 (set! (ly:grob-property beam 'quant-score) ""))))
85 (define ((check-beam-slope-sign comparison) beam)
86 "Check whether the slope of BEAM is correct wrt. COMPARISON."
87 (let* ((posns (ly:grob-property beam 'positions))
88 (slope-sign (- (cdr posns) (car posns)))
89 (correct (comparison slope-sign 0)))
93 (ly:warning (_ "Error in beam quanting. Expected ~S 0, found ~S.")
94 (procedure-name comparison) "0" slope-sign)
95 (set! (ly:grob-property beam 'quant-score)
96 (format "~S 0" (procedure-name comparison))))
97 (set! (ly:grob-property beam 'quant-score) ""))))
99 (define-public (check-quant-callbacks l r)
100 (list Beam::least_squares
103 Beam::shift_region_to_valid
105 (check-beam-quant l r)))
108 (define-public (check-slope-callbacks comparison)
109 (list Beam::least_squares
112 Beam::shift_region_to_valid
114 (check-beam-slope-sign comparison)))