10 static const Symbol*find_ball(int);
11 static const Symbol*find_rest(int);
12 static const Symbol*find_bar(String);
16 /// a symbol with a variable width
17 struct Stretchable_symbol {
20 /// return a string for a symbol in this width.
21 virtual String operator ()(Real width)=0;
22 virtual Interval height(Real width) const =0;
23 static const Stretchable_symbol* get_linestaff(int n);