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--2005 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7 */
   8
   9 #include "self-alignment-interface.hh"
  10
  11 #include "warn.hh"
  12
  13 /* Position centered on parent.  */
  14 MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_parent, 2);
  15 SCM
  16 Self_alignment_interface::centered_on_parent (SCM element_smob, SCM axis)
  17 {
  18   Grob *me = unsmob_grob (element_smob);
  19   Axis a = (Axis) scm_to_int (axis);
  20   Grob *him = me->get_parent (a);
  21   Interval he = him->extent (him, a);
  22
  23   return scm_make_real (he.is_empty () ? 0.0 : he.center ());
  24 }
  25
  26 MAKE_SCHEME_CALLBACK (Self_alignment_interface, aligned_on_parent, 2);
  27 SCM
  28 Self_alignment_interface::aligned_on_parent (SCM element_smob, SCM axis)
  29 {
  30   Grob *me = unsmob_grob (element_smob);
  31   Axis a = (Axis) scm_to_int (axis);
  32   Grob *him = me->get_parent (a);
  33   Interval he = him->extent (him, a);
  34
  35   SCM sym = (a == X_AXIS) ? ly_symbol2scm ("self-alignment-X")
  36     : ly_symbol2scm ("self-alignment-Y");
  37   SCM align_prop (me->internal_get_property (sym));
  38
  39   if (!scm_is_number (align_prop))
  40     return scm_int2num (0);
  41
  42   Real x = 0.0;
  43   Real align = scm_to_double (align_prop);
  44
  45   Interval ext (me->extent (me, a));
  46   if (ext.is_empty ())
  47     programming_error ("can't align on self: empty element");
  48   else
  49     x -= ext.linear_combination (align);
  50
  51   if (!he.is_empty ())
  52     x += he.linear_combination (align);
  53
  54   return scm_make_real (x);
  55 }
  56
  57 /* Position centered on parent. */
  58 MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_other_axis_parent, 2);
  59 SCM
  60 Self_alignment_interface::centered_on_other_axis_parent (SCM element_smob,
  61                                                          SCM axis)
  62 {
  63   Grob *me = unsmob_grob (element_smob);
  64   Axis a = (Axis) scm_to_int (axis);
  65   Grob *him = me->get_parent (other_axis (a));
  66   Interval he = him->extent (him, a);
  67
  68   return scm_make_real (he.is_empty () ? 0.0 : he.center ());
  69 }
  70
  71 /** callback that centers the element on itself
  72     Requires that self-alignment-{X, Y} be set.  */
  73 MAKE_SCHEME_CALLBACK (Self_alignment_interface, aligned_on_self, 2);
  74 SCM
  75 Self_alignment_interface::aligned_on_self (SCM element_smob, SCM axis)
  76 {
  77   Grob *me = unsmob_grob (element_smob);
  78   Axis a = (Axis) scm_to_int (axis);
  79
  80   SCM sym = (a == X_AXIS) ? ly_symbol2scm ("self-alignment-X")
  81     : ly_symbol2scm ("self-alignment-Y");
  82
  83   SCM align (me->internal_get_property (sym));
  84   if (scm_is_number (align))
  85     {
  86       Interval ext (me->extent (me, a));
  87       if (ext.is_empty ())
  88         programming_error ("can't align on self: empty element");
  89       else
  90         return scm_make_real (- ext.linear_combination (scm_to_double (align)));
  91     }
  92   return scm_make_real (0.0);
  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