16.3 Standard Module rect

This module contains useful operations on rectangles. A rectangle is defined as in module stdwin: a pair of points, where a point is a pair of integers. For example, the rectangle

(10, 20), (90, 80)

is a rectangle whose left, top, right and bottom edges are 10, 20, 90 and 80, respectively. Note that the positive vertical axis points down (as in stdwin).

The module defines the following objects:

error

The exception raised by functions in this module when they detect an error. The exception argument is a string describing the problem in more detail.

empty

The rectangle returned when some operations return an empty result. This makes it possible to quickly check whether a result is empty:

>>> import rect
>>> r1 = (10, 20), (90, 80)
>>> r2 = (0, 0), (10, 20)
>>> r3 = rect.intersect([r1, r2])
>>> if r3 is rect.empty: print 'Empty intersection'
Empty intersection
>>>

is_empty(r)

Returns true if the given rectangle is empty. A rectangle (left, top), (right, bottom) is empty if , left >= right or top => bottom. , or . ,

intersect(list)

Returns the intersection of all rectangles in the list argument. It may also be called with a tuple argument. Raises rect.error if the list is empty. Returns rect.empty if the intersection of the rectangles is empty.

union(list)

Returns the smallest rectangle that contains all non-empty rectangles in the list argument. It may also be called with a tuple argument or with two or more rectangles as arguments. Returns rect.empty if the list is empty or all its rectangles are empty.

pointinrect(point, rect)

Returns true if the point is inside the rectangle. By definition, a point (h, v) is inside a rectangle (left, top), (right, bottom) if , left <= h < right and top <= v < bottom. , and . ,

inset(rect, )

Returns a rectangle that lies inside the rect argument by dh pixels horizontally and dv pixels vertically. If dh or dv is negative, the result lies outside rect.

rect2geom(rect)

Converts a rectangle to geometry representation: (left, top), (width, height).

geom2rect(geom)

Converts a rectangle given in geometry representation back to the standard rectangle representation (left, top), (right, bottom).