lily/coherent-ligature-engraver.cc

   1 /*
   2   coherent-ligature-engraver.cc -- implement Coherent_ligature_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c)  2003 Juergen Reuter <reuter@ipd.uka.de>
   7  */
   8
   9 #include "coherent-ligature-engraver.hh"
  10 #include "item.hh"
  11 #include "warn.hh"
  12 #include "staff-symbol-referencer.hh"
  13 #include "spanner.hh"
  14 #include "paper-column.hh"
  15
  16 /*
  17  * This abstract class serves as common superclass for all ligature
  18  * engravers thet produce a single connected graphical object of fixed
  19  * width, consisting of noteheads and other primitives (see class
  20  * Ligature_engraver for more information on the interaction between
  21  * this class and its superclass).  In particular, it cares for the
  22  * following tasks:
  23  *
  24  * - provide a function for putting all grobs of the ligature into a
  25  * single paper column,
  26  *
  27  * - delegate actual creation of ligature to concrete subclass,
  28  *
  29  * - collect all accidentals that occur within the ligature and put
  30  * them at the left side of the ligature (TODO; see function
  31  * collect_accidentals()),
  32  *
  33  * - collapse superflous space after each ligature (TODO).
  34  *
  35  * Concrete subclasses must implement function build_ligature (Spanner
  36  * *, Array<Grob_info>).  This function is responsible for actually
  37  * building the ligature by transforming the array of noteheads.
  38  *
  39  * Currently, there are two subclasses: Gregorian_ligature_engraver
  40  * for Gregorian chant notation (also known as plain song or cantus
  41  * planus) and Mensural_ligature_engraver for white mensural notation.
  42  * Subclasses for other music notation styles such as modal notation
  43  * or ars nova notation may eventually be added.
  44  */
  45
  46 /*
  47  * TODO: local accidentals: collect accidentals that occur within a
  48  * ligature and put them before the ligature.  If an accidental
  49  * changes within a ligature, print a warning (user error) and ignore
  50  * any further accidental for that pitch within that ligature
  51  * (actually, in such a case, the user should split the ligature into
  52  * two separate ligatures).  Similarly, any object that, in ordinary
  53  * notation, may be put to the left or to the right of a note-head,
  54  * should be collected and put before or after the ligature.
  55  *
  56  * TODO: make spacing more robust: do not screw up spacing if user
  57  * erroneously puts rest in ligature.
  58  *
  59  * TODO: for each ligature, add Rod that represents the total length
  60  * of the ligature (to preemptively avoid collision with adjacent
  61  * notes); or maybe just additionally create a
  62  * mensural/vaticana/whatever-ligature grob (e.g. via
  63  * Mensural_ligature::brew_molecule(SCM)) that just consists of a
  64  * bounding box around all primitives of the ligature.
  65  *
  66  * TODO: Maybe move functions fold_up_primitives() and
  67  * join_primitives() from subclasses to here?  N.B. it is not
  68  * appropriate to put these into Ligature_engraver, since, for
  69  * example, Ligature_bracket_engraver does not share any of this code.
  70  */
  71
  72 /*
  73  * TODO: Let superflous space after each ligature collapse.  The
  74  * following code should help in doing so (though it does not yet
  75  * fully work).  Just put the following code into
  76  * Spacing_spanner::do_measure().  I put it temporarily here as memo
  77  * until it really works and I also get Han-Wen's/Jan's permission to
  78  * add it to the spacing spanner code.
  79  */
  80 #if 0 // experimental code to collapse spacing after ligature
  81       SCM incr_scm = lc->get_grob_property ("forced-spacing");
  82       if (incr_scm != SCM_EOL) /* (Paper_column::musical_b (l)) */
  83         {
  84           me->warning (_f ("gotcha: ptr=%ul", lc));//debug
  85           ly_display_scm (lc->self_scm ());
  86           Real distance;
  87           if (incr_scm != SCM_EOL)
  88             {
  89               distance = gh_scm2double (incr_scm);
  90             }
  91           else
  92             {
  93               me->warning ("distance undefined, assuming 0.1");
  94               distance = 0.1;
  95             }
  96           me->warning (_f ("distance=%f", distance));//debug
  97           Real strength = 1.0;
  98           Spaceable_grob::add_spring (lc, rc, distance, strength, false);
  99           if (Item *rb = r->find_prebroken_piece (LEFT))
 100             Spaceable_grob::add_spring (lc, rb, distance, strength, false);
 101
 102           continue;
 103         }
 104 #endif
 105
 106 Coherent_ligature_engraver::Coherent_ligature_engraver ()
 107 {
 108 }
 109
 110 /*
 111  * TODO: move this function to class Item?
 112  */
 113 void
 114 Coherent_ligature_engraver::get_set_column (Item *item, Paper_column *column)
 115 {
 116   Item *parent = dynamic_cast<Item*> (item->get_parent (X_AXIS));
 117   if (!parent)
 118     {
 119       programming_error ("failed tweaking paper column in ligature");
 120       return;
 121     }
 122
 123   String name = parent->name ();
 124   if (!String::compare (name, "PaperColumn"))
 125     {
 126       // Change column not only for targeted item (NoteColumn), but
 127       // also for all associated grobs (NoteSpacing, SeparationItem).
 128       Grob *sl = Staff_symbol_referencer::get_staff_symbol (item);
 129       for (SCM tail = parent->get_grob_property ("elements");
 130            gh_pair_p (tail);
 131            tail = ly_cdr (tail))
 132         {
 133           Item *sibling = unsmob_item (ly_car (tail));
 134           if ((sibling) &&
 135               (Staff_symbol_referencer::get_staff_symbol (sibling) == sl))
 136             {
 137 #if 0 // experimental code to collapse spacing after ligature
 138               Grob *sibling_parent = sibling->get_parent (X_AXIS);
 139               sibling_parent->warning (_f ("Coherent_ligature_engraver: "
 140                                            "setting `spacing-increment = "
 141                                            "0.01': ptr=%ul", parent));
 142               sibling_parent->set_grob_property("forced-spacing",
 143                                               gh_double2scm (0.01));
 144 #endif
 145               sibling->set_parent (column, X_AXIS);
 146             }
 147         }
 148     }
 149   else
 150     {
 151       get_set_column (parent, column);
 152     }
 153 }
 154
 155 /*
 156  * TODO: This function should collect all accidentals that occur
 157  * within the ligature (by scanning through the primitives array) and
 158  * place all of them at the left of the ligature.  If there is an
 159  * alteration within the ligature (e.g. an "f" followed by a "fis"
 160  * somewhere later in the ligature), issue a warning (and maybe create
 161  * an additional natural symbol to explicitly make clear that there is
 162  * an "f" first?).  The warning should suggest the user to break the
 163  * ligature into two or more smaller ligatures such that no alteration
 164  * occurs within the broken ligatures any more.
 165  */
 166 void
 167 Coherent_ligature_engraver::collect_accidentals (Spanner *, Array<Grob_info>)
 168 {
 169   /* TODO */
 170 }
 171
 172 void
 173 compute_delta_pitches (Array<Grob_info> primitives)
 174 {
 175   int prev_pitch = 0;
 176   int delta_pitch = 0;
 177   Item *prev_primitive = 0, *primitive = 0;
 178   for (int i = 0; i < primitives.size(); i++) {
 179     primitive = dynamic_cast<Item*> (primitives[i].grob_);
 180     Music *music_cause = primitives[i].music_cause ();
 181     int pitch =
 182       unsmob_pitch (music_cause->get_mus_property ("pitch"))->steps ();
 183     if (prev_primitive)
 184       {
 185         delta_pitch = pitch - prev_pitch;
 186         prev_primitive->set_grob_property ("delta-pitch",
 187                                            gh_int2scm (delta_pitch));
 188       }
 189     prev_pitch = pitch;
 190     prev_primitive = primitive;
 191   }
 192   primitive->set_grob_property ("delta-pitch", gh_int2scm (0));
 193 }
 194
 195 void
 196 Coherent_ligature_engraver::build_ligature (Spanner *, Array<Grob_info>)
 197 {
 198   programming_error ("Coherent_ligature_engraver::build_ligature (): "
 199                      "this is an abstract method that should not be called, "
 200                      "but overridden by a subclass");
 201 }
 202
 203 void
 204 Coherent_ligature_engraver::typeset_ligature (Spanner *ligature,
 205                                               Array<Grob_info> primitives)
 206 {
 207   // compute some commonly needed context info stored as grob
 208   // properties
 209   compute_delta_pitches (primitives);
 210
 211   // prepare ligature for typesetting
 212   build_ligature (ligature, primitives);
 213   collect_accidentals (ligature, primitives);
 214
 215   // now actually typeset
 216   for (int i = 0; i < primitives.size (); i++)
 217     {
 218       typeset_grob (primitives[i].grob_);
 219     }
 220 }
 221
 222 ENTER_DESCRIPTION (Coherent_ligature_engraver,
 223 /* descr */       "This is an abstract class.  Subclasses such as Gregorian_ligature_engraver handle ligatures by glueing special ligature heads together.",
 224 /* creats*/       "",
 225 /* accepts */     "ligature-event abort-event",
 226 /* acks  */      "note-head-interface rest-interface",
 227 /* reads */       "",
 228 /* write */       "");