RectTools.py

   1 #
   2 # vi: set softtabstop=4 shiftwidth=4 tabstop=8 expandtab:
   3
   4 class Rectangle(object):
   5     def __init__(self, x, y, w, h):
   6         self.x = x
   7         self.y = y
   8         self.width = w
   9         self.height = h
  10
  11     def __eq__(self, other):
  12         if self is other:
  13             return True
  14         if not isinstance(other, Rectangle):
  15             return False
  16         return (self.x == other.x and self.y == other.y
  17                 and self.width == other.width and self.height == other.height)
  18
  19     def __str__(self):
  20         return "(%d,%d) [%dx%d]" % (self.x, self.y, self.width, self.height)
  21
  22     def __repr__(self):
  23         return "Rectangle(%d,%d, %d,%d)" % (
  24                 self.x, self.y, self.width, self.height)
  25
  26
  27 class PolyRect(object):
  28     def __init__(self, rects):
  29         self.rects = rects
  30
  31     def area(self):
  32         return sum([a.width * a.height for a in self.rects])
  33
  34     def subtract(self, r):
  35         """Subtracts one rectangle from the list."""
  36         newrects = []
  37
  38         for i in self.rects:
  39             inter = intersection(i, r)
  40             if inter is None:
  41                 newrects.append(i)
  42             else:
  43                 # Create one rectangle above, one below, one left, one right.
  44                 if i.y < inter.y:
  45                     newrects.append(Rectangle(i.x, i.y, i.width, inter.y - i.y))
  46                 if i.y + i.height > inter.y + inter.height:
  47                     y = inter.y + inter.height
  48                     newrects.append(Rectangle(i.x, y,
  49                                               i.width, i.height - (y - i.y)))
  50                 if i.x < inter.x:
  51                     x = i.x
  52                     y = max(i.y, inter.y)
  53                     width = inter.x - i.x
  54                     height = min(i.y + i.height, inter.y + inter.height) - y
  55                     newrects.append(Rectangle(x, y, width, height))
  56
  57                 if i.x + i.width > inter.x + inter.width:
  58                     x = inter.x + inter.width
  59                     y = max(i.y, inter.y)
  60                     width = i.width - (x - i.x)
  61                     height = min(i.y + i.height, inter.y + inter.height) - y
  62                     newrects.append(Rectangle(x, y, width, height))
  63
  64         return PolyRect(newrects)
  65
  66 def intersection(r1, r2):
  67     x = max(r1.x, r2.x)
  68     width = min(r1.width - (x - r1.x), r2.width - (x - r2.x))
  69     y = max(r1.y, r2.y)
  70     height = min(r1.height - (y - r1.y), r2.height - (y - r2.y))
  71
  72     if width <= 0 or height <= 0:
  73         return None
  74     return Rectangle(x, y, width, height)