Python 0.9.1 as posted in alt.sources

1 files changed, 88 insertions, 0 deletions

diff --git a/lib/rect.py b/lib/rect.py
new file mode 100644
index 0000000..8f61e11
--- /dev/null
+++ b/lib/rect.py
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+# Module 'rect'.
+#
+# Operations on rectangles.
+# There is some normalization: all results return the object 'empty'
+# if their result would contain no points.
+
+
+# Exception.
+#
+error = 'rect.error'
+
+
+# The empty rectangle.
+#
+empty = (0, 0), (0, 0)
+
+
+# Check if a rectangle is empty.
+#
+def is_empty((left, top), (right, bottom)):
+ return left >= right or top >= bottom
+
+
+# Compute the intersection or two or more rectangles.
+# This works with a list or tuple argument.
+#
+def intersect(list):
+ if not list: raise error, 'intersect called with empty list'
+ if is_empty(list[0]): return empty
+ (left, top), (right, bottom) = list[0]
+ for rect in list[1:]:
+ if is_empty(rect):
+ return empty
+ (l, t), (r, b) = rect
+ if left < l: left = l
+ if top < t: top = t
+ if right > r: right = r
+ if bottom > b: bottom = b
+ if is_empty((left, top), (right, bottom)):
+ return empty
+ return (left, top), (right, bottom)
+
+
+# Compute the smallest rectangle containing all given rectangles.
+# This works with a list or tuple argument.
+#
+def union(list):
+ (left, top), (right, bottom) = empty
+ for (l, t), (r, b) in list[1:]:
+ if not is_empty((l, t), (r, b)):
+ if l < left: left = l
+ if t < top: top = t
+ if r > right: right = r
+ if b > bottom: bottom = b
+ res = (left, top), (right, bottom)
+ if is_empty(res):
+ return empty
+ return res
+
+
+# Check if a point is in a rectangle.
+#
+def pointinrect((h, v), ((left, top), (right, bottom))):
+ return left <= h < right and top <= v < bottom
+
+
+# Return a rectangle that is dh, dv inside another
+#
+def inset(((left, top), (right, bottom)), (dh, dv)):
+ left = left + dh
+ top = top + dv
+ right = right - dh
+ bottom = bottom - dv
+ r = (left, top), (right, bottom)
+ if is_empty(r):
+ return empty
+ else:
+ return r
+
+
+# Conversions between rectangles and 'geometry tuples',
+# given as origin (h, v) and dimensions (width, height).
+#
+def rect2geom((left, top), (right, bottom)):
+ return (left, top), (right-left, bottom-top)
+
+def geom2rect((h, v), (width, height)):
+ return (h, v), (h+width, v+height)