将 ThreadPoolTimer 与背景音频 UWP 一起使用答案

【问题标题】：Using ThreadPoolTimer with Background Audio UWP将 ThreadPoolTimer 与背景音频 UWP 一起使用
【发布时间】：2016-05-29 23:45:49
【问题描述】：

我正在使用 BackgroundAudioTask 制作 UWP 应用。我的应用程序运行良好。现在我想在 TextBlock 中添加播放音频的当前位置。

我是在实现音频任务之前做这个方法的：

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 dispatcherTimer 的建议。

我尝试编写此代码（遵循此解决方案：Clock program employing ThreadPoolTimer C# uwp）

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;
                 }

             });
        }

这显然行不通。该应用程序在不更新我的 UI 的情况下进入该方法。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？

【问题讨论】：

“它给了我一个异常”不是一个合适的问题描述。
使用'ThreadPoolTimer.CreatePeriodicTimer(_clockTimer_Tick, TimeSpan.FromMilliseconds(1000)); '创建计时器
你能帮我解决这个问题吗？ stackoverflow.com/questions/37511936/…

标签： c# win-universal-app uwp dispatchertimer

【解决方案1】：

解决办法：

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;
                     }

                 });
            }

【讨论】：