| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| /** |
| * A simple implementation of the [Stopwatch] interface. |
| */ |
| class StopwatchImplementation implements Stopwatch { |
| // The _start and _stop fields capture the time when [start] and [stop] |
| // are called respectively. |
| // If _start is null, then the [Stopwatch] has not been started yet. |
| // If _stop is null, then the [Stopwatch] has not been stopped yet, |
| // or is running. |
| int _start; |
| int _stop; |
| |
| StopwatchImplementation() : _start = null, _stop = null {} |
| |
| void start() { |
| if (_start === null) { |
| // This stopwatch has never been started. |
| _start = _now(); |
| } else { |
| if (_stop === null) { |
| return; |
| } |
| // Restarting this stopwatch. Prepend the elapsed time to the current |
| // start time. |
| _start = _now() - (_stop - _start); |
| _stop = null; |
| } |
| } |
| |
| void stop() { |
| if (_start === null || _stop !== null) { |
| return; |
| } |
| _stop = _now(); |
| } |
| |
| void reset() { |
| if (_start === null) return; |
| // If [_start] is not null, then the stopwatch had already been started. It |
| // may running right now. |
| _start = _now(); |
| if (_stop !== null) { |
| // The watch is not running. So simply set the [_stop] to [_start] thus |
| // having an elapsed time of 0. |
| _stop = _start; |
| } |
| } |
| |
| int get elapsedTicks { |
| if (_start === null) { |
| return 0; |
| } |
| return (_stop === null) ? (_now() - _start) : (_stop - _start); |
| } |
| |
| int get elapsedMicroseconds { |
| return (elapsedTicks * 1000000) ~/ frequency; |
| } |
| |
| int get elapsedMilliseconds { |
| return (elapsedTicks * 1000) ~/ frequency; |
| } |
| |
| int get frequency => _frequency(); |
| |
| external static int _frequency(); |
| external static int _now(); |
| } |