doc/snippets/vertically-spread-markups.ly

   1 \version "2.14"
   2
   3 \header {
   4   texidoc = "Title pages may require to vertically center, stretch or spread markups
   5 throughout the full vertical extent of the paper. Here is a function that achieves
   6 just that, much like the commonly-used `fill-line' markup command."
   7
   8   tagline = ##f
   9 }
  10
  11 \paper {
  12   #(set-paper-size "a6")
  13 }
  14
  15 #(define-markup-command (fill-page layout props args)
  16   (markup-list?)
  17   ;; This code was shamelessly copied from the fill-line function.
  18   #:properties ((text-direction UP)
  19                 (line-space 0.6)
  20                 (page-height #f))
  21
  22   (define (get-fill-space line-count page-height line-space text-heights)
  23     (cond
  24     ((null? text-heights) '())
  25
  26     ;; special case first padding
  27     ((= (length text-heights) line-count)
  28       (cons
  29       (- (- (/ page-height (1- line-count)) (car text-heights))
  30     (/ (car (cdr text-heights)) 2))
  31       (get-fill-space line-count page-height line-space (cdr text-heights))))
  32     ;; special case last padding
  33     ((= (length text-heights) 2)
  34       (list (- (/ page-height (1- line-count))
  35              (+ (/ (car text-heights) 2) (car (cdr text-heights)))) 0))
  36    (else
  37     (let ((default-padding
  38             (- (/ page-height (1- line-count))
  39                (/ (+ (car text-heights) (car (cdr text-heights))) 2))))
  40       (cons
  41        (if (> line-space default-padding)
  42            line-space
  43            default-padding)
  44        (get-fill-space line-count page-height line-space (cdr text-heights)))))))
  45
  46   (let* ((orig-stencils (interpret-markup-list layout props args))
  47          (stencils
  48           (map (lambda (stc)
  49                  (if (ly:stencil-empty? stc)
  50                      point-stencil
  51                      stc)) orig-stencils))
  52          (text-heights
  53           (map (lambda (stc)
  54                  (if (ly:stencil-empty? stc)
  55                      0.0
  56                      (interval-length (ly:stencil-extent stc Y))))
  57                stencils))
  58          (text-height (apply + text-heights))
  59          (line-count (length stencils))
  60          (page-height (- (ly:output-def-lookup layout 'paper-height)
  61                          (+ (ly:output-def-lookup layout 'top-margin)
  62                             (ly:output-def-lookup layout 'bottom-margin))))
  63          (fill-space
  64           (cond
  65            ((= line-count 1)
  66             (list
  67              (/ (- page-height text-height) 2)
  68              (/ (- page-height text-height) 2)))
  69            ((= line-count 2)
  70             (list
  71              (- page-height text-height)))
  72            (else
  73             (get-fill-space line-count page-height line-space text-heights))))
  74
  75          (page-contents (if (= line-count 1)
  76                             (list
  77                              point-stencil
  78                              (car stencils)
  79                              point-stencil)
  80                             stencils)))
  81
  82     (if (null? (remove ly:stencil-empty? orig-stencils))
  83         empty-stencil
  84         (begin
  85           (if (= text-direction UP)
  86               (set! page-contents (reverse page-contents)))
  87           (set! page-contents
  88                 (stack-stencils-padding-list
  89                  Y UP fill-space page-contents))
  90           (if (> line-count 1)
  91               (set! page-contents
  92                     (ly:stencil-translate-axis
  93                      page-contents
  94                      (- (car (ly:stencil-extent (car stencils) Y)))
  95                      Y)))
  96           page-contents))))
  97
  98 \markup \fill-page {
  99   \line { This markup }
 100   \line { is spread }
 101   \line { equally }
 102   \line { on the page. }
 103 }