Add sky-drawer to the framework

sky/framework/animation/controller.sky

Index: sky/framework/animation/controller.sky
diff --git a/sky/framework/animation/controller.sky b/sky/framework/animation/controller.sky
new file mode 100644
index 0000000000000000000000000000000000000000..752a3f4070462399f5d3f8d209ec05346cdd30e3
--- /dev/null
+++ b/sky/framework/animation/controller.sky
@@ -0,0 +1,46 @@
+<!--
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+-->
+<import src="timer.sky" as="Timer" />
+<script>
+module.exports = class Controller {

[esprehn, 2015/01/29 19:03:57]

AnimationController ? It'll print nicer in the console since module names aren't
bound to the class.

[abarth-chromium, 2015/01/29 19:16:45]

Sure!

+  constructor(delegate) {
+    this.delegate_ = delegate;
+    this.timer_ = new Timer(this);
+    this.begin_ = 0;
+    this.end_ = 0;
+    this.curve_ = null;
+    this.isAnimating = false;
+    Object.preventExtensions(this);
+  }
+
+  start(options) {
+    this.begin_ = options.begin;
+    this.end_ = options.end;
+    this.curve_ = options.curve;
+    this.isAnimating = true;
+    this.timer_.start(options.duration);
+  }
+
+  stop() {
+    this.isAnimating = false;
+    this.timer_.stop();
+  }
+
+  positionForTime_(t) {
+    // Explicitly finish animations at |this.end_| in case the curve isn't an
+    // exact numerical transform.
+    if (t == 1)
+      return this.end_;
+    var curvedTime = this.curve_.transform(t);
+    var begin = this.begin_;
+    return begin + (this.end_ - begin) * curvedTime;
+  }
+
+  updateAnimation(t) {
+    this.delegate_.updateAnimation(this.positionForTime_(t));
+  }
+};
+</script>