1 ;;;; layout-page-layout.scm -- page breaking and page layout
3 ;;;; source file of the GNU LilyPond music typesetter
5 ;;;; (c) 2004--2007 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 book-last part-last)
35 (define (max-stretch sys)
37 (ly:grob-property sys 'max-stretch)
40 (define (stretchable? sys)
42 (> (max-stretch sys) 0.0)))
44 (define (height-estimate sys)
47 (ly:grob-property sys 'pure-Y-extent)
48 (paper-system-extent sys Y))))
50 (define (print-system sys)
55 (define (set-line-stretch! sorted-lines rest-height space-left)
56 (if (not (null? sorted-lines))
57 (let* ((line (first sorted-lines))
58 (height (height-estimate line))
59 (stretch (min (max-stretch line)
60 (if (positive? rest-height)
61 (/ (* height space-left) rest-height)
63 (if (stretchable? line)
64 (ly:system-stretch line stretch))
65 (set-line-stretch! (cdr sorted-lines)
66 (if (stretchable? line)
67 (- rest-height height)
69 (- space-left stretch)))))
71 (define (total-padding systems)
72 (let ((layout (ly:paper-book-paper paper-book)))
73 (if (or (null? systems)
74 (null? (cdr systems)))
76 (+ (line-next-padding (car systems) (cadr systems) layout)
77 (total-padding (cdr systems))))))
79 (let* ((page (make-page paper-book
80 'page-number page-number
82 'is-part-last part-last))
83 (paper (ly:paper-book-paper paper-book))
84 (height (page-printable-height page))
85 ; there is a certain amount of impreciseness going on here:
86 ; the system heights are estimated, we aren't using skyline distances
87 ; yet, etc. If we overstretch because of underestimation, the result
88 ; is very bad. So we stick in some extra space, just to be sure.
89 (buffer (/ height 10.0))
90 (total-system-height (+ (apply + (map height-estimate systems))
91 (total-padding systems)))
92 (height-left (- height total-system-height buffer)))
97 (set-line-stretch! (sort systems
99 (< (height-estimate s1)
100 (height-estimate s2))))
101 (apply + (map height-estimate
102 (filter stretchable? systems)))
105 (let ((lines (map print-system systems)))
106 (page-set-property! page 'lines lines)
111 (let* ((paper (ly:paper-book-paper paper-book))
112 (max-space-to-fill (page-maximum-space-to-fill page lines paper))
113 (space-to-fill (if (ly:output-def-lookup
114 paper 'page-limit-inter-system-space #f)
115 (min max-space-to-fill
116 (* (ly:output-def-lookup
117 paper 'page-limit-inter-system-space-factor 1.4)
119 (or (page-ideal-space-left page) 0))))
121 (spacing (space-systems space-to-fill lines ragged paper #f)))
122 (if (and (> (length lines) 1)
123 (or (not (car spacing)) (inf? (car spacing))))
125 (ly:warning (_ "Can't fit systems on page -- ignoring between-system-padding"))
126 (cdr (space-systems space-to-fill lines ragged paper #t)))
130 (define (page-breaking-wrapper paper-book)
131 "Compute line and page breaks by calling the page-breaking paper variable,
132 then performs the post process function using the page-post-process paper
133 variable. Finally, return the pages."
134 (let* ((paper (ly:paper-book-paper paper-book))
135 (pages ((ly:output-def-lookup paper 'page-breaking) paper-book)))
136 ((ly:output-def-lookup paper 'page-post-process) paper pages)
139 (define (post-process-pages layout pages)
140 "If the write-page-layout paper variable is true, dumps page breaks
144 ((parser (ly:modules-lookup (list (current-module)) 'parser))
145 (output-name (ly:parser-output-name parser))
148 (if (ly:output-def-lookup layout 'write-page-layout #f)
149 (write-page-breaks pages output-name))))
152 ;;; Utilities for computing line distances and positions
154 (define (line-extent line)
155 "Return the extent of the line (its lowest and highest Y-coordinates)."
156 (paper-system-extent line Y))
158 (define (line-height line)
159 "Return the system height, that is the length of its vertical extent."
160 (interval-length (line-extent line)))
162 (define (line-next-space line next-line layout)
163 "Return space to use between `line' and `next-line'.
164 `next-line' can be #f, meaning that `line' is the last line."
165 (let* ((title (paper-system-title? line))
166 (next-title (and next-line (paper-system-title? next-line))))
169 (ly:output-def-lookup layout
170 (cond ((and title next-title) 'between-title-space)
171 (title 'after-title-space)
172 (next-title 'before-title-space)
173 (else 'between-system-space))))))
175 (define (line-next-padding line next-line layout)
176 "Return padding to use between `line' and `next-line'.
177 `next-line' can be #f, meaning that `line' is the last line."
178 (let ((default (ly:output-def-lookup layout 'between-system-padding)))
180 (let* ((details (ly:grob-property line 'line-break-system-details))
181 (padding (assq 'next-padding details)))
185 (ly:prob-property line 'next-padding default))))
188 (define (line-minimum-distance line next-line layout ignore-padding)
189 "Minimum distance between `line' reference position and `next-line'
190 reference position. If next-line is #f, return #f."
192 (let ((padding (if ignore-padding
194 (line-next-padding line next-line layout))))
195 (if (or (ly:grob? line) (ly:grob? next-line))
197 (- (interval-start (line-extent line))
198 (interval-end (line-extent next-line)))))
200 (ly:paper-system-minimum-distance line next-line)))))))
202 (define (line-ideal-distance line next-line layout ignore-padding)
203 "Ideal distance between `line' reference position and `next-line'
204 reference position. If next-line is #f, return #f."
207 (+ (- (+ (interval-end (paper-system-staff-extents next-line))
208 (if ignore-padding 0 (line-next-padding line next-line layout)))
209 (interval-start (paper-system-staff-extents line)))
210 (line-next-space line next-line layout)))))
212 (define (first-line-position line layout)
213 "Position of the first line on page"
214 (max (+ (if (ly:prob-property? line 'is-title)
215 ;; do not use page-top-space if first line is a title
217 (ly:output-def-lookup layout 'page-top-space))
218 (interval-end (paper-system-staff-extents line)))
219 (interval-end (line-extent line))))
221 (define (line-ideal-relative-position line prev-line layout ignore-padding)
222 "Return ideal position of `line', relative to `prev-line' position.
223 `prev-line' can be #f, meaning that `line' is the first line."
225 ;; first line on page
226 (first-line-position line layout)
227 ;; not the first line on page
228 (max (line-minimum-distance prev-line line layout ignore-padding)
229 (line-ideal-distance prev-line line layout ignore-padding))))
231 (define (line-minimum-relative-position line prev-line layout ignore-padding)
232 "Return position of `line', relative to `prev-line' position.
233 `prev-line' can be #f, meaning that `line' is the first line."
235 ;; first line on page
236 (first-line-position line layout)
237 ;; not the first line on page
238 (line-minimum-distance prev-line line layout ignore-padding)))
240 (define (line-position-on-page line prev-line prev-position page relative-positionning-fn)
241 "If `line' fits on `page' after `prev-line', which position on page is
242 `prev-position', then return the line's postion on page, otherwise #f.
243 `prev-line' can be #f, meaning that `line' is the first line."
244 (let* ((layout (ly:paper-book-paper (page-property page 'paper-book)))
245 (position (+ (relative-positionning-fn line prev-line layout #f)
246 (if prev-line prev-position 0.0)))
247 (bottom-position (- position
248 (interval-start (line-extent line)))))
251 (define (page-maximum-space-to-fill page lines paper)
252 "Return the space between the first line top position and the last line
253 bottom position. This constitutes the maximum space to fill on `page'
255 (let ((last-line (car (last-pair lines))))
256 (- (page-printable-height page)
257 (first-line-position (first lines) paper)
258 (ly:prob-property last-line
260 (- (interval-start (line-extent last-line))))))
262 (define (page-space-left page relative-positionning-fn)
263 (let ((paper (ly:paper-book-paper (page-property page 'paper-book))))
264 (let bottom-position ((lines (page-property page 'lines))
268 (page-printable-height page)
269 (let* ((line (first lines))
270 (position (line-position-on-page
271 line prev-line prev-position page relative-positionning-fn)))
272 (if (null? (cdr lines))
274 (- (page-printable-height page)
276 (interval-start (line-extent line)))))
277 (bottom-position (cdr lines) line position)))))))
279 (define (page-maximum-space-left page)
280 (page-space-left page line-minimum-relative-position))
282 (define (page-ideal-space-left page)
283 (page-space-left page line-ideal-relative-position))
286 ;;; Utilities for distributing systems on a page
289 (define (space-systems space-to-fill lines ragged paper ignore-padding)
290 "Compute lines positions on page: return force and line positions as a pair.
291 force is #f if lines do not fit on page."
292 (let* ((empty-stencil (ly:make-stencil '() '(0 . 0) '(0 . 0)))
293 (empty-prob (ly:make-prob 'paper-system (list `(stencil . ,empty-stencil))))
294 (cdr-lines (append (cdr lines)
295 (if (<= (length lines) 1)
298 (springs (map (lambda (prev-line line)
299 (list (line-ideal-distance prev-line line paper ignore-padding)
300 (line-next-space prev-line line paper)))
303 (rods (map (let ((i -1))
304 (lambda (prev-line line)
307 (line-minimum-distance prev-line line paper ignore-padding))))
311 (ly:solve-spring-rod-problem springs rods space-to-fill ragged)))
312 (cons (car space-result)
313 (map (let ((topskip (first-line-position (first lines) paper)))
316 (cdr space-result)))))
320 ;;; Page breaking function
323 ;; Optimal distribution of
324 ;; lines over pages; line breaks are a given.
329 ;; - separate function for word-wrap style breaking?
330 ;; - ragged-bottom? ragged-last-bottom?
332 (define (get-path node done)
333 "Follow NODE.PREV, and return as an ascending list of pages. DONE
334 is what have collected so far, and has ascending page numbers."
336 (get-path (page-prev node) (cons node done))
339 (define (combine-penalties force user best-paths
340 inter-system-space force-equalization-factor)
341 (let* ((prev-force (if (null? best-paths)
343 (page-force (car best-paths))))
344 (prev-penalty (if (null? best-paths)
346 (page-penalty (car best-paths))))
347 (relative-force (/ force inter-system-space))
348 (abs-relative-force (abs relative-force)))
349 (+ (* abs-relative-force (+ abs-relative-force 1))
351 (* force-equalization-factor (/ (abs (- prev-force force))
355 (define (walk-paths done-lines best-paths current-lines is-last-part
356 is-last-page current-best paper-book page-alist)
357 "Return the best optimal-page-break-node that contains
358 CURRENT-LINES. DONE-LINES.reversed ++ CURRENT-LINES is a consecutive
359 ascending range of lines, and BEST-PATHS contains the optimal breaks
360 corresponding to DONE-LINES.
362 CURRENT-BEST is the best result sofar, or #f."
363 (let* ((paper (ly:paper-book-paper paper-book))
364 (this-page (make-page
366 'is-last (and is-last-part is-last-page)
367 'is-part-last is-last-page
368 'page-number (if (null? best-paths)
369 (ly:output-def-lookup paper 'first-page-number)
370 (1+ (page-page-number (first best-paths))))))
371 (ragged-all (eq? #t (ly:output-def-lookup paper 'ragged-bottom)))
372 (ragged-last (eq? #t (ly:output-def-lookup paper 'ragged-last-bottom)))
373 (ragged (or ragged-all (and ragged-last is-last-page)))
374 (space-to-fill (page-maximum-space-to-fill this-page current-lines paper))
375 (vertical-spacing (space-systems space-to-fill current-lines ragged paper #f))
376 (satisfied-constraints (car vertical-spacing))
377 (force (if satisfied-constraints
378 (if (and is-last-page ragged-last)
380 satisfied-constraints)
382 (positions (cdr vertical-spacing))
383 (get-break-penalty (lambda (sys)
384 (ly:prob-property sys 'penalty 0.0)))
385 (user-nobreak-penalties (- (apply + (filter negative?
386 (map get-break-penalty
387 (cdr current-lines))))))
388 (user-penalty (+ (max (get-break-penalty (car current-lines)) 0.0)
389 user-nobreak-penalties))
390 (total-penalty (combine-penalties
391 force user-penalty best-paths
392 (ly:output-def-lookup paper 'between-system-space)
393 (ly:output-def-lookup paper 'verticalequalizationfactor 0.3)))
394 (new-best (if (or (not current-best)
395 (and satisfied-constraints
396 (< total-penalty (page-penalty current-best))))
399 (page-set-property! this-page
402 (list (cons 'prev (if (null? best-paths)
405 (cons 'lines current-lines)
407 (cons 'configuration positions)
408 (cons 'penalty total-penalty)))
414 "\nuser pen " user-penalty
415 "\nsatisfied-constraints" satisfied-constraints
416 "\nlast? " is-last-page "ragged?" ragged
417 "\nis-better " is-better " total-penalty " total-penalty "\n"
418 "\nconfig " positions
420 "\nlines: " current-lines "\n")))
422 (display (list "\nnew-best is " (page-lines new-best)
424 (if (null? best-paths)
426 (page-lines (car best-paths))))))
427 (if (and (pair? done-lines)
428 ;; if this page is too full, adding another line won't help
429 satisfied-constraints)
430 (walk-paths (cdr done-lines) (cdr best-paths)
431 (cons (car done-lines) current-lines)
432 is-last-part is-last-page new-best
433 paper-book page-alist)
436 (define (walk-lines done best-paths todo paper-book page-alist is-last-part)
437 "Return the best page breaking as a single
438 page node for optimally breaking TODO ++
439 DONE.reversed. BEST-PATHS is a list of break nodes corresponding to
443 (let* ((this-line (car todo))
444 (is-last-page (null? (cdr todo)))
445 (next (walk-paths done best-paths (list this-line) is-last-part
446 is-last-page #f paper-book page-alist)))
447 (walk-lines (cons this-line done)
448 (cons next best-paths)
454 (define-public (optimal-page-breaks paper-book)
455 "Return pages as a list starting with 1st page. Each page is a 'page Prob."
456 (let* ((paper (ly:paper-book-paper paper-book))
457 (lines (ly:paper-book-systems paper-book))
458 (page-alist (layout->page-init paper))
459 (force-equalization-factor (ly:output-def-lookup
460 paper 'verticalequalizationfactor 0.3))
461 (part-is-last (ly:output-def-lookup paper 'part-is-last)))
462 (ly:message (_ "Calculating page breaks..."))
463 (let* ((best-break-node (walk-lines '() '() lines paper-book page-alist part-is-last))
464 (break-nodes (get-path best-break-node '())))
465 ;(page-set-property! (car (last-pair break-nodes)) 'is-last part-is-last)
466 ;(page-set-property! (car (last-pair break-nodes)) 'is-part-last #t)
467 (if #f; (ly:get-option 'verbose)
470 "\nbreaks: " (map (lambda (node)
471 (ly:prob-property (car (page-lines node))
474 "\nsystems " (map page-lines break-nodes)
475 "\npenalties " (map page-penalty break-nodes)
476 "\nconfigs " (map page-configuration break-nodes)))))
477 ;; construct page stencils.
478 (for-each page-stencil break-nodes)