Baby steps towards an odeon-like animation system. First victim: Drawer.

sky/sdk/lib/base/lerp.dart

Index: sky/sdk/lib/base/lerp.dart
diff --git a/sky/sdk/lib/base/lerp.dart b/sky/sdk/lib/base/lerp.dart
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index 0000000000000000000000000000000000000000..d354d45e075e9806389d8f00b8304e19e133be24
--- /dev/null
+++ b/sky/sdk/lib/base/lerp.dart
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+// 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 'dart:sky';
+
+num lerpNum(num a, num b, double t) => a + (b - a) * t;
+
+Color lerpColor(Color a, Color b, double t) =>
+  new Color.fromARGB(lerpNum(a.alpha, b.alpha, t).toInt(),
+                     lerpNum(a.red, b.red, t).toInt(),
+                     lerpNum(a.green, b.green, t).toInt(),
+                     lerpNum(a.blue, b.blue, t).toInt());
+
+Offset lerpOffset(Offset a, Offset b, double t) =>
+  new Offset(lerpNum(a.dx, b.dx, t),
+             lerpNum(a.dy, b.dy, t));