-
Notifications
You must be signed in to change notification settings - Fork 133
/
countdown_timer.dart
76 lines (65 loc) · 2.48 KB
/
countdown_timer.dart
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import 'dart:async';
/// A simple countdown timer that fires events in regular increments until a
/// duration has passed.
///
/// CountdownTimer implements [Stream] and sends itself as the event. From the
/// timer you can get the [remaining] and [elapsed] time, or [cancel] the
/// timer.
class CountdownTimer extends Stream<CountdownTimer> {
/// Creates a new [CountdownTimer] that fires events in increments of
/// [increment], until the [duration] has passed.
///
/// [stopwatch] is for testing purposes. If you're using CountdownTimer and
/// need to control time in a test, pass a mock or a fake. See [FakeAsync]
/// and [FakeStopwatch].
CountdownTimer(Duration duration, this.increment, {Stopwatch? stopwatch})
: _duration = duration,
_stopwatch = stopwatch ?? Stopwatch(),
_controller = StreamController<CountdownTimer>.broadcast(sync: true) {
_timer = Timer.periodic(increment, _tick);
_stopwatch.start();
}
static const _thresholdMS = 4;
final Duration _duration;
final Stopwatch _stopwatch;
/// The duration between timer events.
final Duration increment;
final StreamController<CountdownTimer> _controller;
late final Timer _timer;
@override
StreamSubscription<CountdownTimer> listen(
void Function(CountdownTimer event)? onData,
{Function? onError,
void Function()? onDone,
bool? cancelOnError}) =>
_controller.stream.listen(onData, onError: onError, onDone: onDone);
Duration get elapsed => _stopwatch.elapsed;
Duration get remaining => _duration - _stopwatch.elapsed;
bool get isRunning => _stopwatch.isRunning;
void cancel() {
_stopwatch.stop();
_timer.cancel();
_controller.close();
}
void _tick(Timer timer) {
var t = remaining;
_controller.add(this);
// timers may have a 4ms resolution
if (t.inMilliseconds < _thresholdMS) {
cancel();
}
}
}