Doc-de: update macros.itely and nitpicks

[lilypond.git] / lily / align-interface.cc

diff --git a/lily/align-interface.cc b/lily/align-interface.cc
index 92c405391dfeb1d00465c629e034fcef8c49365a..36aa81f11153d428eb9adafcfd7f2206766b51b4 100644 (file)
--- a/lily/align-interface.cc
+++ b/lily/align-interface.cc
@@ -3,7 +3,7 @@
 
   source file of the GNU LilyPond music typesetter
 
-  (c) 2000--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
+  (c) 2000--2009 Han-Wen Nienhuys <hanwen@xs4all.nl>
 */
 
 #include "align-interface.hh"
@@ -84,6 +84,8 @@ Align_interface::stretch_after_break (SCM grob)
    an empty extent, delete it from the list instead. If the extent is
    non-empty but there is no skyline available (or pure is true), just
    create a flat skyline from the bounding box */
+// TODO(jneem): the pure and non-pure parts seem to share very little
+// code. Split them into 2 functions, perhaps?
 static void
 get_skylines (Grob *me,
              vector<Grob*> *const elements,
@@ -137,9 +139,33 @@ get_skylines (Grob *me,
            {
              Box b;
              b[a] = extent;
-             b[other_axis (a)] = Interval (-infinity_f, infinity_f);
+             b[other_axis (a)] = Interval (0, infinity_f);
              skylines.insert (b, 0, other_axis (a));
            }
+
+         // This is a hack to get better accuracy on the pure-height of VerticalAlignment.
+         // It's quite common for a treble clef to be the highest element of one system
+         // and for a low note (or lyrics) to be the lowest note on another. The two will
+         // never collide, but the pure-height stuff only works with bounding boxes, so it
+         // doesn't know that. The result is a significant over-estimation of the pure-height,
+         // especially on systems with many staves. To correct for this, we build a skyline
+         // in two parts: the part we did above contains most of the grobs (note-heads, etc.)
+         // while the bit we're about to do only contains the breakable grobs at the beginning
+         // of the system. This way, the tall treble clefs are only compared with the treble
+         // clefs of the other staff and they will be ignored if the staff above is, for example,
+         // lyrics.
+         if (Axis_group_interface::has_interface (g)
+             && !Hara_kiri_group_spanner::request_suicide (g, start, end))
+           {
+             Interval begin_of_line_extent = Axis_group_interface::begin_of_line_pure_height (g, start);
+             if (!begin_of_line_extent.is_empty ())
+               {
+                 Box b;
+                 b[a] = begin_of_line_extent;
+                 b[other_axis (a)] = Interval (-infinity_f, -1);
+                 skylines.insert (b, 0, other_axis (a));
+               }
+           }
        }
 
       if (skylines.is_empty ())
@@ -224,8 +250,10 @@ Align_interface::get_extents_aligned_translates (Grob *me,
        }
     }
 
+  // So far, we've computed the translates for all the non-empty elements.
+  // Here, we set the translates for the empty elements: an empty element
+  // gets the same translation as the last non-empty element before it.
   vector<Real> all_translates;
-
   if (!translates.empty ())
     {
       Real w = translates[0];