lily/stem.cc

   1 /*
   2   stem.cc -- implement Stem
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1996--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7   Jan Nieuwenhuizen <janneke@gnu.org>
   8
   9   TODO: This is way too hairy
  10
  11   TODO: fix naming.
  12
  13   Stem-end, chord-start, etc. is all confusing naming.
  14 */
  15
  16 #include "stem.hh"
  17
  18 #include <math.h>               // rint
  19
  20 #include "lookup.hh"
  21 #include "directional-element-interface.hh"
  22 #include "note-head.hh"
  23 #include "warn.hh"
  24 #include "output-def.hh"
  25 #include "rhythmic-head.hh"
  26 #include "font-interface.hh"
  27 #include "paper-column.hh"
  28 #include "misc.hh"
  29 #include "beam.hh"
  30 #include "rest.hh"
  31 #include "group-interface.hh"
  32 #include "staff-symbol-referencer.hh"
  33 #include "side-position-interface.hh"
  34 #include "dot-column.hh"
  35 #include "stem-tremolo.hh"
  36
  37 void
  38 Stem::set_beaming (Grob *me, int beam_count, Direction d)
  39 {
  40   SCM pair = me->get_property ("beaming");
  41
  42   if (!scm_is_pair (pair))
  43     {
  44       pair = scm_cons (SCM_EOL, SCM_EOL);
  45       me->set_property ("beaming", pair);
  46     }
  47
  48   SCM lst = index_get_cell (pair, d);
  49   for (int i = 0; i < beam_count; i++)
  50     lst = scm_cons (scm_int2num (i), lst);
  51   index_set_cell (pair, d, lst);
  52 }
  53
  54 int
  55 Stem::get_beaming (Grob *me, Direction d)
  56 {
  57   SCM pair = me->get_property ("beaming");
  58   if (!scm_is_pair (pair))
  59     return 0;
  60
  61   SCM lst = index_get_cell (pair, d);
  62   return scm_ilength (lst);
  63 }
  64
  65 Interval
  66 Stem::head_positions (Grob *me)
  67 {
  68   if (head_count (me))
  69     {
  70       Drul_array<Grob *> e (extremal_heads (me));
  71       return Interval (Staff_symbol_referencer::get_position (e[DOWN]),
  72                        Staff_symbol_referencer::get_position (e[UP]));
  73     }
  74   return Interval ();
  75 }
  76
  77 Real
  78 Stem::chord_start_y (Grob *me)
  79 {
  80   Interval hp = head_positions (me);
  81   if (!hp.is_empty ())
  82     return hp[get_direction (me)] * Staff_symbol_referencer::staff_space (me)
  83       * 0.5;
  84   return 0;
  85 }
  86
  87 Real
  88 Stem::stem_end_position (Grob *me)
  89 {
  90   SCM p = me->get_property ("stem-end-position");
  91   Real pos;
  92   if (!scm_is_number (p))
  93     {
  94       pos = get_default_stem_end_position (me);
  95       me->set_property ("stem-end-position", scm_make_real (pos));
  96     }
  97   else
  98     pos = scm_to_double (p);
  99
 100   return pos;
 101 }
 102
 103 Direction
 104 Stem::get_direction (Grob *me)
 105 {
 106   Direction d = get_grob_direction (me);
 107
 108   if (!d)
 109     {
 110       d = get_default_dir (me);
 111       // urg, AAARGH!
 112       set_grob_direction (me, d);
 113     }
 114   return d;
 115 }
 116
 117 void
 118 Stem::set_stemend (Grob *me, Real se)
 119 {
 120   // todo: margins
 121   Direction d = get_direction (me);
 122
 123   if (d && d * head_positions (me)[get_direction (me)] >= se * d)
 124     me->warning (_ ("weird stem size, check for narrow beams"));
 125
 126   me->set_property ("stem-end-position", scm_make_real (se));
 127 }
 128
 129 /* Note head that determines hshift for upstems
 130    WARNING: triggers direction  */
 131 Grob *
 132 Stem::support_head (Grob *me)
 133 {
 134   if (head_count (me) == 1)
 135     /* UGH. */
 136     return unsmob_grob (scm_car (me->get_property ("note-heads")));
 137   return first_head (me);
 138 }
 139
 140 int
 141 Stem::head_count (Grob *me)
 142 {
 143   return Pointer_group_interface::count (me, ly_symbol2scm ("note-heads"));
 144 }
 145
 146 /* The note head which forms one end of the stem.
 147    WARNING: triggers direction  */
 148 Grob *
 149 Stem::first_head (Grob *me)
 150 {
 151   Direction d = get_direction (me);
 152   if (d)
 153     return extremal_heads (me)[-d];
 154   return 0;
 155 }
 156
 157 /* The note head opposite to the first head.  */
 158 Grob *
 159 Stem::last_head (Grob *me)
 160 {
 161   Direction d = get_direction (me);
 162   if (d)
 163     return extremal_heads (me)[d];
 164   return 0;
 165 }
 166
 167 /*
 168   START is part where stem reaches `last' head.
 169
 170   This function returns a drul with (bottom-head, top-head).
 171 */
 172 Drul_array<Grob *>
 173 Stem::extremal_heads (Grob *me)
 174 {
 175   const int inf = 1000000;
 176   Drul_array<int> extpos;
 177   extpos[DOWN] = inf;
 178   extpos[UP] = -inf;
 179
 180   Drul_array<Grob *> exthead (0, 0);
 181   for (SCM s = me->get_property ("note-heads"); scm_is_pair (s);
 182        s = scm_cdr (s))
 183     {
 184       Grob *n = unsmob_grob (scm_car (s));
 185       int p = Staff_symbol_referencer::get_rounded_position (n);
 186
 187       Direction d = LEFT;
 188       do
 189         {
 190           if (d * p > d * extpos[d])
 191             {
 192               exthead[d] = n;
 193               extpos[d] = p;
 194             }
 195         }
 196       while (flip (&d) != DOWN);
 197     }
 198   return exthead;
 199 }
 200
 201 static int
 202 integer_compare (int const &a, int const &b)
 203 {
 204   return a - b;
 205 }
 206
 207 /* The positions, in ascending order.  */
 208 Array<int>
 209 Stem::note_head_positions (Grob *me)
 210 {
 211   Array<int> ps;
 212   for (SCM s = me->get_property ("note-heads"); scm_is_pair (s);
 213        s = scm_cdr (s))
 214     {
 215       Grob *n = unsmob_grob (scm_car (s));
 216       int p = Staff_symbol_referencer::get_rounded_position (n);
 217
 218       ps.push (p);
 219     }
 220
 221   ps.sort (integer_compare);
 222   return ps;
 223 }
 224
 225 void
 226 Stem::add_head (Grob *me, Grob *n)
 227 {
 228   n->set_property ("stem", me->self_scm ());
 229   n->add_dependency (me);
 230
 231   if (Note_head::has_interface (n))
 232     Pointer_group_interface::add_grob (me, ly_symbol2scm ("note-heads"), n);
 233   else if (Rest::has_interface (n))
 234     Pointer_group_interface::add_grob (me, ly_symbol2scm ("rests"), n);
 235 }
 236
 237 bool
 238 Stem::is_invisible (Grob *me)
 239 {
 240   Real stemlet_length = robust_scm2double (me->get_property ("stemlet-length"),
 241                                            0.0);
 242
 243   return !((head_count (me)
 244             || stemlet_length > 0.0)
 245            && scm_to_int (me->get_property ("duration-log")) >= 1);
 246 }
 247
 248 Direction
 249 Stem::get_default_dir (Grob *me)
 250 {
 251   int staff_center = 0;
 252   Interval hp = head_positions (me);
 253   if (hp.is_empty ())
 254     return CENTER;
 255
 256   int udistance = (int) (UP *hp[UP] - staff_center);
 257   int ddistance = (int) (DOWN *hp[DOWN] - staff_center);
 258
 259   if (sign (ddistance - udistance))
 260     return Direction (sign (ddistance - udistance));
 261
 262   return to_dir (me->get_property ("neutral-direction"));
 263 }
 264
 265 Real
 266 Stem::get_default_stem_end_position (Grob *me)
 267 {
 268   Real ss = Staff_symbol_referencer::staff_space (me);
 269   int durlog = duration_log (me);
 270   SCM s;
 271   Array<Real> a;
 272
 273   /* WARNING: IN HALF SPACES */
 274   Real length = 7;
 275   SCM scm_len = me->get_property ("length");
 276   if (scm_is_number (scm_len))
 277     length = scm_to_double (scm_len);
 278   else
 279     {
 280       s = me->get_property ("lengths");
 281       if (scm_is_pair (s))
 282         length = 2 * scm_to_double (robust_list_ref (durlog - 2, s));
 283     }
 284
 285   /* URGURGURG
 286      'set-default-stemlen' sets direction too.   */
 287   Direction dir = get_direction (me);
 288   if (!dir)
 289     {
 290       dir = get_default_dir (me);
 291       set_grob_direction (me, dir);
 292     }
 293
 294   /* Stems in unnatural (forced) direction should be shortened,
 295      according to [Roush & Gourlay] */
 296   Interval hp = head_positions (me);
 297   if (dir && dir * hp[dir] >= 0)
 298     {
 299       SCM sshorten = me->get_property ("stem-shorten");
 300       SCM scm_shorten = scm_is_pair (sshorten)
 301         ? robust_list_ref ((duration_log (me) - 2) >? 0, sshorten) : SCM_EOL;
 302       Real shorten = 2* robust_scm2double (scm_shorten, 0);
 303
 304       /* On boundary: shorten only half */
 305       if (abs (head_positions (me)[dir]) <= 1)
 306         shorten *= 0.5;
 307
 308       length -= shorten;
 309     }
 310
 311   /* Tremolo stuff.  */
 312   Grob *t_flag = unsmob_grob (me->get_property ("tremolo-flag"));
 313   if (t_flag && !unsmob_grob (me->get_property ("beam")))
 314     {
 315       /* Crude hack: add extra space if tremolo flag is there.
 316
 317       We can't do this for the beam, since we get into a loop
 318       (Stem_tremolo::raw_stencil () looks at the beam.) --hwn  */
 319
 320       Real minlen = 1.0
 321         + 2 * Stem_tremolo::raw_stencil (t_flag).extent (Y_AXIS).length ()
 322         / ss;
 323
 324       if (durlog >= 3)
 325         {
 326           Interval flag_ext = flag (me).extent (Y_AXIS);
 327           if (!flag_ext.is_empty ())
 328             minlen += 2 * flag_ext.length () / ss;
 329
 330           /* The clash is smaller for down stems (since the tremolo is
 331              angled up.) */
 332           if (dir == DOWN)
 333             minlen -= 1.0;
 334         }
 335       length = length >? (minlen + 1.0);
 336     }
 337
 338   Real st = dir ? hp[dir] + dir * length : 0;
 339
 340   /* TODO: change name  to extend-stems to staff/center/'()  */
 341   bool no_extend_b = to_boolean (me->get_property ("no-stem-extend"));
 342   if (!no_extend_b && dir * st < 0)
 343     st = 0.0;
 344
 345   /* Make a little room if we have a upflag and there is a dot.
 346      previous approach was to lengthen the stem. This is not
 347      good typesetting practice.  */
 348   if (!get_beam (me) && dir == UP
 349       && durlog > 2)
 350     {
 351       Grob *closest_to_flag = extremal_heads (me)[dir];
 352       Grob *dots = closest_to_flag
 353         ? Rhythmic_head::get_dots (closest_to_flag) : 0;
 354
 355       if (dots)
 356         {
 357           Real dp = Staff_symbol_referencer::get_position (dots);
 358           Real flagy = flag (me).extent (Y_AXIS)[-dir] * 2 / ss;
 359
 360           /* Very gory: add myself to the X-support of the parent,
 361              which should be a dot-column. */
 362           if (dir * (st + flagy - dp) < 0.5)
 363             {
 364               Grob *par = dots->get_parent (X_AXIS);
 365
 366               if (Dot_column::has_interface (par))
 367                 {
 368                   Side_position_interface::add_support (par, me);
 369
 370                   /* TODO: apply some better logic here. The flag is
 371                      curved inwards, so this will typically be too
 372                      much. */
 373                 }
 374             }
 375         }
 376     }
 377   return st;
 378 }
 379
 380 /* The log of the duration (Number of hooks on the flag minus two)  */
 381 int
 382 Stem::duration_log (Grob *me)
 383 {
 384   SCM s = me->get_property ("duration-log");
 385   return (scm_is_number (s)) ? scm_to_int (s) : 2;
 386 }
 387
 388 void
 389 Stem::position_noteheads (Grob *me)
 390 {
 391   if (!head_count (me))
 392     return;
 393
 394   Link_array<Grob> heads
 395     = extract_grob_array (me, ly_symbol2scm ("note-heads"));
 396
 397   heads.sort (compare_position);
 398   Direction dir = get_direction (me);
 399
 400   if (dir < 0)
 401     heads.reverse ();
 402
 403   Real thick = thickness (me);
 404
 405   Grob *hed = support_head (me);
 406   Real w = hed->extent (hed, X_AXIS)[dir];
 407   for (int i = 0; i < heads.size (); i++)
 408     heads[i]->translate_axis (w - heads[i]->extent (heads[i], X_AXIS)[dir],
 409                               X_AXIS);
 410
 411   bool parity = true;
 412   Real lastpos = Real (Staff_symbol_referencer::get_position (heads[0]));
 413   for (int i = 1; i < heads.size (); i++)
 414     {
 415       Real p = Staff_symbol_referencer::get_position (heads[i]);
 416       Real dy = fabs (lastpos- p);
 417
 418       /*
 419         dy should always be 0.5, 0.0, 1.0, but provide safety margin
 420         for rounding errors.
 421       */
 422       if (dy < 1.1)
 423         {
 424           if (parity)
 425             {
 426               Real ell = heads[i]->extent (heads[i], X_AXIS).length ();
 427
 428               Direction d = get_direction (me);
 429               /*
 430                 Reversed head should be shifted ell-thickness, but this
 431                 looks too crowded, so we only shift ell-0.5*thickness.
 432
 433                 This leads to assymetry: Normal heads overlap the
 434                 stem 100% whereas reversed heads only overlaps the
 435                 stem 50%
 436               */
 437
 438               Real reverse_overlap = 0.5;
 439               heads[i]->translate_axis ((ell - thick * reverse_overlap) * d,
 440                                         X_AXIS);
 441
 442               if (is_invisible (me))
 443                 heads[i]->translate_axis (-thick * (2 - reverse_overlap) * d,
 444                                           X_AXIS);
 445
 446               /* TODO:
 447
 448               For some cases we should kern some more: when the
 449               distance between the next or prev note is too large, we'd
 450               get large white gaps, eg.
 451
 452               |
 453               X|
 454               |X  <- kern this.
 455               |
 456               X
 457
 458               */
 459             }
 460           parity = !parity;
 461         }
 462       else
 463         parity = true;
 464
 465       lastpos = int (p);
 466     }
 467 }
 468
 469 MAKE_SCHEME_CALLBACK (Stem, before_line_breaking, 1);
 470 SCM
 471 Stem::before_line_breaking (SCM smob)
 472 {
 473   Grob *me = unsmob_grob (smob);
 474
 475   /*
 476     Do the calculations for visible stems, but also for invisible stems
 477     with note heads (i.e. half notes.)
 478   */
 479   if (head_count (me))
 480     {
 481       stem_end_position (me);   // ugh. Trigger direction calc.
 482       position_noteheads (me);
 483     }
 484
 485   return SCM_UNSPECIFIED;
 486 }
 487
 488 /*
 489   ugh.
 490   When in a beam with tuplet brackets, brew_mol is called early,
 491   caching a wrong value.
 492 */
 493 MAKE_SCHEME_CALLBACK (Stem, height, 2);
 494 SCM
 495 Stem::height (SCM smob, SCM ax)
 496 {
 497   Axis a = (Axis)scm_to_int (ax);
 498   Grob *me = unsmob_grob (smob);
 499   assert (a == Y_AXIS);
 500
 501   /*
 502     ugh. - this dependency should be automatic.
 503   */
 504   Grob *beam = get_beam (me);
 505   if (beam)
 506     {
 507       Beam::after_line_breaking (beam->self_scm ());
 508     }
 509
 510   SCM mol = me->get_uncached_stencil ();
 511   Interval iv;
 512   if (mol != SCM_EOL)
 513     iv = unsmob_stencil (mol)->extent (a);
 514   if (Grob *b = get_beam (me))
 515     {
 516       Direction d = get_direction (me);
 517       if (d == CENTER)
 518         {
 519           programming_error ("no stem direction");
 520           d = UP;
 521         }
 522       iv[d] += d * Beam::get_thickness (b) * 0.5;
 523     }
 524
 525   return ly_interval2scm (iv);
 526 }
 527
 528 Stencil
 529 Stem::flag (Grob *me)
 530 {
 531   /* TODO: maybe property stroke-style should take different values,
 532      e.g. "" (i.e. no stroke), "single" and "double" (currently, it's
 533      '() or "grace").  */
 534   String flag_style;
 535
 536   SCM flag_style_scm = me->get_property ("flag-style");
 537   if (scm_is_symbol (flag_style_scm))
 538     flag_style = ly_symbol2string (flag_style_scm);
 539
 540   if (flag_style == "no-flag")
 541     return Stencil ();
 542
 543   bool adjust = true;
 544
 545   String staffline_offs;
 546   if (String::compare (flag_style, "mensural") == 0)
 547     /* Mensural notation: For notes on staff lines, use different
 548        flags than for notes between staff lines.  The idea is that
 549        flags are always vertically aligned with the staff lines,
 550        regardless if the note head is on a staff line or between two
 551        staff lines.  In other words, the inner end of a flag always
 552        touches a staff line.
 553     */
 554     {
 555       if (adjust)
 556         {
 557           int p = (int) (rint (stem_end_position (me)));
 558           staffline_offs
 559             = Staff_symbol_referencer::on_staffline (me, p) ? "0" : "1";
 560         }
 561       else
 562         {
 563           staffline_offs = "2";
 564         }
 565     }
 566   else
 567     {
 568       staffline_offs = "";
 569     }
 570
 571   char dir = (get_direction (me) == UP) ? 'u' : 'd';
 572   String font_char = flag_style
 573     + to_string (dir) + staffline_offs + to_string (duration_log (me));
 574   Font_metric *fm = Font_interface::get_default_font (me);
 575   Stencil flag = fm->find_by_name ("flags." + font_char);
 576   if (flag.is_empty ())
 577     me->warning (_f ("flag `%s' not found", font_char));
 578
 579   SCM stroke_style_scm = me->get_property ("stroke-style");
 580   if (scm_is_string (stroke_style_scm))
 581     {
 582       String stroke_style = ly_scm2string (stroke_style_scm);
 583       if (!stroke_style.is_empty ())
 584         {
 585           String font_char = to_string (dir) + stroke_style;
 586           Stencil stroke = fm->find_by_name ("flags." + font_char);
 587           if (stroke.is_empty ())
 588             me->warning (_f ("flag stroke `%s' not found", font_char));
 589           else
 590             flag.add_stencil (stroke);
 591         }
 592     }
 593
 594   return flag;
 595 }
 596
 597 MAKE_SCHEME_CALLBACK (Stem, width_callback, 2);
 598 SCM
 599 Stem::width_callback (SCM e, SCM ax)
 600 {
 601   Axis a = (Axis) scm_to_int (ax);
 602   assert (a == X_AXIS);
 603   Grob *me = unsmob_grob (e);
 604
 605   Interval r;
 606
 607   if (is_invisible (me))
 608     {
 609       r.set_empty ();
 610     }
 611   else if (unsmob_grob (me->get_property ("beam")) || abs (duration_log (me)) <= 2)
 612     {
 613       r = Interval (-1, 1);
 614       r *= thickness (me) / 2;
 615     }
 616   else
 617     {
 618       r = flag (me).extent (X_AXIS)
 619         + thickness (me) / 2;
 620     }
 621   return ly_interval2scm (r);
 622 }
 623
 624 Real
 625 Stem::thickness (Grob *me)
 626 {
 627   return scm_to_double (me->get_property ("thickness"))
 628     * Staff_symbol_referencer::line_thickness (me);
 629 }
 630
 631 MAKE_SCHEME_CALLBACK (Stem, print, 1);
 632 SCM
 633 Stem::print (SCM smob)
 634 {
 635   Grob *me = unsmob_grob (smob);
 636   Stencil mol;
 637   Direction d = get_direction (me);
 638
 639   Real stemlet_length = robust_scm2double (me->get_property ("stemlet-length"),
 640                                            0.0);
 641   bool stemlet = stemlet_length > 0.0;
 642
 643   /* TODO: make the stem start a direction ?
 644      This is required to avoid stems passing in tablature chords.  */
 645   Grob *lh
 646     = to_boolean (me->get_property ("avoid-note-head"))
 647     ? last_head (me)
 648     : first_head (me);
 649   Grob *beam = get_beam (me);
 650
 651   if (!lh && !stemlet)
 652     return SCM_EOL;
 653
 654   if (!lh && stemlet && !beam)
 655     return SCM_EOL;
 656
 657   if (is_invisible (me))
 658     return SCM_EOL;
 659
 660   Real y2 = stem_end_position (me);
 661   Real y1 = y2;
 662   Real half_space = Staff_symbol_referencer::staff_space (me) * 0.5;
 663
 664   if (lh)
 665     y2 = Staff_symbol_referencer::get_position (lh);
 666   else if (stemlet)
 667     {
 668       Real beam_translation = Beam::get_beam_translation (beam);
 669       Real beam_thickness = Beam::get_thickness (beam);
 670       int beam_count = beam_multiplicity (me).length () + 1;
 671
 672       y2 -= d
 673         * (0.5 * beam_thickness
 674            + beam_translation * (0 >? (beam_count - 1))
 675            + stemlet_length) / half_space;
 676     }
 677
 678   Interval stem_y (y1 <? y2, y2 >? y1);
 679
 680   if (Grob *hed = support_head (me))
 681     {
 682       /*
 683         must not take ledgers into account.
 684       */
 685       Interval head_height = hed->extent (hed, Y_AXIS);
 686       Real y_attach = Note_head::stem_attachment_coordinate (hed, Y_AXIS);
 687
 688       y_attach = head_height.linear_combination (y_attach);
 689       stem_y[Direction (-d)] += d * y_attach / half_space;
 690     }
 691
 692   // URG
 693   Real stem_width = thickness (me);
 694   Real blot
 695     = me->get_layout ()->get_dimension (ly_symbol2scm ("blotdiameter"));
 696
 697   Box b = Box (Interval (-stem_width / 2, stem_width / 2),
 698                Interval (stem_y[DOWN] * half_space, stem_y[UP] * half_space));
 699
 700   Stencil ss = Lookup::round_filled_box (b, blot);
 701   mol.add_stencil (ss);
 702
 703   if (!get_beam (me) && abs (duration_log (me)) > 2)
 704     {
 705       Stencil fl = flag (me);
 706       fl.translate_axis (stem_y[d] * half_space - d * blot / 2, Y_AXIS);
 707       fl.translate_axis (stem_width / 2, X_AXIS);
 708       mol.add_stencil (fl);
 709     }
 710
 711   return mol.smobbed_copy ();
 712 }
 713
 714 /*
 715   move the stem to right of the notehead if it is up.
 716 */
 717 MAKE_SCHEME_CALLBACK (Stem, offset_callback, 2);
 718 SCM
 719 Stem::offset_callback (SCM element_smob, SCM)
 720 {
 721   Grob *me = unsmob_grob (element_smob);
 722   Real r = 0.0;
 723
 724   if (Grob *f = first_head (me))
 725     {
 726       Interval head_wid = f->extent (f, X_AXIS);
 727       Real attach = 0.0;
 728
 729       if (is_invisible (me))
 730         attach = 0.0;
 731       else
 732         attach = Note_head::stem_attachment_coordinate (f, X_AXIS);
 733
 734       Direction d = get_direction (me);
 735       Real real_attach = head_wid.linear_combination (d * attach);
 736       r = real_attach;
 737
 738       /* If not centered: correct for stem thickness.  */
 739       if (attach)
 740         {
 741           Real rule_thick = thickness (me);
 742           r += -d * rule_thick * 0.5;
 743         }
 744     }
 745   else
 746     {
 747       SCM rests = me->get_property ("rests");
 748       if (scm_is_pair (rests))
 749         {
 750           Grob *rest = unsmob_grob (scm_car (rests));
 751           r = rest->extent (rest, X_AXIS).center ();
 752         }
 753     }
 754   return scm_make_real (r);
 755 }
 756
 757 Spanner *
 758 Stem::get_beam (Grob *me)
 759 {
 760   SCM b = me->get_property ("beam");
 761   return dynamic_cast<Spanner *> (unsmob_grob (b));
 762 }
 763
 764 Stem_info
 765 Stem::get_stem_info (Grob *me)
 766 {
 767   /* Return cached info if available */
 768   SCM scm_info = me->get_property ("stem-info");
 769   if (!scm_is_pair (scm_info))
 770     {
 771       calc_stem_info (me);
 772       scm_info = me->get_property ("stem-info");
 773     }
 774
 775   Stem_info si;
 776   si.dir_ = get_grob_direction (me);
 777   si.ideal_y_ = scm_to_double (scm_car (scm_info));
 778   si.shortest_y_ = scm_to_double (scm_cadr (scm_info));
 779   return si;
 780 }
 781
 782 /* TODO: add extra space for tremolos!  */
 783 void
 784 Stem::calc_stem_info (Grob *me)
 785 {
 786   Direction my_dir = get_grob_direction (me);
 787
 788   if (!my_dir)
 789     {
 790       programming_error ("no stem dir set");
 791       my_dir = UP;
 792     }
 793
 794   Real staff_space = Staff_symbol_referencer::staff_space (me);
 795   Grob *beam = get_beam (me);
 796   Real beam_translation = Beam::get_beam_translation (beam);
 797   Real beam_thickness = Beam::get_thickness (beam);
 798   int beam_count = Beam::get_direction_beam_count (beam, my_dir);
 799
 800   /* Simple standard stem length */
 801   SCM lengths = me->get_property ("beamed-lengths");
 802   Real ideal_length
 803     = scm_to_double (robust_list_ref (beam_count - 1, lengths))
 804
 805     * staff_space
 806     /* stem only extends to center of beam
 807      */
 808     - 0.5 * beam_thickness;
 809
 810   /* Condition: sane minimum free stem length (chord to beams) */
 811   lengths = me->get_property ("beamed-minimum-free-lengths");
 812   Real ideal_minimum_free
 813     = scm_to_double (robust_list_ref (beam_count - 1, lengths))
 814     * staff_space;
 815
 816   /* UGH
 817      It seems that also for ideal minimum length, we must use
 818      the maximum beam count (for this direction):
 819
 820      \score{ \notes\relative c''{ [a8 a32] }}
 821
 822      must be horizontal. */
 823   Real height_of_my_beams = beam_thickness
 824     + (beam_count - 1) * beam_translation;
 825
 826   Real ideal_minimum_length = ideal_minimum_free
 827     + height_of_my_beams
 828     /* stem only extends to center of beam */
 829     - 0.5 * beam_thickness;
 830
 831   ideal_length = ideal_length >? ideal_minimum_length;
 832
 833   /* Convert to Y position, calculate for dir == UP */
 834   Real note_start
 835     =     /* staff positions */
 836     head_positions (me)[my_dir] * 0.5
 837     * my_dir * staff_space;
 838   Real ideal_y = note_start + ideal_length;
 839
 840   /* Conditions for Y position */
 841
 842   /* Lowest beam of (UP) beam must never be lower than second staffline
 843
 844   Reference?
 845
 846   Although this (additional) rule is probably correct,
 847   I expect that highest beam (UP) should also never be lower
 848   than middle staffline, just as normal stems.
 849
 850   Reference?
 851
 852   Obviously not for grace beams.
 853
 854   Also, not for knees.  Seems to be a good thing. */
 855   bool no_extend_b = to_boolean (me->get_property ("no-stem-extend"));
 856   bool is_knee = to_boolean (beam->get_property ("knee"));
 857   if (!no_extend_b && !is_knee)
 858     {
 859       /* Highest beam of (UP) beam must never be lower than middle
 860          staffline */
 861       ideal_y = ideal_y >? 0;
 862       /* Lowest beam of (UP) beam must never be lower than second staffline */
 863       ideal_y = ideal_y >? (-staff_space
 864                             - beam_thickness + height_of_my_beams);
 865     }
 866
 867   ideal_y -= robust_scm2double (beam->get_property ("shorten"), 0);
 868
 869   Real minimum_free
 870     = scm_to_double (robust_list_ref
 871                      (beam_count - 1,
 872                       me->get_property
 873                       ("beamed-extreme-minimum-free-lengths")))
 874     * staff_space;
 875
 876   Real minimum_length = minimum_free
 877     + height_of_my_beams
 878     /* stem only extends to center of beam */
 879     - 0.5 * beam_thickness;
 880
 881   ideal_y *= my_dir;
 882   Real minimum_y = note_start + minimum_length;
 883   Real shortest_y = minimum_y * my_dir;
 884
 885   me->set_property ("stem-info",
 886                     scm_list_2 (scm_make_real (ideal_y),
 887                                 scm_make_real (shortest_y)));
 888 }
 889
 890 Slice
 891 Stem::beam_multiplicity (Grob *stem)
 892 {
 893   SCM beaming = stem->get_property ("beaming");
 894   Slice le = int_list_to_slice (scm_car (beaming));
 895   Slice ri = int_list_to_slice (scm_cdr (beaming));
 896   le.unite (ri);
 897   return le;
 898 }
 899
 900 /* FIXME:  Too many properties  */
 901 ADD_INTERFACE (Stem, "stem-interface",
 902                "The stem represent the graphical stem.  "
 903                "In addition, it internally connects note heads, beams and"
 904                "tremolos. "
 905                "Rests and whole notes have invisible stems.",
 906                "tremolo-flag french-beaming "
 907                "avoid-note-head thickness "
 908                "stemlet-length rests "
 909                "stem-info beamed-lengths beamed-minimum-free-lengths "
 910                "beamed-extreme-minimum-free-lengths lengths beam stem-shorten "
 911                "duration-log beaming neutral-direction stem-end-position "
 912                "note-heads direction length flag-style "
 913                "no-stem-extend stroke-style");
 914
 915 /****************************************************************/
 916
 917 Stem_info::Stem_info ()
 918 {
 919   ideal_y_ = shortest_y_ = 0;
 920   dir_ = CENTER;
 921 }
 922
 923 void
 924 Stem_info::scale (Real x)
 925 {
 926   ideal_y_ *= x;
 927   shortest_y_ *= x;
 928 }