From a0f921dc791dd79c1ab9a1291ba115e055950649 Mon Sep 17 00:00:00 2001
From: Han-Wen Nienhuys <hanwen@xs4all.nl>
Date: Tue, 12 Dec 2006 14:40:02 +0100
Subject: [PATCH] Support tablature slides. Do this by adding 'extra-dy
 property for line-spanner.

---
 lily/glissando-engraver.cc     |  1 +
 lily/line-spanner.cc           | 18 ++++++++++++------
 ly/engraver-init.ly            |  4 +++-
 scm/define-grob-properties.scm |  3 ++-
 scm/lily.scm                   |  1 +
 5 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/lily/glissando-engraver.cc b/lily/glissando-engraver.cc
index 91dd733cb8..4c506df38d 100644
--- a/lily/glissando-engraver.cc
+++ b/lily/glissando-engraver.cc
@@ -73,6 +73,7 @@ Glissando_engraver::stop_translation_timestep ()
 {
   if (last_line_ && last_line_->get_bound (RIGHT))
     last_line_ = 0;
+
   if (line_)
     {
       if (last_line_)
diff --git a/lily/line-spanner.cc b/lily/line-spanner.cc
index 48d4b3aa9b..2f99a0dce2 100644
--- a/lily/line-spanner.cc
+++ b/lily/line-spanner.cc
@@ -205,6 +205,9 @@ Line_spanner::print (SCM smob)
   Offset my_off;
   Offset his_off;
 
+  Real extra_dy = robust_scm2double (me->get_property ("extra-dy"),
+				     0.0);
+  
   if (bound[RIGHT]->break_status_dir ())
     {
       if (bound[LEFT]->break_status_dir ())
@@ -247,11 +250,11 @@ Line_spanner::print (SCM smob)
       Real yoff = this_common_y->relative_coordinate (all_common_y, Y_AXIS);
 
       Offset p1 (bound[LEFT]->extent (commonx, X_AXIS)[RIGHT],
-		 this_ext.center () + yoff);
+		 this_ext.center () + yoff - extra_dy / 2);
       Offset p2 (bound[RIGHT]->extent (commonx, X_AXIS)[LEFT],
-		 next_ext.center () + yoff);
+		 next_ext.center () + yoff + extra_dy / 2);
 
-      Offset dz (p2 -p1);
+      Offset dz (p2 - p1);
       Real len = dz.length ();
 
       Offset dir = dz * (1 / len);
@@ -288,13 +291,15 @@ Line_spanner::print (SCM smob)
 	  his_off[ax] = bound[LEFT]->relative_coordinate (common[a], ax);
 	}
 
-      ofxy = dxy * (off / dxy.length ());
+      ofxy = dxy * (off / dxy.length ()) ;
       dxy -= 2*ofxy;
 
+      dxy[Y_AXIS] += extra_dy;
+      
       Stencil line = line_stencil (me, Offset (0, 0), dxy);
 
       line.translate_axis (bound[LEFT]->extent (bound[LEFT], X_AXIS).length () / 2, X_AXIS);
-      line.translate (ofxy - my_off + his_off);
+      line.translate (ofxy - my_off + his_off + Offset (0, -extra_dy/2));
       return line.smobbed_copy ();
     }
 }
@@ -305,7 +310,8 @@ ADD_INTERFACE (Line_spanner,
 	       "@code{dashed-line}, @code{trill}, \n"
 	       "@code{dotted-line} or @code{zigzag}.\n"
 	       "\n",
-	       
+
+	       "extra-dy "
 	       "arrow "
 	       "gap "
 	       "thickness "
diff --git a/ly/engraver-init.ly b/ly/engraver-init.ly
index 938a0c856e..afb0be2dc4 100644
--- a/ly/engraver-init.ly
+++ b/ly/engraver-init.ly
@@ -654,7 +654,7 @@ AncientRemoveEmptyStaffContext = \context {
   \alias "Voice"
   \consists "Tab_note_heads_engraver"
   \consists "Tab_harmonic_engraver"
-
+  
   \remove "Note_heads_engraver"
   \remove "Fingering_engraver"
   \remove "New_fingering_engraver"
@@ -669,6 +669,8 @@ AncientRemoveEmptyStaffContext = \context {
 
   %% No accidental in tablature !
   \remove Accidental_engraver
+
+  \override Glissando #'extra-dy = #0.75
 }
 
 \context {
diff --git a/scm/define-grob-properties.scm b/scm/define-grob-properties.scm
index 9d0d665b88..24f1fe0a2b 100644
--- a/scm/define-grob-properties.scm
+++ b/scm/define-grob-properties.scm
@@ -136,7 +136,8 @@ edges '(@var{left-text} . @var{right-text}).")
 		     "How much of the bound a spanner should enclose:
 +1 = completely, 0 = center, -1 not at all.")
      (expand-limit ,integer? "maximum number of measures expanded in church rests.")
-     ;; remove me? 
+     ;; remove me?
+     (extra-dy ,number? "Slope glissandi this much extra.")
      (extra-X-extent ,number-pair? "A grob is enlarged in X dimension
 by this much.")
      (extra-Y-extent ,number-pair? "See @code{extra-X-extent}.")
diff --git a/scm/lily.scm b/scm/lily.scm
index 32ab98e88e..d64fd57f4e 100644
--- a/scm/lily.scm
+++ b/scm/lily.scm
@@ -106,6 +106,7 @@ on errors, and print a stack trace.")
 
 (if (ly:get-option 'verbose)
     (begin
+      (ly:set-option 'protected-scheme-parsing #f)
       (debug-enable 'debug)
       (debug-enable 'backtrace)
       (read-enable 'positions)))
-- 
2.39.5