-/*
- 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--2006 Han-Wen Nienhuys <hanwen@xs4all.nl>
+
+ TODO:
+ - add support for different stretch/shrink constants?
+*/
+
+#include <cstdio>
+
+#include "libc-extension.hh" // isinf
+#include "simple-spacer.hh"
+#include "paper-column.hh"
+#include "spring.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. */
+
+/*
+ positive force = expanding, negative force = compressing.
+*/
+
+Simple_spacer::Simple_spacer ()
+{
+ /*
+ Give an extra penalty for compression. Needed to avoid compressing
+ tightly spaced lines.
+ */
+ active_count_ = 0;
+ force_ = 0.;
+ indent_ = 0.0;
+ default_space_ = 20 PT;
+}
+
+void
+Simple_spacer::add_rod (int l, int r, Real dist)
+{
+ if (isinf (dist) || isnan (dist))
+ {
+ programming_error ("ignoring weird minimum distance");
+ 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_;
+
+ if (total_dist < dist)
+ for (int i = l; i < r; i++)
+ springs_[i].ideal_ *= dist / total_dist;
+
+ return;
+ }
+
+ Real d = range_ideal_len (l, r);
+ Real block_stretch = dist - d;
+
+ Real block_force = c * block_stretch;
+ force_ = max (force_, block_force);
+
+ for (int i = l; i < r; i++)
+ springs_[i].block_force_ = max (block_force, springs_[i].block_force_);
+}
+
+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_;
+ 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].is_active_)
+ den += 1 * springs_[i].inverse_hooke_;
+ }
+
+ 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].is_active_)
+ bf = max (bf, springs_[i].block_force_);
+ return bf;
+}
+
+Real
+Simple_spacer::active_springs_stiffness () const
+{
+ Real stiff = range_stiffness (0, springs_.size ());
+ if (isinf (stiff))
+ {
+ /*
+ all springs are inactive. Take the stiffness of the
+ latest spring to block.
+ */
+
+ Real max_block_force = -infinity_f;
+ int max_i = -1;
+ for (int i = 0; i < springs_.size (); i++)
+ {
+ if (springs_[i].block_force_ > max_block_force)
+ {
+ max_i = i;
+ max_block_force = springs_[i].block_force_;
+ }
+ }
+
+ stiff = 1/springs_[max_i].inverse_hooke_;
+ }
+ return stiff;
+}
+
+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].is_active_
+ && springs_[i].block_force_ >= force_)
+ {
+ springs_[i].is_active_ = 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_);
+
+ return l;
+}
+
+bool
+Simple_spacer::is_active () const
+{
+ return active_count_;
+}
+
+void
+Simple_spacer::my_solve_linelen ()
+{
+ while (is_active ())
+ {
+ force_ = active_blocking_force ();
+ Real conf = configuration_length ();
+
+ if (conf < line_len_)
+ {
+ force_ += (line_len_ - conf) * active_springs_stiffness ();
+ break;
+ }
+ else
+ set_active_states ();
+ }
+}
+
+void
+Simple_spacer::my_solve_natural_len ()
+{
+ Real line_len_force = 0.0;
+
+ while (is_active ())
+ {
+ force_ = max (active_blocking_force (), 0.0);
+ Real conf = configuration_length ();
+
+ if (conf < line_len_)
+ {
+ line_len_force = force_
+ + (line_len_ - conf)
+ * active_springs_stiffness ();
+ }
+
+ if (force_ < 1e-8) // ugh.,
+ break;
+
+ set_active_states ();
+ }
+
+ force_ = line_len_force;
+}
+
+/****************************************************************/
+
+Spring_description::Spring_description ()
+{
+ ideal_ = 0.0;
+ inverse_hooke_ = 0.0;
+ is_active_ = true;
+ block_force_ = 0.0;
+}
+
+bool
+Spring_description::is_sane () const
+{
+ return (inverse_hooke_ >= 0)
+ && ideal_ > 0
+ && !isinf (ideal_) && !isnan (ideal_);
+}
+
+Real
+Spring_description::length (Real f) const
+{
+ if (!is_active_)
+ f = block_force_;
+ return ideal_ + f * inverse_hooke_;
+}
+/****************************************************************/
+
+/*
+ TODO: should a add penalty for widely varying spring forces (caused
+ by constraints, eg.
+
+
+ . =====
+ . | |
+ .o|o|x ##x
+ .
+
+ The ## forces the notes apart; we shouldn't allow the O's to touch
+ this closely.
+*/
+void
+Simple_spacer_wrapper::solve (Column_x_positions *positions, bool ragged)
+{
+ if (ragged)
+ spacer_->my_solve_natural_len ();
+ else
+ spacer_->my_solve_linelen ();
+
+ positions->force_ = spacer_->force_;
+
+ /*
+ We used to have a penalty for compression, no matter what, but that
+ fucked up wtk1-fugue2 (taking 3 full pages.)
+ */
+ positions->config_.push (spacer_->indent_);
+ for (int i = 0; i < spacer_->springs_.size (); i++)
+ {
+ Real l = spacer_->springs_[i].length ((ragged) ? 0.0 : spacer_->force_);
+ positions->config_.push (positions->config_.top () + l);
+ /*
+ we have l>= 0 here, up to rounding errors
+ */
+ }
+
+ /*
+ For raggedright, we must have a measure of music density: this is
+ to prevent lots of short lines (which all have force = 0).
+ */
+ if (ragged)
+ {
+ positions->satisfies_constraints_
+ = positions->config_.top () < spacer_->line_len_;
+ }
+ else
+ positions->satisfies_constraints_ = spacer_->is_active ();
+
+ positions->cols_ = spaced_cols_;
+ positions->loose_cols_ = loose_cols_;
+
+ /*
+ 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_property ("penalty");
+ if (scm_is_number (p))
+ {
+ if (scm_to_double (p) < -9999)
+ break_satisfy = break_satisfy && (i == 0 || i == sz -1);
+ if (scm_to_double (p) > 9999)
+ break_satisfy = break_satisfy && ! (i == 0 || i == sz -1);
+ }
+ }
+
+ positions->satisfies_constraints_
+ = positions->satisfies_constraints_ && break_satisfy;
+}
+
+void
+Simple_spacer::add_spring (Real ideal, Real inverse_hooke)
+{
+ Spring_description desc;
+
+ desc.ideal_ = ideal;
+ desc.inverse_hooke_ = inverse_hooke;
+ if (!desc.is_sane ())
+ {
+ programming_error ("insane spring found, setting to unit");
+
+ desc.inverse_hooke_ = 1.0;
+ desc.ideal_ = 1.0;
+ }
+
+ if (!inverse_hooke)
+ desc.is_active_ = false;
+ else
+ {
+ /*
+ desc.is_active_ ?
+ */
+ desc.block_force_ = -desc.ideal_ / desc.inverse_hooke_;
+ // block at distance 0
+
+ active_count_++;
+ }
+ springs_.push (desc);
+}
+
+static int
+compare_paper_column_rank (Grob *const &a,
+ Grob *const &b)
+{
+ return Paper_column::get_rank (a) - Paper_column::get_rank (b);
+}
+
+void
+Simple_spacer_wrapper::add_columns (Link_array<Grob> const &icols)
+{
+ Link_array<Grob> cols (icols);
+ cols.clear ();
+
+ for (int i = 0; i < icols.size (); i++)
+ if (scm_is_pair (icols[i]->get_object ("between-cols")))
+ loose_cols_.push (icols[i]);
+ else
+ cols.push (icols[i]);
+
+ spaced_cols_ = cols;
+ for (int i = 0; i < cols.size () - 1; i++)
+ {
+ Spring_smob *spring = 0;
+
+ for (SCM s = cols[i]->get_object ("ideal-distances");
+ !spring && scm_is_pair (s);
+ s = scm_cdr (s))
+ {
+ Spring_smob *sp = unsmob_spring (scm_car (s));
+
+ if (sp->other_ == cols[i + 1])
+ spring = sp;
+ }
+
+ if (!spring)
+ programming_error (_f ("No spring between column %d and next one",
+ Paper_column::get_rank (cols[i])));
+
+ Real ideal = (spring) ? spring->distance_ : spacer_->default_space_;
+ Real inverse_hooke = (spring) ? spring->inverse_strength_ : 1.0;
+
+ spacer_->add_spring (ideal, inverse_hooke);
+ }
+
+ for (int i = 0; i < cols.size () - 1; i++)
+ {
+ for (SCM s = Spaceable_grob::get_minimum_distances (cols[i]);
+ scm_is_pair (s); s = scm_cdr (s))
+ {
+ Grob *other = unsmob_grob (scm_caar (s));
+ int j = binsearch_links (cols, other, &compare_paper_column_rank);
+ if (j >= 0 && cols[j] == other)
+ spacer_->add_rod (i, j, scm_to_double (scm_cdar (s)));
+ }
+
+ if (i
+ && to_boolean (cols[i]->get_property ("keep-inside-line")))
+ {
+ Interval e = cols[i]->extent (cols[i], X_AXIS);
+ if (!e.is_empty ())
+ {
+ spacer_->add_rod (i, cols.size () - 1, e[RIGHT]);
+ spacer_->add_rod (0, i, e[LEFT]);
+ }
+ }
+ }
+}
+
+Simple_spacer_wrapper::Simple_spacer_wrapper ()
+{
+ spacer_ = new Simple_spacer ();
+}
+
+Simple_spacer_wrapper::~Simple_spacer_wrapper ()
+{
+ delete spacer_;
+}
+Simple_spacer_wrapper::Simple_spacer_wrapper (Simple_spacer_wrapper const &)
+{
+}