Organize sky/framework/animation

sky/framework/animation/generators.dart

 // 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;
 
-class FrameGenerator {
+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(
@@ skipping 23 matching lines @@
 
   void _tick(double timeStamp) {
     _animationId = 0;
     _controller.add(timeStamp);
     if (!_cancelled) {
       _scheduleTick();
     }
   }
 }
 
-class AnimationGenerator {
+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;
@@ skipping 35 matching lines @@
   // 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 Animation {
-  Stream<double> get onValueChanged => _controller.stream;
+class Simulation extends Generator {
+  Stream<double> get onTick => _stream;
+  final System system;
 
-  double get value => _value;
+  FrameGenerator _generator;
+  Stream<double> _stream;
+  double _previousTime = 0.0;
 
-  void set value(double value) {
-    stop();
-   _setValue(value);
-  }
+  Simulation(this.system, {Function terminationCondition, Function onDone}) {
+    _generator = new FrameGenerator(onDone: onDone);
+    _stream = _generator.onTick.map(_update);
 
-  bool get isAnimating => _animation != null;
-
-  StreamController _controller = new StreamController(sync: true);
-
-  AnimationGenerator _animation;
-
-  double _value;
-
-  void _setValue(double value) {
-    _value = value;
-    _controller.add(_value);
-  }
-
-  void stop() {
-    if (_animation != null) {
-      _animation.cancel();
-      _animation = null;
+    if (terminationCondition != null) {
+      bool done = false;
+      _stream = _stream.takeWhile((_) {
+        if (done)
+          return false;
+        done = terminationCondition();
+        return true;
+      });
     }
   }
 
-  void animateTo(double newValue, double duration,
-      { Curve curve: linear, double initialDelay: 0.0 }) {
-    stop();
+  void cancel() {
+    _generator.cancel();
+  }
 
-    _animation = new AnimationGenerator(
-        duration: duration,
-        begin: _value,
-        end: newValue,
-        curve: curve,
-        initialDelay: initialDelay);
-
-    _animation.onTick.listen(_setValue, onDone: () {
-      _animation = null;
-    });
+  double _update(double timeStamp) {
+    double previousTime = _previousTime;
+    _previousTime = timeStamp;
+    if (previousTime == 0.0)
+      return timeStamp;
+    double deltaT = timeStamp - previousTime;
+    system.update(deltaT);
+    return timeStamp;
   }
 }