2 gourlay-breaking.cc -- implement Gourlay_breaking
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
9 #include "gourlay-breaking.hh"
11 #include <cmath> // rint
15 #include "international.hh"
17 #include "output-def.hh"
18 #include "paper-column.hh"
19 #include "paper-score.hh"
20 #include "simple-spacer.hh"
24 /// How often to print operator pacification marks?
25 const int HAPPY_DOTS = 3;
28 Helper to trace back an optimal path
32 /** this was the previous. If negative, this break should not be
33 considered: this path has infinite energy
38 Which system number so far?
43 Column_x_positions line_config_;
54 printf ("prev break %d, line %d, demerits %f\n",
55 prev_break_, line_, demerits_);
60 print_break_nodes (vector<Break_node> const &arr)
62 for (vsize i = 0; i < arr.size (); i++)
64 printf ("node %d: ", i);
70 This algorithms is adapted from the OSU Tech report on breaking lines.
72 this function is longish, but not very complicated.
74 TODO: should rewrite. See the function in scm/page-layout.scm for
77 vector<Column_x_positions>
78 Gourlay_breaking::solve ()
80 vector<Break_node> optimal_paths;
82 = pscore_->root_system ()->columns ();
84 vector<vsize> breaks = pscore_->find_break_indices ();
86 Break_node first_node;
87 optimal_paths.push_back (first_node);
89 bool ragged_right = to_boolean (pscore_->layout ()->c_variable ("ragged-right"));
90 bool ragged_last = to_boolean (pscore_->layout ()->c_variable ("ragged-last"));
92 Real worst_force = 0.0;
93 for (vsize break_idx = 1; break_idx < breaks.size (); break_idx++)
96 start with a short line, add measures. At some point
97 the line becomes infeasible. Then we don't try to add more
99 int minimal_start_idx = -1;
100 Column_x_positions minimal_sol;
101 Column_x_positions backup_sol;
103 Real minimal_demerits = infinity_f;
105 for (vsize start_idx = break_idx; start_idx--;)
107 vector<Grob*> line (all.begin () + breaks[start_idx],
108 all.begin () + breaks[break_idx] + 1);
111 = line_dimensions_int (pscore_->layout (), optimal_paths[start_idx].line_);
112 bool last_line = break_idx == breaks.size () - 1;
113 bool ragged = ragged_right || (last_line && ragged_last);
115 Column_x_positions cp = get_line_configuration (line, line_dims[RIGHT] - line_dims[LEFT],
116 line_dims[LEFT], ragged);
117 if (ragged && last_line)
120 if (fabs (cp.force_) > worst_force)
121 worst_force = fabs (cp.force_);
124 We remember this solution as a "should always work
125 solution", in case everything fucks up. */
126 if (start_idx == break_idx - 1)
131 if (optimal_paths[start_idx].demerits_ >= infinity_f)
132 this_demerits = infinity_f;
134 this_demerits = combine_demerits (optimal_paths[start_idx].line_config_, cp)
135 + optimal_paths[start_idx].demerits_;
137 if (this_demerits < minimal_demerits)
139 minimal_start_idx = start_idx;
141 minimal_demerits = this_demerits;
145 we couldn't satisfy the constraints, this won't get better
146 if we add more columns, so we get on with the next one
148 if (!cp.satisfies_constraints_)
153 if (minimal_start_idx < 0)
155 bnod.demerits_ = infinity_f;
156 bnod.line_config_ = backup_sol;
157 bnod.prev_break_ = break_idx - 1;
161 bnod.prev_break_ = minimal_start_idx;
162 bnod.demerits_ = minimal_demerits;
163 bnod.line_config_ = minimal_sol;
165 bnod.line_ = optimal_paths[bnod.prev_break_].line_ + 1;
166 optimal_paths.push_back (bnod);
168 if (! (break_idx % HAPPY_DOTS))
169 progress_indication (string ("[") + to_string (break_idx) + "]");
172 /* do the last one */
173 if (breaks.size () % HAPPY_DOTS)
174 progress_indication (string ("[") + to_string (breaks.size ()) + "]");
176 progress_indication ("\n");
178 vector<int> final_breaks;
179 vector<Column_x_positions> lines;
181 /* skip 0-th element, since it is a "dummy" elt*/
182 for (vsize i = optimal_paths.size () - 1; i > 0;)
184 final_breaks.push_back (i);
185 vsize prev = optimal_paths[i].prev_break_;
190 if (be_verbose_global)
192 message (_f ("Optimal demerits: %f",
193 optimal_paths.back ().demerits_) + "\n");
196 if (optimal_paths.back ().demerits_ >= infinity_f)
197 warning (_ ("no feasible line breaking found"));
199 for (vsize i = final_breaks.size (); i--;)
201 Column_x_positions cp (optimal_paths[final_breaks[i]].line_config_);
203 lines.push_back (cp);
204 if (!cp.satisfies_constraints_)
205 warning (_ ("can't find line breaking that satisfies constraints"));
210 Gourlay_breaking::Gourlay_breaking ()
215 TODO: uniformity parameter to control rel. importance of spacing differences.
219 mixing break penalties and constraint-failing solutions is confusing.
222 Gourlay_breaking::combine_demerits (Column_x_positions const &prev,
223 Column_x_positions const &this_one) const
225 Real break_penalties = 0.0;
226 Grob *pc = this_one.cols_.back ();
229 SCM pen = pc->get_property ("line-break-penalty");
230 if (scm_is_number (pen) && fabs (scm_to_double (pen)) < 10000)
231 break_penalties += scm_to_double (pen);
235 Q: do we want globally non-cramped lines, or locally equally
238 There used to be an example file input/test/uniform-breaking to
239 demonstrate problems with this approach. When music is gradually
240 becoming denser, the uniformity requirement makes lines go from
241 cramped to even more cramped (because going from cramped
242 3meas/line to relatively loose 2meas/line is such a big step.
246 Real demerit = abs (this_one.force_) + abs (prev.force_ - this_one.force_)
249 if (!this_one.satisfies_constraints_)
252 If it doesn't satisfy constraints, we make this one
255 add 20000 to the demerits, so that a break penalty
256 of -10000 won't change the result */
257 demerit = max ((demerit + 20000), 2000.0);