/*
- simple-spacer.cc -- implement Simple_spacer
+ simple-spacer.cc -- implement Simple_spacer
source file of the GNU LilyPond music typesetter
- (c) 1999 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+ (c) 1999--2002 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+
+ TODO:
+ - add support for different stretch/shrink constants?
+
+*/
+
+#include <math.h>
+#include <libc-extension.hh> // isinf
+
+#include "simple-spacer.hh"
+#include "paper-column.hh"
+#include "spring.hh"
+#include "rod.hh"
+#include "warn.hh"
+#include "column-x-positions.hh"
+#include "spaceable-grob.hh"
+#include "dimensions.hh"
+
+
+/*
+ A simple spacing constraint solver. The approach:
+
+ Stretch the line uniformly until none of the constraints (rods)
+ block. It then is very wide.
+
+ Compress until the next constraint blocks,
+
+ Mark the springs over the constrained part to be non-active.
+
+ Repeat with the smaller set of non-active constraints, until all
+ constraints blocked, or until the line is as short as desired.
+
+ This is much simpler, and much much faster than full scale
+ Constrained QP. On the other hand, a situation like this will not
+ be typeset as dense as possible, because
+
+ c4 c4 c4 c4
+ veryveryverylongsyllable2 veryveryverylongsyllable2
+ " "4 veryveryverylongsyllable2 syllable4
+
+
+ can be further compressed to
+
+
+ c4 c4 c4 c4
+ veryveryverylongsyllable2 veryveryverylongsyllable2
+ " "4 veryveryverylongsyllable2 syllable4
+
+
+ Perhaps this is not a bad thing, because the 1st looks better anyway. */
+
+
+Simple_spacer::Simple_spacer ()
+{
+ /*
+ Give an extra penalty for compression. Needed to avoid compressing
+ tightly spaced lines.
+ */
+ compression_penalty_b_ = false;
+ active_count_ = 0;
+ force_f_ = 0.;
+ indent_f_ =0.0;
+ default_space_f_ = 20 PT;
+}
+
+void
+Simple_spacer::add_rod (int l, int r, Real dist)
+{
+ if (isinf (dist) || isnan (dist))
+ {
+ programming_error ("Weird minimum distance. Ignoring");
+ return;
+ }
+
+ Real c = range_stiffness (l,r);
+ if (isinf (c))
+ {
+ /*
+ If a spring is fixed, we have to do something here:
+ we let the rod override the spring.
+ */
+ Real total_dist = 0.;
+ for (int i = l ; i < r; i++)
+ total_dist += springs_[i].ideal_f_;
+
+ if (total_dist < dist)
+ for (int i = l ; i < r; i++)
+ springs_[i].ideal_f_ *= dist/total_dist;
+
+ return;
+ }
+
+ Real d = range_ideal_len (l,r);
+ Real block_stretch = dist - d;
+
+ Real block_force = c * block_stretch;
+ force_f_ = force_f_ >? block_force;
+
+ for (int i=l; i < r; i++)
+ springs_[i].block_force_f_ = block_force >?
+ springs_[i].block_force_f_ ;
+}
+
+Real
+Simple_spacer::range_ideal_len (int l, int r) const
+{
+ Real d =0.;
+ for (int i=l; i < r; i++)
+ d += springs_[i].ideal_f_;
+ return d;
+}
+
+Real
+Simple_spacer::range_stiffness (int l, int r) const
+{
+ Real den =0.0;
+ for (int i=l; i < r; i++)
+ {
+ if (springs_[i].active_b_)
+ den += 1 / springs_[i].hooke_f_;
+ }
+
+ return 1 / den;
+}
+
+Real
+Simple_spacer::active_blocking_force () const
+{
+ Real bf = - infinity_f;
+ for (int i=0; i < springs_.size (); i++)
+ if (springs_[i].active_b_)
+ {
+ bf = bf >? springs_[i].block_force_f_;
+ }
+ return bf;
+}
+
+Real
+Simple_spacer::active_springs_stiffness () const
+{
+ Real den = 0.0;
+ for (int i=0; i < springs_.size (); i++)
+ if (springs_[i].active_b_)
+ {
+ den += 1 / springs_[i].hooke_f_;
+ }
+ return 1/den;
+}
+
+void
+Simple_spacer::set_active_states ()
+{
+ /* float comparison is safe, since force is only copied. */
+ for (int i=0 ; i <springs_.size (); i++)
+ if (springs_[i].active_b_
+ && springs_[i].block_force_f_ >= force_f_)
+ {
+ springs_[i].active_b_ = false;
+ active_count_ --;
+ }
+}
+
+Real
+Simple_spacer::configuration_length () const
+{
+ Real l =0.;
+ for (int i=0; i < springs_.size (); i++)
+ l += springs_[i].length (force_f_);
+
+ return l;
+}
+
+bool
+Simple_spacer::active_b () const
+{
+ return active_count_;
+}
+
+void
+Simple_spacer::my_solve_linelen ()
+{
+ while (active_b ())
+ {
+ force_f_ = active_blocking_force ();
+ Real conf = configuration_length ();
+
+ if (conf < line_len_f_)
+ {
+ force_f_ += (line_len_f_ - conf) * active_springs_stiffness ();
+ break;
+ }
+ else
+ set_active_states ();
+ }
+}
+
+
+void
+Simple_spacer::my_solve_natural_len ()
+{
+ while (active_b ())
+ {
+ force_f_ = active_blocking_force () >? 0.0;
+
+ if (force_f_ < 1e-8) // ugh.,
+ break;
+
+ set_active_states ();
+ }
+}
+
+void
+Simple_spacer::add_columns (Link_array<Grob> cols)
+{
+ for (int i = cols.size (); i--;)
+ if (gh_pair_p (cols[i]->get_grob_property ("between-cols")))
+ {
+ loose_cols_.push (cols[i]);
+ cols.del (i);
+ }
- */
+ spaced_cols_ = cols;
+ for (int i=0; i < cols.size () - 1; i++)
+ {
+ Spring_smob *spring = 0;
+
+ for (SCM s = cols[i]->get_grob_property ("ideal-distances");
+ !spring && gh_pair_p (s);
+ s = ly_cdr (s))
+ {
+ Spring_smob *sp = unsmob_spring (ly_car (s));
+
+
+ if (sp->other_ == cols[i+1])
+ spring = sp;
+ }
+
+ Spring_description desc;
+ if (spring)
+ {
+ desc.ideal_f_ = spring->distance_f_;
+ desc.hooke_f_ = spring->strength_f_;
+ }
+ else
+ {
+ programming_error (_f("No spring between column %d and next one",
+ Paper_column::rank_i (cols[i])
+ ));
+ desc.hooke_f_ = 1.0;
+ desc.ideal_f_ = default_space_f_;
+
+ continue;
+ }
+
+ if (!desc.sane_b ())
+ {
+ programming_error ("Insane spring found. Setting to unit spring.");
+
+ desc.hooke_f_ = 1.0;
+ desc.ideal_f_ = 1.0;
+ }
+
+ if (isinf (desc.hooke_f_))
+ {
+ desc.active_b_ = false;
+ springs_.push (desc);
+ }
+ else
+ {
+ desc.block_force_f_ = - desc.hooke_f_ * desc.ideal_f_; // block at distance 0
+ springs_.push (desc);
+
+ active_count_ ++;
+ }
+
+ if (spring->expand_only_b_)
+ {
+ compression_penalty_b_ = true;
+ }
+
+ }
+
+ for (int i=0; i < cols.size () - 1; i++)
+ {
+ for (SCM s = Spaceable_grob::get_minimum_distances (cols[i]);
+ gh_pair_p (s); s = ly_cdr (s))
+ {
+ Grob * other = unsmob_grob (ly_caar (s));
+ int oi = cols.find_i (other);
+ if (oi >= 0)
+ {
+ add_rod (i, oi, gh_scm2double (ly_cdar (s)));
+ }
+ }
+ }
+
+ /*
+ TODO: should support natural length on only the last line.
+ */
+ if (line_len_f_ < 0)
+ my_solve_natural_len ();
+ else
+ my_solve_linelen ();
+}
+
+#include <stdio.h>
+
+void
+Simple_spacer::solve (Column_x_positions *positions, bool ragged) const
+{
+ positions->force_f_ = force_f_;
+ if ((force_f_ < 0))
+ {
+
+ /*
+ We used to have a penalty for compression, no matter what, but that
+ fucked up wtk1-fugue2 (taking 3 full pages.)
+
+ maybe this should be tunable?
+ */
+ if (compression_penalty_b_)
+ positions->force_f_ *= 2; // hmm.
+ }
+
+ positions->config_.push (indent_f_);
+ for (int i=0; i <springs_.size (); i++)
+ {
+ if (ragged)
+ {
+ // ragged right operation: do not apply any force
+ positions->config_.push (positions->config_.top () + springs_[i].length (0.0));
+ }
+ else
+ {
+ positions->config_.push (positions->config_.top () + springs_[i].length (force_f_));
+ }
+ }
+ positions->cols_ = spaced_cols_;
+ positions->loose_cols_ = loose_cols_;
+
+ positions->satisfies_constraints_b_ = (line_len_f_ < 0) || active_b ();
+
+
+ /*
+ Check if breaking constraints are met.
+ */
+ bool break_satisfy = true;
+ int sz = positions->cols_.size ();
+ for (int i = sz; i--; )
+ {
+ SCM p = positions->cols_[i]->get_grob_property( "penalty");
+ if (gh_number_p (p))
+ {
+ if (gh_scm2double (p) < -9999)
+ break_satisfy = break_satisfy && (i == 0 || i == sz -1);
+ if (gh_scm2double (p) > 9999)
+ break_satisfy = break_satisfy && !(i == 0 || i == sz -1);
+ }
+
+ }
+
+ positions->satisfies_constraints_b_ =
+ positions->satisfies_constraints_b_ && break_satisfy;
+}
+
+/****************************************************************/
+
+Spring_description::Spring_description ()
+{
+ ideal_f_ =0.0;
+ hooke_f_ =0.0;
+ active_b_ = true;
+ block_force_f_ = 0.0;
+}
+
+bool
+Spring_description::sane_b () const
+{
+ return (hooke_f_ > 0) && !isinf (ideal_f_) && !isnan (ideal_f_);
+}
+Real
+Spring_description::length (Real f) const
+{
+ if (!active_b_)
+ f = block_force_f_;
+ return ideal_f_ + f / hooke_f_ ;
+}
projects / lilypond.git / blobdiff