Allow fixed spacing of symbols in church rests (issue 319910043 by address@hidden)

[david . nalesnik]

Reviewers: ,

Message:
Please review.  Thanks!

Description:
Allow fixed spacing of symbols in church rests

By default, the symbols making up a church rest are spread to fill
the available space in a measure.

Setting the new property "church-rest-inner-padding" places symbols
at the given distance from each other independently of measure width.
Settings are disregarded if symbols would overlap as a consequence
or would exceed the default separation, which is taken as a maximum.

Please review this at https://codereview.appspot.com/319910043/

Affected files (+33, -6 lines):
  M lily/multi-measure-rest.cc
  M scm/define-grob-interfaces.scm
  M scm/define-grob-properties.scm


Index: lily/multi-measure-rest.cc
diff --git a/lily/multi-measure-rest.cc b/lily/multi-measure-rest.cc
index  
7f2a720d6f809e06736272397e703d577d70f827..916fa49139d728ffb7409deba991c189582e5dfb  
100644
--- a/lily/multi-measure-rest.cc
+++ b/lily/multi-measure-rest.cc
@@ -319,17 +319,41 @@ Multi_measure_rest::church_rest (Grob *me,  
Font_metric *musfont, int measure_cou

   /* Make outer padding this much bigger.  */
   Real outer_padding_factor = 1.5;
-  Real inner_padding = (space - symbols_width)
-                       / (2 * outer_padding_factor + (symbol_count - 1));
-  if (inner_padding < 0)
-    inner_padding = 1.0;
+
+  Real default_inner_padding = (space - symbols_width)
+                               / (2 * outer_padding_factor + (symbol_count  
- 1));
+  if (default_inner_padding < 0)
+    default_inner_padding = 1.0;
+
+  Real inner_padding;
+  Real left_offset;
+
+  SCM symbol_separation = me->get_property ("church-rest-inner-padding");
+
+  if (scm_is_number (symbol_separation))
+    {
+      inner_padding = max (0.0, robust_scm2double (symbol_separation,  
1.0));
+      /*
+        Default is to spread symbols as widely as possible (with an
+        outer margin) within the available space.  Use default as a
+        sensible maximum for user values.
+      */
+      inner_padding = min (default_inner_padding, inner_padding);
+      left_offset = (space - symbols_width - (inner_padding *  
(symbol_count - 1)))
+                    / 2;
+    }
+  else
+    {
+      inner_padding = default_inner_padding;
+      left_offset = outer_padding_factor * inner_padding;
+    }

   Stencil mol;
   for (SCM s = mols; scm_is_pair (s); s = scm_cdr (s))
     mol.add_at_edge (X_AXIS, LEFT, *unsmob<Stencil> (scm_car (s)),
                      inner_padding);
   mol.align_to (X_AXIS, LEFT);
-  mol.translate_axis (outer_padding_factor * inner_padding, X_AXIS);
+  mol.translate_axis (left_offset, X_AXIS);

   return mol;
 }
Index: scm/define-grob-interfaces.scm
diff --git a/scm/define-grob-interfaces.scm b/scm/define-grob-interfaces.scm
index  
d5f23113961f88049016d1670f252d535c9fb3ee..864e2b04966ffdb8a8f098de9f4ddc1c0c90d5db  
100644
--- a/scm/define-grob-interfaces.scm
+++ b/scm/define-grob-interfaces.scm
@@ -209,7 +209,7 @@ accidentals)."
 (ly:add-interface
  'multi-measure-interface
  "Multi measure rest, and the text or number that is printed over it."
- '(bound-padding))
+ '(bound-padding church-rest-inner-padding))

 (ly:add-interface
  'note-name-interface
Index: scm/define-grob-properties.scm
diff --git a/scm/define-grob-properties.scm b/scm/define-grob-properties.scm
index  
06358986b077bad2934e73eeac7fac2c4850c4af..6ceb67b65016fd6275a71092c8528dc35fdf1d5f  
100644
--- a/scm/define-grob-properties.scm
+++ b/scm/define-grob-properties.scm
@@ -177,6 +177,9 @@ when a spanner is broken at a line break.")
      (chord-dots-limit ,integer? "Limits the column of dots
 on each chord to the height of the chord plus
 @code{chord-dots-limit} staff-positions.")
+     (church-rest-inner-padding ,number? "The distance between
+symbols in a multi-measure church rest.  If unset, distance is
+proportional to the size of the measure.")
      (circled-tip ,boolean? "Put a circle at start/@/end of
 hairpins (al/@/del niente).")
      (clef-alignments ,list? "An alist of parent-alignments