src/clip.c

   1 /*!
   2  * \file src/clip.c
   3  *
   4  * \brief Functions for inserting points into objects.
   5  *
   6  * <hr>
   7  *
   8  * <h1><b>Copyright.</b></h1>\n
   9  *
  10  * PCB, interactive printed circuit board design
  11  *
  12  * Copyright (C) 1994,1995,1996 Thomas Nau
  13  *
  14  * Copyright (C) 2004 harry eaton
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful,
  22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  * GNU General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with this program; if not, write to the Free Software
  28  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  29  *
  30  * Contact addresses for paper mail and Email:
  31  * Thomas Nau, Schlehenweg 15, 88471 Baustetten, Germany
  32  * Thomas.Nau@rz.uni-ulm.de
  33  */
  34
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include "config.h"
  38 #endif
  39
  40 #include <assert.h>
  41 #include <math.h>
  42 #include <stdlib.h>
  43
  44 #include "global.h"
  45 #include "data.h"
  46 #include "draw.h"
  47 #include "mymem.h"
  48
  49 #ifdef HAVE_LIBDMALLOC
  50 #include <dmalloc.h>
  51 #endif
  52
  53 /*!
  54  * \brief Clip the line to the clipBox.
  55  *
  56  * Clip X,Y to the given bounding box, plus a margin.
  57  *
  58  * \return true if something to be drawn, false if the whole thing is
  59  * clipped.
  60  */
  61 bool
  62 ClipLine (double minx, double miny, double maxx, double maxy,
  63           double *x1, double *y1,
  64           double *x2, double *y2,
  65           double margin)
  66 {
  67   double d, r;
  68
  69   minx -= margin;
  70   miny -= margin;
  71   maxx += margin;
  72   maxy += margin;
  73
  74   /* clip first point on left side */
  75   if (*x1 < minx)
  76     {
  77       if (*x2 < minx)
  78         return false;
  79       d = *x2 - *x1;
  80       r = (minx - *x1) / d;
  81       *x1 = minx;
  82       *y1 += r * (*y2 - *y1);
  83     }
  84   /* clip second point on left side */
  85   if (*x2 < minx)
  86     {
  87       d = *x1 - *x2;
  88       r = (minx - *x2) / d;
  89       *x2 = minx;
  90       *y2 += r * (*y1 - *y2);
  91     }
  92   /* clip first point on right side */
  93   if (*x1 > maxx)
  94     {
  95       if (*x2 > maxx)
  96         return false;
  97       d = *x2 - *x1;
  98       r = (maxx - *x1) / d;
  99       *x1 = maxx;
 100       *y1 += r * (*y2 - *y1);
 101     }
 102   /* clip second point on right side */
 103   if (*x2 > maxx)
 104     {
 105       d = *x1 - *x2;
 106       r = (maxx - *x2) / d;
 107       *x2 = maxx;
 108       *y2 += r * (*y1 - *y2);
 109     }
 110
 111   /* clip first point on top */
 112   if (*y1 < miny)
 113     {
 114       if (*y2 < miny)
 115         return false;
 116       d = *y2 - *y1;
 117       r = (miny - *y1) / d;
 118       *y1 = miny;
 119       *x1 += r * (*x2 - *x1);
 120     }
 121   /* clip second point on top */
 122   if (*y2 < miny)
 123     {
 124       d = *y1 - *y2;
 125       r = (miny - *y2) / d;
 126       *y2 = miny;
 127       *x2 += r * (*x1 - *x2);
 128     }
 129   /* clip first point on bottom */
 130   if (*y1 > maxy)
 131     {
 132       if (*y2 > maxy)
 133         return false;
 134       d = *y2 - *y1;
 135       r = (maxy - *y1) / d;
 136       *y1 = maxy;
 137       *x1 += r * (*x2 - *x1);
 138     }
 139   /* clip second point on top */
 140   if (*y2 > maxy)
 141     {
 142       d = *y1 - *y2;
 143       r = (maxy - *y2) / d;
 144       *y2 = maxy;
 145       *x2 += r * (*x1 - *x2);
 146     }
 147   return true;
 148 }