lily/simple-spacer.cc

   1 /*
   2   simple-spacer.cc -- implement Simple_spacer
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1999--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7
   8   TODO:
   9   - add support for different stretch/shrink constants?
  10 */
  11
  12 #include <cstdio>
  13
  14 #include "column-x-positions.hh"
  15 #include "dimensions.hh"
  16 #include "international.hh"
  17 #include "libc-extension.hh"    // isinf
  18 #include "paper-column.hh"
  19 #include "simple-spacer.hh"
  20 #include "spaceable-grob.hh"
  21 #include "spring.hh"
  22 #include "warn.hh"
  23
  24 /*
  25   A simple spacing constraint solver. The approach:
  26
  27   Stretch the line uniformly until none of the constraints (rods)
  28   block.  It then is very wide.
  29
  30   Compress until the next constraint blocks,
  31
  32   Mark the springs over the constrained part to be non-active.
  33
  34   Repeat with the smaller set of non-active constraints, until all
  35   constraints blocked, or until the line is as short as desired.
  36
  37   This is much simpler, and much much faster than full scale
  38   Constrained QP. On the other hand, a situation like this will not
  39   be typeset as dense as possible, because
  40
  41   c4                   c4           c4                  c4
  42   veryveryverylongsyllable2         veryveryverylongsyllable2
  43   " "4                 veryveryverylongsyllable2        syllable4
  44
  45
  46   can be further compressed to
  47
  48
  49   c4    c4                        c4   c4
  50   veryveryverylongsyllable2       veryveryverylongsyllable2
  51   " "4  veryveryverylongsyllable2      syllable4
  52
  53
  54   Perhaps this is not a bad thing, because the 1st looks better anyway.  */
  55
  56 /*
  57   positive force = expanding, negative force = compressing.
  58 */
  59
  60 Simple_spacer::Simple_spacer ()
  61 {
  62   line_len_ = 0.0;
  63   force_ = 0.0;
  64   fits_ = true;
  65   ragged_ = true;
  66 }
  67
  68 Real
  69 Simple_spacer::force () const
  70 {
  71   return force_;
  72 }
  73
  74 bool
  75 Simple_spacer::fits () const
  76 {
  77   return fits_;
  78 }
  79
  80 Real
  81 Simple_spacer::rod_force (int l, int r, Real dist)
  82 {
  83   Real c = range_stiffness (l, r);
  84   Real d = range_ideal_len (l, r);
  85   Real block_stretch = dist - d;
  86   return c * block_stretch;
  87 }
  88
  89 void
  90 Simple_spacer::add_rod (int l, int r, Real dist)
  91 {
  92   if (isinf (dist) || isnan (dist))
  93     {
  94       programming_error ("ignoring weird minimum distance");
  95       return;
  96     }
  97
  98   Real block_force = rod_force (l, r, dist);
  99
 100   if (isinf (block_force))
 101     {
 102       Real spring_dist = range_ideal_len (l, r);
 103       if (spring_dist < dist)
 104         for (int i = l; i < r; i++)
 105           springs_[i].ideal_ *= dist / spring_dist;
 106
 107       return;
 108     }
 109   force_ = max (force_, block_force);
 110   for (int i = l; i < r; i++)
 111     springs_[i].block_force_ = max (block_force, springs_[i].block_force_);
 112 }
 113
 114 Real
 115 Simple_spacer::range_ideal_len (int l, int r) const
 116 {
 117   Real d = 0.;
 118   for (int i = l; i < r; i++)
 119     d += springs_[i].ideal_;
 120   return d;
 121 }
 122
 123 Real
 124 Simple_spacer::range_stiffness (int l, int r) const
 125 {
 126   Real den = 0.0;
 127   for (int i = l; i < r; i++)
 128     den += springs_[i].inverse_hooke_;
 129
 130   return 1 / den;
 131 }
 132
 133 Real
 134 Simple_spacer::configuration_length (Real force) const
 135 {
 136   Real l = 0.;
 137   for (vsize i = 0; i < springs_.size (); i++)
 138     l += springs_[i].length (force);
 139
 140   return l;
 141 }
 142
 143 void
 144 Simple_spacer::solve (Real line_len, bool ragged)
 145 {
 146   Real conf = configuration_length (force_);
 147
 148   ragged_ = ragged;
 149   line_len_ = line_len;
 150   if (conf < line_len_)
 151     force_ = expand_line ();
 152   else if (conf > line_len_)
 153     force_ = compress_line ();
 154
 155   if (ragged && force_ < 0)
 156     fits_ = false;
 157 }
 158
 159 Real
 160 Simple_spacer::expand_line ()
 161 {
 162   double inv_hooke = 0;
 163   double cur_len = configuration_length (force_);
 164
 165   fits_ = true;
 166   for (vsize i=0; i < springs_.size (); i++)
 167     inv_hooke += springs_[i].inverse_hooke_;
 168
 169   assert (cur_len <= line_len_);
 170   return (line_len_ - cur_len) / inv_hooke + force_;
 171 }
 172
 173 Real
 174 Simple_spacer::compress_line ()
 175 {
 176   double inv_hooke = 0;
 177   double cur_len = configuration_length (force_);
 178   double cur_force = force_;
 179
 180   fits_ = true;
 181   for (vsize i=0; i < springs_.size (); i++)
 182     inv_hooke += springs_[i].inverse_hooke_;
 183
 184   assert (line_len_ <= cur_len);
 185
 186   vector<Spring_description> sorted_springs = springs_;
 187   sort (sorted_springs.begin (), sorted_springs.end (), greater<Spring_description> ());
 188   for (vsize i = 0; i < sorted_springs.size (); i++)
 189     {
 190       Spring_description sp = sorted_springs[i];
 191
 192       assert (sp.block_force_ <= cur_force);
 193       if (isinf (sp.block_force_))
 194         break;
 195
 196       double block_dist = (cur_force - sp.block_force_) * inv_hooke;
 197       if (cur_len - block_dist < line_len_)
 198         {
 199          cur_force += (line_len_ - cur_len) / inv_hooke;
 200          cur_len = line_len_;
 201
 202          /*
 203            Paranoia check.
 204           */
 205          assert (fabs (configuration_length (cur_force) - cur_len) < 1e-6);
 206          return cur_force;
 207         }
 208
 209       cur_len -= block_dist;
 210       inv_hooke -= sp.inverse_hooke_;
 211       cur_force = sp.block_force_;
 212     }
 213
 214   fits_ = false;
 215   return cur_force;
 216 }
 217
 218 void
 219 Simple_spacer::add_spring (Real ideal, Real inverse_hooke)
 220 {
 221   Spring_description description;
 222
 223   description.ideal_ = ideal;
 224   description.inverse_hooke_ = inverse_hooke;
 225   if (!description.is_sane ())
 226     {
 227       programming_error ("insane spring found, setting to unit");
 228
 229       description.inverse_hooke_ = 1.0;
 230       description.ideal_ = 1.0;
 231     }
 232
 233   description.block_force_ = -description.ideal_ / description.inverse_hooke_;
 234   // block at distance 0
 235
 236   springs_.push_back (description);
 237 }
 238
 239 vector<Real>
 240 Simple_spacer::spring_positions () const
 241 {
 242   vector<Real> ret;
 243   ret.push_back (0.);
 244
 245   for (vsize i = 0; i < springs_.size (); i++)
 246     ret.push_back (ret.back () + springs_[i].length (ragged_ && force_ > 0 ? 0.0 : force_));
 247   return ret;
 248 }
 249
 250 /****************************************************************/
 251
 252 Spring_description::Spring_description ()
 253 {
 254   ideal_ = 0.0;
 255   inverse_hooke_ = 0.0;
 256   block_force_ = 0.0;
 257 }
 258
 259 bool
 260 Spring_description::is_sane () const
 261 {
 262   return (inverse_hooke_ >= 0)
 263     && ideal_ > 0
 264     && !isinf (ideal_) && !isnan (ideal_)
 265     && (inverse_hooke_ == 0.0 || fabs (inverse_hooke_) > 1e-8)
 266     ;
 267 }
 268
 269 Real
 270 Spring_description::length (Real f) const
 271 {
 272   return ideal_ + max (f, block_force_) * inverse_hooke_;
 273 }
 274
 275 /****************************************************************/
 276
 277 /*
 278   TODO: should a add penalty for widely varying spring forces (caused
 279   by constraints, eg.
 280
 281
 282   .     =====
 283   .     |   |
 284   .o|o|x ##x
 285   .
 286
 287   The ## forces the notes apart; we shouldn't allow the O's to touch
 288   this closely.
 289 */
 290
 291 struct Rod_description
 292 {
 293   vsize r_;
 294   Real dist_;
 295
 296   bool operator< (const Rod_description r)
 297   {
 298     return r_ < r.r_;
 299   }
 300
 301   Rod_description ()
 302   {
 303     r_ = 0;
 304     dist_ = 0;
 305   }
 306
 307   Rod_description (vsize r, Real d)
 308   {
 309     r_ = r;
 310     dist_ = d;
 311   }
 312 };
 313
 314 struct Column_description
 315 {
 316   vector<Rod_description> rods_;
 317   vector<Rod_description> end_rods_;   /* use these if they end at the last column of the line */
 318   Real ideal_;
 319   Real inverse_hooke_;
 320   Real end_ideal_;
 321   Real end_inverse_hooke_;
 322   SCM break_permission_;
 323   Interval keep_inside_line_;
 324
 325   Column_description ()
 326   {
 327     ideal_ = 0;
 328     inverse_hooke_ = 0;
 329     end_ideal_ = 0;
 330     end_inverse_hooke_ = 0;
 331     break_permission_ = SCM_EOL;
 332   }
 333 };
 334
 335 static bool
 336 is_loose (Grob *g)
 337 {
 338   return (scm_is_pair (g->get_object ("between-cols")));
 339 }
 340
 341 static Grob*
 342 maybe_find_prebroken_piece (Grob *g, Direction d)
 343 {
 344   Grob *ret = dynamic_cast<Item*> (g)->find_prebroken_piece (d);
 345   if (ret)
 346     return ret;
 347   return g;
 348 }
 349
 350 static Grob*
 351 next_spaceable_column (vector<Grob*> const &list, vsize starting)
 352 {
 353   for (vsize i = starting+1; i < list.size (); i++)
 354     if (!is_loose (list[i]))
 355       return list[i];
 356   return 0;
 357 }
 358
 359 static void
 360 get_column_spring (Grob *this_col, Grob *next_col, Real *ideal, Real *inv_hooke)
 361 {
 362   Spring_smob *spring = 0;
 363
 364   for (SCM s = this_col->get_object ("ideal-distances");
 365        !spring && scm_is_pair (s);
 366        s = scm_cdr (s))
 367     {
 368       Spring_smob *sp = unsmob_spring (scm_car (s));
 369
 370       if (sp->other_ == next_col)
 371         spring = sp;
 372     }
 373
 374   if (!spring)
 375     programming_error (_f ("No spring between column %d and next one",
 376                            Paper_column::get_rank (this_col)));
 377
 378   *ideal = (spring) ? spring->distance_ : 5.0;
 379   *inv_hooke = (spring) ? spring->inverse_strength_ : 1.0;
 380 }
 381
 382 static Column_description
 383 get_column_description (vector<Grob*> const &cols, vsize col_index, bool line_starter)
 384 {
 385   Grob *col = cols[col_index];
 386   if (line_starter)
 387     col = maybe_find_prebroken_piece (col, RIGHT);
 388
 389   Column_description description;
 390   Grob *next_col = next_spaceable_column (cols, col_index);
 391   if (next_col)
 392     get_column_spring (col, next_col, &description.ideal_, &description.inverse_hooke_);
 393   Grob *end_col = dynamic_cast<Item*> (cols[col_index+1])->find_prebroken_piece (LEFT);
 394   if (end_col)
 395     get_column_spring (col, end_col, &description.end_ideal_, &description.end_inverse_hooke_);
 396
 397   for (SCM s = Spaceable_grob::get_minimum_distances (col);
 398        scm_is_pair (s); s = scm_cdr (s))
 399     {
 400       Grob *other = unsmob_grob (scm_caar (s));
 401       vsize j = binary_search (cols, other, Paper_column::less_than, col_index);
 402       if (j != VPOS)
 403         {
 404           if (cols[j] == other)
 405             description.rods_.push_back (Rod_description (j, scm_to_double (scm_cdar (s))));
 406           else /* it must end at the LEFT prebroken_piece */
 407             description.end_rods_.push_back (Rod_description (j, scm_to_double (scm_cdar (s))));
 408         }
 409     }
 410   if (!line_starter && to_boolean (col->get_property ("keep-inside-line")))
 411     description.keep_inside_line_ = col->extent (col, X_AXIS);
 412   description.break_permission_ = col->get_property ("line-break-permission");
 413   return description;
 414 }
 415
 416 vector<Real>
 417 get_line_forces (vector<Grob*> const &columns,
 418                  Real line_len, Real indent, bool ragged)
 419 {
 420   vector<vsize> breaks;
 421   vector<Real> force;
 422   vector<Grob*> non_loose;
 423   vector<Column_description> cols;
 424   SCM force_break = ly_symbol2scm ("force");
 425
 426   for (vsize i = 0; i < columns.size (); i++)
 427     if (!is_loose (columns[i]) || Paper_column::is_breakable (columns[i]))
 428       non_loose.push_back (columns[i]);
 429
 430   breaks.clear ();
 431   breaks.push_back (0);
 432   cols.push_back (Column_description ());
 433   for (vsize i = 1; i < non_loose.size () - 1; i++)
 434     {
 435       if (Paper_column::is_breakable (non_loose[i]))
 436         breaks.push_back (cols.size ());
 437
 438       cols.push_back (get_column_description (non_loose, i, false));
 439     }
 440   breaks.push_back (cols.size ());
 441   force.resize (breaks.size () * breaks.size (), infinity_f);
 442
 443   for (vsize b = 0; b < breaks.size () - 1; b++)
 444     {
 445       cols[breaks[b]] = get_column_description (non_loose, breaks[b], true);
 446       vsize st = breaks[b];
 447
 448       for (vsize c = b+1; c < breaks.size (); c++)
 449         {
 450           vsize end = breaks[c];
 451           Simple_spacer spacer;
 452
 453           for (vsize i = breaks[b]; i < end - 1; i++)
 454             spacer.add_spring (cols[i].ideal_, cols[i].inverse_hooke_);
 455           spacer.add_spring (cols[end-1].end_ideal_, cols[end-1].end_inverse_hooke_);
 456
 457
 458           for (vsize i = breaks[b]; i < end; i++)
 459             {
 460               for (vsize r = 0; r < cols[i].rods_.size (); r++)
 461                 if (cols[i].rods_[r].r_ < end)
 462                   spacer.add_rod (i - st, cols[i].rods_[r].r_ - st, cols[i].rods_[r].dist_);
 463               for (vsize r = 0; r < cols[i].end_rods_.size (); r++)
 464                 if (cols[i].end_rods_[r].r_ == end)
 465                   spacer.add_rod (i - st, end - st, cols[i].end_rods_[r].dist_);
 466               if (!cols[i].keep_inside_line_.is_empty ())
 467                 {
 468                   spacer.add_rod (i - st, end - st, cols[i].keep_inside_line_[RIGHT]);
 469                   spacer.add_rod (0, i - st, cols[i].keep_inside_line_[LEFT]);
 470                 }
 471             }
 472           spacer.solve ((b == 0) ? line_len - indent : line_len, ragged);
 473
 474           /* add a (convex) penalty for compression. We do this _only_ in get_line_forces,
 475              not get_line_configuration. This is temporary, for backwards compatibility;
 476              the old line/page-breaking stuff ignores page breaks when it calculates line
 477              breaks, so compression penalties can result in scores (eg. wtk-fugue) blowing
 478              up to too many pages. */
 479           Real f = spacer.force ();
 480           force[b * breaks.size () + c] = f - (f < 0 ? f*f*f*f*4 : 0);
 481
 482           if (end < cols.size () && cols[end].break_permission_ == force_break)
 483             break;
 484           if (!spacer.fits ())
 485             {
 486               if (c == b + 1)
 487                 force[b * breaks.size () + c] = -200000;
 488               else
 489                 force[b * breaks.size () + c] = infinity_f;
 490               break;
 491             }
 492         }
 493     }
 494   return force;
 495 }
 496
 497 Column_x_positions
 498 get_line_configuration (vector<Grob*> const &columns,
 499                         Real line_len,
 500                         Real indent,
 501                         bool ragged)
 502 {
 503   vector<Column_description> cols;
 504   Simple_spacer spacer;
 505   Column_x_positions ret;
 506
 507   ret.cols_.push_back (dynamic_cast<Item*> (columns[0])->find_prebroken_piece (RIGHT));
 508   for (vsize i = 1; i < columns.size () - 1; i++)
 509     {
 510       if (is_loose (columns[i]))
 511         ret.loose_cols_.push_back (columns[i]);
 512       else
 513         ret.cols_.push_back (columns[i]);
 514     }
 515   ret.cols_.push_back (dynamic_cast<Item*> (columns.back ())->find_prebroken_piece (LEFT));
 516
 517   /* since we've already put our line-ending column in the column list, we can ignore
 518      the end_XXX_ fields of our column_description */
 519   for (vsize i = 0; i < ret.cols_.size () - 1; i++)
 520     {
 521       cols.push_back (get_column_description (ret.cols_, i, i == 0));
 522       spacer.add_spring (cols[i].ideal_, cols[i].inverse_hooke_);
 523     }
 524   for (vsize i = 0; i < cols.size (); i++)
 525     {
 526       for (vsize r = 0; r < cols[i].rods_.size (); r++)
 527         spacer.add_rod (i, cols[i].rods_[r].r_, cols[i].rods_[r].dist_);
 528
 529       if (!cols[i].keep_inside_line_.is_empty ())
 530         {
 531           spacer.add_rod (i, cols.size (), cols[i].keep_inside_line_[RIGHT]);
 532           spacer.add_rod (0, i, cols[i].keep_inside_line_[LEFT]);
 533         }
 534     }
 535
 536   spacer.solve (line_len, ragged);
 537   ret.force_ = spacer.force ();
 538
 539   /*
 540     We used to have a penalty for compression, no matter what, but that
 541     fucked up wtk1-fugue2 (taking 3 full pages.)
 542   */
 543   ret.config_ = spacer.spring_positions ();
 544   for (vsize i = 0; i < ret.config_.size (); i++)
 545     ret.config_[i] += indent;
 546
 547   ret.satisfies_constraints_ = spacer.fits ();
 548
 549   /*
 550     Check if breaking constraints are met.
 551   */
 552   for (vsize i = 1; i < ret.cols_.size () - 1; i++)
 553     {
 554       SCM p = ret.cols_[i]->get_property ("line-break-permission");
 555       if (p == ly_symbol2scm ("force"))
 556         ret.satisfies_constraints_ = false;
 557     }
 558
 559   return ret;
 560 }
 561