无法使用Dispatcher从背后的代码更新UWP UI

问题描述

我有一个来自 MediaTransportControls 的派生类，并尝试根据某些事件禁用上一个和下一个跟踪按钮。我写了以下

I have a derived class from MediaTransportControls and trying to disable previous and next track buttons based on some events. I wrote following

public class MyMediaTransportControls : MediaTransportControls
{
    public static readonly DependencyProperty IsPreviousTrackButtonEnabledProperty = DependencyProperty.Register(
        "IsPreviousTrackButtonEnabled", typeof(bool), typeof(MyMediaTransportControls), new PropertyMetadata(false, IsPreviousTrackButtonEnabledChangedCallback));

    private static async void IsPreviousTrackButtonEnabledChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var mediaTransportControls = d as MyMediaTransportControls;

        if(mediaTransportControls?.GetTemplateChild("PreviousTrackButton") is Button previousTrackButton)
        {
            await mediaTransportControls.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
            {
                previousTrackButton.IsEnabled = (bool)e.NewValue;
            });
        }
    }

    public bool IsPreviousTrackButtonEnabled
    {
        get { return (bool) GetValue(IsPreviousTrackButtonEnabledProperty); }
        set { SetValue(IsPreviousTrackButtonEnabledProperty, value); }
    }
}

我已经使用数据绑定来绑定 IsPreviousTrackButtonEnabled 和ViewModel逻辑。但是，我发现即使设置 previousTrackButton.IsEnabled ，它也不会影响UI。不过有时，在调试时，我可以看到对UI的影响。

I have used data binding to bind IsPreviousTrackButtonEnabled with the ViewModel logic. However, I find that even when previousTrackButton.IsEnabled is set it has no impact on the UI. Sometime, though, when debuging, I can see the impact on UI.

更新

MediaTransportControls 提供自己的 ControlTemplate ，我希望不要创建自己的模板并对其进行数据绑定。

The MediaTransportControls provide its own ControlTemplate and I wish not to create my own template and do data binding with it.

推荐答案

写入通知属性已更改的事件处理程序

Write Notify Property Changed Event Handler

 INotifyPropertyChanged

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