pyx/bbox.py

   1 #!/usr/bin/env python
   2 #
   3 #
   4 # Copyright (C) 2002 Jörg Lehmann <joergl@users.sourceforge.net>
   5 # Copyright (C) 2002 André Wobst <wobsta@users.sourceforge.net>
   6 #
   7 # This file is part of PyX (http://pyx.sourceforge.net/).
   8 #
   9 # PyX is free software; you can redistribute it and/or modify
  10 # it under the terms of the GNU General Public License as published by
  11 # the Free Software Foundation; either version 2 of the License, or
  12 # (at your option) any later version.
  13 #
  14 # PyX is distributed in the hope that it will be useful,
  15 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 # GNU General Public License for more details.
  18 #
  19 # You should have received a copy of the GNU General Public License
  20 # along with PyX; if not, write to the Free Software
  21 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22
  23 import unit
  24
  25 # helper routine for bbox manipulations
  26
  27 def _nmin(x, y):
  28     """minimum of two values, where None represents +infinity, not -infinity as
  29     in standard min implementation of python"""
  30     if x is None: return y
  31     if y is None: return x
  32     return min(x,y)
  33
  34 #
  35 # class representing bounding boxes
  36 #
  37
  38 class bbox:
  39
  40     """class for bounding boxes"""
  41
  42     def __init__(self, llx=None, lly=None, urx=None, ury=None):
  43         self.llx=llx
  44         self.lly=lly
  45         self.urx=urx
  46         self.ury=ury
  47
  48     def __add__(self, other):
  49         """join two bboxes"""
  50
  51         return bbox(_nmin(self.llx, other.llx), _nmin(self.lly, other.lly),
  52                     max(self.urx, other.urx), max(self.ury, other.ury))
  53
  54     def __mul__(self, other):
  55         """return intersection of two bboxes"""
  56
  57         return bbox(max(self.llx, other.llx), max(self.lly, other.lly),
  58                     _nmin(self.urx, other.urx), _nmin(self.ury, other.ury))
  59
  60     def __str__(self):
  61         return "%s %s %s %s" % (self.llx, self.lly, self.urx, self.ury)
  62
  63     def write(self, file):
  64         file.write("%%%%BoundingBox: %d %d %d %d\n" %
  65                    (self.llx, self.lly, self.urx, self.ury))
  66         # TODO: add HighResBBox
  67
  68     def intersects(self, other):
  69         """check, if two bboxes intersect eachother"""
  70
  71         return not (self.llx > other.urx or
  72                     self.lly > other.ury or
  73                     self.urx < other.llx or
  74                     self.ury < other.lly)
  75
  76     def transform(self, trafo):
  77         """return bbox transformed by trafo"""
  78         # we have to transform all four corner points of the bbox
  79         (llx, lly)=trafo._apply(self.llx, self.lly)
  80         (lrx, lry)=trafo._apply(self.urx, self.lly)
  81         (urx, ury)=trafo._apply(self.urx, self.ury)
  82         (ulx, uly)=trafo._apply(self.llx, self.ury)
  83
  84         # now, by sorting, we obtain the lower left and upper right corner
  85         # of the new bounding box.
  86
  87         return bbox(min(llx, lrx, urx, ulx), min(lly, lry, ury, uly),
  88                     max(llx, lrx, urx, ulx), max(lly, lry, ury, uly))
  89
  90     def enhance(self, size):
  91         """return bbox enhanced in all directions by size"""
  92         size = unit.topt(unit.length(size, default_type="v"))
  93         return bbox(self.llx-size, self.lly-size,
  94                     self.urx+size, self.ury+size)
  95
  96     def rect(self):
  97         """return rectangle corresponding to bbox"""
  98         import path
  99         return path._rect(self.llx, self.lly, self.urx-self.llx, self.ury-self.lly)