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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. /// /// Example: /// ```dart /// var leftTop = const Point(0, 0); /// var rightBottom = const Point(200, 400); /// ``` class Point { final T x; final T y; /// Creates a point with the provided [x] and [y] coordinates. const Point(T x, T y) : this.x = x, this.y = y; String toString() => 'Point(\$x, \$y)'; /// Whether [other] is a point with the same coordinates as this point. /// /// Returns `true` if [other] is a [Point] with [x] and [y] /// coordinates equal to the corresponding coordinates of this point, /// and `false` otherwise. /// /// Example: /// ```dart /// var result = const Point(0, 0) == const Point(0, 0); // true /// result = const Point(1.0, 0) == const Point(-1.0, 0); // false /// ``` bool operator ==(Object other) => other is Point && x == other.x && y == other.y; int get hashCode => SystemHash.hash2(x.hashCode, y.hashCode); /// Add [other] to `this`, as if both points were vectors. /// /// Returns the resulting "vector" as a Point. /// /// Example: /// ```dart /// var point = const Point(10, 100) + const Point(10, 10); // Point(20, 110) /// point = const Point(-10, -20) + const Point(10, 100); // Point(0, 80) /// ``` Point operator +(Point other) { return Point((x + other.x) as T, (y + other.y) as T); } /// Subtract [other] from `this`, as if both points were vectors. /// /// Returns the resulting "vector" as a Point. /// /// Example: /// ```dart /// var point = const Point(10, 100) - const Point(10, 10); // Point(0, 90) /// point = const Point(-10, -20) - const Point(10, 100); // Point(-110, -120) /// ``` Point operator -(Point other) { return Point((x - other.x) as T, (y - other.y) as T); } /// Scale this point by [factor] as if it were a vector. /// /// **Important Note**: This function accepts a `num` as its argument only so /// that you can scale `Point` objects by an `int` factor. Because the /// `*` operator always returns the same type of `Point` as it is called on, /// passing in a double [factor] on a `Point` _causes_ _a_ /// _runtime_ _error_. /// /// Example: /// ```dart /// // Integer values. /// var point = const Point(10, 100) * 10; // Point(100, 1000) /// point = const Point(-10, -100) * 5; // Point(-50, -500) /// // Double values. /// var doublePoint = Point(10.0, 100.0) * 1.5; // Point(15.0, 150.0) /// // Runtime error due the invalid type cast. /// var newPoint = const Point(10, 100) * 1.5; // Throws. /// ``` Point operator *(num /*T|int*/ factor) { return Point((x * factor) as T, (y * factor) as T); } /// Get the straight line (Euclidean) distance between the origin (0, 0) and /// this point. /// /// Example: /// ```dart /// var magnitude = const Point(0, 0).magnitude; // 0.0 /// magnitude = const Point(10, 0).magnitude; // 10.0 /// magnitude = const Point(0, -10).magnitude; // 10.0 /// magnitude = const Point(10, 10).magnitude; // 14.142135623730951 /// ``` double get magnitude => sqrt(x * x + y * y); /// Returns the distance between `this` and [other]. /// ```dart /// var distanceTo = const Point(0, 0).distanceTo(const Point(0, 0)); // 0.0 /// distanceTo = const Point(0, 0).distanceTo(const Point(10, 0)); // 10.0 /// distanceTo = const Point(0, 0).distanceTo(const Point(0, -10)); // 10.0 /// distanceTo = const Point(-10, 0).distanceTo(const Point(100, 0)); // 110.0 /// ``` double distanceTo(Point 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. /// /// Example: /// ```dart /// var squaredDistance = /// const Point(0, 0).squaredDistanceTo(const Point(0, 0)); // 0.0 /// squaredDistance = /// const Point(0, 0).squaredDistanceTo(const Point(10, 0)); // 100 /// squaredDistance = /// const Point(0, 0).squaredDistanceTo(const Point(0, -10)); // 100 /// squaredDistance = /// const Point(-10, 0).squaredDistanceTo(const Point(100, 0)); // 12100 /// ``` T squaredDistanceTo(Point other) { var dx = x - other.x; var dy = y - other.y; return (dx * dx + dy * dy) as T; } }