将 ThreadPoolTimer 与背景音频 UWP 结合使用

Question

我正在使用BackgroundAudioTask制作UWP应用程序。我的应用程序运行良好。现在我想在文本块中添加播放的音频的当前位置。

在实现音频任务之前，我正在执行此方法：

private TimeSpan TotalTime;
        private DispatcherTimer timerRadioTime;
        private void radioPlayer_MediaOpened(object sender, RoutedEventArgs e)
        {
            TotalTime = radioPlayer.NaturalDuration.TimeSpan;
            // Create a timer that will update the counters and the time slider
            timerRadioTime = new DispatcherTimer();
            timerRadioTime.Interval = TimeSpan.FromSeconds(1);
            timerRadioTime.Tick += TimerRadioTime_Tick;
            timerRadioTime.Start();
        }
        private void TimerRadioTime_Tick(object sender, object e)
        {
            //Check if the audio finished calculate it's total time
            if (radioPlayer.NaturalDuration.TimeSpan.TotalSeconds > 0)
            {
                if (TotalTime.TotalSeconds > 0)
                {
                    // Updating timer
                    TimeSpan currentPos = radioPlayer.Position;
                    var currentTime = string.Format("{0:00}:{1:00}", (currentPos.Hours * 60) + currentPos.Minutes, currentPos.Seconds);
                    radioTimerBlock.Text = currentTime;
                }
            }
        }

当我实现后台任务时，它给了我一个异常。经过研究，我看到了使用ThreadPoolTimer而不是调度程序计时器的建议。

我尝试编写此代码（遵循此解决方案：使用ThreadPoolTimer C# uwp的时钟程序）

ThreadPoolTimer timer;
        // for displaying time only
        private void CurrentPlayer_MediaOpened(MediaPlayer sender, object args)
        {
            _clockTimer_Tick(timer);
        }

        private async void _clockTimer_Tick(ThreadPoolTimer timer)
        {
            var dispatcher = Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher;
            await dispatcher.RunAsync(
             CoreDispatcherPriority.Normal, () =>
             {
                 // Your UI update code goes here!
                 if (CurrentPlayer.NaturalDuration.TotalSeconds > 0)
                 {
                     TimeSpan currentPos = CurrentPlayer.Position;
                     var currentTime = string.Format("{0:00}:{1:00}", (currentPos.Hours * 60) + currentPos.Minutes, currentPos.Seconds);
                     CurrentPosition.Text = currentTime;
                 }
             });
        }

这显然是行不通的。应用在不更新我的 UI 的情况下输入方法。我真的不明白timer应该是什么。关于如何让它运行的任何想法？

Answer 1

解决方案：

ThreadPoolTimer timer;
            // for displaying time only
            private void CurrentPlayer_MediaOpened(MediaPlayer sender, object args)
            {
                timer = ThreadPoolTimer.CreatePeriodicTimer(_clockTimer_Tick, TimeSpan.FromSeconds(1));
            }

            private async void _clockTimer_Tick(ThreadPoolTimer timer)
            {
                var dispatcher = Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher;
                await dispatcher.RunAsync(
                 CoreDispatcherPriority.Normal, () =>
                 {
                     // Your UI update code goes here!
                     if (CurrentPlayer.NaturalDuration.TotalSeconds < 0)
                     {
                         TimeSpan currentPos = CurrentPlayer.Position;
                         var currentTime = string.Format("{0:00}:{1:00}", (currentPos.Hours * 60) + currentPos.Minutes, currentPos.Seconds);
                         CurrentPosition.Text = currentTime;
                     }
                 });
            }