2 page-spacing.cc - implement routines for spacing
3 systems vertically on pages
5 source file of the GNU LilyPond music typesetter
7 (c) 2006 Joe Neeman <joeneeman@gmail.com>
10 #include "page-spacing.hh"
14 A much simplified rods-and-springs problem.
22 Real inverse_spring_k_;
24 Line_details last_line_;
26 Page_spacing (Real page_height)
28 page_height_ = page_height;
34 void append_system (const Line_details &line);
35 void prepend_system (const Line_details &line);
40 Page_spacing::calc_force ()
42 if (rod_height_ + last_line_.bottom_padding_ >= page_height_ || !inverse_spring_k_)
45 force_ = (page_height_ - rod_height_ - last_line_.bottom_padding_ - spring_len_) / inverse_spring_k_;
49 Page_spacing::append_system (const Line_details &line)
51 rod_height_ += last_line_.padding_;
53 rod_height_ += line.extent_.length ();
54 spring_len_ += line.space_;
55 inverse_spring_k_ += line.inverse_hooke_;
63 Page_spacing::prepend_system (const Line_details &line)
66 rod_height_ += line.padding_;
70 rod_height_ += line.extent_.length ();
71 spring_len_ += line.space_;
72 inverse_spring_k_ += line.inverse_hooke_;
78 Page_spacing::clear ()
80 force_ = rod_height_ = spring_len_ = 0;
81 inverse_spring_k_ = 0;
84 /* for each forbidden page break, merge the systems around it into one system. */
85 static vector<Line_details>
86 compress_lines (const vector<Line_details> &orig)
88 vector<Line_details> ret;
90 for (vsize i = 0; i < orig.size (); i++)
92 if (i < orig.size () - 1 && orig[i].page_permission_ == SCM_EOL)
94 Line_details compressed = orig[i+1];
95 compressed.extent_[DOWN] = orig[i].extent_[DOWN];
96 compressed.extent_[UP] = orig[i].extent_[UP] + orig[i+1].extent_.length () + orig[i].padding_;
97 compressed.space_ += orig[i].space_;
98 compressed.inverse_hooke_ += orig[i].inverse_hooke_;
100 /* we don't need the force_ field for the vertical spacing,
101 so we use force_ = -1 to signal that the line was compressed
102 (and force_ = +1 otherwise).
103 This makes uncompression much easier. */
104 compressed.force_ = -1;
105 ret.push_back (compressed);
110 ret.push_back (orig[i]);
111 ret.back ().force_ = 1;
117 /* translate the number of systems-per-page into something meaningful for
118 the uncompressed lines.
121 uncompress_solution (vector<vsize> const &systems_per_page,
122 vector<Line_details> const &compressed)
127 for (vsize i = 0; i < systems_per_page.size (); i++)
129 int compressed_count = 0;
130 for (vsize j = start_sys; j < start_sys + systems_per_page[i]; j++)
131 if (compressed[j].force_ < 0)
134 ret.push_back (systems_per_page[i] + compressed_count);
135 start_sys += systems_per_page[i];
140 /* the cases for page_count = 1 or 2 can be done in O(n) time. Since they
141 are by far the most common cases, we have special functions for them */
142 static Spacing_result
143 space_systems_on_1_page (vector<Line_details> const &lines, Real page_height, bool ragged)
145 Page_spacing space (page_height);
148 for (vsize i = 0; i < lines.size (); i++)
149 space.append_system (lines[i]);
151 ret.systems_per_page_.push_back (lines.size ());
152 ret.force_.push_back (ragged ? min (space.force_, 0.0) : space.force_);
153 ret.penalty_ = lines.back ().page_penalty_ + lines.back ().turn_penalty_;
154 ret.demerits_ = ret.force_.back () * ret.force_.back () + ret.penalty_;
159 static Spacing_result
160 space_systems_on_2_pages (vector<Line_details> const &lines,
165 /* if there is a forced break, this reduces to 2 1-page problems */
166 for (vsize i = 0; i < lines.size () - 1; i++)
167 if (lines[i].page_permission_ == ly_symbol2scm ("force"))
169 vector<Line_details> lines1 (lines.begin (), lines.begin () + i + 1);
170 vector<Line_details> lines2 (lines.begin () + i + 1, lines.end ());
171 Spacing_result p1 = space_systems_on_1_page (lines1, page_height, ragged);
172 Spacing_result p2 = space_systems_on_1_page (lines2, page_height, ragged || ragged_last);
174 p1.systems_per_page_.push_back (p2.systems_per_page_[0]);
175 p1.force_.push_back (p2.force_[0]);
176 p1.penalty_ += p2.penalty_ - lines[i].turn_penalty_;
177 p1.demerits_ += p2.demerits_ - lines[i].turn_penalty_;
181 vector<Real> page1_force;
182 vector<Real> page2_force;
183 Page_spacing page1 (page_height);
184 Page_spacing page2 (page_height);
186 page1_force.resize (lines.size () - 1, infinity_f);
187 page2_force.resize (lines.size () - 1, infinity_f);
189 for (vsize i = 0; i < page1_force.size (); i++)
191 page1.append_system (lines[i]);
192 page2.prepend_system (lines[lines.size () - 1 - i]);
193 page1_force[i] = (ragged && page1.force_ < 0 && i > 0) ? infinity_f : page1.force_;
195 if (ragged || ragged_last)
196 page2_force[page2_force.size () - 1 - i] =
197 (page2.force_ < 0 && i < page1_force.size () - 1) ? infinity_f : 0;
199 page2_force[page2_force.size () - 1 - i] = page2.force_;
202 vsize best_sys_count = 1;
203 Real best_demerits = infinity_f;
204 for (vsize i = 0; i < page1_force.size (); i++)
206 Real dem = page1_force[i] * page1_force[i]
207 + page2_force[i] * page2_force[i]
208 + lines[i+1].page_penalty_
209 + lines.back ().page_penalty_ + lines.back ().turn_penalty_;
210 if (dem < best_demerits)
213 best_sys_count = i+1;
218 ret.systems_per_page_.push_back (best_sys_count);
219 ret.systems_per_page_.push_back (lines.size () - best_sys_count);
220 ret.force_.push_back (page1_force[best_sys_count-1]);
221 ret.force_.push_back (page2_force[best_sys_count-1]);
222 ret.penalty_ = lines[best_sys_count-1].page_penalty_
223 + lines.back ().page_penalty_
224 + lines.back ().turn_penalty_;
225 ret.demerits_ = best_demerits;
230 Page_spacer::Page_spacer (vector<Line_details> const &lines, Real page_height, bool ragged, bool ragged_last)
233 page_height_ = page_height;
236 ragged_last_ = ragged_last;
240 Page_spacer::solve (vsize page_count)
242 if (page_count > max_page_count_)
246 ret.force_.resize (page_count);
247 ret.systems_per_page_.resize (page_count);
249 vsize system = lines_.size () - 1;
251 if (isinf (state_.at (system, page_count-1).demerits_))
252 return Spacing_result (); /* bad number of pages */
254 if (isinf (state_.at (system, page_count-1).demerits_))
255 return Spacing_result (); /* bad number of pages */
257 ret.penalty_ = state_.at (system, page_count-1).penalty_
258 + lines_.back ().page_penalty_ + lines_.back ().turn_penalty_;
260 for (vsize p = page_count; p--;)
262 assert (system != VPOS);
264 Page_spacing_node const &ps = state_.at (system, p);
265 ret.force_[p] = ps.force_;
266 ret.demerits_ += ps.force_ * ps.force_;
268 ret.systems_per_page_[p] = system + 1;
270 ret.systems_per_page_[p] = system - ps.prev_;
273 ret.demerits_ += ret.penalty_;
278 Page_spacer::resize (vsize page_count)
280 assert (page_count > 0);
282 if (max_page_count_ >= page_count)
285 state_.resize (lines_.size (), page_count, Page_spacing_node ());
286 for (vsize page = max_page_count_; page < page_count; page++)
287 for (vsize line = page; line < lines_.size (); line++)
288 if (!calc_subproblem (page, line))
291 max_page_count_ = page_count;
295 Page_spacer::calc_subproblem (vsize page, vsize line)
297 Page_spacing space (page_height_);
298 Page_spacing_node &cur = state_.at (line, page);
299 bool ragged = ragged_ || (ragged_last_ && line == lines_.size () - 1);
301 for (vsize page_start = line+1; page_start > page && page_start--;)
303 Page_spacing_node const *prev = page > 0 ? &state_.at (page_start-1, page-1) : 0;
305 space.prepend_system (lines_[page_start]);
306 if (page_start < line && (isinf (space.force_) || (space.force_ < 0 && ragged)))
309 if (page > 0 || page_start == 0)
311 if (line == lines_.size () - 1 && ragged_last_ && space.force_ > 0)
314 Real dem = fabs (space.force_) + (prev ? prev->demerits_ : 0);
317 penalty = lines_[page_start-1].page_penalty_
318 + (page % 2 == 0) ? lines_[page_start-1].turn_penalty_ : 0;
321 if (dem < cur.demerits_)
324 cur.force_ = space.force_;
325 cur.penalty_ = penalty + (prev ? prev->penalty_ : 0);
326 cur.prev_ = page_start - 1;
331 && lines_[page_start-1].page_permission_ == ly_symbol2scm ("force"))
334 return !isinf (cur.demerits_);
338 min_page_count (vector<Line_details> const &lines, Real page_height, bool ragged)
341 Real cur_rod_height = 0;
343 for (vsize i = 0; i < lines.size (); i++)
345 Real ext_len = lines[i].extent_.length ();
346 Real next_height = cur_rod_height
347 + (ragged ? max (ext_len, lines[i].space_) : ext_len)
348 + ((i > 0 && cur_rod_height > 0) ? lines[i-1].padding_: 0);
350 if ((next_height > page_height && cur_rod_height > 0)
351 || (i > 0 && lines[i-1].page_permission_ == ly_symbol2scm ("force")))
354 cur_rod_height = ragged ? max (ext_len, lines[i].space_) : ext_len;
357 cur_rod_height = next_height;
363 space_systems_on_min_pages (vector<Line_details> const &lines,
365 Real odd_pages_penalty,
369 vector<Line_details> compressed_lines = compress_lines (lines);
370 vsize min_p_count = min_page_count (compressed_lines, page_height, ragged);
373 if (min_p_count == 1)
375 Spacing_result candidate1 = space_systems_on_1_page (compressed_lines, page_height, ragged || ragged_last);
376 candidate1.force_.back () += odd_pages_penalty;
377 candidate1.demerits_ += odd_pages_penalty;
378 if (compressed_lines.size () == 1)
382 Spacing_result candidate2 = space_systems_on_2_pages (compressed_lines, page_height, ragged, ragged_last);
383 ret = (candidate1.demerits_ < candidate2.demerits_) ?
384 candidate1 : candidate2;
387 else if (min_p_count == 2)
388 ret = space_systems_on_2_pages (compressed_lines, page_height, ragged, ragged_last);
391 Page_spacer ps (compressed_lines, page_height, ragged, ragged_last);
392 Spacing_result candidate1 = ps.solve (min_p_count);
393 if (min_p_count % 2 == 0)
397 candidate1.force_.back () += odd_pages_penalty;
398 candidate1.demerits_ += odd_pages_penalty;
400 if (min_p_count == compressed_lines.size ())
404 Spacing_result candidate2 = ps.solve (min_p_count + 1);
405 ret = (candidate1.demerits_ < candidate2.demerits_) ?
406 candidate1 : candidate2;
410 ret.systems_per_page_ = uncompress_solution (ret.systems_per_page_, compressed_lines);
415 space_systems_on_best_pages (vector<Line_details> const &lines,
417 Real odd_pages_penalty,
421 vector<Line_details> compressed_lines = compress_lines (lines);
422 vsize min_p_count = min_page_count (compressed_lines, page_height, ragged);
424 Page_spacer ps (compressed_lines, page_height, ragged, ragged_last);
425 Spacing_result best = ps.solve (min_p_count);
426 best.force_.back () += (min_p_count % 2) ? odd_pages_penalty : 0;
427 best.demerits_ += (min_p_count % 2) ? odd_pages_penalty : 0;
429 for (vsize i = min_p_count+1; i <= compressed_lines.size (); i++)
431 Spacing_result cur = ps.solve (i);
432 cur.demerits_ += (i % 2) ? odd_pages_penalty : 0;
433 if (cur.demerits_ < best.demerits_)
437 best.systems_per_page_ = uncompress_solution (best.systems_per_page_, compressed_lines);