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Side by Side Diff: sky/sdk/lib/framework/animation/animated_value.dart

Issue 1221883002: Remove package:sky/framework (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 5 months ago
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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 'generators.dart';
8
9 typedef void Callback ();
10
11 class AnimatedValue {
12 StreamController<double> _controller = new StreamController<double>.broadcast( sync: true);
13 AnimationGenerator _animation;
14 Completer _completer;
15 double _value;
16
17 AnimatedValue(double initial, { Callback onChange }) {
18 _value = initial;
19 _onChange = onChange;
20 }
21 Callback _onChange;
22
23 // A stream of change in value from |initial|. The stream does not
24 // contain the initial value. Consumers should check the initial value via
25 // the |value| accessor.
26 // TODO(ianh): Rename this to valueStream once we've landed the fn2 fork
27 Stream<double> get onValueChanged => _controller.stream;
28
29 double get value => _value;
30
31 void set value(double value) {
32 stop();
33 _setValue(value);
34 }
35
36 bool get isAnimating => _animation != null;
37
38 void _setValue(double value) {
39 _value = value;
40 _controller.add(_value);
41 if (_onChange != null)
42 _onChange();
43 }
44
45 void _done() {
46 _animation = null;
47 if (_completer == null)
48 return;
49 Completer completer = _completer;
50 _completer = null;
51 completer.complete(_value);
52 }
53
54 void stop() {
55 if (_animation != null) {
56 _animation.cancel(); // will call _done() if it isn't already finished
57 _done();
58 }
59 }
60
61 Future<double> animateTo(double newValue, double duration,
62 { Curve curve: linear, double initialDelay: 0.0 }) {
63 stop();
64
65 _animation = new AnimationGenerator(
66 duration: duration,
67 begin: _value,
68 end: newValue,
69 curve: curve,
70 initialDelay: initialDelay)
71 ..onTick.listen(_setValue, onDone: _done);
72
73 _completer = new Completer();
74 return _completer.future;
75 }
76
77 double get remainingTime {
78 if (_animation == null)
79 return 0.0;
80 return _animation.remainingTime;
81 }
82
83 }
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