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1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 import 'curves.dart'; | |
6 import 'dart:async'; | |
7 import 'dart:math' as math; | |
8 import 'dart:sky' as sky; | |
9 import 'mechanics.dart'; | |
10 | |
11 abstract class Generator { | |
12 Stream<double> get onTick; | |
13 void cancel(); | |
14 } | |
15 | |
16 class FrameGenerator extends Generator { | |
17 Function onDone; | |
18 StreamController _controller; | |
19 | |
20 Stream<double> get onTick => _controller.stream; | |
21 | |
22 int _animationId = 0; | |
23 bool _cancelled = false; | |
24 | |
25 FrameGenerator({this.onDone}) { | |
26 _controller = new StreamController( | |
27 sync: true, | |
28 onListen: _scheduleTick, | |
29 onCancel: cancel); | |
30 } | |
31 | |
32 void cancel() { | |
33 if (_cancelled) { | |
34 return; | |
35 } | |
36 if (_animationId != 0) { | |
37 sky.window.cancelAnimationFrame(_animationId); | |
38 } | |
39 _animationId = 0; | |
40 _cancelled = true; | |
41 if (onDone != null) { | |
42 onDone(); | |
43 } | |
44 } | |
45 | |
46 void _scheduleTick() { | |
47 assert(_animationId == 0); | |
48 _animationId = sky.window.requestAnimationFrame(_tick); | |
49 } | |
50 | |
51 void _tick(double timeStamp) { | |
52 _animationId = 0; | |
53 _controller.add(timeStamp); | |
54 if (!_cancelled) { | |
55 _scheduleTick(); | |
56 } | |
57 } | |
58 } | |
59 | |
60 class AnimationGenerator extends Generator { | |
61 Stream<double> get onTick => _stream; | |
62 final double initialDelay; | |
63 final double duration; | |
64 final double begin; | |
65 final double end; | |
66 final Curve curve; | |
67 | |
68 FrameGenerator _generator; | |
69 Stream<double> _stream; | |
70 bool _done = false; | |
71 double _lastTime; | |
72 | |
73 AnimationGenerator({ | |
74 this.initialDelay: 0.0, | |
75 this.duration, | |
76 this.begin: 0.0, | |
77 this.end: 1.0, | |
78 this.curve: linear, | |
79 Function onDone | |
80 }) { | |
81 assert(curve != null); | |
82 assert(duration != null && duration > 0.0); | |
83 _generator = new FrameGenerator(onDone: onDone); | |
84 | |
85 double startTime = 0.0; | |
86 _stream = _generator.onTick.map((timeStamp) { | |
87 if (startTime == 0.0) | |
88 startTime = timeStamp; | |
89 | |
90 double t = (timeStamp - (startTime + initialDelay)) / duration; | |
91 _lastTime = math.max(0.0, math.min(t, 1.0)); | |
92 return _lastTime; | |
93 }) | |
94 .takeWhile(_checkForCompletion) | |
95 .where((t) => t >= 0.0) | |
96 .map(_transform); | |
97 } | |
98 | |
99 double get remainingTime { | |
100 if (_lastTime == null) | |
101 return duration; | |
102 return duration - _lastTime; | |
103 } | |
104 | |
105 void cancel() { | |
106 _generator.cancel(); | |
107 } | |
108 | |
109 double _transform(double t) { | |
110 if (_done) | |
111 return end; | |
112 return begin + (end - begin) * curve.transform(t); | |
113 } | |
114 | |
115 // This is required because Dart Streams don't have takeUntil (inclusive). | |
116 bool _checkForCompletion(double t) { | |
117 if (_done) | |
118 return false; | |
119 | |
120 _done = t >= 1; | |
121 return true; | |
122 } | |
123 } | |
124 | |
125 class Simulation extends Generator { | |
126 Stream<double> get onTick => _stream; | |
127 final System system; | |
128 | |
129 FrameGenerator _generator; | |
130 Stream<double> _stream; | |
131 double _previousTime = 0.0; | |
132 | |
133 Simulation(this.system, {Function terminationCondition, Function onDone}) { | |
134 _generator = new FrameGenerator(onDone: onDone); | |
135 _stream = _generator.onTick.map(_update); | |
136 | |
137 if (terminationCondition != null) { | |
138 bool done = false; | |
139 _stream = _stream.takeWhile((_) { | |
140 if (done) | |
141 return false; | |
142 done = terminationCondition(); | |
143 return true; | |
144 }); | |
145 } | |
146 } | |
147 | |
148 void cancel() { | |
149 _generator.cancel(); | |
150 } | |
151 | |
152 double _update(double timeStamp) { | |
153 double previousTime = _previousTime; | |
154 _previousTime = timeStamp; | |
155 if (previousTime == 0.0) | |
156 return timeStamp; | |
157 double deltaT = timeStamp - previousTime; | |
158 system.update(deltaT); | |
159 return timeStamp; | |
160 } | |
161 } | |
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