Windows IoT Raspberry Pi 3 c#音频播放在不同的页面 [英] Windows IoT Raspberry Pi 3 c# Audio Playback in Different Pages
问题描述
我正在Rasp Pi 3上制作一个应用程序,在这里我可以触发播放页面"上的按钮以使用页面中的MediaPlayer激活音频播放.一旦我切换到另一个页面,音频将继续在后台播放,但是一旦我导航回播放页面",音频仍在播放,但是由于我的mediaPlayer = new MediaPlayer(),我失去了对MediaPlayer的控制.线.如果处于重复模式,我将无法停止播放&如果我触发了另一条消息,则新的&现有消息将同时播放.
I am making an app on Rasp Pi 3 where I can trigger a button on "Playback Page" to activate an audio playback using MediaPlayer in a page. Once I switch to another page, the audio will remain playing in the background but once I navigate back to the "Playback Page" the audio is still playing but i lost control of the MediaPlayer due to my mediaPlayer = new MediaPlayer(); line. if it's on repeat mode I can't stop playing & if i trigger another message, both new & existing message will play concurrently.
即使在页面之间切换,如何确保一次只播放一个MediaPlayer. 请帮忙.谢谢.
How do I ensure that there is only one MediaPlayer playing at a time even when I switch between pages. Please help. Thank you.
修改后的代码:
public sealed partial class MessagePage : Page
{
private object syncObj = new object();
public MessagePage()
{
this.InitializeComponent();
startclock();
this.Home.Click += Home_Click;
this.Message.Click += Message_Click;
//mediaPlayer = new MediaPlayer();
mediaPlayer = this.GetInstance();
//mediaPlayer.MediaEnded += MediaPlayer_MediaEnded;
//mediaPlayer.MediaOpened += MediaPlayer_MediaOpened;
}
public MediaPlayer GetInstance()
{
lock (syncObj)
{
if (mediaPlayer == null)
{
mediaPlayer = new MediaPlayer();
mediaPlayer.MediaEnded += MediaPlayer_MediaEnded;
mediaPlayer.MediaOpened += MediaPlayer_MediaOpened;
}
}
return mediaPlayer;
}
}
旧代码:
public MessagePage()
{
this.InitializeComponent();
startclock();
this.Home.Click += Home_Click;
this.Message.Click += Message_Click;
mediaPlayer = new MediaPlayer();
mediaPlayer.MediaEnded += MediaPlayer_MediaEnded;
}
private async void Btn_Click(object sender, RoutedEventArgs e)
{
StorageFolder externalDevices = KnownFolders.RemovableDevices;
IReadOnlyList<StorageFolder> externalDrives = await externalDevices.GetFoldersAsync();
StorageFolder usbStorage = externalDrives[0];
if (usbStorage != null)
{
StorageFolder storageFolder = KnownFolders.RemovableDevices;
StorageFile audioFile = await usbStorage.GetFileAsync("message1.mp3");
mediaPlayer.Source = Windows.Media.Core.MediaSource.CreateFromStorageFile(audioFile);
mediaPlayer.Play();
TextBlock.Text = "Playing Message 1...";
}
else
{
TextBlock.Text = "No USB Storage Detected...";
};
}
推荐答案
You need to use singleton pattern here.The singleton pattern is a software design pattern that restricts the instantiation of a class to one object. This is useful when exactly one object is needed to coordinate actions across the system.
private static readonly object syncObj = new object();
public MediaPlayer GetInstance()
{
lock (syncObj)
{
if (mediaPlayer == null)
{
mediaPlayer = new MediaPlayer();
mediaPlayer.MediaEnded += MediaPlayer_MediaEnded;
}
}
return mediaPlayer;
}
public MessagePage()
{
this.InitializeComponent();
startclock();
this.Home.Click += Home_Click;
this.Message.Click += Message_Click;
//mediaPlayer = new MediaPlayer();
mediaPlayer = this.GetInstance();
}
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