Index: sdk/lib/math/point.dart |
diff --git a/sdk/lib/math/point.dart b/sdk/lib/math/point.dart |
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+// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
+// for details. All rights reserved. Use of this source code is governed by a |
+// BSD-style license that can be found in the LICENSE file. |
+part of dart.math; |
+ |
+/** |
+ * A utility class for representing two-dimensional positions. |
+ */ |
+class Point<T extends num> { |
+ final T x; |
+ final T y; |
+ |
+ const Point([T x = 0, T y = 0]): this.x = x, this.y = y; |
+ |
+ String toString() => 'Point($x, $y)'; |
+ |
+ bool operator ==(other) { |
+ if (other is !Point) return false; |
+ return x == other.x && y == other.y; |
+ } |
+ |
+ int get hashCode => _JenkinsSmiHash.hash2(x.hashCode, y.hashCode); |
+ |
+ /** |
+ * Add [other] to `this`, as if both points were vectors. |
+ * |
+ * Returns the resulting "vector" as a Point. |
+ */ |
+ Point<T> operator +(Point<T> other) { |
+ return new Point<T>(x + other.x, y + other.y); |
+ } |
+ |
+ /** |
+ * Subtract [other] from `this`, as if both points were vectors. |
+ * |
+ * Returns the resulting "vector" as a Point. |
+ */ |
+ Point<T> operator -(Point<T> other) { |
+ return new Point<T>(x - other.x, y - other.y); |
+ } |
+ |
+ /** |
+ * Scale this point by [factor] as if it was a vector. |
+ * |
+ * *Important* *Note*: This function accepts a `num` as its argument only so |
+ * that you can scale Point<double> objects by an `int` factor. Because the |
+ * star operator always returns the same type of Point that originally called |
+ * it, passing in a double [factor] on a `Point<int>` _causes_ _a_ |
+ * _runtime_ _error_ in checked mode. |
+ */ |
+ Point<T> operator *(num factor) { |
+ return new Point<T>(x * factor, y * factor); |
+ } |
+ |
+ /** |
+ * Get the straight line (Euclidean) distance between the origin (0, 0) and |
+ * this point. |
+ */ |
+ double get magnitude => sqrt(x * x + y * y); |
+ |
+ /** |
+ * Returns the distance between `this` and [other]. |
+ */ |
+ double distanceTo(Point<T> other) { |
+ var dx = x - other.x; |
+ var dy = y - other.y; |
+ return sqrt(dx * dx + dy * dy); |
+ } |
+ |
+ /** |
+ * Returns the squared distance between `this` and [other]. |
+ * |
+ * Squared distances can be used for comparisons when the actual value is not |
+ * required. |
+ */ |
+ T squaredDistanceTo(Point<T> other) { |
+ var dx = x - other.x; |
+ var dy = y - other.y; |
+ return dx * dx + dy * dy; |
+ } |
+} |