2 item.cc -- implement Item
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
11 #include "paper-score.hh"
13 #include "paper-column.hh"
14 #include "lily-guile.hh"
16 #include "group-interface.hh"
19 Item::clone (int count) const
21 return new Item (*this, count);
24 Item::Item (SCM s, Object_key const *key)
27 broken_to_drul_[LEFT] = broken_to_drul_[RIGHT]= 0;
28 Group_interface::add_thing (this, ly_symbol2scm ("interfaces"), ly_symbol2scm ("item-interface"));
32 Item copy ctor. Copy nothing: everything should be a elt property
33 or a special purpose pointer (such as broken_to_drul_[]) */
34 Item::Item (Item const &s, int copy_count)
35 : Grob (s, copy_count)
37 broken_to_drul_[LEFT] = broken_to_drul_[RIGHT] = 0;
41 Item::is_breakable (Grob *me)
46 if (!dynamic_cast<Item *> (me))
47 me->programming_error ("only items can be breakable.");
49 Item *i = dynamic_cast<Item *> (me->get_parent (X_AXIS));
50 return (i) ? Item::is_breakable (i) : to_boolean (me->get_property ("breakable"));
54 Item::get_column () const
56 Item *parent = dynamic_cast<Item *> (get_parent (X_AXIS));
57 return parent ? parent->get_column () : 0;
61 Item::get_system () const
63 Grob *g = get_parent (X_AXIS);
64 return g ? g->get_system () : 0;
68 Item::copy_breakable_items ()
70 Drul_array<Item *> new_copies;
75 Grob *dolly = clone (count++);
76 Item *item = dynamic_cast<Item *> (dolly);
77 pscore_->system_->typeset_grob (item);
80 while (flip (&i) != LEFT);
81 broken_to_drul_ = new_copies;
85 Item::is_broken () const
87 return broken_to_drul_[LEFT] || broken_to_drul_[RIGHT];
91 Generate items for begin and end-of line.
94 Item::discretionary_processing ()
99 if (Item::is_breakable (this))
100 copy_breakable_items ();
104 Item::find_broken_piece (System *l) const
106 if (get_system () == l)
107 return (Item *) (this);
112 Grob *s = broken_to_drul_[d];
113 if (s && s->get_system () == l)
116 while (flip (&d) != LEFT);
122 Item::find_prebroken_piece (Direction d) const
124 Item *me = (Item *) (this);
127 return dynamic_cast<Item *> (broken_to_drul_[d]);
131 Item::break_status_dir () const
135 Item *i = dynamic_cast<Item *> (original_);
137 return (i->broken_to_drul_[LEFT] == this) ? LEFT : RIGHT;
144 Item::handle_prebroken_dependencies ()
146 Grob::handle_prebroken_dependencies ();
149 Can't do this earlier, because try_visibility_lambda () might set
150 the elt property transparent, which would then be copied.
154 give the item to break-visibility itself, so the function can do
155 more complicated things.
157 SCM vis = get_property ("break-visibility");
158 if (ly_c_procedure_p (vis))
160 SCM args = scm_list_n (scm_int2num (break_status_dir ()), SCM_UNDEFINED);
161 SCM result = scm_apply_0 (vis, args);
162 bool trans = ly_scm2bool (scm_car (result));
163 bool empty = ly_scm2bool (scm_cdr (result));
169 set_extent (SCM_EOL, X_AXIS);
170 set_extent (SCM_EOL, Y_AXIS);
173 set_property ("print-function", SCM_EOL);
178 Item::do_derived_mark () const
180 if (broken_to_drul_[LEFT])
181 scm_gc_mark (broken_to_drul_[LEFT]->self_scm ());
182 if (broken_to_drul_[RIGHT])
183 scm_gc_mark (broken_to_drul_[RIGHT]->self_scm ());
190 return dynamic_cast<Item *> (unsmob_grob (s));
197 "Grobs can be distinguished in their role in the horizontal spacing.\n"
198 "Many grobs define constraints on the spacing by their sizes. For\n"
199 "example, note heads, clefs, stems, and all other symbols with a fixed\n"
200 "shape. These grobs form a subtype called @code{Item}.\n"
203 "Some items need special treatment for line breaking. For example, a\n"
204 "clef is normally only printed at the start of a line (i.e. after a\n"
205 "line break). To model this, `breakable' items (clef, key signature,\n"
206 "bar lines, etc.) are copied twice. Then we have three versions of each\n"
207 "breakable item: one version if there is no line break, one version\n"
208 "that is printed before the line break (at the end of a system), one\n"
209 "version that is printed after the line break.\n"
211 "Whether these versions are visible and take up space, is determined by\n"
212 "the outcome of the @code{break-visibility}. This grob property is a\n"
213 "function taking a direction (-1, 0 or 1) as argument. It returns a\n"
214 "cons of booleans, signifying whether this grob should be transparent\n"
215 "and have no extent.\n"
217 "The following variables for break-visibility are predefined:\n"
219 " grob will show: before no after\n"
220 " break break break\n"
221 " all-invisible no no no\n"
222 " begin-of-line-visible no no yes\n"
223 " end-of-line-visible yes no no\n"
224 " all-visible yes yes yes\n"
225 " begin-of-line-invisible yes yes no\n"
226 " end-of-line-invisible no yes yes\n"
228 "no-spacing-rods break-visibility breakable")