如何使用LockScreen.SetImageUri设置Windows phone8锁屏背景

Question

我在IsolatedStorage中有一个图像，我想以编程方式将其设置为设备锁定屏幕背景。我的问题是我无法获得LockScreen.SetImageUri所需的正确路径。从引用http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206968(v=vs.105).aspx可以明显看出，`“ms-appdata:/ local /”是本地镜像所需的前身。

var schema = isAppResource ? "ms-appx:///" : "ms-appdata:///Local/";
var uri = new Uri(schema + filePathOfTheImage, UriKind.Absolute);

我已经在我的应用程序IsolatedStorage中创建了一个名为Pictures的文件夹，其中保存了CameraCaptureTask中的jpg图像。我尝试了几种方法通过上面的方案访问此文件夹中的图像，但我总是在下一行收到ArgumentException

Windows.Phone.System.UserProfile.LockScreen.SetImageUri(uri);

然而，在调试时，我看到了uri = "ms-appdata:///Local/Pictures/WP_20130812_001.jpg"，这怎么会不正确呢？

我的实现如下

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 the IsolatedStorage folder named Pictures
        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;
        }
    }
}

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());
}

}

如何将LockScreen.SetImageUri修改为正确的预期uri？

Answer 1

为了从应用程序设置锁定屏幕图像，您可能希望将您的应用程序声明为锁定屏幕提供程序。您可以通过添加以下标记来修改WMAppManifest.xml文件来完成此操作：

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

检查清单文件中是否有此标记。

Answer 2

我希望这能帮助你解决你的问题。

如果您的应用程序已安装，请确保它是背景图像提供程序。如果没有，则转到settings -> lock screen -> background并从列表中选择您的应用程序。

在编程方面：

1.在应用程序清单文件中声明应用程序的意图使用XML编辑器编辑WMAppManifest.xml，确保存在以下扩展：

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

2.编写更改背景图像的代码以下是如何编写设置背景的代码的示例。

private async void lockHelper(Uri backgroundImageUri, string backgroundAction)
        {
            try
            {
                //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 LockScreenManager.RequestAccessAsync();
                //Check the status to make sure we were given permission. 
                bool isProvider = LockScreenManager.IsProvidedByCurrentApplication; if (isProvider)
                {
                    //Do the update. 
                    Windows.Phone.System.UserProfile.LockScreen.SetImageUri(backgroundImageUri);
                    System.Diagnostics.Debug.WriteLine("New current image set to {0}", backgroundImageUri.ToString());
                }
                else { MessageBox.Show("You said no, so I can't update your background."); }
            }
            catch (System.Exception ex) { System.Diagnostics.Debug.WriteLine(ex.ToString()); }
        }

关于Uris，有很多选择，但请记住：

要使用应用程序中附带的图像，请使用ms-appx:/

Uri imageUri = new Uri("ms-appx:///background1.png", UriKind.RelativeOrAbsolute); LockScreen.SetImageUri(imageUri);

要使用存储在本地文件夹中的图像，请使用ms-appdata:/ Local /shared/shared内容必须是/shared/shellcontent子文件夹或其下的

Uri imageUri = new Uri("ms-appdata:///local/shared/shellcontent/background2.png", UriKind.RelativeOrAbsolute); LockScreen.SetImageUri(imageUri);