X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fpage-breaking.cc;h=668231f63aa95f6ab8092f0c2c547189a4861ab1;hb=644ed77f9c0165e22290549660e71ff3ead573d5;hp=96b9d3a0dbb0b4505e8dc07017b0e9f83f54b71a;hpb=6932257f068f0ea88c3191dff3ccc22765e0ab74;p=lilypond.git diff --git a/lily/page-breaking.cc b/lily/page-breaking.cc index 96b9d3a0db..668231f63a 100644 --- a/lily/page-breaking.cc +++ b/lily/page-breaking.cc @@ -7,6 +7,62 @@ (c) 2006--2009 Joe Neeman */ +/* + This is a utility class for page-breaking algorithms. There are some complex + parts of this class, some of which are useful to understand if you intend + to write a page breaking algorithm (ie. a subclass of Page_breaking). Most + of these complexities were introduced in order to break the problem of + page-breaking into simpler subproblems and to hide some of the bookkeeping + complexities of page breaking from the page breaking algorithms. + + COMPRESSED LINES + There are several functions that actually distribute systems across pages + (for example, the space_systems_XXX and pack_systems_XXX functions). If + each of these functions had to handle \noPageBreak, it would be a mess. + Therefore, we handle \noPageBreak by "compressing" the list of systems + before doing any layout: we concatenate any two systems separated by a + \noPageBreak into a single system. The page-breaking functions can do their + magic without encountering a \noPageBreak; we then "uncompress" the systems + at the end. We almost always work with cached_line_details_, which are + "compressed." + + CHUNKS + The basic operation of a page breaking algorithm is to repeatedly request + some systems from the line-breaker and place those systems on some pages. + With each repetition, the page breaking algorithm asks the line-breaker for + some systems that it thinks will help it achieve a better layout. The + Page_breaking class provides functionality to facilitate this in the case + that the page breaking algorithm only cares about the number of systems. + + Even if a page breaking algorithm only cares number of systems, there may + be many ways to satisfy its request. For example, in a piece with 2 scores + and a request for 10 systems, we could return 5 systems from each score or + 4 from the first and 6 from the second. Even within a score, we might + want to try several different line breaking configurations with a fixed + system count; if there is a forced \pageBreak, for example, we might wish + to tweak the number of systems on both sides of the \pageBreak independently. + + The Page_breaking class takes care of finding these configurations. It + divides the piece into "chunks" and sets up the line-breaker in such a way + that the number of systems in each chunk can be modified independently. + Chunks never cross score boundaries; each title and markup is its own chunk. + When a page breaking algorithm requests a number of systems, the Page_breaker + stores an array of potential configurations, which the page breaking + algorithm can iterate over using current_configuration(vsize). + + LINE_DIVISION + A Line_division is simply a way of storing the exact way in which the + total number of systems is distributed among chunks. Note that a + Line_division may not (in fact, usually will not) describe all of the chunks + in the entire book. Rather, it will describe the subset of chunks that lie + between some fixed starting and ending point. This subset of chunks changes + whenever a page breaking algorithm asks to consider a different pair of + starting and ending breakpoints. In particular, a Line_division should be + discarded after a call to set_current_breakpoints, since that Line_division + refers to a subset of chunks which might be different from the current + subset of chunks under consideration. +*/ + #include "page-breaking.hh" #include "international.hh" @@ -101,8 +157,20 @@ Page_breaking::Page_breaking (Paper_book *pb, Break_predicate is_break) ragged_ = to_boolean (pb->paper_->c_variable ("ragged-bottom")); ragged_last_ = to_boolean (pb->paper_->c_variable ("ragged-last-bottom")); page_top_space_ = robust_scm2double (pb->paper_->c_variable ("page-top-space"), 0); - systems_per_page_ = robust_scm2int (pb->paper_->c_variable ("systems-per-page"), 0); - max_systems_per_page_ = robust_scm2int (pb->paper_->c_variable ("max-systems-per-page"), 0); + systems_per_page_ = max (0, robust_scm2int (pb->paper_->c_variable ("systems-per-page"), 0)); + max_systems_per_page_ = max (0, robust_scm2int (pb->paper_->c_variable ("max-systems-per-page"), 0)); + min_systems_per_page_ = max (0, robust_scm2int (pb->paper_->c_variable ("min-systems-per-page"), 0)); + + if (systems_per_page_ && (max_systems_per_page_ || min_systems_per_page_)) + { + warning (_f ("ignoring min-systems-per-page and max-systems-per-page because systems-per-page was set")); + min_systems_per_page_ = max_systems_per_page_ = 0; + } + if (max_systems_per_page_ && min_systems_per_page_ > max_systems_per_page_) + { + warning (_f ("min-systems-per-page is larger than max-systems-per-page, ignoring both values")); + min_systems_per_page_ = max_systems_per_page_ = 0; + } create_system_list (); find_chunks_and_breaks (is_break); @@ -136,6 +204,12 @@ Page_breaking::max_systems_per_page () const return max_systems_per_page_; } +int +Page_breaking::min_systems_per_page () const +{ + return min_systems_per_page_; +} + Real Page_breaking::page_top_space () const { @@ -148,6 +222,40 @@ Page_breaking::system_count () const return system_count_; } +bool +Page_breaking::too_many_lines (int line_count) const +{ + return max_systems_per_page () > 0 && line_count > max_systems_per_page (); +} + +bool +Page_breaking::too_few_lines (int line_count) const +{ + return line_count < min_systems_per_page (); +} + +Real +Page_breaking::line_count_penalty (int line_count) const +{ + if (too_many_lines (line_count)) + return (line_count - max_systems_per_page ()) * TERRIBLE_SPACING_PENALTY; + if (too_few_lines (line_count)) + return (min_systems_per_page () - line_count) * TERRIBLE_SPACING_PENALTY; + + return 0; +} + +int +Page_breaking::line_count_status (int line_count) const +{ + if (too_many_lines (line_count)) + return SYSTEM_COUNT_TOO_MANY; + if (too_few_lines (line_count)) + return SYSTEM_COUNT_TOO_FEW; + + return SYSTEM_COUNT_OK; +} + /* translate indices into breaks_ into start-end parameters for the line breaker */ void Page_breaking::line_breaker_args (vsize sys, @@ -651,8 +759,15 @@ Page_breaking::min_page_count (vsize configuration, vsize first_page_num) Real cur_rod_height = 0; Real cur_spring_height = 0; Real cur_page_height = page_height (first_page_num, false); + int line_count = 0; cache_line_details (configuration); + + // If the first line on a page has titles, allow them some extra space. + if (cached_line_details_.size () + && cached_line_details_[0].compressed_nontitle_lines_count_ < cached_line_details_[0].compressed_lines_count_) + cur_page_height += page_top_space (); + for (vsize i = 0; i < cached_line_details_.size (); i++) { Real ext_len = cached_line_details_[i].extent_.length (); @@ -660,21 +775,27 @@ Page_breaking::min_page_count (vsize configuration, vsize first_page_num) + ((cur_rod_height > 0) ? cached_line_details_[i].padding_: 0); Real next_spring_height = cur_spring_height + cached_line_details_[i].space_; Real next_height = next_rod_height + (ragged () ? next_spring_height : 0); + int next_line_count = line_count + cached_line_details_[i].compressed_nontitle_lines_count_; - - if ((next_height > cur_page_height && cur_rod_height > 0) + if ((!too_few_lines (line_count) && (next_height > cur_page_height && cur_rod_height > 0)) + || too_many_lines (next_line_count) || (i > 0 && cached_line_details_[i-1].page_permission_ == ly_symbol2scm ("force"))) { + line_count = cached_line_details_[i].compressed_nontitle_lines_count_; cur_rod_height = ext_len; cur_spring_height = cached_line_details_[i].space_; cur_page_height = page_height (first_page_num + ret, false); + + if (cached_line_details_[i].compressed_nontitle_lines_count_ < cached_line_details_[i].compressed_lines_count_) + cur_page_height += page_top_space (); ret++; } else { cur_rod_height = next_rod_height; cur_spring_height = next_spring_height; + line_count = next_line_count; } } @@ -693,7 +814,8 @@ Page_breaking::min_page_count (vsize configuration, vsize first_page_num) cur_page_height = page_height (first_page_num + ret - 1, true); Real cur_height = cur_rod_height + ((ragged_last () || ragged ()) ? cur_spring_height : 0); - if (cur_height > cur_page_height + if (!too_few_lines (line_count - cached_line_details_.back ().compressed_nontitle_lines_count_) + && cur_height > cur_page_height /* don't increase the page count if the last page had only one system */ && cur_rod_height > cached_line_details_.back ().extent_.length ()) ret++; @@ -866,13 +988,21 @@ Page_breaking::space_systems_with_fixed_number_per_page (vsize configuration, } res.systems_per_page_.push_back (line - page_first_line); + res.force_.push_back (space.force_); res.penalty_ += cached_line_details_[line-1].page_penalty_; + if (system_count_on_this_page != systems_per_page_) + { + res.penalty_ += TERRIBLE_SPACING_PENALTY; + res.system_count_status_ |= ((system_count_on_this_page < systems_per_page_)) + ? SYSTEM_COUNT_TOO_FEW : SYSTEM_COUNT_TOO_MANY; + } + page_first_line = line; } /* Recalculate forces for the last page because we know now that is - was really the last page. */ + really the last page. */ space.resize (page_height (first_page_num + page, true)); res.force_.back () = space.force_; return finalize_spacing_result (configuration, res); @@ -881,6 +1011,7 @@ Page_breaking::space_systems_with_fixed_number_per_page (vsize configuration, Page_spacing_result Page_breaking::pack_systems_on_least_pages (vsize configuration, vsize first_page_num) { + // TODO: add support for min/max-systems-per-page. Page_spacing_result res; vsize page = 0; vsize page_first_line = 0; @@ -950,7 +1081,7 @@ Page_breaking::finalize_spacing_result (vsize configuration, Page_spacing_result Real line_force = 0; Real line_penalty = 0; - Real page_force = 0; + Real page_demerits = res.penalty_; Real page_weighting = robust_scm2double (book_->paper_->c_variable ("page-spacing-weight"), 10); for (vsize i = 0; i < uncompressed_line_details_.size (); i++) @@ -962,10 +1093,8 @@ Page_breaking::finalize_spacing_result (vsize configuration, Page_spacing_result for (vsize i = 0; i < res.force_.size (); i++) { Real f = res.force_[i]; - if (isinf (f) && res.systems_per_page_[i] == 1) - f = 20000; - page_force += f * f; + page_demerits += min(f*f, BAD_SPACING_PENALTY); } /* for a while we tried averaging page and line forces across pages instead @@ -973,7 +1102,7 @@ Page_breaking::finalize_spacing_result (vsize configuration, Page_spacing_result with a very bad page force (for example because of a forced page break), the page breaker will put in a _lot_ of pages so that the bad force becomes averaged out over many pages. */ - res.demerits_ = line_force + line_penalty + (page_force + res.penalty_) * page_weighting; + res.demerits_ = line_force + line_penalty + page_demerits * page_weighting; return res; } @@ -990,13 +1119,18 @@ Page_breaking::space_systems_on_1_page (vector const &lines, Real { Page_spacing space (page_height, page_top_space_); Page_spacing_result ret; + int line_count = 0; for (vsize i = 0; i < lines.size (); i++) - space.append_system (lines[i]); + { + space.append_system (lines[i]); + line_count += lines[i].compressed_nontitle_lines_count_; + } ret.systems_per_page_.push_back (lines.size ()); ret.force_.push_back (ragged ? min (space.force_, 0.0) : space.force_); - ret.penalty_ = lines.back ().page_penalty_ + lines.back ().turn_penalty_; + ret.penalty_ = line_count_penalty (line_count) + lines.back ().page_penalty_ + lines.back ().turn_penalty_; + ret.system_count_status_ |= line_count_status (line_count); /* don't do finalize_spacing_result () because we are only an internal function */ return ret; @@ -1028,24 +1162,48 @@ Page_breaking::space_systems_on_2_pages (vsize configuration, vsize first_page_n vector page1_force; vector page2_force; + + // page1_penalty and page2_penalty store the penalties based + // on min-systems-per-page and max-systems-per-page. + vector page1_penalty; + vector page2_penalty; + + // page1_status and page2_status keep track of whether the min-systems-per-page + // and max-systems-per-page constraints are satisfied. + vector page1_status; + vector page2_status; + Page_spacing page1 (page1_height, page_top_space_); Page_spacing page2 (page2_height, page_top_space_); + int page1_line_count = 0; + int page2_line_count = 0; page1_force.resize (cached_line_details_.size () - 1, infinity_f); page2_force.resize (cached_line_details_.size () - 1, infinity_f); + page1_penalty.resize (cached_line_details_.size () - 1, infinity_f); + page2_penalty.resize (cached_line_details_.size () - 1, infinity_f); + page1_status.resize (cached_line_details_.size () - 1, 0); + page2_status.resize (cached_line_details_.size () - 1, 0); /* find the page 1 and page 2 forces for each page-breaking position */ for (vsize i = 0; i < page1_force.size (); i++) { page1.append_system (cached_line_details_[i]); page2.prepend_system (cached_line_details_[cached_line_details_.size () - 1 - i]); + page1_line_count += cached_line_details_[i].compressed_nontitle_lines_count_; + page2_line_count += cached_line_details_[cached_line_details_.size () - 1 - i].compressed_nontitle_lines_count_; + page1_force[i] = (ragged1 && page1.force_ < 0 && i > 0) ? infinity_f : page1.force_; + page1_penalty[i] = line_count_penalty (page1_line_count); + page1_status[i] = line_count_status (page1_line_count); if (ragged2) page2_force[page2_force.size () - 1 - i] = (page2.force_ < 0 && i + 1 < page1_force.size ()) ? infinity_f : 0; else page2_force[page2_force.size () - 1 - i] = page2.force_; + page2_penalty[page2_penalty.size () - 1 - i] = line_count_penalty (page2_line_count); + page2_status[page2_penalty.size () - 1 - i] = line_count_status (page2_line_count); } /* find the position that minimises the sum of the page forces */ @@ -1054,8 +1212,12 @@ Page_breaking::space_systems_on_2_pages (vsize configuration, vsize first_page_n for (vsize i = 0; i < page1_force.size (); i++) { Real f = page1_force[i] * page1_force[i] + page2_force[i] * page2_force[i]; - Real uneven = 2 * (page1_force[i] - page2_force[i]); - Real dem = uneven * uneven + f + + // NOTE: we treat max-systems-per-page and min-systems-per-page as soft + // constraints. That is, we penalize harshly when they don't happen + // but we don't completely reject. + Real dem = f + + page1_penalty[i] + page2_penalty[i] + cached_line_details_[i+1].page_penalty_ + cached_line_details_.back ().page_penalty_ + cached_line_details_.back ().turn_penalty_; if (dem < best_demerits) @@ -1070,9 +1232,11 @@ Page_breaking::space_systems_on_2_pages (vsize configuration, vsize first_page_n ret.systems_per_page_.push_back (cached_line_details_.size () - best_sys_count); ret.force_.push_back (page1_force[best_sys_count-1]); ret.force_.push_back (page2_force[best_sys_count-1]); + ret.system_count_status_ = page1_status[best_sys_count-1] | page2_status[best_sys_count-1]; ret.penalty_ = cached_line_details_[best_sys_count-1].page_penalty_ + cached_line_details_.back ().page_penalty_ - + cached_line_details_.back ().turn_penalty_; + + cached_line_details_.back ().turn_penalty_ + + page1_penalty[best_sys_count-1] + page2_penalty[best_sys_count-1]; /* don't do finalize_spacing_result () because we are only an internal function */ return ret;