Rationalize Dart mojo and sky package structure

sky/framework/animation/generators.dart

Index: sky/framework/animation/generators.dart
diff --git a/sky/framework/animation/generators.dart b/sky/framework/animation/generators.dart
deleted file mode 100644
index 7dab878a1b1ddf46b66a645b6768f679a6ce388f..0000000000000000000000000000000000000000
--- a/sky/framework/animation/generators.dart
+++ /dev/null
@@ -1,161 +0,0 @@
-// 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 'curves.dart';
-import 'dart:async';
-import 'dart:math' as math;
-import 'dart:sky' as sky;
-import 'mechanics.dart';
-
-abstract class Generator {
-  Stream<double> get onTick;
-  void cancel();
-}
-
-class FrameGenerator extends Generator {
-  Function onDone;
-  StreamController _controller;
-
-  Stream<double> get onTick => _controller.stream;
-
-  int _animationId = 0;
-  bool _cancelled = false;
-
-  FrameGenerator({this.onDone}) {
-    _controller = new StreamController(
-      sync: true,
-      onListen: _scheduleTick,
-      onCancel: cancel);
-  }
-
-  void cancel() {
-    if (_cancelled) {
-      return;
-    }
-    if (_animationId != 0) {
-      sky.window.cancelAnimationFrame(_animationId);
-    }
-    _animationId = 0;
-    _cancelled = true;
-    if (onDone != null) {
-      onDone();
-    }
-  }
-
-  void _scheduleTick() {
-    assert(_animationId == 0);
-    _animationId = sky.window.requestAnimationFrame(_tick);
-  }
-
-  void _tick(double timeStamp) {
-    _animationId = 0;
-    _controller.add(timeStamp);
-    if (!_cancelled) {
-      _scheduleTick();
-    }
-  }
-}
-
-class AnimationGenerator extends Generator {
-  Stream<double> get onTick => _stream;
-  final double initialDelay;
-  final double duration;
-  final double begin;
-  final double end;
-  final Curve curve;
-
-  FrameGenerator _generator;
-  Stream<double> _stream;
-  bool _done = false;
-  double _lastTime;
-
-  AnimationGenerator({
-    this.initialDelay: 0.0,
-    this.duration,
-    this.begin: 0.0,
-    this.end: 1.0,
-    this.curve: linear,
-    Function onDone
-  }) {
-    assert(curve != null);
-    assert(duration != null && duration > 0.0);
-    _generator = new FrameGenerator(onDone: onDone);
-
-    double startTime = 0.0;
-    _stream = _generator.onTick.map((timeStamp) {
-      if (startTime == 0.0)
-        startTime = timeStamp;
-
-      double t = (timeStamp - (startTime + initialDelay)) / duration;
-      _lastTime = math.max(0.0, math.min(t, 1.0));
-      return _lastTime;
-    })
-    .takeWhile(_checkForCompletion)
-    .where((t) => t >= 0.0)
-    .map(_transform);
-  }
-
-  double get remainingTime {
-    if (_lastTime == null)
-      return duration;
-    return duration - _lastTime;
-  }
-
-  void cancel() {
-    _generator.cancel();
-  }
-
-  double _transform(double t) {
-    if (_done)
-      return end;
-    return begin + (end - begin) * curve.transform(t);
-  }
-
-  // This is required because Dart Streams don't have takeUntil (inclusive).
-  bool _checkForCompletion(double t) {
-    if (_done)
-      return false;
-
-    _done = t >= 1;
-    return true;
-  }
-}
-
-class Simulation extends Generator {
-  Stream<double> get onTick => _stream;
-  final System system;
-
-  FrameGenerator _generator;
-  Stream<double> _stream;
-  double _previousTime = 0.0;
-
-  Simulation(this.system, {Function terminationCondition, Function onDone}) {
-    _generator = new FrameGenerator(onDone: onDone);
-    _stream = _generator.onTick.map(_update);
-
-    if (terminationCondition != null) {
-      bool done = false;
-      _stream = _stream.takeWhile((_) {
-        if (done)
-          return false;
-        done = terminationCondition();
-        return true;
-      });
-    }
-  }
-
-  void cancel() {
-    _generator.cancel();
-  }
-
-  double _update(double timeStamp) {
-    double previousTime = _previousTime;
-    _previousTime = timeStamp;
-    if (previousTime == 0.0)
-      return timeStamp;
-    double deltaT = timeStamp - previousTime;
-    system.update(deltaT);
-    return timeStamp;
-  }
-}