2 gourlay-breaking.cc -- implement Gourlay_breaking
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2002 Han-Wen Nienhuys <hanwen@cs.uu.nl>
8 #include <math.h> // rint
11 #include "gourlay-breaking.hh"
12 #include "column-x-positions.hh"
15 #include "paper-column.hh"
16 #include "paper-score.hh"
17 #include "paper-def.hh"
18 #include "simple-spacer.hh"
21 /// How often to print operator pacification marks?
22 const int HAPPY_DOTS_I = 3;
25 Helper to trace back an optimal path
28 /** this was the previous. If negative, this break should not be
29 considered: this path has infinite energy
34 Which system number so far?
39 Column_x_positions line_config_;
50 This algorithms is adapted from the OSU Tech report on breaking lines.
52 this function is longish, but not very complicated.
55 Array<Column_x_positions>
56 Gourlay_breaking::do_solve () const
58 Array<Break_node> optimal_paths;
59 Link_array<Grob> all =
60 pscore_->system_->columns ();
62 Array<int> breaks = find_break_indices ();
64 Break_node first_node ;
65 optimal_paths.push (first_node);
67 Real worst_force = 0.0;
69 for (int break_idx=1; break_idx< breaks.size (); break_idx++)
72 start with a short line, add measures. At some point
73 the line becomes infeasible. Then we don't try to add more
75 int minimal_start_idx = -1;
76 Column_x_positions minimal_sol;
77 Column_x_positions backup_sol;
79 Real minimal_demerits = infinity_f;
81 bool ragged = to_boolean (pscore_->paper_->get_scmvar ("raggedright"));
83 for (int start_idx = break_idx; start_idx--;)
85 Link_array<Grob> line = all.slice (breaks[start_idx], breaks[break_idx]+1);
87 line[0] = dynamic_cast<Item*> (line[0]) ->find_prebroken_piece (RIGHT);
88 line.top () = dynamic_cast<Item*> (line.top ())->find_prebroken_piece (LEFT);
90 Column_x_positions cp;
94 = pscore_->paper_->line_dimensions_int (optimal_paths[start_idx].line_);
95 Simple_spacer * sp = generate_spacing_problem (line, line_dims);
96 sp->solve (&cp, ragged);
99 if (fabs (cp.force_) > worst_force)
100 worst_force = fabs (cp.force_);
103 We remember this solution as a "should always work
104 solution", in case everything fucks up. */
105 if (start_idx == break_idx - 1)
110 if (optimal_paths[start_idx].demerits_ >= infinity_f)
111 this_demerits = infinity_f;
113 this_demerits = combine_demerits (optimal_paths[start_idx].line_config_, cp)
114 + optimal_paths[start_idx].demerits_;
116 if (this_demerits < minimal_demerits)
118 minimal_start_idx = start_idx;
120 minimal_demerits = this_demerits;
124 we couldn't satisfy the constraints, this won't get better
125 if we add more columns, so we get on with the next one
127 if (!cp.satisfies_constraints_b_)
133 if (minimal_start_idx < 0)
135 bnod.demerits_ = infinity_f;
136 bnod.line_config_ = backup_sol;
137 bnod.prev_break_ = break_idx - 1;
141 bnod.prev_break_ = minimal_start_idx;
142 bnod.demerits_ = minimal_demerits;
143 bnod.line_config_ = minimal_sol;
145 bnod.line_ = optimal_paths[bnod.prev_break_].line_ + 1;
146 optimal_paths.push (bnod);
148 if (! (break_idx % HAPPY_DOTS_I))
149 progress_indication (String ("[") + to_string (break_idx) + "]");
152 /* do the last one */
153 if (breaks.size () % HAPPY_DOTS_I)
154 progress_indication (String ("[") + to_string (breaks.size()) + "]");
157 progress_indication ("\n");
159 Array<int> final_breaks;
160 Array<Column_x_positions> lines;
162 /* skip 0-th element, since it is a "dummy" elt*/
163 for (int i = optimal_paths.size ()-1; i> 0;)
165 final_breaks.push (i);
166 int prev = optimal_paths[i].prev_break_;
171 if (verbose_global_b)
172 printf ("Optimal demerits: %f\n", optimal_paths.top ().demerits_);
174 if (optimal_paths.top ().demerits_ >= infinity_f)
175 warning (_ ("No feasible line breaking found"));
177 for (int i= final_breaks.size (); i--;)
179 Column_x_positions cp (optimal_paths[final_breaks[i]].line_config_);
182 if(!cp.satisfies_constraints_b_)
183 warning ("Could not find line breaking that satisfies constraints.");
189 Gourlay_breaking::Gourlay_breaking ()
196 TODO: uniformity parameter to control rel. importance of spacing differences.
200 mixing break penalties and constraint-failing solutions is confusing.
203 Gourlay_breaking::combine_demerits (Column_x_positions const &prev,
204 Column_x_positions const &this_one) const
206 Real break_penalties = 0.0;
207 Grob * pc = this_one.cols_.top ();
210 SCM pen = pc->get_grob_property ("penalty");
211 if (gh_number_p (pen) && fabs (gh_scm2double (pen)) < 10000)
213 break_penalties += gh_scm2double (pen);
219 Q: do want globally non-cramped lines, or locally equally cramped lines.
221 Real demerit = abs (this_one.force_) + 0.1 *abs (prev.force_ - this_one.force_)
224 Real demerit = abs (this_one.force_) + break_penalties;
227 if (!this_one.satisfies_constraints_b_)
230 If it doesn't satisfy constraints, we make this one
233 add 20000 to the demerits, so that a break penalty
234 of -10000 won't change the result */
235 demerit = (demerit + 20000) >? 2000;