Issue 3468: lilypond-book and spaces in application name

[lilypond.git] / Documentation / snippets / centering-markup-on-note-heads-automatically.ly

diff --git a/Documentation/snippets/centering-markup-on-note-heads-automatically.ly b/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
index 509534a91b52878a72145a66ae105ac0012138cf..b5342b4131087cb01e02db78f097b8bbe0e1352d 100644 (file)
--- a/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
+++ b/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
@@ -1,53 +1,65 @@
-%% Do not edit this file; it is automatically
-%% generated from LSR http://lsr.dsi.unimi.it
-%% This file is in the public domain.
-\version "2.13.4"
+% DO NOT EDIT this file manually; it is automatically
+% generated from Documentation/snippets/new
+% Make any changes in Documentation/snippets/new/
+% and then run scripts/auxiliar/makelsr.py
+%
+% This file is in the public domain.
+%% Note: this file works from version 2.17.6
+\version "2.17.6"
 
 \header {
-  lsrtags = "text, tweaks-and-overrides"
-
+  lsrtags = "text, tweaks-and-overrides, contexts-and-engravers"
   texidoc = "
 For technical reasons, text scripts attached to note heads cannot
 easily be centered on a note head's width, unlike articulations.
 
-Instead of using trial-and-error offset tweaks, this snippet accesses a
-note head (or rest) from the @code{TextScript} object's horizontal
-parent (a paper column), using its extent to correct the positioning.
-
-
-
+Instead of using trial-and-error offset tweaks, this snippet uses a
+Scheme engraver to reset the horizontal parent of each markup to a
+@code{NoteColumn}.  This also allows text to follow note heads which have
+been shifted via @code{force-hshift}.
 "
   doctitle = "Centering markup on note heads automatically"
 } % begin verbatim
 
-textScriptCenterOnNote = \override TextScript #'X-offset =
-#(lambda (grob)
-   (let* ((paper-col (ly:grob-parent grob X))
-          (elts (ly:grob-object paper-col 'elements))
-          (rhythmic-head
-           (if (ly:grob-array? elts)
-               (let loop ((array-idx 0))
-                 (call/cc
-                  (lambda (return)
-                    (let ((array-len (ly:grob-array-length elts)))
-                      (if (< array-idx (1- array-len))
-                          (let ((elt (ly:grob-array-ref elts array-idx)))
-                            (if (grob::has-interface elt
-                                                     'rhythmic-head-interface)
-                                (return elt)
-                                (loop (1+ array-idx)))))
-                      grob))))
-               grob)))
 
-     (+
-      (ly:self-alignment-interface::x-aligned-on-self grob)
-      (interval-center
-       (ly:grob-robust-relative-extent rhythmic-head rhythmic-head X)))))
+#(define (Text_align_engraver ctx)
+  (let ((scripts '())
+        (note-column #f))
+    (make-engraver
+     (acknowledgers
+      ((note-column-interface trans grob source)
+       ;; cache NoteColumn in this Voice context
+       (set! note-column grob))
+      ((text-script-interface trans grob source)
+       ;; whenever a TextScript is acknowledged,
+       ;; add it to `scripts' list
+       (set! scripts (cons grob scripts))))
+     ((stop-translation-timestep trans)
+      ;; if any TextScript grobs exist,
+      ;; set NoteColumn as X-parent
+      (for-each (lambda (script)
+                 (set! (ly:grob-parent script X) note-column))
+               scripts)
+      ;; clear scripts ready for next timestep
+      (set! scripts '())))))
 
-\relative c' {
-  \override TextScript #'self-alignment-X = #CENTER
-  \textScriptCenterOnNote
-  <c e g c>1-\markup \arrow-head #Y #UP ##t
-  <c e g c>1-\markup \huge "^"
+\layout {
+  \context {
+    \Voice
+    \consists #Text_align_engraver
+    \override TextScript.X-offset =
+      #ly:self-alignment-interface::aligned-on-x-parent
+    \override TextScript.self-alignment-X = #CENTER
+  }
 }
 
+\new Staff <<
+  \relative c'' {
+    \override NoteColumn.force-hshift = #3
+    c1-\markup { \arrow-head #Y #DOWN ##t }
+  }
+  \\
+  \relative c' {
+    a4 a-\markup { \huge ^ } a a
+  }
+>>