Windows Phone 8의 잠금 화면 배경

private async void LockHelper(string filePathOfTheImage, bool isAppResource)
{
    try
    {
        var isProvider = Windows.Phone.System.UserProfile.LockScreenManager.IsProvidedByCurrentApplication;
        if (!isProvider)
        {
            // If you're not the provider, this call will prompt the user for permission.
            // Calling RequestAccessAsync from a background agent is not allowed.
            var op = await Windows.Phone.System.UserProfile.LockScreenManager.RequestAccessAsync();

            // Only do further work if the access was granted.
            isProvider = op == Windows.Phone.System.UserProfile.LockScreenRequestResult.Granted;
        }

        if (isProvider)
        {
            // At this stage, the app is the active lock screen background provider.

            // The following code example shows the new URI schema.
            // ms-appdata points to the root of the local app data folder.
            // ms-appx points to the Local app install folder, to reference resources bundled in the XAP package.
            var schema = isAppResource ? "ms-appx:///" : "ms-appdata:///Local/";
            var uri = new Uri(schema + filePathOfTheImage, UriKind.Absolute);

            // Set the lock screen background image.
            Windows.Phone.System.UserProfile.LockScreen.SetImageUri(uri);

            // Get the URI of the lock screen background image.
            var currentImage = Windows.Phone.System.UserProfile.LockScreen.GetImageUri();
            System.Diagnostics.Debug.WriteLine("The new lock screen background image is set to {0}", currentImage.ToString());
        }
        else
        {
            MessageBox.Show("You said no, so I can't update your background.");
        }
    }
    catch (System.Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex.ToString());
    }
}

protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
    base.OnNavigatedTo(e);

    string lockscreenKey = "WallpaperSettings";
    string lockscreenValue = "0";

    bool lockscreenValueExists = NavigationContext.QueryString.TryGetValue(lockscreenKey, out lockscreenValue);

    if (lockscreenValueExists)
    {
        // Navigate the user to your app's lock screen settings screen here, 
        // or indicate that the lock screen background image is updating.
    }
}

private async void btnGoToLockSettings_Click(object sender, RoutedEventArgs e)
{
    // Launch URI for the lock screen settings screen.
    var op = await Windows.System.Launcher.LaunchUriAsync(new Uri("ms-settings-lock:"));
}