libgeda/src/m_box.c

   1 /* gEDA - GPL Electronic Design Automation
   2  * libgeda - gEDA's library
   3  * Copyright (C) 1998-2010 Ales Hvezda
   4  * Copyright (C) 1998-2010 gEDA Contributors (see ChangeLog for details)
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA
  19  */
  20
  21 /*! \file m_box.c
  22  *
  23  *  \brief Low-level mathmatical functions for boxes
  24  */
  25
  26 #include <config.h>
  27 #include <math.h>
  28 #include <stdio.h>
  29
  30 #include "libgeda_priv.h"
  31
  32 #ifdef HAVE_LIBDMALLOC
  33 #include <dmalloc.h>
  34 #endif
  35
  36
  37 /*! \brief Calculates the distance between the given point and the closest
  38  *  point on the perimeter or interior of the box.
  39  *
  40  *  \param [in] box    The box.
  41  *  \param [in] x      The x coordinate of the given point.
  42  *  \param [in] y      The y coordinate of the given point.
  43  *  \param [in] solid  TRUE if the box should be treated as solid, FALSE if
  44  *  the box should be treated as hollow.
  45  *  \return The shortest distance from the box to the point.  With a solid
  46  *  shape, this function returns a distance of zero for interior points.  With
  47  *  an invalid parameter, this function returns G_MAXDOUBLE.
  48  */
  49 double m_box_shortest_distance (BOX *box, int x, int y, int solid)
  50 {
  51   double shortest_distance;
  52   double x1, y1, x2, y2;
  53   double dx, dy;
  54
  55   g_return_val_if_fail (box != NULL, G_MAXDOUBLE);
  56
  57   x1 = (double) min (box->upper_x, box->lower_x);
  58   y1 = (double) min (box->upper_y, box->lower_y);
  59   x2 = (double) max (box->upper_x, box->lower_x);
  60   y2 = (double) max (box->upper_y, box->lower_y);
  61
  62   dx = min (((double)x) - x1, x2 - ((double)x));
  63   dy = min (((double)y) - y1, y2 - ((double)y));
  64
  65   if (solid) {
  66     dx = min (dx, 0);
  67     dy = min (dy, 0);
  68   }
  69
  70   if (dx < 0) {
  71     if (dy < 0) {
  72       shortest_distance = sqrt ((dx * dx) + (dy * dy));
  73     } else {
  74       shortest_distance = fabs (dx);
  75     }
  76   } else {
  77     if (dy < 0) {
  78       shortest_distance = fabs (dy);
  79     } else {
  80       shortest_distance = min (dx, dy);
  81     }
  82   }
  83
  84   return shortest_distance;
  85 }