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