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| ;;;; This file is part of LilyPond, the GNU music typesetter. | |
| ;;;; | |
| ;;;; Copyright (C) 2000--2020 Jan Nieuwenhuizen <[email protected]> | |
| ;;;; | |
| ;;;; LilyPond is free software: you can redistribute it and/or modify | |
| ;;;; it under the terms of the GNU General Public License as published by | |
| ;;;; the Free Software Foundation, either version 3 of the License, or | |
| ;;;; (at your option) any later version. | |
| ;;;; | |
| ;;;; LilyPond is distributed in the hope that it will be useful, | |
| ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| ;;;; GNU General Public License for more details. | |
| ;;;; | |
| ;;;; You should have received a copy of the GNU General Public License | |
| ;;;; along with LilyPond. If not, see <http://www.gnu.org/licenses/>. | |
| ;; Determine whether an auto beam should be extended to the right | |
| ;; of the current stem. We start anywhere, except mid-measure in | |
| ;; 3/4 time. We end according to the follwing rules, in order of | |
| ;; decreasing priority: | |
| ;; | |
| ;; 1. end <type> | |
| ;; 2. end <greater type> | |
| ;; 3. if 1-2 not specified, end at beatStructure intervals | |
| ;; | |
| ;; Rationale: | |
| ;; | |
| ;; [user override] | |
| ;; 1. override for specific duration type | |
| ;; 2. overrides apply to shorter durations | |
| ;; | |
| ;; defined in scm/time-signature-settings.scm: | |
| ;; 1. Default grouping for common time signatures | |
| (define-public (default-auto-beam-check context dir measure-pos test-beam) | |
| (define (get name default) | |
| (let ((value (ly:context-property context name))) | |
| (if (not (null? value)) value default))) | |
| (define (ending-moments group-list base-length) | |
| (let ((beat 0)) | |
| (map-in-order (lambda (x) | |
| (set! beat (+ beat x)) | |
| (* base-length beat)) | |
| group-list))) | |
| (define (larger-setting type sorted-alist) | |
| (assoc type sorted-alist <=)) | |
| (define (beat-end? moment beat-endings) | |
| (pair? (memv moment beat-endings))) ;; member returns a list if found, not #t | |
| ;; Start of actual auto-beam test routine | |
| ;; | |
| ;; | |
| ;; Don't start auto beams on grace notes | |
| (and (or (zero? (ly:moment-grace (ly:context-now context))) | |
| (!= dir START)) | |
| (let* ((base-length (cond ((get 'baseMoment #f) => ly:moment-main) | |
| (else 1/4))) | |
| (measure-length (cond ((get 'measureLength #f) => ly:moment-main) | |
| (else 1))) | |
| (time-signature-fraction | |
| (get 'timeSignatureFraction '(4 . 4))) | |
| (beat-structure (get 'beatStructure '(1 1 1 1))) | |
| (beat-endings (ending-moments beat-structure base-length)) | |
| (exceptions (sort (map | |
| (lambda (a) | |
| (if (pair? (car a)) | |
| (cons (/ (caar a) (cdar a)) | |
| (cdr a)) | |
| a)) | |
| (assoc-get 'end | |
| (get 'beamExceptions '()) | |
| '())) | |
| car<)) | |
| (function (if (= dir START) 'begin 'end)) | |
| (beam-half-measure (get 'beamHalfMeasure #t)) | |
| (type (ly:moment-main test-beam)) | |
| (non-grace (ly:moment-main measure-pos)) | |
| (pos (if (negative? non-grace) | |
| (+ measure-length non-grace) | |
| non-grace)) | |
| (type-grouping (assoc-get type exceptions '())) | |
| (default-rule (and (null? type-grouping) | |
| (larger-setting type exceptions))) | |
| (default-grouping (and default-rule (cdr default-rule))) | |
| (default-beat-length (and default-rule (car default-rule))) | |
| (exception-grouping (if (null? type-grouping) | |
| default-grouping | |
| type-grouping)) | |
| (grouping-moment (if (null? type-grouping) | |
| default-beat-length | |
| type)) | |
| (exception-moments (and exception-grouping | |
| (ending-moments | |
| exception-grouping grouping-moment)))) | |
| (if (= dir START) | |
| ;; Start rules -- #t if beam is allowed to start | |
| (or beam-half-measure ;; Start anywhere, but option for mid-measure | |
| (not (= (+ pos pos) measure-length)) | |
| (not (= 3 (car time-signature-fraction))) ;; in triple meter | |
| (not (= (denominator type) ;; when the beamed note is 1/6 of a measure | |
| (* 2 (cdr time-signature-fraction))))) | |
| ;; End rules -- #t if beam is required to end | |
| (or (zero? pos) ;; end at measure beginning | |
| (if exception-grouping | |
| (beat-end? pos exception-moments) ;; check exception rule | |
| (beat-end? pos beat-endings))))))) ;; no exception, so check beat ending | |
| (define-public (extract-beam-exceptions music) | |
| "Creates a value useful for setting @code{beamExceptions} from @var{music}." | |
| (define (car> a b) (> (car a) (car b))) | |
| (define (beatify! lst) | |
| ;; takes a collection of end points, sorts them, and returns the | |
| ;; non-zero differences as beaming pattern | |
| (let ((s (sort-list! lst <))) | |
| (remove! zero? | |
| (map - s (cons 0 s))))) | |
| (let ((res '())) | |
| (let analyze ((m (unfold-repeats-fully (event-chord-reduce music))) | |
| (pos 0)) | |
| ;; enter beam ends from m starting at pos into res, return new pos | |
| (cond ((music-is-of-type? m 'bar-check) 0) | |
| ((music-is-of-type? m 'simultaneous-music) | |
| (fold (lambda (m prev) (max (analyze m pos) prev)) | |
| pos | |
| (ly:music-property m 'elements))) | |
| ((not (music-is-of-type? m 'rhythmic-event)) | |
| (let ((elt (ly:music-property m 'element))) | |
| (fold analyze | |
| (if (ly:music? elt) (analyze elt pos) pos) | |
| (ly:music-property m 'elements)))) | |
| ;; Have rhythmic event. | |
| ((any | |
| (lambda (art) | |
| (and (music-is-of-type? art 'beam-event) | |
| (= (ly:music-property art 'span-direction START) STOP))) | |
| (ly:music-property m 'articulations)) | |
| (let* ((len (duration-length (ly:music-property m 'duration))) | |
| (pos (+ pos len)) | |
| (ass (assv len res))) | |
| (cond ((or (zero? len) (not (integer? (/ pos len)))) | |
| (ly:warning m (_ "Beam end fits no pattern"))) | |
| (ass | |
| (set-cdr! ass (cons (/ pos len) (cdr ass)))) | |
| (else | |
| (set! res (cons (list len (/ pos len)) res)))) | |
| pos)) | |
| (else | |
| (+ pos (duration-length (ly:music-property m 'duration)))))) | |
| ;; takes the output from the loop, generates actual beam exceptions | |
| (list | |
| (cons 'end | |
| (map! | |
| (lambda (l) | |
| (cons (car l) | |
| (beatify! (cdr l)))) | |
| (sort-list! res car>)))))) | |