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# Copyright 2015 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Objects for convenient manipulation of points and other surface areas."""
import collections
class Point(collections.namedtuple('Point', ['x', 'y'])):
"""Object to represent an (x, y) point on a surface.
Args:
x, y: Two numeric coordinates that define the point.
"""
__slots__ = ()
def __str__(self):
"""Get a useful string representation of the object."""
return '(%s, %s)' % (self.x, self.y)
def __add__(self, other):
"""Sum of two points, e.g. p + q."""
if isinstance(other, Point):
return Point(self.x + other.x, self.y + other.y)
else:
return NotImplemented
def __mul__(self, factor):
"""Multiplication on the right is not implemented."""
# This overrides the default behaviour of a tuple multiplied by a constant
# on the right, which does not make sense for a Point.
return NotImplemented
def __rmul__(self, factor):
"""Multiply a point by a scalar factor on the left, e.g. 2 * p."""
return Point(factor * self.x, factor * self.y)
class Rectangle(
collections.namedtuple('Rectangle', ['top_left', 'bottom_right'])):
"""Object to represent a rectangle on a surface.
Args:
top_left: A pair of (left, top) coordinates. Might be given as a Point
or as a two-element sequence (list, tuple, etc.).
bottom_right: A pair (right, bottom) coordinates.
"""
__slots__ = ()
def __new__(cls, top_left, bottom_right):
if not isinstance(top_left, Point):
top_left = Point(*top_left)
if not isinstance(bottom_right, Point):
bottom_right = Point(*bottom_right)
return super(Rectangle, cls).__new__(cls, top_left, bottom_right)
def __str__(self):
"""Get a useful string representation of the object."""
return '[%s, %s]' % (self.top_left, self.bottom_right)
@property
def center(self):
"""Get the point at the center of the rectangle."""
return 0.5 * (self.top_left + self.bottom_right)
@classmethod
def FromDict(cls, d):
"""Create a rectangle object from a dictionary.
Args:
d: A dictionary (or mapping) of the form, e.g., {'top': 0, 'left': 0,
'bottom': 1, 'right': 1}.
"""
return cls(Point(d['left'], d['top']), Point(d['right'], d['bottom']))
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