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--2007 Juergen Reuter <reuter@ipd.uka.de>
   7 */
   8
   9 #include "coherent-ligature-engraver.hh"
  10
  11 #include "warn.hh"
  12 #include "paper-column.hh"
  13 #include "pitch.hh"
  14 #include "pointer-group-interface.hh"
  15 #include "spanner.hh"
  16 #include "staff-symbol-referencer.hh"
  17 #include "stream-event.hh"
  18
  19 /*
  20  * This abstract class serves as common superclass for all ligature
  21  * engravers thet produce a single connected graphical object of fixed
  22  * width, consisting of noteheads and other primitives (see class
  23  * Ligature_engraver for more information on the interaction between
  24  * this class and its superclass).  In particular, it cares for the
  25  * following tasks:
  26  *
  27  * - provide a function for putting all grobs of the ligature into a
  28  * single paper column,
  29  *
  30  * - delegate actual creation of ligature to concrete subclass,
  31  *
  32  * - collect all accidentals that occur within the ligature and put
  33  * them at the left side of the ligature (TODO; see function
  34  * collect_accidentals ()),
  35  *
  36  * - collapse superflous space after each ligature (TODO).
  37  *
  38  * Concrete subclasses must implement function build_ligature (Spanner
  39  * *, vector<Grob_info>).  This function is responsible for actually
  40  * building the ligature by transforming the array of noteheads.
  41  *
  42  * Currently, there are two subclasses: Gregorian_ligature_engraver
  43  * for Gregorian chant notation (also known as plain song or cantus
  44  * planus) and Mensural_ligature_engraver for white mensural notation.
  45  * Subclasses for other music notation styles such as modal notation
  46  * or ars nova notation may eventually be added.
  47  */
  48
  49 /*
  50  * TODO: local accidentals: collect accidentals that occur within a
  51  * ligature and put them before the ligature.  If an accidental
  52  * changes within a ligature, print a warning (user error) and ignore
  53  * any further accidental for that pitch within that ligature
  54  * (actually, in such a case, the user should split the ligature into
  55  * two separate ligatures).  Similarly, any object that, in ordinary
  56  * notation, may be put to the left or to the right of a note-head,
  57  * should be collected and put before or after the ligature.
  58  *
  59  * TODO: make spacing more robust: do not screw up spacing if user
  60  * erroneously puts rest in ligature.
  61  *
  62  * TODO: for each ligature, add Rod that represents the total length
  63  * of the ligature (to preemptively avoid collision with adjacent
  64  * notes); or maybe just additionally create a
  65  * mensural/vaticana/whatever-ligature grob (e.g. via
  66  * Mensural_ligature::print (SCM)) that just consists of a
  67  * bounding box around all primitives of the ligature.
  68  *
  69  * TODO: Maybe move functions fold_up_primitives () and
  70  * join_primitives () from subclasses to here?  N.B. it is not
  71  * appropriate to put these into Ligature_engraver, since, for
  72  * example, Ligature_bracket_engraver does not share any of this code.
  73  */
  74
  75
  76 /*
  77  * TODO: move this function to class Item?
  78  */
  79 void
  80 Coherent_ligature_engraver::move_related_items_to_column
  81 (Item *item, Paper_column *target_column, Real offset)
  82 {
  83   Paper_column *source_column = item->get_column ();
  84   Grob *staff_symbol = Staff_symbol_referencer::get_staff_symbol (item);
  85   extract_item_set (source_column, "elements", elements);
  86   for (vsize i = elements.size (); i--;)
  87     {
  88       Item *sibling = elements[i];
  89       if (!sibling)
  90         // should not occur, but who knows... -jr
  91         continue;
  92
  93       if (Staff_symbol_referencer::get_staff_symbol (sibling) != staff_symbol)
  94         // sibling is from a staff different than that of the item of
  95         // interest
  96         continue;
  97
  98 #if 0 /* experimental code to collapse spacing after ligature */
  99       Grob *sibling_parent = sibling->get_parent (X_AXIS);
 100       sibling_parent->warning (_f ("Coherent_ligature_engraver: "
 101                                    "setting `spacing-increment="
 102                                    "0.01': ptr=%ul", parent));
 103       sibling_parent->set_property ("forced-spacing",
 104                                     scm_from_double (0.01));
 105 #endif
 106
 107       sibling->set_parent (target_column, X_AXIS);
 108       sibling->translate_axis (offset, X_AXIS);
 109     }
 110 }
 111
 112 /*
 113  * TODO: This function should collect all accidentals that occur
 114  * within the ligature (by scanning through the primitives array) and
 115  * place all of them at the left of the ligature.  If there is an
 116  * alteration within the ligature (e.g. an "f" followed by a "fis"
 117  * somewhere later in the ligature), issue a warning (and maybe create
 118  * an additional natural symbol to explicitly make clear that there is
 119  * an "f" first?).  The warning should suggest the user to break the
 120  * ligature into two or more smaller ligatures such that no alteration
 121  * occurs within the broken ligatures any more.
 122  */
 123 void
 124 Coherent_ligature_engraver::collect_accidentals (Spanner *, vector<Grob_info>)
 125 {
 126   /* TODO */
 127 }
 128
 129 void
 130 compute_delta_pitches (vector<Grob_info> primitives)
 131 {
 132   int prev_pitch = 0;
 133   int delta_pitch = 0;
 134   Item *prev_primitive = 0, *primitive = 0;
 135   for (vsize i = 0; i < primitives.size (); i++)
 136     {
 137       primitive = dynamic_cast<Item *> (primitives[i].grob ());
 138       Stream_event *cause = primitives[i].event_cause ();
 139       int pitch
 140         = unsmob_pitch (cause->get_property ("pitch"))->steps ();
 141       if (prev_primitive)
 142         {
 143           delta_pitch = pitch - prev_pitch;
 144           prev_primitive->set_property ("delta-position",
 145                                         scm_from_int (delta_pitch));
 146         }
 147       prev_pitch = pitch;
 148       prev_primitive = primitive;
 149     }
 150   primitive->set_property ("delta-position", scm_from_int (0));
 151 }
 152
 153 void
 154 Coherent_ligature_engraver::typeset_ligature (Spanner *ligature,
 155                                               vector<Grob_info> primitives)
 156 {
 157   // compute some commonly needed context info stored as grob
 158   // properties
 159   compute_delta_pitches (primitives);
 160
 161   // prepare ligature for typesetting
 162   build_ligature (ligature, primitives);
 163   collect_accidentals (ligature, primitives);
 164 }
 165
 166 // no ADD_ACKNOWLEDGER / ADD_ACKNOWLEDGER / ADD_TRANSLATOR macro calls
 167 // since this class is abstract