| # 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'])) |