Fix note spacing with melismata

Recede the extra-spacing-height of LyricText and similar items.
Create property skyline-vertical-padding for vertical padding of
left- and right-skylines used in note spacing.

4 files changed, 24 insertions, 11 deletions

diff --git a/input/regression/lyrics-melisma-beam.ly b/input/regression/lyrics-melisma-beam.ly
index 008bb69e7b..811acc80ca 100644
--- a/input/regression/lyrics-melisma-beam.ly
+++ b/input/regression/lyrics-melisma-beam.ly
@@ -1,7 +1,8 @@
 \version "2.12.0"
 \header
 {
-  texidoc = "Melismata are triggered by manual beams." 
+  texidoc = "Melismata are triggered by manual beams.  Notes in a
+  melisma take their natural spacing over a long syllable."
 }
 
   \layout { ragged-right = ##t }
@@ -13,9 +14,9 @@
   \new Staff
   \relative c'' {
     \set Staff.autoBeaming = ##f
-    c8 c8[ c8 c8]  c8    }
-  
-  \lyricsto "" \new Lyrics \lyricmode { bla bla bla }
+    g4 d8[ b8 d8 g8]  g4
+  }
+  \lyricsto "" \new Lyrics \lyricmode { bla blaa -- bla }
 >>
 
 
diff --git a/lily/separation-item.cc b/lily/separation-item.cc
index 5df19544eb..013e457034 100644
--- a/lily/separation-item.cc
+++ b/lily/separation-item.cc
@@ -80,7 +80,8 @@ Skyline
 Separation_item::conditional_skyline (Grob *me, Grob *left)
 {
   vector<Box> bs = boxes (me, left);
-  return Skyline (bs, 0.0, Y_AXIS, LEFT);
+  Real horizon_padding = robust_scm2double (me->get_property ("skyline-vertical-padding"), 0.0);
+  return Skyline (bs, horizon_padding, Y_AXIS, LEFT);
 }
 
 
@@ -90,8 +91,8 @@ Separation_item::calc_skylines (SCM smob)
 {
   Item *me = unsmob_item (smob);
   vector<Box> bs = boxes (me, 0);
-  /* todo: the horizon_padding is somewhat arbitrary */
-  return Skyline_pair (bs, 0.0, Y_AXIS).smobbed_copy ();
+  Real horizon_padding = robust_scm2double (me->get_property ("skyline-vertical-padding"), 0.0);
+  return Skyline_pair (bs, horizon_padding, Y_AXIS).smobbed_copy ();
 }
 
 /* if left is non-NULL, get the boxes corresponding to the
@@ -189,4 +190,5 @@ ADD_INTERFACE (Separation_item,
 	       "elements "
 	       "padding "
 	       "horizontal-skylines "
+	       "skyline-vertical-padding "
 	       );
diff --git a/scm/define-grob-properties.scm b/scm/define-grob-properties.scm
index 9f36ecb89b..e92bf9ce34 100644
--- a/scm/define-grob-properties.scm
+++ b/scm/define-grob-properties.scm
@@ -721,6 +721,11 @@ vertical distance between two staves, it is possible to have a
 configuration which would result in a tight interleaving of grobs from
 the top staff and the bottom staff.  The larger this parameter is, the
 farther apart the staves are placed in such a configuration.")
+     (skyline-vertical-padding ,number? "The amount by which the left
+and right skylines of a column are padded vertically, beyond the
+@code{Y-extent}s and @code{extra-spacing-height}s of the constituent
+grobs in the column.  Increase this to prevent interleaving of grobs
+from adjacent columns.")
      (slash-negative-kern ,number? "The space to remove between
 slashes in percent repeat glyphs.  Larger values bring the two
 elements closer together.")
diff --git a/scm/define-grobs.scm b/scm/define-grobs.scm
index 14e7212a0b..59f756e8a0 100644
--- a/scm/define-grobs.scm
+++ b/scm/define-grobs.scm
@@ -492,6 +492,7 @@
 	(font-family . sans)
 	(font-size . 1.5)
 	(stencil . ,ly:text-interface::print)
+	(extra-spacing-height . (0.2 . -0.2))
 	(word-space . 0.0)
 	(meta . ((class . Item)
 		 (interfaces . (chord-name-interface
@@ -516,7 +517,6 @@
 			(next-note . (extra-space . 0.5))
 			(right-edge . (extra-space . 0.5))))
 	(stencil . ,ly:clef::print)
-	(extra-spacing-height . (-0.5 . 0.5))
 	(Y-offset . ,ly:staff-symbol-referencer::callback)
 	(meta . ((class . Item)
 		 (interfaces . (break-aligned-interface
@@ -583,7 +583,6 @@
 			(next-note . (extra-space . 0.5))
 			(right-edge . (extra-space . 0.5))))
 	(stencil . ,ly:clef::print)
-	(extra-spacing-height . (-0.5 . 0.5))
 	(Y-offset . ,ly:staff-symbol-referencer::callback)
 	(meta . ((class . Item)
 		 (interfaces . (break-aligned-interface
@@ -611,7 +610,6 @@
 			(next-note . (extra-space . 0.5))
 			(right-edge . (extra-space . 0.5))))
 	(stencil . ,ly:clef::print)
-	(extra-spacing-height . (-0.5 . 0.5))
 	(Y-offset . ,ly:staff-symbol-referencer::callback)
 	(meta . ((class . Item)
 		 (interfaces . (break-aligned-interface
@@ -855,6 +853,7 @@
 	(after-line-breaking . ,ly:chord-name::after-line-breaking)
 	(fret-diagram-details . ((finger-code . below-string)))
 	(stencil . ,fret-board::calc-stencil)
+	(extra-spacing-height . (0.2 . -0.2))
 	(meta . ((class . Item)
 		 (interfaces . (chord-name-interface
 				font-interface
@@ -1078,6 +1077,7 @@
 	(break-align-symbol . left-edge)
 	(break-visibility . ,center-invisible)
 	(non-musical . #t)
+	(extra-spacing-height . (+inf.0 . -inf.0))
 	(space-alist . (
 			(ambitus . (extra-space . 2.0))
 			(breathing-sign . (minimum-space . 0.0))
@@ -1157,6 +1157,9 @@
     (LyricText
      . (
 	(extra-spacing-width . (0.0 . 0.0))
+	;; Recede in height for purposes of note spacing,
+	;; so notes in melismata can be freely spaced above lyrics
+	(extra-spacing-height . (0.2 . -0.2))
 	(font-series . medium)
 	(font-size . 1.0)
 	(self-alignment-X . ,CENTER)
@@ -1302,6 +1305,7 @@
 	(before-line-breaking . ,ly:paper-column::before-line-breaking)
 	(full-measure-extra-space . 1.0)
 	(horizontal-skylines . ,ly:separation-item::calc-skylines)
+	(skyline-vertical-padding . 0.15)
 	;;		      (stencil . ,ly:paper-column::print)
 
 	(line-break-permission . allow)
@@ -1338,6 +1342,7 @@
      . (
 	(axes . (,X ,Y))
 	(horizontal-skylines . ,ly:separation-item::calc-skylines)
+	(skyline-vertical-padding . 0.15)
 	(X-extent . ,ly:axis-group-interface::width)
 	(Y-extent . ,ly:axis-group-interface::height)
 	(meta . ((class . Item)
@@ -1353,7 +1358,7 @@
 	(duration-log . ,note-head::calc-duration-log)
 	(extra-spacing-height . ,ly:note-head::include-ledger-line-height)
 	(glyph-name . ,note-head::calc-glyph-name)
-        (ligature-flexa . #f)
+	(ligature-flexa . #f)
 	(stem-attachment . ,ly:note-head::calc-stem-attachment)
 	(stencil . ,ly:note-head::print)
 	(X-offset . ,ly:note-head::stem-x-shift)