]> git.donarmstrong.com Git - lilypond.git/blobdiff - scm/output-lib.scm
Merge branch 'master' into translation
[lilypond.git] / scm / output-lib.scm
index 8f81340e6d68219b092797bbd9c3b9d423831fc2..4533cf2a965a8c95eb22b3dcf84d21dc2e5ad8f7 100644 (file)
 
     (ly:text-interface::interpret-markup layout props text)))
 
+(define-public (grob::unpure-Y-extent-from-stencil pure-function)
+  "The unpure height will come from a stencil whereas the pure
+   height will come from @code{pure-function}."
+  (ly:make-unpure-pure-container ly:grob::stencil-height pure-function))
+
+(define-public grob::unpure-horizontal-skylines-from-stencil
+  (ly:make-unpure-pure-container
+    ly:grob::horizontal-skylines-from-stencil
+    ly:grob::pure-simple-horizontal-skylines-from-extents))
+
+(define-public grob::always-horizontal-skylines-from-stencil
+  (ly:make-unpure-pure-container
+    ly:grob::horizontal-skylines-from-stencil))
+
+(define-public grob::unpure-vertical-skylines-from-stencil
+  (ly:make-unpure-pure-container
+    ly:grob::vertical-skylines-from-stencil
+    ly:grob::pure-simple-vertical-skylines-from-extents))
+
+(define-public grob::always-vertical-skylines-from-stencil
+  (ly:make-unpure-pure-container
+    ly:grob::vertical-skylines-from-stencil))
+
+(define-public grob::always-vertical-skylines-from-element-stencils
+  (ly:make-unpure-pure-container
+    ly:grob::vertical-skylines-from-element-stencils
+    ly:grob::pure-vertical-skylines-from-element-stencils))
+
+(define-public grob::always-horizontal-skylines-from-element-stencils
+  (ly:make-unpure-pure-container
+    ly:grob::horizontal-skylines-from-element-stencils
+    ly:grob::pure-horizontal-skylines-from-element-stencils))
+
+;; Using this as a callback for a grob's Y-extent promises
+;; that the grob's stencil does not depend on line-spacing.
+;; We use this promise to figure the space required by Clefs
+;; and such at the note-spacing stage.
+
+(define-public grob::always-Y-extent-from-stencil
+  (ly:make-unpure-pure-container ly:grob::stencil-height))
+
+(define-public (layout-line-thickness grob)
+  "Get the line thickness of the @var{grob}'s corresponding layout."
+  (let* ((layout (ly:grob-layout grob))
+         (line-thickness (ly:output-def-lookup layout 'line-thickness)))
+
+        line-thickness))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; beam slope
 
+;; even though kievan noteheads do not have stems, their
+;; invisible stems help with beam placement
+;; this assures that invisible stems for kievan notes are aligned
+;; to the center of kievan noteheads. that is thus where the beams'
+;; x extrema will fall
+(define-public (stem::kievan-offset-callback grob)
+  (let* ((note-heads (ly:grob-object grob 'note-heads))
+         (note-heads-grobs (if (not (null? note-heads))
+                               (ly:grob-array->list note-heads)
+                               '()))
+         (first-note-head (if (not (null? note-heads-grobs))
+                              (car note-heads-grobs)
+                              '()))
+         (note-head-w (if (not (null? first-note-head))
+                          (ly:grob-extent first-note-head first-note-head X)
+                          '(0 . 0))))
+    (interval-center note-head-w)))
+
+
 ;; sets position of beams for Kievan notation
-(define-public (beam::get-positions grob)
-    (let* ((stems (ly:grob-object grob 'stems))
-           (stems-grobs (if (not (null? stems))
-                            (ly:grob-array->list stems)
-                            '()))
-           (first-stem (if (not (null? stems-grobs))
-                          (car stems-grobs)
-                          '()))
-           (note-heads (if (not (null? first-stem))
-                          (ly:grob-object first-stem 'note-heads)
-                          '()))
-           (note-heads-grobs (if (not (null? note-heads))
-                                (ly:grob-array->list note-heads)
-                                '()))
-           (first-note-head (if (not (null? note-heads-grobs))
-                               (car note-heads-grobs)
-                               '()))
-           (style (if (not (null? first-note-head))
-                     (ly:grob-property first-note-head 'style)
-                     '())))
-          (if (and (symbol? style) (string-match "kievan*" (symbol->string style)))
-              (let* ((next-stem (cadr stems-grobs))
-                     (next-note-heads (if (not (null? next-stem))
-                                         (ly:grob-object next-stem 'note-heads)
-                                         '()))
-                     (next-note-heads-grobs (if (not (null? next-note-heads))
-                                               (ly:grob-array->list next-note-heads)
-                                               '()))
-                     (next-note-head (if (not (null? next-note-heads-grobs))
-                                        (car next-note-heads-grobs)
-                                        '()))
-                     (left-pos (ly:grob-property first-note-head 'Y-offset))
-                     (right-pos (ly:grob-property next-note-head 'Y-offset))
-                     (direction (ly:grob-property grob 'direction))
-                     (left-height (if (= direction DOWN)
-                                     (+ (car (ly:grob::stencil-height first-note-head)) 0.75)
-                                      (- (cdr (ly:grob::stencil-height first-note-head)) 0.75)))
-                     (right-height (if (= direction DOWN)
-                                      (+ (car (ly:grob::stencil-height next-note-head)) 0.75)
-                                       (- (cdr (ly:grob::stencil-height next-note-head)) 0.75))))
-                    (cons (+ left-pos left-height) (+ right-pos right-height)))
-              (beam::place-broken-parts-individually grob))))
-
-(define-public (beam::get-quantized-positions grob)
-    (let* ((stems (ly:grob-object grob 'stems))
-           (stems-grobs (if (not (null? stems))
-                            (ly:grob-array->list stems)
-                            '()))
-           (first-stem (if (not (null? stems-grobs))
-                          (car stems-grobs)
-                          '()))
-           (note-heads (if (not (null? first-stem))
-                          (ly:grob-object first-stem 'note-heads)
-                          '()))
-           (note-heads-grobs (if (not (null? note-heads))
-                                (ly:grob-array->list note-heads)
-                                '()))
-           (first-note-head (if (not (null? note-heads-grobs))
-                               (car note-heads-grobs)
-                               '()))
-           (style (if (not (null? first-note-head))
-                     (ly:grob-property first-note-head 'style)
-                     '())))
-          (if (and (symbol? style) (string-match "kievan*" (symbol->string style)))
-              (let* ((next-stem (cadr stems-grobs))
-                     (next-note-heads (if (not (null? next-stem))
-                                         (ly:grob-object next-stem 'note-heads)
-                                         '()))
-                     (next-note-heads-grobs (if (not (null? next-note-heads))
-                                               (ly:grob-array->list next-note-heads)
-                                               '()))
-                     (next-note-head (if (not (null? next-note-heads-grobs))
-                                        (car next-note-heads-grobs)
-                                        '()))
-                     (left-pos (ly:grob-property first-note-head 'Y-offset))
-                     (right-pos (ly:grob-property next-note-head 'Y-offset))
-                     (direction (ly:grob-property grob 'direction))
-                     (left-height (if (= direction DOWN)
-                                     (+ (car (ly:grob::stencil-height first-note-head)) 0.75)
-                                      (- (cdr (ly:grob::stencil-height first-note-head)) 0.75)))
-                     (right-height (if (= direction DOWN)
-                                      (+ (car (ly:grob::stencil-height next-note-head)) 0.75)
-                                       (- (cdr (ly:grob::stencil-height next-note-head)) 0.75))))
-                    (cons (+ left-pos left-height) (+ right-pos right-height)))
-              (ly:beam::set-stem-lengths grob))))
+(define-public (beam::get-kievan-positions grob)
+  (let* ((stems (ly:grob-object grob 'stems))
+         (stems-grobs (if (not (null? stems))
+                          (ly:grob-array->list stems)
+                          '()))
+         (first-stem (if (not (null? stems-grobs))
+                         (car stems-grobs)
+                         '()))
+         (note-heads (if (not (null? first-stem))
+                         (ly:grob-object first-stem 'note-heads)
+                         '()))
+         (note-heads-grobs (if (not (null? note-heads))
+                               (ly:grob-array->list note-heads)
+                               '()))
+         (first-note-head (if (not (null? note-heads-grobs))
+                              (car note-heads-grobs)
+                              '()))
+         (next-stem (if (not (null? stems))
+                        (cadr stems-grobs)
+                        '()))
+         (next-note-heads (if (not (null? next-stem))
+                              (ly:grob-object next-stem 'note-heads)
+                              '()))
+         (next-note-heads-grobs (if (not (null? next-note-heads))
+                                    (ly:grob-array->list next-note-heads)
+                                    '()))
+         (next-note-head (if (not (null? next-note-heads-grobs))
+                             (car next-note-heads-grobs)
+                             '()))
+         (left-pos (ly:grob-property first-note-head 'Y-offset))
+         (right-pos (ly:grob-property next-note-head 'Y-offset))
+         (direction (ly:grob-property grob 'direction))
+         (first-nh-height (ly:grob::stencil-height first-note-head))
+         (next-nh-height (ly:grob::stencil-height next-note-head))
+         (left-height (if (= direction DOWN)
+                          (+ (car first-nh-height) 0.75)
+                          (- (cdr first-nh-height) 0.75)))
+         (right-height (if (= direction DOWN)
+                           (+ (car next-nh-height) 0.75)
+                           (- (cdr next-nh-height) 0.75))))
+    (cons (+ left-pos left-height) (+ right-pos right-height))))
+
+(define-public (beam::get-kievan-quantized-positions grob)
+  (let* ((pos (ly:grob-property grob 'positions))
+         (stems (ly:grob-object grob 'stems))
+         (stems-grobs (if (not (null? stems))
+                          (ly:grob-array->list stems)
+                          '())))
+    (for-each
+      (lambda (g)
+        (ly:grob-set-property! g 'stem-begin-position 0)
+        (ly:grob-set-property! g 'length 0))
+      stems-grobs)
+    pos))
 
 ;; calculates each slope of a broken beam individually
 (define-public (beam::place-broken-parts-individually grob)
    (ly:side-position-interface::calc-cross-staff g)))
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; side-position stuff
+
+(define-public (only-if-beamed g)
+  (any (lambda (x) (ly:grob? (ly:grob-object x 'beam)))
+       (ly:grob-array->list (ly:grob-object g 'side-support-elements))))
+
+(define-public side-position-interface::y-aligned-side
+  (ly:make-unpure-pure-container
+    ly:side-position-interface::y-aligned-side
+    ly:side-position-interface::pure-y-aligned-side))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; self-alignment stuff
+
+(define-public self-alignment-interface::y-aligned-on-self
+  (ly:make-unpure-pure-container
+    ly:self-alignment-interface::y-aligned-on-self
+    ly:self-alignment-interface::pure-y-aligned-on-self))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; staff symbol
+
+(define staff-symbol-referencer::callback
+  (ly:make-unpure-pure-container ly:staff-symbol-referencer::callback))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; note heads
 
   (ly:duration-log
    (ly:event-property (event-cause grob) 'duration)))
 
-(define-public (stem::length grob)
-  (let* ((ss (ly:staff-symbol-staff-space grob))
-         (beg (ly:grob-property grob 'stem-begin-position))
-         (beam (ly:grob-object grob 'beam))
-         (note-heads (ly:grob-object grob 'note-heads))
-         (note-heads-grobs (if (not (null? note-heads))
-                              (ly:grob-array->list note-heads)
-                              '()))
-         (first-note-head (if (not (null? note-heads-grobs))
-                             (car note-heads-grobs)
-                             '()))
-         (style (if (not (null? first-note-head))
-                    (ly:grob-property first-note-head 'style)
-                   '())))
-    (cond
-      ((and (symbol? style) (string-match "kievan*" (symbol->string style))) 0.0)
-      ((null? beam) (abs (- (ly:stem::calc-stem-end-position grob) beg)))
-      (else
-        (begin
-          (ly:programming-error
-            "stem::length called but will not be used for beamed stem.")
-          0.0)))))
-
-(define-public (stem::pure-length grob beg end)
-  (let* ((ss (ly:staff-symbol-staff-space grob))
-         (beg (ly:grob-pure-property grob 'stem-begin-position 0 1000)))
-    (abs (- (ly:stem::pure-calc-stem-end-position grob 0 2147483646) beg))))
-
 (define (stem-stub::do-calculations grob)
   (and (ly:grob-property (ly:grob-parent grob X) 'cross-staff)
        (not (ly:grob-property (ly:grob-parent grob X) 'transparent))))
   (if (stem-stub::do-calculations grob)
       (let* ((dad (ly:grob-parent grob X))
              (refp (ly:grob-common-refpoint grob dad Y))
-             (stem_ph (ly:grob-pure-height dad refp 0 1000000))
-             (my_ph (ly:grob-pure-height grob refp 0 1000000))
+             (stem_ph (ly:grob-pure-height dad refp 0 INFINITY-INT))
+             (my_ph (ly:grob-pure-height grob refp 0 INFINITY-INT))
              ;; only account for distance if stem is on different staff than stub
              (dist (if (grob::has-interface refp 'hara-kiri-group-spanner-interface)
                        0
         (if (interval-empty? (interval-intersection stem_ph my_ph)) #f (coord-translate stem_ph dist)))
       #f))
 
-;; FIXME: NEED TO FIND A BETTER WAY TO HANDLE KIEVAN NOTATION
+(define-public (note-head::calc-kievan-duration-log grob)
+  (min 3
+       (ly:duration-log
+         (ly:event-property (event-cause grob) 'duration))))
+
 (define-public (note-head::calc-duration-log grob)
-  (let ((style (ly:grob-property grob 'style)))
-    (if (and (symbol? style) (string-match "kievan*" (symbol->string style)))
-      (min 3
-        (ly:duration-log
-       (ly:event-property (event-cause grob) 'duration)))
-      (min 2
-       (ly:duration-log
-       (ly:event-property (event-cause grob) 'duration))))))
+  (min 2
+       (ly:duration-log
+         (ly:event-property (event-cause grob) 'duration))))
 
 (define-public (dots::calc-dot-count grob)
   (ly:duration-dot-count
@@ -472,15 +505,36 @@ and duration-log @var{log}."
       (cons -0.1 0.1)))
 
 (define-public (pure-from-neighbor-interface::extra-spacing-height grob)
-  (let* ((height (ly:grob-pure-height grob grob 0 10000000))
+  (let* ((height (ly:grob-pure-height grob grob 0 INFINITY-INT))
          (from-neighbors (interval-union
                             height
                             (ly:axis-group-interface::pure-height
                               grob
                               0
-                              10000000))))
+                              INFINITY-INT))))
     (coord-operation - from-neighbors height)))
 
+;; If there are neighbors, we place the height at their midpoint
+;; to avoid protrusion of this pure height out of the vertical
+;; axis group on either side.  This will minimize the impact of the
+;; grob on pure minimum translations.
+
+;; TODO - there is a double call to axis-group-interface::pure-height
+;; here and then in the extra-spacing-height function above. Can/should this
+;; be rolled into one?
+(define-public (pure-from-neighbor-interface::pure-height grob beg end)
+  (let* ((height (ly:axis-group-interface::pure-height
+                  grob
+                  0
+                  INFINITY-INT))
+         (c (interval-center height)))
+    (if (interval-empty? height) empty-interval (cons c c))))
+
+;; Minimizes the impact of the height on vertical spacing while allowing
+;; it to appear in horizontal skylines of paper columns if necessary.
+(define-public pure-from-neighbor-interface::height-if-pure
+  (ly:make-unpure-pure-container #f pure-from-neighbor-interface::pure-height))
+
 (define-public (pure-from-neighbor-interface::account-for-span-bar grob)
   (let* ((esh (pure-from-neighbor-interface::extra-spacing-height grob))
          (hsb (ly:grob-property grob 'has-span-bar))
@@ -661,6 +715,11 @@ and duration-log @var{log}."
   (assoc-get (ly:grob-property grob 'alteration)
              standard-alteration-glyph-name-alist))
 
+(define-public accidental-interface::height
+  (ly:make-unpure-pure-container
+    ly:accidental-interface::height
+    ly:accidental-interface::pure-height))
+
 (define-public cancellation-glyph-name-alist
   '((0 . "accidentals.natural")))
 
@@ -798,6 +857,15 @@ and duration-log @var{log}."
       (- y-center (ly:grob-relative-coordinate me y-ref Y))))))
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; offset callbacks
+
+(define-public (pure-chain-offset-callback grob start end prev-offset)
+  "Sometimes, a chained offset callback is unpure and there is
+   no way to write a pure function that estimates its behavior.
+   In this case, we use a pure equivalent that will simply pass
+   the previous calculated offset value."
+  prev-offset)
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
@@ -847,8 +915,7 @@ and duration-log @var{log}."
                            (ly:grob-relative-coordinate spanner common-y Y)))
                      (interval-end
                       (ly:grob-robust-relative-extent dots common X))
-                     ;; TODO: use real infinity constant.
-                     -10000))))
+                     (- INFINITY-INT)))))
         (right-x (max (- (interval-start
                           (ly:grob-robust-relative-extent right-span common X))
                          padding)
@@ -902,24 +969,21 @@ and duration-log @var{log}."
 ;; fingering
 
 (define-public (fingering::calc-text grob)
-  (let* ((event (event-cause grob))
-        (digit (ly:event-property event 'digit)))
-
-    (number->string digit 10)))
+  (let ((event (event-cause grob)))
+    (or (ly:event-property event 'text #f)
+        (number->string (ly:event-property event 'digit) 10))))
 
 (define-public (string-number::calc-text grob)
-  (let ((digit (ly:event-property (event-cause grob) 'string-number)))
-
-    (number->string digit 10)))
+  (let ((event (event-cause grob)))
+    (or (ly:event-property event 'text #f)
+        (number->string (ly:event-property event 'string-number) 10))))
 
 (define-public (stroke-finger::calc-text grob)
-  (let* ((digit (ly:event-property (event-cause grob) 'digit))
-        (text (ly:event-property (event-cause grob) 'text)))
-
-    (if (string? text)
-       text
+  (let ((event (event-cause grob)))
+    (or (ly:event-property event 'text #f)
        (vector-ref (ly:grob-property grob 'digit-names)
-                   (1- (max (min 5 digit) 1))))))
+                   (1- (max 1
+                             (min 5 (ly:event-property event 'digit))))))))
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -951,6 +1015,71 @@ between the two text elements."
                                             '(bound-details left padding)
                                             (+ my-padding script-padding)))))))
 
+(define-public ((elbowed-hairpin coords mirrored?) grob)
+  "Create hairpin based on a list of @var{coords} in @code{(cons x y)}
+form.  @code{x} is the portion of the width consumed for a given line
+and @code{y} is the portion of the height.  For example,
+@code{'((0.3 . 0.7) (0.8 . 0.9) (1.0 . 1.0))} means that at the point
+where the hairpin has consumed 30% of its width, it must
+be at 70% of its height.  Once it is to 80% width, it
+must be at 90% height.  It finishes at
+100% width and 100% height.  @var{mirrored?} indicates if the hairpin
+is mirrored over the Y-axis or if just the upper part is drawn.
+Returns a function that accepts a hairpin grob as an argument
+and draws the stencil based on its coordinates.
+@lilypond[verbatim,quote]
+#(define simple-hairpin
+  (elbowed-hairpin '((1.0 . 1.0)) #t))
+
+\\relative c' {
+  \\override Hairpin #'stencil = #simple-hairpin
+  a\\p\\< a a a\\f
+}
+@end lilypond
+"
+  (define (pair-to-list pair)
+    (list (car pair) (cdr pair)))
+  (define (normalize-coords goods x y)
+    (map
+      (lambda (coord)
+        (cons (* x (car coord)) (* y (cdr coord))))
+      goods))
+  (define (my-c-p-s points thick decresc?)
+    (make-connected-path-stencil
+      points
+      thick
+      (if decresc? -1.0 1.0)
+      1.0
+      #f
+      #f))
+  ; outer let to trigger suicide
+  (let ((sten (ly:hairpin::print grob)))
+    (if (grob::is-live? grob)
+      (let* ((decresc? (eq? (ly:grob-property grob 'grow-direction) LEFT))
+             (thick (ly:grob-property grob 'thickness 0.1))
+             (thick (* thick (layout-line-thickness grob)))
+             (xex (ly:stencil-extent sten X))
+             (lenx (interval-length xex))
+             (yex (ly:stencil-extent sten Y))
+             (leny (interval-length yex))
+             (xtrans (+ (car xex) (if decresc? lenx 0)))
+             (ytrans (car yex))
+             (uplist (map pair-to-list
+                          (normalize-coords coords lenx (/ leny 2))))
+             (downlist (map pair-to-list
+                            (normalize-coords coords lenx (/ leny -2)))))
+      (ly:stencil-translate
+        (ly:stencil-add
+          (my-c-p-s uplist thick decresc?)
+          (if mirrored? (my-c-p-s downlist thick decresc?) empty-stencil))
+        (cons xtrans ytrans)))
+      '())))
+
+(define-public flared-hairpin
+  (elbowed-hairpin '((0.95 . 0.4) (1.0 . 1.0)) #t))
+
+(define-public constante-hairpin
+  (elbowed-hairpin '((1.0 . 0.0) (1.0 . 1.0)) #f))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; lyrics
@@ -967,6 +1096,9 @@ between the two text elements."
 (define-public ((grob::calc-property-by-copy prop) grob)
   (ly:event-property (event-cause grob) prop))
 
+(define-public ((grob::calc-property-by-non-event-cause prop) grob)
+  (ly:grob-property (non-event-cause grob) prop))
+
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; fret boards
@@ -978,6 +1110,14 @@ between the two text elements."
     (ly:grob-property grob 'dot-placement-list))))
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; slurs
+
+(define-public slur::height
+  (ly:make-unpure-pure-container
+    ly:slur::height
+    ly:slur::pure-height))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; scripts
 
@@ -1093,6 +1233,14 @@ between the two text elements."
      (interval-center extent))))
 
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; axis group interface
+
+(define-public axis-group-interface::height
+  (ly:make-unpure-pure-container
+    ly:axis-group-interface::height
+    ly:axis-group-interface::pure-height))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; ambitus
 
@@ -1135,3 +1283,13 @@ between the two text elements."
 (define-public (laissez-vibrer::print grob)
  (ly:tie::print grob))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; volta-bracket
+
+(define-public (volta-bracket-interface::pure-height grob start end)
+  (let ((edge-height (ly:grob-property grob 'edge-height)))
+    (if (number-pair? edge-height)
+       (let ((smaller (min (car edge-height) (cdr edge-height)))
+             (larger (max (car edge-height) (cdr edge-height))))
+         (interval-union '(0 . 0) (cons smaller larger)))
+       '(0 . 0))))