Adding more methods to Position and PositionComponent, and also more tests.

lib/components/component.dart

@@ -29,6 +29,26 @@ abstract class PositionComponent extends Component {
   double x = 0.0, y = 0.0, angle = 0.0;
   double width = 0.0, height = 0.0;
 
+  Position get position => new Position(x, y);
+  void set position(Position position) {
+    this.x = position.x;
+    this.y = position.y;
+  }
+
+  Position get size => new Position(width, height);
+  void set size(Position size) {
+    this.width = size.x;
+    this.height = size.y;
+  }
+
+  Rect get rect => new Rect.fromLTWH(x, y, width, height);
+  void set rect(Rect rect) {
+    this.x = rect.left;
+    this.y = rect.top;
+    this.width = rect.width;
+    this.height = rect.height;
+  }
+
   double angleBetween(PositionComponent c) {
     return (atan2(c.x - this.x, this.y - c.y) - PI / 2) % (2 * PI);
   }
@@ -45,14 +65,6 @@ abstract class PositionComponent extends Component {
     canvas.rotate(angle);
     canvas.translate(-width/2, -height/2);
   }
-
-  Position toPosition() {
-    return new Position(x, y);
-  }
-
-  Rect toRect() {
-    return new Rect.fromLTWH(x, y, width, height);
-  }
 }
 
 class SpriteComponent extends PositionComponent {

lib/position.dart

@@ -41,6 +41,10 @@ class Position {
     return this;
   }
 
+  double dotProduct(Position p) {
+    return this.x * p.x + this.y * p.y;
+  }
+
   double length() {
     return math.sqrt(math.pow(this.x, 2) + math.pow(this.y, 2));
   }
@@ -73,4 +77,8 @@ class Position {
   String toString() {
     return "($x, $y)";
   }
+
+  static ui.Rect rectFrom(Position topLeft, Position size) {
+    return new ui.Rect.fromLTWH(topLeft.x, topLeft.y, size.x, size.y);
+  }
 }

test/component_test.dart

@@ -0,0 +1,51 @@
+import 'package:test/test.dart';
+import 'dart:ui';
+
+import 'package:flame/components/component.dart';
+import 'package:flame/position.dart';
+
+void main() {
+  group('component test', () {
+    test('test get/set x/y or position', () {
+      PositionComponent c = new SpriteComponent();
+      c.x = 2.2;
+      c.y = 3.4;
+      expect(c.position.x, 2.2);
+      expect(c.position.y, 3.4);
+
+      c.position = new Position(1.0, 0.0);
+      expect(c.x, 1.0);
+      expect(c.y, 0.0);
+    });
+
+    test('test get/set widt/height or size', () {
+      PositionComponent c = new SpriteComponent();
+      c.width = 2.2;
+      c.height = 3.4;
+      expect(c.size.x, 2.2);
+      expect(c.size.y, 3.4);
+
+      c.size = new Position(1.0, 0.0);
+      expect(c.width, 1.0);
+      expect(c.height, 0.0);
+    });
+
+    test('test get/set rect', () {
+      PositionComponent c = new SpriteComponent();
+      c.x = 0.0;
+      c.y = 1.0;
+      c.width = 2.0;
+      c.height = 2.0;
+      expect(c.rect.left, 0.0);
+      expect(c.rect.top, 1.0);
+      expect(c.rect.width, 2.0);
+      expect(c.rect.height, 2.0);
+
+      c.rect = new Rect.fromLTWH(10.0, 10.0, 1.0, 1.0);
+      expect(c.x, 10.0);
+      expect(c.y, 10.0);
+      expect(c.width, 1.0);
+      expect(c.height, 1.0);
+    });
+  });
+}

test/position_test.dart

@@ -1,15 +1,40 @@
 import 'package:test/test.dart';
+import 'dart:math' as math;
 
 import 'package:flame/position.dart';
 
+void expectDouble(double d1, double d2) {
+  expect((d1 - d2).abs() <= 0.0001, true);
+}
+
 void main() {
   group('position test', () {
     test('test add', () {
       Position p = new Position(0.0, 5.0);
       Position p2 = p.add(new Position(5.0, 5.0));
       expect(p, p2);
-      expect(p.x, 5.0);
-      expect(p.y, 10.0);
+      expectDouble(p.x, 5.0);
+      expectDouble(p.y, 10.0);
+    });
+
+    test('test clone', () {
+      Position p = new Position(1.0, 0.0);
+      Position clone = p.clone();
+
+      clone.times(2.0);
+      expectDouble(p.x, 1.0);
+      expectDouble(clone.x, 2.0);
+    });
+
+    test('test rotate', () {
+      Position p = new Position(1.0, 0.0).rotate(math.PI / 2);
+      expectDouble(p.x, 0.0);
+      expectDouble(p.y, 1.0);
+    });
+
+    test('test length', () {
+      Position p = new Position(3.0, 4.0);
+      expectDouble(p.length(), 5.0);
     });
   });
 }