1 ;;;; layout-page-layout.scm -- page breaking and page layout
3 ;;;; source file of the GNU LilyPond music typesetter
5 ;;;; (c) 2004--2009 Jan Nieuwenhuizen <janneke@gnu.org>
6 ;;;; Han-Wen Nienhuys <hanwen@xs4all.nl>
8 (define-module (scm layout-page-layout)
9 #:use-module (srfi srfi-1)
10 #:use-module (oop goops describe)
11 #:use-module (oop goops)
12 #:use-module (scm paper-system)
13 #:use-module (scm page)
14 #:use-module (scm layout-page-dump)
16 #:export (post-process-pages optimal-page-breaks make-page-from-systems
18 stretchable-line? ; delete me
19 ;; utilities for writing custom page breaking functions
20 line-height line-next-space line-next-padding
21 line-minimum-distance line-ideal-distance
23 line-ideal-relative-position line-minimum-relative-position
24 page-maximum-space-to-fill page-maximum-space-left space-systems))
26 ; this is for 2-pass spacing. Delete me.
27 (define (stretchable-line? line)
28 "Say whether a system can be stretched."
29 (not (or (ly:prob-property? line 'is-title)
30 (let ((system-extent (paper-system-staff-extents line)))
31 (= (interval-start system-extent)
32 (interval-end system-extent))))))
34 (define (stretch-and-draw-page paper-book systems page-number ragged
35 is-last-bookpart is-bookpart-last-page)
36 (define (max-stretch sys)
38 (ly:grob-property sys 'max-stretch)
41 (define (stretchable? sys)
43 (> (max-stretch sys) 0.0)))
45 (define (height-estimate sys)
48 (ly:grob-property sys 'pure-Y-extent)
49 (paper-system-extent sys Y))))
51 (define (print-system sys)
56 (define (set-line-stretch! sorted-lines rest-height space-left)
57 (if (not (null? sorted-lines))
58 (let* ((line (first sorted-lines))
59 (height (height-estimate line))
60 (stretch (min (max-stretch line)
61 (if (positive? rest-height)
62 (/ (* height space-left) rest-height)
64 (if (stretchable? line)
65 (ly:system-stretch line stretch))
66 (set-line-stretch! (cdr sorted-lines)
67 (if (stretchable? line)
68 (- rest-height height)
70 (- space-left stretch)))))
72 (define (total-padding systems)
73 (let ((layout (ly:paper-book-paper paper-book)))
74 (if (or (null? systems)
75 (null? (cdr systems)))
77 (+ (line-next-padding (car systems) (cadr systems) layout)
78 (total-padding (cdr systems))))))
80 (let* ((page (make-page paper-book
81 'page-number page-number
82 'is-last-bookpart is-last-bookpart
83 'is-bookpart-last-page is-bookpart-last-page))
84 (paper (ly:paper-book-paper paper-book))
85 (height (page-printable-height page))
86 ; there is a certain amount of impreciseness going on here:
87 ; the system heights are estimated, we aren't using skyline distances
88 ; yet, etc. If we overstretch because of underestimation, the result
89 ; is very bad. So we stick in some extra space, just to be sure.
90 (buffer (/ height 10.0))
91 (total-system-height (+ (apply + (map height-estimate systems))
92 (total-padding systems)))
93 (height-left (- height total-system-height buffer)))
98 (set-line-stretch! (sort systems
100 (< (height-estimate s1)
101 (height-estimate s2))))
102 (apply + (map height-estimate
103 (filter stretchable? systems)))
106 (let ((lines (map print-system systems)))
107 (page-set-property! page 'lines lines)
112 (let* ((paper (ly:paper-book-paper paper-book))
113 (max-space-to-fill (page-maximum-space-to-fill page lines paper))
114 (space-to-fill (if (ly:output-def-lookup
115 paper 'page-limit-inter-system-space #f)
116 (min max-space-to-fill
117 (* (ly:output-def-lookup
118 paper 'page-limit-inter-system-space-factor 1.4)
120 (or (page-ideal-space-left page) 0))))
122 (spacing (space-systems space-to-fill lines ragged paper #f)))
123 (if (and (> (length lines) 1)
124 (or (not (car spacing)) (inf? (car spacing))))
126 (ly:warning (_ "Can't fit systems on page -- ignoring between-system-padding"))
127 (cdr (space-systems space-to-fill lines ragged paper #t)))
131 (define (page-breaking-wrapper paper-book)
132 "Compute line and page breaks by calling the page-breaking paper variable,
133 then performs the post process function using the page-post-process paper
134 variable. Finally, return the pages."
135 (let* ((paper (ly:paper-book-paper paper-book))
136 (pages ((ly:output-def-lookup paper 'page-breaking) paper-book)))
137 ((ly:output-def-lookup paper 'page-post-process) paper pages)
140 (define (post-process-pages layout pages)
141 "If the write-page-layout paper variable is true, dumps page breaks
145 ((parser (ly:modules-lookup (list (current-module)) 'parser))
146 (output-name (ly:parser-output-name parser))
149 (if (ly:output-def-lookup layout 'write-page-layout #f)
150 (write-page-breaks pages output-name))))
153 ;;; Utilities for computing line distances and positions
155 (define (line-extent line)
156 "Return the extent of the line (its lowest and highest Y-coordinates)."
157 (paper-system-extent line Y))
159 (define (line-height line)
160 "Return the system height, that is the length of its vertical extent."
161 (interval-length (line-extent line)))
163 (define (line-next-space line next-line layout)
164 "Return space to use between `line' and `next-line'.
165 `next-line' can be #f, meaning that `line' is the last line."
166 (let* ((title (paper-system-title? line))
167 (next-title (and next-line (paper-system-title? next-line))))
170 (ly:output-def-lookup layout
171 (cond ((and title next-title) 'between-title-space)
172 (title 'after-title-space)
173 (next-title 'before-title-space)
174 (else 'between-system-space))))))
176 (define (line-next-padding line next-line layout)
177 "Return padding to use between `line' and `next-line'.
178 `next-line' can be #f, meaning that `line' is the last line."
179 (let ((default (ly:output-def-lookup layout 'between-system-padding)))
181 (let* ((details (ly:grob-property line 'line-break-system-details))
182 (padding (assq 'next-padding details)))
186 (ly:prob-property line 'next-padding default))))
189 (define (line-minimum-distance line next-line layout ignore-padding)
190 "Minimum distance between `line' reference position and `next-line'
191 reference position. If next-line is #f, return #f."
193 (let ((padding (if ignore-padding
195 (line-next-padding line next-line layout))))
196 (if (or (ly:grob? line) (ly:grob? next-line))
198 (- (interval-start (line-extent line))
199 (interval-end (line-extent next-line)))))
201 (ly:paper-system-minimum-distance line next-line)))))))
203 (define (line-ideal-distance line next-line layout ignore-padding)
204 "Ideal distance between `line' reference position and `next-line'
205 reference position. If next-line is #f, return #f."
208 (+ (- (+ (interval-end (paper-system-staff-extents next-line))
209 (if ignore-padding 0 (line-next-padding line next-line layout)))
210 (interval-start (paper-system-staff-extents line)))
211 (line-next-space line next-line layout)))))
213 (define (first-line-position line layout)
214 "Position of the first line on page"
215 (max (+ (if (ly:prob-property? line 'is-title)
216 ;; do not use page-top-space if first line is a title
218 (ly:output-def-lookup layout 'page-top-space))
219 (interval-end (paper-system-staff-extents line)))
220 (interval-end (line-extent line))))
222 (define (line-ideal-relative-position line prev-line layout ignore-padding)
223 "Return ideal position of `line', relative to `prev-line' position.
224 `prev-line' can be #f, meaning that `line' is the first line."
226 ;; first line on page
227 (first-line-position line layout)
228 ;; not the first line on page
229 (max (line-minimum-distance prev-line line layout ignore-padding)
230 (line-ideal-distance prev-line line layout ignore-padding))))
232 (define (line-minimum-relative-position line prev-line layout ignore-padding)
233 "Return position of `line', relative to `prev-line' position.
234 `prev-line' can be #f, meaning that `line' is the first line."
236 ;; first line on page
237 (first-line-position line layout)
238 ;; not the first line on page
239 (line-minimum-distance prev-line line layout ignore-padding)))
241 (define (line-position-on-page line prev-line prev-position page relative-positionning-fn)
242 "If `line' fits on `page' after `prev-line', which position on page is
243 `prev-position', then return the line's postion on page, otherwise #f.
244 `prev-line' can be #f, meaning that `line' is the first line."
245 (let* ((layout (ly:paper-book-paper (page-property page 'paper-book)))
246 (position (+ (relative-positionning-fn line prev-line layout #f)
247 (if prev-line prev-position 0.0)))
248 (bottom-position (- position
249 (interval-start (line-extent line)))))
252 (define (page-maximum-space-to-fill page lines paper)
253 "Return the space between the first line top position and the last line
254 bottom position. This constitutes the maximum space to fill on `page'
256 (let ((last-line (car (last-pair lines))))
257 (- (page-printable-height page)
258 (first-line-position (first lines) paper)
259 (ly:prob-property last-line
261 (- (interval-start (line-extent last-line))))))
263 (define (page-space-left page relative-positionning-fn)
264 (let ((paper (ly:paper-book-paper (page-property page 'paper-book))))
265 (let bottom-position ((lines (page-property page 'lines))
269 (page-printable-height page)
270 (let* ((line (first lines))
271 (position (line-position-on-page
272 line prev-line prev-position page relative-positionning-fn)))
273 (if (null? (cdr lines))
275 (- (page-printable-height page)
277 (interval-start (line-extent line)))))
278 (bottom-position (cdr lines) line position)))))))
280 (define (page-maximum-space-left page)
281 (page-space-left page line-minimum-relative-position))
283 (define (page-ideal-space-left page)
284 (page-space-left page line-ideal-relative-position))
287 ;;; Utilities for distributing systems on a page
290 (define (space-systems space-to-fill lines ragged paper ignore-padding)
291 "Compute lines positions on page: return force and line positions as a pair.
292 force is #f if lines do not fit on page."
293 (let* ((empty-stencil (ly:make-stencil '() '(0 . 0) '(0 . 0)))
294 (empty-prob (ly:make-prob 'paper-system (list `(stencil . ,empty-stencil))))
295 (cdr-lines (append (cdr lines)
296 (if (<= (length lines) 1)
299 (springs (map (lambda (prev-line line)
300 (list (line-ideal-distance prev-line line paper ignore-padding)
301 (line-next-space prev-line line paper)))
304 (rods (map (let ((i -1))
305 (lambda (prev-line line)
308 (line-minimum-distance prev-line line paper ignore-padding))))
312 (ly:solve-spring-rod-problem springs rods space-to-fill ragged)))
313 (cons (car space-result)
314 (map (let ((topskip (first-line-position (first lines) paper)))
317 (cdr space-result)))))
321 ;;; Page breaking function
324 ;; Optimal distribution of
325 ;; lines over pages; line breaks are a given.
330 ;; - separate function for word-wrap style breaking?
331 ;; - ragged-bottom? ragged-last-bottom?
333 (define (get-path node done)
334 "Follow NODE.PREV, and return as an ascending list of pages. DONE
335 is what have collected so far, and has ascending page numbers."
337 (get-path (page-prev node) (cons node done))
340 (define (combine-penalties force user best-paths
341 inter-system-space force-equalization-factor)
342 (let* ((prev-force (if (null? best-paths)
344 (page-force (car best-paths))))
345 (prev-penalty (if (null? best-paths)
347 (page-penalty (car best-paths))))
348 (relative-force (/ force inter-system-space))
349 (abs-relative-force (abs relative-force)))
350 (+ (* abs-relative-force (+ abs-relative-force 1))
352 (* force-equalization-factor (/ (abs (- prev-force force))
356 (define (walk-paths done-lines best-paths current-lines is-last-bookpart
357 is-bookpart-last-page current-best paper-book page-alist)
358 "Return the best optimal-page-break-node that contains
359 CURRENT-LINES. DONE-LINES.reversed ++ CURRENT-LINES is a consecutive
360 ascending range of lines, and BEST-PATHS contains the optimal breaks
361 corresponding to DONE-LINES.
363 CURRENT-BEST is the best result sofar, or #f."
364 (let* ((paper (ly:paper-book-paper paper-book))
365 (this-page (make-page
367 'is-last-bookpart is-last-bookpart
368 'is-bookpart-last-page is-bookpart-last-page
369 'page-number (if (null? best-paths)
370 (ly:output-def-lookup paper 'first-page-number)
371 (1+ (page-page-number (first best-paths))))))
372 (ragged-all (eq? #t (ly:output-def-lookup paper 'ragged-bottom)))
373 (ragged-last (eq? #t (ly:output-def-lookup paper 'ragged-last-bottom)))
374 (ragged (or ragged-all (and ragged-last is-bookpart-last-page)))
375 (space-to-fill (page-maximum-space-to-fill this-page current-lines paper))
376 (vertical-spacing (space-systems space-to-fill current-lines ragged paper #f))
377 (satisfied-constraints (car vertical-spacing))
378 (force (if satisfied-constraints
379 (if (and is-bookpart-last-page ragged-last)
381 satisfied-constraints)
383 (positions (cdr vertical-spacing))
384 (get-break-penalty (lambda (sys)
385 (ly:prob-property sys 'penalty 0.0)))
386 (user-nobreak-penalties (- (apply + (filter negative?
387 (map get-break-penalty
388 (cdr current-lines))))))
389 (user-penalty (+ (max (get-break-penalty (car current-lines)) 0.0)
390 user-nobreak-penalties))
391 (total-penalty (combine-penalties
392 force user-penalty best-paths
393 (ly:output-def-lookup paper 'between-system-space)
394 (ly:output-def-lookup paper 'verticalequalizationfactor 0.3)))
395 (new-best (if (or (not current-best)
396 (and satisfied-constraints
397 (< total-penalty (page-penalty current-best))))
400 (page-set-property! this-page
403 (list (cons 'prev (if (null? best-paths)
406 (cons 'lines current-lines)
408 (cons 'configuration positions)
409 (cons 'penalty total-penalty)))
415 "\nuser pen " user-penalty
416 "\nsatisfied-constraints" satisfied-constraints
417 "\nlast? " is-bookpart-last-page "ragged?" ragged
418 "\nis-better " is-better " total-penalty " total-penalty "\n"
419 "\nconfig " positions
421 "\nlines: " current-lines "\n")))
423 (display (list "\nnew-best is " (page-lines new-best)
425 (if (null? best-paths)
427 (page-lines (car best-paths))))))
428 (if (and (pair? done-lines)
429 ;; if this page is too full, adding another line won't help
430 satisfied-constraints)
431 (walk-paths (cdr done-lines) (cdr best-paths)
432 (cons (car done-lines) current-lines)
433 is-last-bookpart is-bookpart-last-page new-best
434 paper-book page-alist)
437 (define (walk-lines done best-paths todo paper-book page-alist is-last-bookpart)
438 "Return the best page breaking as a single
439 page node for optimally breaking TODO ++
440 DONE.reversed. BEST-PATHS is a list of break nodes corresponding to
444 (let* ((this-line (car todo))
445 (is-bookpart-last-page (null? (cdr todo)))
446 (next (walk-paths done best-paths (list this-line) is-last-bookpart
447 is-bookpart-last-page #f paper-book page-alist)))
448 (walk-lines (cons this-line done)
449 (cons next best-paths)
455 (define-public (optimal-page-breaks paper-book)
456 "Return pages as a list starting with 1st page. Each page is a 'page Prob."
457 (let* ((paper (ly:paper-book-paper paper-book))
458 (lines (ly:paper-book-systems paper-book))
459 (page-alist (layout->page-init paper))
460 (force-equalization-factor (ly:output-def-lookup
461 paper 'verticalequalizationfactor 0.3))
462 (is-last-bookpart (ly:output-def-lookup paper 'is-last-bookpart)))
463 (ly:message (_ "Calculating page breaks..."))
464 (let* ((best-break-node (walk-lines '() '() lines paper-book page-alist is-last-bookpart))
465 (break-nodes (get-path best-break-node '())))
466 (if #f; (ly:get-option 'verbose)
469 "\nbreaks: " (map (lambda (node)
470 (ly:prob-property (car (page-lines node))
473 "\nsystems " (map page-lines break-nodes)
474 "\npenalties " (map page-penalty break-nodes)
475 "\nconfigs " (map page-configuration break-nodes)))))
476 ;; construct page stencils.
477 (for-each page-stencil break-nodes)