lily/self-aligment-interface.cc

   1 /*
   2   self-alignment-interface.cc
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8
   9 #include "self-alignment-interface.hh"
  10 #include "warn.hh"
  11
  12 /* Position centered on parent.  */
  13 MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_parent, 2);
  14 SCM
  15 Self_alignment_interface::centered_on_parent (SCM element_smob, SCM axis)
  16 {
  17   Grob *me = unsmob_grob (element_smob);
  18   Axis a = (Axis) ly_scm2int (axis);
  19   Grob *him = me->get_parent (a);
  20   Interval he = him->extent (him, a);
  21
  22   return  scm_make_real (he.is_empty () ? 0.0 : he.center ());
  23 }
  24
  25 MAKE_SCHEME_CALLBACK (Self_alignment_interface, aligned_on_parent, 2);
  26 SCM
  27 Self_alignment_interface::aligned_on_parent (SCM element_smob, SCM axis)
  28 {
  29   Grob *me = unsmob_grob (element_smob);
  30   Axis a = (Axis) ly_scm2int (axis);
  31   Grob *him = me->get_parent (a);
  32   Interval he = him->extent (him, a);
  33
  34   SCM sym= (a == X_AXIS) ? ly_symbol2scm ("self-alignment-X")
  35     : ly_symbol2scm ("self-alignment-Y");
  36   SCM align_prop (me->internal_get_property (sym));
  37
  38   if (!ly_c_number_p (align_prop))
  39     return scm_int2num (0);
  40
  41   Real x = 0.0;
  42   Real align = ly_scm2double (align_prop);
  43
  44   Interval ext (me->extent (me, a));
  45   if (ext.is_empty ())
  46     programming_error ("I'm empty. Can't align on self");
  47   else
  48     x -= ext.linear_combination (align) ;
  49
  50   if (!he.is_empty ())
  51     x += he.linear_combination (align);
  52
  53   return scm_make_real (x);
  54 }
  55
  56 /* Position centered on parent. */
  57 MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_other_axis_parent, 2);
  58 SCM
  59 Self_alignment_interface::centered_on_other_axis_parent (SCM element_smob,
  60                                                          SCM axis)
  61 {
  62   Grob *me = unsmob_grob (element_smob);
  63   Axis a = (Axis) ly_scm2int (axis);
  64   Grob *him = me->get_parent (other_axis (a));
  65   Interval he = him->extent (him, a);
  66
  67   return  scm_make_real (he.is_empty () ? 0.0 : he.center ());
  68 }
  69
  70 /** callback that centers the element on itself
  71     Requires that self-alignment-{X, Y} be set.  */
  72 MAKE_SCHEME_CALLBACK (Self_alignment_interface, aligned_on_self, 2);
  73 SCM
  74 Self_alignment_interface::aligned_on_self (SCM element_smob, SCM axis)
  75 {
  76   Grob *me = unsmob_grob (element_smob);
  77   Axis a = (Axis) ly_scm2int (axis);
  78
  79   SCM sym= (a == X_AXIS) ? ly_symbol2scm ("self-alignment-X")
  80     : ly_symbol2scm ("self-alignment-Y");
  81
  82   SCM align (me->internal_get_property (sym));
  83   if (ly_c_number_p (align))
  84     {
  85       Interval ext (me->extent (me, a));
  86       if (ext.is_empty ())
  87         programming_error ("I'm empty. Can't align on self");
  88       else
  89         return scm_make_real (- ext.linear_combination (ly_scm2double (align)));
  90     }
  91   return scm_make_real (0.0);
  92 }
  93
  94
  95 ADD_INTERFACE (Self_alignment_interface, "self-alignment-interface",
  96                "Position this object on itself and/or on its parent. To this end, the following functions "
  97                " are provided: \n"
  98                "@table @code \n"
  99                "@item Self_alignment_interface::aligned_on_self\n"
 100                "  Align self on reference point, using @code{self-alignment-X} and "
 101                "@code{self-alignment-Y}."
 102                "@item Self_alignment_interface::aligned_on_parent\n"
 103                "@item Self_alignment_interface::centered_on_parent\n"
 104                "  Shift the object so its own reference point is centered on the  "
 105                " extent of the parent \n"
 106                "@item Self_alignment_interface::centered_on_other_axis_parent\n"
 107                " For X-axis, center on the Y-parent, and vice versa.\n "
 108                "@end table\n",
 109                "self-alignment-X self-alignment-Y");
 110