lily/rest-collision.cc: adjust all rests in column

lily/rest-collision.cc: adjust all rests in column

Process all rests in a noteColumn, not just the first; fix issue 1618.
Print warning only for rests that are moved but don't fit; fix issue 1547.

[Graham Percival (old account), 2011-04-25 22:24:24]

patch from Keith for magical rest collisions

[Keith, 2011-04-25 23:40:12]

Thanks, Graham.
The increased indent, from enclosing a lot of code in a loop, destroyed the
usually beautiful side-by-side diff.
Here is git diff -b :

--- a/lily/rest-collision.cc
+++ b/lily/rest-collision.cc
@@ -201,27 +201,26 @@ Rest_collision::calc_positioning_done (SCM smob)
       /*
 	Rests and notes.
       */
-      if (rests.size () > 1)
-	warning (_ ("too many colliding rests"));
-      Grob *rcol = 0;
-      Direction dir = CENTER;
+      // Count how many rests we move
+      Drul_array<int> rcount (0, 0);
 
-      for (vsize i = rests.size (); !rcol && i--;)
-	if (Note_column::dir (rests[i]))
+      for (vsize i = 0; i < rests.size (); i++)
 	  {
-	    rcol = rests[i];
-	    dir = Note_column::dir (rcol);
-	  }
-
+	  Grob *rcol = rests[i];
       if (!rcol)
-	return SCM_BOOL_T;
+	    continue;
 
+	  Direction dir = Note_column::dir (rcol);
       Grob *rest = Note_column::get_rest (rcol);
-      Grob *common = common_refpoint_of_array (notes, rcol, Y_AXIS);
+	  // Do not compute a translation for pre-positioned rests,
+	  //  nor count them for the "too many colliding rests" warning
+	  if (scm_is_number (rest->get_property ("staff-position")))
+	    continue;
 
+	  Grob *common = common_refpoint_of_array (notes, rcol, Y_AXIS);
       Interval restdim = rest->extent (common, Y_AXIS);
       if (restdim.is_empty ())
-	return SCM_BOOL_T;
+	    continue;
 
       Real staff_space = Staff_symbol_referencer::staff_space (rcol);
       Real minimum_dist = robust_scm2double (me->get_property
("minimum-distance"), 1.0) * staff_space;
@@ -271,6 +270,9 @@ Rest_collision::calc_positioning_done (SCM smob)
 	}
 
       Rest::translate (rest, discrete_y);
+	  if (rcount[dir]++)
+	    rest->warning (_ ("too many colliding rests"));
+	}
     }
   return SCM_BOOL_T;
 }

[Keith, 2011-04-26 04:43:43]

I resolved my internet problem and uploaded a version with regtest
 http://codereview.appspot.com/4442083/

Please direct your reviews there.