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 # TODO: - shouldn't we rename bbox.transform to bbox.transformed? (AW, 23.1.03)
  24 #       - it would be nice to have a real bbox.transform (AW, 23.1.03)
  25
  26 import unit
  27
  28 # helper routine for bbox manipulations
  29
  30 def _nmin(x, y):
  31     """minimum of two values, where None represents +infinity, not -infinity as
  32     in standard min implementation of python"""
  33     if x is None: return y
  34     if y is None: return x
  35     return min(x,y)
  36
  37 #
  38 # class representing bounding boxes
  39 #
  40
  41 class bbox:
  42
  43     """class for bounding boxes"""
  44
  45     def __init__(self, llx=None, lly=None, urx=None, ury=None):
  46         self.llx=llx
  47         self.lly=lly
  48         self.urx=urx
  49         self.ury=ury
  50
  51     def __add__(self, other):
  52         """join two bboxes"""
  53
  54         return bbox(_nmin(self.llx, other.llx), _nmin(self.lly, other.lly),
  55                     max(self.urx, other.urx), max(self.ury, other.ury))
  56
  57     def __mul__(self, other):
  58         """return intersection of two bboxes"""
  59
  60         return bbox(max(self.llx, other.llx), max(self.lly, other.lly),
  61                     _nmin(self.urx, other.urx), _nmin(self.ury, other.ury))
  62
  63     def __str__(self):
  64         return "%s %s %s %s" % (self.llx, self.lly, self.urx, self.ury)
  65
  66     def write(self, file):
  67         file.write("%%%%BoundingBox: %d %d %d %d\n" %
  68                    (self.llx, self.lly, self.urx, self.ury))
  69         # TODO: add HighResBBox
  70
  71     def intersects(self, other):
  72         """check, if two bboxes intersect eachother"""
  73
  74         return not (self.llx > other.urx or
  75                     self.lly > other.ury or
  76                     self.urx < other.llx or
  77                     self.ury < other.lly)
  78
  79     def transform(self, trafo):
  80         """return bbox transformed by trafo"""
  81         # we have to transform all four corner points of the bbox
  82         (llx, lly)=trafo._apply(self.llx, self.lly)
  83         (lrx, lry)=trafo._apply(self.urx, self.lly)
  84         (urx, ury)=trafo._apply(self.urx, self.ury)
  85         (ulx, uly)=trafo._apply(self.llx, self.ury)
  86
  87         # now, by sorting, we obtain the lower left and upper right corner
  88         # of the new bounding box.
  89
  90         return bbox(min(llx, lrx, urx, ulx), min(lly, lry, ury, uly),
  91                     max(llx, lrx, urx, ulx), max(lly, lry, ury, uly))
  92
  93     def enhance(self, size):
  94         """return bbox enhanced in all directions by size"""
  95         size = unit.topt(unit.length(size, default_type="v"))
  96         return bbox(self.llx-size, self.lly-size,
  97                     self.urx+size, self.ury+size)
  98
  99     def rect(self):
 100         """return rectangle corresponding to bbox"""
 101         import path
 102         return path._rect(self.llx, self.lly, self.urx-self.llx, self.ury-self.lly)