小编blu*_*ean的帖子

我正在构建一个WP8应用程序,它使用来自Internet的图像来更改锁定屏幕的背景.我按照预定代理和锁屏的教程,但我有一个问题.

当我尝试从计划代理下载新的背景图像时,我得到:

+       $exception  {System.UnauthorizedAccessException: Invalid cross-thread access.
   at MS.Internal.XcpImports.CheckThread()
   at System.Windows.DependencyObject..ctor(UInt32 nativeTypeIndex, IntPtr constructDO)
   at System.Windows.Media.Imaging.BitmapImage..ctor()
   at TileLockAgent.ScheduledAgent.lockScreenClient_OpenReadCompleted(Object sender, OpenReadCompletedEventArgs e)
   at System.Net.WebClient.OnOpenReadCompleted(OpenReadCompletedEventArgs e)
   at System.Net.WebClient.OpenReadOperationCompleted(Object arg)
   at System.Threading.WaitCallback.Invoke(Object state)
   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()}   System.Exception {System.UnauthorizedAccessException}

代码是:

string fileName;

try
{
    var currentImage = LockScreen.GetImageUri();

    if (currentImage.ToString().EndsWith("_1.jpg"))
    {
        fileName = "LockBackground_2.jpg";
    }
    else
    {
        fileName = …

我在Haskell中有这段代码拒绝编译:

data (Eq a, Num a, Show a) => Mat a = Mat {nexp :: Int, mat :: QT a}
 deriving (Eq, Show)

data (Eq a , Show a ) => QT a = C a | Q (QT a ) (QT a ) (QT a ) (QT a )
 deriving (Eq, Show)


cs:: (Num t) => Mat t -> [t]

cs(Mat nexp (Q a b c d)) =(css (nexp-1) a c)++(css (nexp-1) b d)
    where
        css 0 (C a) …