X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=Documentation%2Fsnippets%2Fcentering-markup-on-note-heads-automatically.ly;h=6b48240774121091d67c099ca73b6203d7cb47c1;hb=493fa01bf15b02089b985bcba87c5a9a1be7f3b9;hp=e9138f1dff11c3a5ad19a450141957ce93c08453;hpb=f115fc1bdeb3fdd356db670ef4fe3e6b9aee019c;p=lilypond.git

diff --git a/Documentation/snippets/centering-markup-on-note-heads-automatically.ly b/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
index e9138f1dff..6b48240774 100644
--- a/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
+++ b/Documentation/snippets/centering-markup-on-note-heads-automatically.ly
@@ -1,18 +1,22 @@
-%% Do not edit this file; it is automatically
-%% generated from LSR http://lsr.dsi.unimi.it
+%% DO NOT EDIT this file manually; it is automatically
+%% generated from LSR http://lsr.di.unimi.it
+%% Make any changes in LSR itself, or in Documentation/snippets/new/ ,
+%% and then run scripts/auxiliar/makelsr.py
+%%
 %% This file is in the public domain.
-\version "2.13.16"
+\version "2.18.0"
 
 \header {
-  lsrtags = "text, tweaks-and-overrides"
+  lsrtags = "contexts-and-engravers, text, tweaks-and-overrides"
 
   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}.
 
 
 
@@ -20,29 +24,44 @@ parent (a paper column), using its extent to correct the positioning.
   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 grob))
-
-     (for-each
-      (lambda (idx)
-        (let ((elt (ly:grob-array-ref elts idx)))
-          (if (grob::has-interface elt
-                                   'rhythmic-grob-interface)
-              (set! rhythmic-head elt))))
-      (reverse (iota (ly:grob-array-length elts))))
-
-     (+
-      (ly:self-alignment-interface::x-aligned-on-self grob)
-      (interval-center
-       (ly:grob-robust-relative-extent rhythmic-head rhythmic-head X)))))
-
-\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 "^"
+#(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 '())))))
+
+\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
+  }
+>>