'System.IO.FileNotFoundException'

Question

MyApp.DLL中发生'System.IO.FileNotFoundException'

C＃代码如下。错误指针在LockScreen.SetImageUri（uri）上指示“这是将要执行的下一个语句”。

public partial class MainPage : PhoneApplicationPage
{
    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }


    private async void SetBackground1(object sender, RoutedEventArgs e)
    {
        if (await LockScreenManager.RequestAccessAsync() == LockScreenRequestResult.Granted)
        {
            var uri = new Uri("ms-appx:///Assets/1.jpg", UriKind.Absolute);
            LockScreen.SetImageUri(uri);
        }
        else
        {
            MessageBox.Show("You said no, so I can't update your background.");
        }
    }
}

Answer 1

将图像保存到隔离存储而不是项目文件夹。然后，只要你愿意，就可以从隔离的存储中检索图像，

  var lockimageuri = new Uri("ms-appdata:///Local/" + "lockimage0.jpg", UriKind.Absolute);
  LockScreen.SetImageUri(lockimageuri);

这里locimage0.jpg是隔离存储中的图像。

以下是将图像保存到独立存储空间的代码。

   using (var store = IsolatedStorageFile.GetUserStoreForApplication())
   {
          string filePath = "lockimage0.jpg";
          if (store.FileExists(filePath))
          {
                store.DeleteFile(filePath);
          }
          IsolatedStorageFileStream fileStream = store.CreateFile(filePath);
          wbm.SaveJpeg(fileStream, wbm.PixelWidth, wbm.PixelHeight, 0, 100);
          fileStream.Close();
     }

此外，您可以使用此方法从项目文件夹中读取本地图像。

 private WriteableBitmap ReadLocalImage(string Uri)
    {
        StreamResourceInfo sri = null;
        Uri uri = new Uri(Uri, UriKind.Relative);
        sri = Application.GetResourceStream(uri);
        BitmapImage bitmap = new BitmapImage();
        bitmap.CreateOptions = BitmapCreateOptions.None;
        bitmap.SetSource(sri.Stream);
        WriteableBitmap wb = new WriteableBitmap(bitmap);
        return wb;

    }

这就是我在我的应用程序中实现自定义锁定屏幕的方式。

还要确保您更新了清单文件

<Extensions>
  <Extension ExtensionName="LockScreen_Background" ConsumerID="{111DFF24-AA15-4A96-8006-2BFF8122084F}" TaskID="_default" />
</Extensions>

我也试过在本地项目文件夹中使用图像，这对我来说也很好。这是我试过的代码。

private async void SetLockScreen()
{
           //Check to see if the app is currently the lock screen provider
           if (!LockScreenManager.IsProvidedByCurrentApplication)
           {
                //Request to be lock screen provider
                await LockScreenManager.RequestAccessAsync();
           }

           //Check to see if the app is currently the lock screen provider
           if (LockScreenManager.IsProvidedByCurrentApplication)
           {
                //Set the image to the lock screen image
                Uri imageUri = new Uri("ms-appx:///Images/lockscreen.png", UriKind.RelativeOrAbsolute);
               LockScreen.SetImageUri(imageUri);
           }
  }

Answer 2

请确保图片位于指定位置，并且Build Action属性设置为Content：