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可以看出，“ms-appdata：/// local /”是本地图像的必需前体。

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

我在我的应用程序IsolatedStorage中创建了一个名为Pictures的文件夹，其中jpg图像是从CameraCaptureTask中保存的。我已经尝试了几种通过上述方案访问此文件夹中的图像的方法，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uri = "ms-appdata:///Local/Pictures/WP_20130812_001.jpg"，这是怎么回事？

我的实施如下

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

要从应用程序设置锁定屏幕图像，您可能希望将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

我希望这可以帮助您解决问题。

如果您的应用已安装，请确保它是背景图片提供商。如果没有，那么转到设置 - ＆gt;锁屏 - ＆gt;背景，并从列表中选择您的应用程序。

在程序方面：

<强> 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，确保存在以下扩展名：

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

<强> 2。编写代码以更改背景图像以下是如何编写用于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：

要使用应用中附带的图片，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 / shellcontent 必须在/ shared / shellcontent子文件夹中或之下

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

如何使用LockScreen.SetImageUri设置Windows Phone 8锁屏背景

2 个答案: