2 gourlay-breaking.cc -- implement Gourlay_breaking
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
9 #include "gourlay-breaking.hh"
11 #include <math.h> // rint
16 #include "paper-column.hh"
17 #include "paper-score.hh"
18 #include "output-def.hh"
19 #include "simple-spacer.hh"
22 /// How often to print operator pacification marks?
23 const int HAPPY_DOTS_I = 3;
26 Helper to trace back an optimal path
30 /** this was the previous. If negative, this break should not be
31 considered: this path has infinite energy
36 Which system number so far?
41 Column_x_positions line_config_;
52 printf ("prev break %d, line %d, demerits %f\n",
53 prev_break_, line_, demerits_);
58 print_break_nodes (Array<Break_node> const &arr)
60 for (int i = 0; i < arr.size (); i++)
62 printf ("node %d: ", i);
68 This algorithms is adapted from the OSU Tech report on breaking lines.
70 this function is longish, but not very complicated.
72 TODO: should rewrite. See the function in scm/page-layout.scm for
75 Array<Column_x_positions>
76 Gourlay_breaking::do_solve () const
78 Array<Break_node> optimal_paths;
80 = pscore_->root_system ()->columns ();
82 Array<int> breaks = find_break_indices ();
84 Break_node first_node;
85 optimal_paths.push (first_node);
87 bool ragged_right = to_boolean (pscore_->layout ()->c_variable ("raggedright"));
88 bool ragged_last = to_boolean (pscore_->layout ()->c_variable ("raggedlast"));
90 Real worst_force = 0.0;
91 for (int break_idx = 1; break_idx < breaks.size (); break_idx++)
94 start with a short line, add measures. At some point
95 the line becomes infeasible. Then we don't try to add more
97 int minimal_start_idx = -1;
98 Column_x_positions minimal_sol;
99 Column_x_positions backup_sol;
101 Real minimal_demerits = infinity_f;
103 for (int start_idx = break_idx; start_idx--;)
105 Link_array<Grob> line = all.slice (breaks[start_idx], breaks[break_idx] + 1);
107 line[0] = dynamic_cast<Item *> (line[0])->find_prebroken_piece (RIGHT);
108 line.top () = dynamic_cast<Item *> (line.top ())->find_prebroken_piece (LEFT);
110 Column_x_positions cp;
114 = line_dimensions_int (pscore_->layout (), optimal_paths[start_idx].line_);
115 Simple_spacer_wrapper *sp = generate_spacing_problem (line, line_dims);
116 bool last_line = break_idx == breaks.size () - 1;
117 bool ragged = ragged_right
118 || (last_line && ragged_last);
120 sp->solve (&cp, ragged);
124 if (ragged && last_line)
127 if (fabs (cp.force_) > worst_force)
128 worst_force = fabs (cp.force_);
131 We remember this solution as a "should always work
132 solution", in case everything fucks up. */
133 if (start_idx == break_idx - 1)
138 if (optimal_paths[start_idx].demerits_ >= infinity_f)
139 this_demerits = infinity_f;
141 this_demerits = combine_demerits (optimal_paths[start_idx].line_config_, cp)
142 + optimal_paths[start_idx].demerits_;
144 if (this_demerits < minimal_demerits)
146 minimal_start_idx = start_idx;
148 minimal_demerits = this_demerits;
152 we couldn't satisfy the constraints, this won't get better
153 if we add more columns, so we get on with the next one
155 if (!cp.satisfies_constraints_)
160 if (minimal_start_idx < 0)
162 bnod.demerits_ = infinity_f;
163 bnod.line_config_ = backup_sol;
164 bnod.prev_break_ = break_idx - 1;
168 bnod.prev_break_ = minimal_start_idx;
169 bnod.demerits_ = minimal_demerits;
170 bnod.line_config_ = minimal_sol;
172 bnod.line_ = optimal_paths[bnod.prev_break_].line_ + 1;
173 optimal_paths.push (bnod);
175 if (! (break_idx % HAPPY_DOTS_I))
176 progress_indication (String ("[") + to_string (break_idx) + "]");
179 /* do the last one */
180 if (breaks.size () % HAPPY_DOTS_I)
181 progress_indication (String ("[") + to_string (breaks.size ()) + "]");
183 progress_indication ("\n");
185 Array<int> final_breaks;
186 Array<Column_x_positions> lines;
188 /* skip 0-th element, since it is a "dummy" elt*/
189 for (int i = optimal_paths.size () - 1; i > 0;)
191 final_breaks.push (i);
192 int prev = optimal_paths[i].prev_break_;
197 if (be_verbose_global)
199 message (_f ("Optimal demerits: %f",
200 optimal_paths.top ().demerits_) + "\n");
203 if (optimal_paths.top ().demerits_ >= infinity_f)
204 warning (_ ("no feasible line breaking found"));
206 for (int i = final_breaks.size (); i--;)
208 Column_x_positions cp (optimal_paths[final_breaks[i]].line_config_);
211 if (!cp.satisfies_constraints_)
212 warning (_ ("can't find line breaking that satisfies constraints"));
217 Gourlay_breaking::Gourlay_breaking ()
222 TODO: uniformity parameter to control rel. importance of spacing differences.
226 mixing break penalties and constraint-failing solutions is confusing.
229 Gourlay_breaking::combine_demerits (Column_x_positions const &prev,
230 Column_x_positions const &this_one) const
232 Real break_penalties = 0.0;
233 Grob *pc = this_one.cols_.top ();
236 SCM pen = pc->get_property ("penalty");
237 if (scm_is_number (pen) && fabs (scm_to_double (pen)) < 10000)
239 break_penalties += scm_to_double (pen);
244 Q: do we want globally non-cramped lines, or locally equally
247 There used to be an example file input/test/uniform-breaking to
248 demonstrate problems with this approach. When music is gradually
249 becoming denser, the uniformity requirement makes lines go from
250 cramped to even more cramped (because going from cramped
251 3meas/line to relatively loose 2meas/line is such a big step.
255 Real demerit = abs (this_one.force_) + abs (prev.force_ - this_one.force_)
258 if (!this_one.satisfies_constraints_)
261 If it doesn't satisfy constraints, we make this one
264 add 20000 to the demerits, so that a break penalty
265 of -10000 won't change the result */
266 demerit = max ((demerit + 20000), 2000.0);