lily/ambitus-engraver.cc

   1 /*
   2   ambitus-engraver.cc -- implement Ambitus_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2002--2003 Juergen Reuter <reuter@ipd.uka.de>
   7 */
   8
   9 #include "engraver.hh"
  10 #include "item.hh"
  11 #include "note-head.hh"
  12 #include "staff-symbol-referencer.hh"
  13 #include "event.hh"
  14 #include "pitch.hh"
  15
  16 /*
  17  * This class implements an engraver for ambitus grobs.
  18  *
  19  * TODO: There are quite some conceptional issues left open:
  20  *
  21  * - Many publishers put ambitus _before_ the first occurrence of a
  22  * clef.  Hence, formally the pitches are undefined in this case.  Of
  23  * course, one could always silently assume that ambitus pitches refer
  24  * to the first occurrence of a clef.  Or should we, by default, put
  25  * the ambitus always after the first clef, if any?
  26  *
  27  * - Enharmonically equal pitches: Assume piece contains once a "gis",
  28  * another time an "aes" as highest pitch.  Which one should be
  29  * selected for the ambitus grob?  The "aes", because it is
  30  * musically/notationally "higher" than "gis"?  Or "gis", because (if
  31  * using pure temperament) it has a slightly higher frequency?  Or
  32  * that pitch that come closer to the key signature?  But there may be
  33  * key signature changes in the piece...
  34  *
  35  * - Multiple voices in single staff: Assume a vocal piece of music,
  36  * where the soprano voice and the alto voice are put into the same
  37  * staff (this is generally a bad idea, but unfortunately common
  38  * practice).  Then, there probably should be two ambitus grobs, one
  39  * for each voice.  But how can you see which ambitus grob refers to
  40  * which voice?  Most probably you can guess it from the fact that the
  41  * ambitus of the alto voice typically lies in a lower range than that
  42  * of the soprano voice, but this is just a heuristic rather than a
  43  * generally valid rule.  In the case of only two voices, using stems
  44  * in the ambitus grob might help, but probably looks quite ugly.
  45  *
  46  * - If a piece consists of several loosely coupled sections, should
  47  * there be multiple ambitus grobs allowed, one for each section?
  48  * Then there probably should be some "\ambitus" event added to
  49  * mudela, stating where an ambitus grob should be placed.  This
  50  * ambitus grob should then represent the ambitus in the range of time
  51  * between this "\ambitus" event and the next one (or the end of the
  52  * piece, if there is no more such event).  To be compliant with the
  53  * current implementation, we might implicitly assume an "\ambitus"
  54  * event at the beginning of the piece, but then the question where
  55  * to put this first ambitus grob (before/after the clef?) becomes
  56  * even more urgent.
  57  *
  58  * - Incipits of transcribed music may need special treatment for
  59  * ambitus, since, for readability, the ambitus most probably should
  60  * not refer to the ancient clefs of the incipit, but rather to the
  61  * clefs used in the transcribed parts.
  62  */
  63 class Ambitus_engraver : public Engraver
  64 {
  65 public:
  66 TRANSLATOR_DECLARATIONS(Ambitus_engraver);
  67   virtual void process_music ();
  68   virtual void acknowledge_grob (Grob_info);
  69   virtual void stop_translation_timestep ();
  70   virtual void finalize ();
  71
  72 private:
  73   void create_ambitus ();
  74   Item *ambitus_;
  75   int/*bool*/ is_typeset;
  76   Pitch pitch_min, pitch_max;
  77 };
  78
  79 Ambitus_engraver::Ambitus_engraver ()
  80 {
  81   ambitus_ = 0;
  82   is_typeset = 0;
  83
  84   /*
  85    * (pitch_min > pitch_max) means that pitches are not yet
  86    * initialized
  87    */
  88   pitch_min = Pitch (0, 0, +1);
  89   pitch_max = Pitch (0, 0, -1);
  90 }
  91
  92 void
  93 Ambitus_engraver::process_music ()
  94 {
  95   /*
  96    * Ensure that ambitus is created in the very first timestep (on
  97    * which lily does not call start_translation_timestep ()).
  98    * Otherwise, if a voice begins with a rest, the ambitus grob will
  99    * be placed after the rest.
 100    */
 101   if (!ambitus_) {
 102     create_ambitus ();
 103   }
 104 }
 105
 106 void
 107 Ambitus_engraver::stop_translation_timestep ()
 108 {
 109   if (ambitus_ && !is_typeset)
 110     {
 111       /*
 112        * Evaluate centralCPosition not until now, since otherwise we
 113        * may then oversee a clef that is defined in a staff context if
 114        * we are in a voice context; centralCPosition would then be
 115        * assumed to be 0.
 116        */
 117       SCM c0 = get_property ("centralCPosition");
 118       ambitus_->set_grob_property ("c0-position", c0);
 119
 120       /*
 121        * Similar for keySignature.
 122        */
 123       SCM key_signature = get_property ("keySignature");
 124       ambitus_->set_grob_property ("accidentals", key_signature);
 125
 126       typeset_grob (ambitus_);
 127       is_typeset = 1;
 128     }
 129 }
 130
 131 void
 132 Ambitus_engraver::acknowledge_grob (Grob_info info)
 133 {
 134   Item *item = dynamic_cast <Item *>(info.grob_);
 135   if (item)
 136     {
 137       if (Note_head::has_interface (info.grob_))
 138         {
 139           Music *nr = info.music_cause ();
 140           if (nr && nr->is_mus_type ("note-event"))
 141             {
 142               Pitch pitch = *unsmob_pitch (nr->get_mus_property ("pitch"));
 143               if (Pitch::compare (pitch_min, pitch_max) > 0) // already init'd?
 144                 {
 145                   // not yet init'd; use current pitch to init min/max
 146                   pitch_min = pitch;
 147                   pitch_max = pitch;
 148                 }
 149               else if (Pitch::compare (pitch, pitch_max) > 0) // new max?
 150                 {
 151                   pitch_max = pitch;
 152                 }
 153               else if (Pitch::compare (pitch, pitch_min) < 0) // new min?
 154                 {
 155                   pitch_min = pitch;
 156                 }
 157             }
 158         }
 159     }
 160 }
 161
 162 void
 163 Ambitus_engraver::create_ambitus ()
 164 {
 165   SCM basicProperties = get_property ("Ambitus");
 166   ambitus_ = new Item (basicProperties); is_typeset = 0;
 167   announce_grob (ambitus_, SCM_EOL);
 168 }
 169
 170 void
 171 Ambitus_engraver::finalize ()
 172 {
 173   if (ambitus_)
 174     {
 175       if (Pitch::compare (pitch_min, pitch_max) <= 0)
 176         {
 177           ambitus_->set_grob_property ("pitch-min",
 178                                          pitch_min.smobbed_copy ());
 179           ambitus_->set_grob_property ("pitch-max",
 180                                          pitch_max.smobbed_copy ());
 181         }
 182       else // have not seen any pitch, so forget about the ambitus
 183         {
 184           /*
 185            * Do not print a warning on empty ambitus range, since this
 186            * most probably arises from an empty voice, such as shared
 187            * global timesig/clef definitions.
 188            */
 189 #if 0
 190           ambitus_->warning("empty ambitus range [ignored]");
 191 #endif
 192           ambitus_->suicide();
 193         }
 194     }
 195 }
 196
 197 ENTER_DESCRIPTION(Ambitus_engraver,
 198 /* descr */       "",
 199 /* creats*/       "Ambitus",
 200 /* accepts */ "",
 201 /* acks  */     "note-head-interface",
 202 /* reads */       "",
 203 /* write */       "");