如何在屏幕上显示当前相机分辨率

Question

我试图在屏幕上显示当前的摄像机分辨率，以便用户知道当前的分辨率，并在需要时随时进行调整。 在我的应用程序中，所有相机功能都可以使用，但是由于某种原因，每当我尝试访问当前相机分辨率并将其显示在文本框中时，都会收到UnauthorizedAccessException。 我尝试查询OnNavigatedTo事件和camera_Initialized事件中的分辨率值。 我在做什么错，我如何更改当前的实现方式才能正常工作？

MainPage.xaml.cs

protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        if ((PhotoCamera.IsCameraTypeSupported(CameraType.Primary) == true) ||
             (PhotoCamera.IsCameraTypeSupported(CameraType.FrontFacing) == true))
        {
            // Initialize the camera, when available.
            if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary))
            {
                // Use front-facing camera if available.
                camera = new PhotoCamera(CameraType.Primary);

                camera.Initialized += camera_Initialized;

                viewfinderBrush.SetSource(camera);

                //display current resolution
                resolutionValueTextBlock.Text = "resolution: " + camera.Resolution.ToString();  //UnauthorizedAccessException occurs here
            }
        }
        ...
    }

void camera_Initialized(object sender, CameraOperationCompletedEventArgs e)
    {
        if (e.Succeeded)
        {
            if (Settings.firstRun.Value)
            {
                //Set highest camera resolution on first run and by default
                Size resolution = camera.AvailableResolutions.OrderByDescending(s => s.Width).First();
                camera.Resolution = resolution;

                //display current resolution
                resolutionValueTextBlock.Text = "resolution: " + camera.Resolution.ToString();  //UnauthorizedAccessException

                ...

            }
            else
            {
                Size resolution = camera.AvailableResolutions.ElementAt(Settings.tempResolutionIndex.Value);
                camera.Resolution = resolution;

                //display current resolution
                resolutionValueTextBlock.Text = "resolution: " + camera.Resolution.ToString(); //UnauthorizedAccessException
            }                     
        }
    }

Answer 1

由于您尝试在UI上显示某些内容，因此需要使用Dispatcher进行显示。

Deployment.Current.Dispatcher.BeginInvoke( ()=> { resolutionValueTextBlock.Text = "resolution: " + camera.Resolution.ToString(); });