From ef230538606138ba9110aa797a0c887aeb40893e Mon Sep 17 00:00:00 2001
From: fred <fred>
Date: Fri, 25 Jul 1997 19:34:41 +0000
Subject: [PATCH] lilypond-0.0.76

---
 lily/include/spring-spacer.hh | 98 +++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 lily/include/spring-spacer.hh

diff --git a/lily/include/spring-spacer.hh b/lily/include/spring-spacer.hh
new file mode 100644
index 0000000000..2b540085f2
--- /dev/null
+++ b/lily/include/spring-spacer.hh
@@ -0,0 +1,98 @@
+/*
+  spring-spacer.hh -- declare Spring_spacer
+
+  source file of the GNU LilyPond music typesetter
+
+  (c) 1997 Han-Wen Nienhuys <hanwen@stack.nl>
+*/
+
+
+#ifndef SPRING_SPACER_HH
+#define SPRING_SPACER_HH
+
+#include "line-spacer.hh"
+#include "plist.hh"
+#include "col-info.hh"
+
+/** the problem, given by the columns (which include constraints) and
+    intercolumn spacing. The problem is:
+
+    Generate a spacing which
+    \begin{itemize}
+    \item
+    Satisfies spacing constraints (notes can't be printed through each other)
+    \item
+    Looks good, ie tries to conform to  an ideal spacing as much as possible.
+    \end{itemize}
+    This is converted by regarding idealspacing as "springs" attached
+    to columns. The equilibrium of one spring is the ideal
+    distance. The columns have a size, this imposes "hard" constraints
+    on the distances. This transforms the problem into a quadratic
+    programming problem with linear constraints.
+
+    The quality is given by the total potential energy in the
+    springs. The lower the energy, the better the configuration.
+
+    TODO: make item widths work per pstaff.
+
+*/
+
+class Spring_spacer : public Line_spacer {
+    friend class Durations_iter;
+    
+    Pointer_list<Idealspacing *> ideal_p_list_;
+    Array<Colinfo> cols;
+    Array<Colinfo> loose_col_arr_;
+    
+    /// mark column #i# as being loose.
+    void loosen_column(int i);
+    /// the index of #c# in #cols#
+    int col_id(PCol const *c) const;
+
+    /// generate an (nonoptimal) solution
+    Vector find_initial_solution() const;
+
+    /// check if problem is too tight
+    bool check_feasible() const;
+
+    /// does #this# contain the column #w#? 
+    bool contains(PCol const *w);
+
+    /// make the energy function
+    void make_matrices(Matrix &quad, Vector &lin,Real&) const;
+
+    /// generate the LP constraints
+    void make_constraints(Mixed_qp& lp) const;
+
+
+    void handle_loose_cols();
+    void position_loose_cols(Vector &) const;
+   /**
+       add a idealspacing to the problem.
+      
+    One pair of columns can have no, one or more idealspacings,
+    since they can be "summed" if the columns to which #i# refers are
+    not in this problem, the spacing is ignored.
+    */
+    void add_ideal(Idealspacing const *i);
+    Vector try_initial_solution() const;
+    void calc_idealspacing();
+
+    Score_column* scol_l(int);
+    void connect(int i,int j, Real,Real);
+public:
+    static Line_spacer *constructor();
+    Array<PCol*> error_pcol_l_arr() const;
+
+    virtual   Array<Real> solve() const;
+    virtual  void add_column(PCol  *, bool fixed=false, Real fixpos=0.0);
+ 
+
+    virtual Vector default_solution() const;
+    virtual   bool check_constraints(Vector v) const;
+    virtual    void OK() const;
+    virtual    void print() const;
+    virtual    void prepare();
+};
+
+#endif // SPRING_SPACER_HH
-- 
2.39.5