hdr/linespace.hh

   1 #ifndef PROBLEM_HH
   2 #define PROBLEM_HH
   3
   4 #include "glob.hh"
   5 #include "plist.hh"
   6 #include "varray.hh"
   7 #include "vector.hh"
   8 #include "interval.hh"
   9
  10 /// helper struct for #Spacing_problem#
  11 struct Colinfo {
  12     const PCol *pcol_;
  13     const Real* fixpos;
  14     Interval width;
  15
  16     /* *************** */
  17     Colinfo();
  18     void operator=(Colinfo const&);
  19     Colinfo(Colinfo const&);
  20     ~Colinfo();
  21     Colinfo(const PCol*,const Real*);
  22     void print() const;
  23     bool fixed() const { return fixpos;}
  24     Real fixed_position()const { return *fixpos; }
  25     Real minright() const { return width.right; }
  26     Real minleft() const { return -width.left; }
  27 };
  28
  29
  30 /** the problem, given by the columns (which include constraints) and
  31     intercolumn spacing. The problem is:
  32
  33     Generate a spacing which
  34     \begin{itemize}
  35     \item
  36     Satisfies spacing constraints (notes can't be printed through each other)
  37     \item
  38     Looks good, ie tries to conform to  an ideal spacing as much as possible.
  39     \end{itemize}
  40     This is converted by regarding idealspacing as "springs" attached
  41     to columns. The equilibrium of one spring is the ideal
  42     distance. The columns have a size, this imposes "hard" constraints
  43     on the distances. This transforms the problem into a quadratic
  44     programming problem with linear constraints.
  45
  46     The quality is given by the total potential energy in the
  47     springs. The lower the energy, the better the configuration.
  48 */
  49 class Spacing_problem {
  50     Array<const Idealspacing*> ideals;
  51     Array<Colinfo> cols;
  52
  53     /// the index of #c# in #cols#
  54     int col_id(const PCol *c) const;
  55
  56     /// generate an (nonoptimal) solution
  57     Vector find_initial_solution() const;
  58
  59     /// check if problem is too tight
  60     bool check_feasible() const;
  61
  62     /// does #this# contain the column #w#?
  63     bool contains(const PCol *w);
  64
  65     /// make the energy function
  66     void make_matrices(Matrix &quad, Vector &lin,Real&) const;
  67
  68     /// generate the LP constraints
  69     void make_constraints(Mixed_qp& lp) const;
  70
  71 public:
  72     /** solve the spacing problem
  73
  74       @return the column positions, and the energy (last element)
  75
  76       */
  77     Array<Real> solve() const;
  78
  79
  80     /**
  81        add a idealspacing to the problem.
  82
  83     One pair of columns can have no, one or more idealspacings,
  84     since they can be "summed" if the columns to which #i# refers are
  85     not in this problem, the spacing is ignored.
  86     */
  87     void add_ideal(const Idealspacing *i);
  88
  89
  90     /** add a col to the problem. columns have to be added left to right. The column contains
  91       info on it's minimum width.
  92     */
  93     void add_column(const PCol *, bool fixed=false, Real fixpos=0.0);
  94
  95
  96
  97     bool check_constraints(Vector v) const;
  98
  99     Vector try_initial_solution() const;
 100     void OK() const;
 101     void print() const;
 102     void print_ideal(const Idealspacing*)const;
 103 };
 104
 105
 106 #endif