Move Point and Rect over to dart:math, to be re-exported by dart:html.

sdk/lib/math/rectangle.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 dart.math;
+
+/**
+ * A base class for representing two-dimensional axis-aligned rectangles.
+ */
+abstract class RectangleBase<T extends num> {

[Ivan Posva, 2013/10/08 17:28:44]

Why is this RectangleBase class exported? Do you expect other subclasses?

+  // Not used, but keeps the VM from complaining about Rectangle having a const

[floitsch, 2013/10/02 08:54:09]

Remove comment. As a base class the const constructor is used from sub-classes.

[Emily Fortuna, 2013/10/02 18:32:40]

Oops, that was left over from when I was using this class as a mixin.

+  // constructor and this one not.
+  const RectangleBase();
+
+  /**
+   * The number of units `left` of the origin where this rectangle's top left

[floitsch, 2013/10/02 08:54:09]

The x-coordinate of the upper-left corner.
or
The x-coordinate of the left edge.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   * corner can be found.
+   */
+  T get left;
+  /**
+   * The number of units from the `top` origin point where this rectangle's top

[floitsch, 2013/10/02 08:54:09]

The y-coordinate of the upper left corner.
or
The y-coordinate of the top edge.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   * left corner can be found.
+   */
+  T get top;
+  /** The `width` of the rectangle. */
+  T get width;
+  /** The `height` of the rectangle. */
+  T get height;
+
+  /**
+   * The number of units `right` of the origin where this rectangle's bottom
+   * right corner can be found.
+   */
+  T get right => left + width;
+  /**
+   * The number of units below the origin where this rectangle's bottom
+   * right corner can be found.
+   */
+  T get bottom => top + height;
+
+  String toString() {
+    return '($left, $top, $width, $height)';

[floitsch, 2013/10/02 08:54:09]

We are using "( ... )" to write iterables now.
I'm ok with the notation, but would prefer another one.
Also: when reading (1, 2, 3, 4) I would never guess, that 3 and 4 are the width
and height.

[Emily Fortuna, 2013/10/02 18:32:40]

Adjusted. Let me know if you'd like further change.

+  }
+
+  bool operator ==(other) {
+    if (other is !Rectangle) return false;
+    return left == other.left && top == other.top && width == other.width &&
+        height == other.height;
+  }
+
+  int get hashCode => _JenkinsSmiHash.hash4(left.hashCode, top.hashCode,
+      width.hashCode, height.hashCode);
+
+  /**
+   * Computes the intersection of this rectangle and the rectangle parameter.

[floitsch, 2013/10/02 08:54:09]

`this` and [other].

I tend to avoid repeating the type of `this`, so that the documentation works
also for sub-classes.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   * Returns null if there is no intersection.

[floitsch, 2013/10/02 08:54:09]

New line before.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   */
+  Rectangle<T> intersection(Rectangle<T> rect) {
+    var x0 = max(left, rect.left);
+    var x1 = min(left + width, rect.left + rect.width);
+
+    if (x0 <= x1) {
+      var y0 = max(top, rect.top);
+      var y1 = min(top + height, rect.top + rect.height);
+
+      if (y0 <= y1) {
+        return new Rectangle<T>(x0, y0, x1 - x0, y1 - y0);
+      }
+    }
+    return null;
+  }
+
+
+  /**
+   * Returns whether a rectangle intersects this rectangle.

[floitsch, 2013/10/02 08:54:09]

Returns `true` if `this` intersects (with?) [other].

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   */
+  bool intersects(Rectangle other) {
+    return (left <= other.left + other.width && other.left <= left + width &&
+        top <= other.top + other.height && other.top <= top + height);
+  }
+
+  /**
+   * Returns a new rectangle which completely contains this rectangle and the

[floitsch, 2013/10/02 08:54:09]

ditto (`this` [other])

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+   * input rectangle.
+   */
+  Rectangle<T> union(Rectangle<T> rect) {
+    var right = max(this.left + this.width, rect.left + rect.width);
+    var bottom = max(this.top + this.height, rect.top + rect.height);
+
+    var left = min(this.left, rect.left);
+    var top = min(this.top, rect.top);
+
+    return new Rectangle<T>(left, top, right - left, bottom - top);
+  }
+
+  /**
+   * Tests whether this rectangle entirely contains another rectangle.
+   */
+  bool contains(Rectangle another) {
+    return left <= another.left &&
+           left + width >= another.left + another.width &&
+           top <= another.top &&
+           top + height >= another.top + another.height;
+  }
+
+  /**
+   * Tests whether this rectangle entirely contains a point.

[floitsch, 2013/10/02 08:54:09]

-entirely-

+   */
+  bool containsPoint(Point another) {
+    return another.x >= left &&
+           another.x <= left + width &&
+           another.y >= top &&
+           another.y <= top + height;
+  }
+
+  Rectangle<T> ceil() => new Rectangle<T>(left.ceil(), top.ceil(), width.ceil(),

[floitsch, 2013/10/02 08:54:09]

same as for Point: This must return a Rectangle<int>.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+      height.ceil());
+  Rectangle<T> floor() => new Rectangle<T>(left.floor(), top.floor(),
+      width.floor(), height.floor());
+  Rectangle<T> round() => new Rectangle<T>(left.round(), top.round(),
+      width.round(), height.round());
+
+  /**
+   * Truncates coordinates to integers and returns the result as a new
+   * rectangle.
+   */
+  Rectangle<int> truncate() => new Rectangle<int>(left.toInt(), top.toInt(),
+      width.toInt(), height.toInt());
+
+  Point<T> get topLeft => new Point<T>(this.left, this.top);
+  Point<T> get bottomRight => new Point<T>(this.left + this.width,
+      this.top + this.height);
+
+  static List<T> _calculateVerticesFromPoints(Point<T> a, Point<T> b) {
+    var tempLeft;

[floitsch, 2013/10/02 08:54:09]

Remove "temp" prefixes in the function.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+    var tempWidth;
+    if (a.x < b.x) {
+      tempLeft = a.x;
+      tempWidth = b.x - tempLeft;
+    } else {
+      tempLeft = b.x;
+      tempWidth = a.x - tempLeft;
+    }
+    var tempTop;
+    var tempHeight;
+    if (a.y < b.y) {
+      tempTop = a.y;
+      tempHeight = b.y - tempTop;
+    } else {
+      tempTop = b.y;
+      tempHeight = a.y - tempTop;
+    }
+    return [tempLeft, tempTop, tempWidth, tempHeight];
+  }
+}
+
+
+/**
+ * A class for representing two-dimensional rectangles.
+ *
+ * This class is distinctive from RectangleBase in that it enforces that its

[floitsch, 2013/10/02 08:54:09]

This sentence isn't true: The RectangleBase only exposes getters. So this class
has the same interface as the Base.

[Emily Fortuna, 2013/10/02 18:32:40]

Done.

+ * properties are immutable.
+ */
+class Rectangle<T> extends RectangleBase<T> {
+  final T left;
+  final T top;
+  final T width;
+  final T height;
+
+  const Rectangle(this.left, this.top, this.width, this.height);
+
+  factory Rectangle.fromPoints(Point<T> a, Point<T> b) {
+    var list = RectangleBase._calculateVerticesFromPoints(a, b);
+    return new Rectangle<T>(list[0], list[1], list[2], list[3]);
+  }
+}
+
+/**
+ * A class for representing two-dimensional axis-aligned rectangles with mutable
+ * properties.
+ */
+class MutableRectangle<T>  extends RectangleBase<T> implements Rectangle<T> {

[floitsch, 2013/10/02 08:54:09]

Unless used and needed, I would prefer not to have this class.

[Emily Fortuna, 2013/10/02 18:32:40]

Removed.

+  T left;
+  T top;
+  T width;
+  T height;
+
+  MutableRectangle(this.left, this.top, this.width, this.height);
+
+  factory MutableRectangle.fromPoints(Point<T> a, Point<T> b) {
+    var list = RectangleBase._calculateVerticesFromPoints(a, b);
+    return new MutableRectangle<T>(list[0], list[1], list[2], list[3]);
+  }
+}