I got the next message at the designer: System.NullReferenceException
Object reference not set to an instance of an object.
at WPF.MDI.MdiContainer.MdiContainer_Loaded(Object sender, RoutedEventArgs e)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
at System.Windows.BroadcastEventHelper.BroadcastEvent(DependencyObject root, RoutedEvent routedEvent)
at System.Windows.BroadcastEventHelper.BroadcastLoadedEvent(Object root)
at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
I have a application that has a page that receives multiple packets from a TCP/IP server. Every time it receives it tries to run an event using Dispatcher.BeginInvoke which runs the event. The problem is that the event only runs on the first time Dispatcher.BeginInvoke. I believe that the reason for this is that because the thread is already running it can not be started again. Also, I have tried the Backgroundworker class and as soon as it hits my code I get an "Invalid cross thread access" error which makes me put the code back into the Silverlight Dispatcher.BeginInvoke and the origional problem occurs. How do I fix my problem?
Without seeing your code it is hard to say. I think the issue here is that you are using the Dispatcher.BeginInvoke which is actually saying, marshal any work onto the UI thread. what could be happening is that if you first action does not complete or blocks the UI then subsequent events may not bubble up to the UI thread which would not show anything.
You were right in trying another thread. Firstly do your work on another thread. At the point of updating the UI, put that bit in the Dispatcher call. So what you are saying is: Do my work on another thread. Once it is complete and I want to update my UI, marshal it onto the UI thread using the dispatcher.
Please remember that the actual code is at my office at work and I am at home. I have network security rules that don't allow me to bring code home. However, this is a Silverlight page control the Do Work Complete bw_RunWorkerCompleted is the Async event that is called once the bw_DoWork is finishes. Now, 'TimeLine timeline' is a codeplex control which is a sub-control on the main page control that displays a Silverlight timeline. How it works is that a wcf call is made which fills the timeline's List<Event> events collection that is a property of the TimeLine control. Now, when timeline.UpdateEvents is called the timeline control iterates the list and re-draws the timeline with each of the collection's event objects. The Backgroundworker class provides an Async run event and on event complete combination. I have to put the 'while (!autoEvent.WaitOne())', sorry I forgot the while in the while loop, to wait until the main thread signals so that the Dispatch.BeginInvoke(timeline.UpdateEvents) is blocked unitl the collection is updated by the wcf call or I get an exception. I know that my discription is a bit sketchy but this is all I can go on as far a specifics until in the morning. If you can help that would be great!
I have created a simple silverlight application in VS2010(Silverlight 5) for open exe file. I host the application on my iis 7 and it is working fine. when i host in online(server), the elevated permission is failed and not entered to automationfactory. kindly suggest for open exe in online.
Actually, i used image capturing in my project. I would like to open the saved picture from client machine through web browser, same time i have to save image in database. For that only i simply ask, how to open a file.
Hello Code Project,
I have a requirement in Silverlight, that If a TextBox[ContentControl] have validation error, then the appearence should be like a red wavy line, with a tool tip of error content. If it is possible , please help me with a sample silverlight application..
Correct, you have to go with silverlight only. Prism is one of the popular MVVM frame work. there no mandatory that you need to use all of these things, You can create your app with out them as well. But Building WPF/Silverlight is advisable.
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