Adding Point & Rect primitives

tools/dom/src/Point.dart

+// 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 html;
+
+/// A utility class for representing two-dimensional positions.

[Jennifer Messerly, 2013/03/05 02:35:21]

just curious, why /// here but /** */ below?
(i don't care either way, just noticed it :) )

[blois, 2013/03/05 21:43:33]

No reason, changed.

+class Point {
+  final num x;
+  final num y;
+
+  Point([num x = 0, num y = 0]): x = x, y = y;

[Jennifer Messerly, 2013/03/05 02:35:21]

this could be "const" to allow construction of const points

[blois, 2013/03/05 21:43:33]

Done.

+
+  String toString() {

[Jennifer Messerly, 2013/03/05 02:35:21]

both are valid, but sometimes I like using inline style for this:

    String toString() => '($x, $y)';

[blois, 2013/03/05 21:43:33]

Done.

+    return '($x, $y)';
+  }
+
+  bool operator ==(other) {
+    if (other is !Point) return false;
+    return x == other.x && y == other.y;
+  }
+
+  Point operator +(Point other) {
+    return new Point(x + other.x, y + other.y);
+  }
+
+  Point operator -(Point other) {
+    return new Point(x - other.x, y - other.y);
+  }
+
+  Point operator *(num factor) {
+    return new Point(x * factor, y * factor);
+  }
+
+  /**
+   * Returns the distance between two points.
+   */
+  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 two points.
+   *
+   * Squared distances can be used for comparisons when the actual value is not
+   * required.
+   */
+  num squaredDistanceTo(Point other) {
+    var dx = x - other.x;
+    var dy = y - other.y;
+    return dx * dx + dy * dy;
+  }
+
+  Point ceil() => new Point(x.ceil(), y.ceil());
+  Point floor() => new Point(x.floor(), y.floor());
+  Point round() => new Point(x.round(), y.round());
+
+  /**
+   * Truncates x and y to integers and returns the result as a new point.
+   */
+  Point toInt() => new Point(x.toInt(), y.toInt());
+}