如何在 Windows Phone 8 中使用 IsolatedStorage 设置锁屏背景

Question

我希望能够使用我的 IsolatedStorage 中的图像来修改锁定屏幕背景，但我无法获取 IsolatedStorage 文件路径的正确语法来设置锁定屏幕背景。

在http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206968(v=vs.105).aspx 之后，一旦从名为Recent 的列表中选择了图像，我将在按钮单击事件中调用LockHelper 方法（该列表已从PictureRepository.cs 填充，从IsolatedStorage 加载图像）

private void recent_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {            
        capturedPicture = (sender as LongListSelector).SelectedItem as CapturedPicture;

        if (capturedPicture != null)
        {
            //filename is the name of the image in IsolatedStorage
            fileName = capturedPicture.FileName;
        }
    }

void setAsLockScreenMenuItem_Click(object sender, EventArgs e)
    {
        if (!String.IsNullOrEmpty(fileName)) 
        {
            //PictureRepository.IsolatedStoragePath is a string = "Pictures"                
            LockHelper("isostore:/" + PictureRepository.IsolatedStoragePath + "/" + fileName, false);  //results in FileNotFoundException
            LockHelper(PictureRepository.IsolatedStoragePath + "/" + fileName, false);  //results in ArgumentException
        }
        else
        {
            MessageBoxResult result = MessageBox.Show("You must select an image to set it as your lock screen.", "Notice", MessageBoxButton.OK);
            if (result == MessageBoxResult.OK)
            {
                return;
            }
        }
    }

一旦调用LockHelper，事件就会继续

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);

                //The Error Occurs Here!
                // 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
            {
                MessageBoxResult result = MessageBox.Show("Cannot update your lock screen background at this time.", "Notice", MessageBoxButton.OK);
                if (result == MessageBoxResult.OK)
                {
                    return;
                }
            }
        }
        catch (System.Exception ex)
        {
            System.Diagnostics.Debug.WriteLine(ex.ToString());
        }
    }

错误发生在Windows.Phone.System.UserProfile.LockScreen.SetImageUri(uri); 方法中的LockHelper 上。它是 FileNotFoundException 提及 The filename, directory name, or volume label syntax is incorrect. (Exception from HRESULT: 0x8007007B) 或 ArgumentException。我引用的所有地方都说使用IsolatedStorage Uri 应该是ms-appdata:///local/ 然后是IsolatedStorage 文件路径（在我的情况下为Pictures/imagename.jpg），我相信我的错误在于Uri 路径，但我不确定的正确语法？如果不是这个，还有其他想法吗？

Answer 1

这对我有用：

const string filePathOfTheImage = "/Shared/ShellContent/shot2.jpg"; //This is where my image is in isostore

var uri = new Uri("ms-appdata:///local" + filePathOfTheImage, UriKind.Absolute);

另外，我使用WP Power Tools 来跟踪我的应用存储空间。希望这会有所帮助。

Answer 2

在nokia developer 试试这个。希望你能找到解决办法。