lily/include/simple-spacer.hh

   1 /*
   2   simple-spacer.hh -- declare Simple_spacer
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1999--2001 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7
   8  */
   9
  10 #ifndef SIMPLE_SPACER_HH
  11 #define SIMPLE_SPACER_HH
  12
  13 #include "parray.hh"
  14 #include "lily-proto.hh"
  15
  16
  17 struct Spring_description
  18 {
  19   Real ideal_f_;
  20   Real hooke_f_;
  21   bool active_b_;
  22
  23   Real block_force_f_;
  24
  25   Real length (Real force) const;
  26   Spring_description ();
  27
  28   bool sane_b () const;
  29 };
  30
  31 /**
  32    A simple spacing constraint solver. The approach:
  33
  34    Stretch the line uniformly until none of the constraints (rods)
  35    block.  It then is very wide.
  36
  37
  38       Compress until the next constraint blocks,
  39
  40       Mark the springs over the constrained part to be non-active.
  41
  42    Repeat with the smaller set of non-active constraints, until all
  43    constraints blocked, or until the line is as short as desired.
  44
  45    This is much simpler, and much much faster than full scale
  46    Constrained QP. On the other hand, a situation like this will not
  47    be typeset as dense as possible, because
  48
  49    c4                   c4           c4                  c4
  50    veryveryverylongsyllable2         veryveryverylongsyllable2
  51    " "4                 veryveryverylongsyllable2        syllable4
  52
  53
  54    can be further compressed to
  55
  56
  57    c4    c4                        c4   c4
  58    veryveryverylongsyllable2       veryveryverylongsyllable2
  59    " "4  veryveryverylongsyllable2      syllable4
  60
  61
  62    Perhaps this is not a bad thing, because the 1st looks better anyway.  */
  63 struct Simple_spacer
  64 {
  65   Array<Spring_description> springs_;
  66   Link_array<Grob> spaced_cols_;
  67   Link_array<Grob> loose_cols_;
  68   Real force_f_;
  69   Real indent_f_;
  70   Real line_len_f_;
  71   Real default_space_f_;
  72
  73
  74   Simple_spacer ();
  75
  76   void solve (Column_x_positions *) const;
  77   void add_columns (Link_array<Grob>);
  78   void my_solve_linelen ();
  79   void my_solve_natural_len ();
  80   Real active_springs_stiffness () const;
  81   Real range_stiffness (int, int) const;
  82   void add_rod (int l, int r, Real dist);
  83   Real range_ideal_len (int l, int r)const;
  84   Real active_blocking_force ()const;
  85   Real configuration_length ()const;
  86   void set_active_states ();
  87   bool active_b () const;
  88 };
  89
  90 #endif /* SIMPLE_SPACER_HH */
  91