+
+ // 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))
+ {
+ extent = Axis_group_interface::rest_of_line_pure_height (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));
+ }
+ }
+