Much of the confusion with asynchronous programming seems to stem from the fact. Hosting wpf ui crossthread and crossprocess diaries of a. Note theres also a threadpool and threadpooltimer api for the uwp, which can be. Of course this wont work if performed before the rootvisual has been assigned. I understand that the response thread is going to be a background worker thread and i am assuming that i have to be in the ui thread to execute the function. Oct 26, 2009 also, the bitness of the native component needs to be matched with that of the host process. Hi jon, yes, in most cases when you need to show busy indicator you need to execute the longrunning process on a separate thread, so that the ui thread is not blocked.
If im at runtime and i am not on the ui thread, i execute the action through the dispatcher. You can access the dispatcher object for the ui thread through the. How to show and refresh the busyindicator in ui for wpf. Dispatcher concept is a mechanism introduced in wpf, with the help of which developer can have more explicit control on this ui.
May 10, 2010 the simple way to fix this is to simply do all the processing in the ui thread, but mostly that is not a practical solution. Deal with performance in wpf applications dot net tricks. For example, if you want to update a displayed progress bar the code to update it. If the calling thread has access to the dispatcher, the button is updated by accessing the members of the button.
Both silverlight and wpf have the concept of a ui thread. Get the silverlight main dispatcher before the rootvisual has. With the asynchronicity question still dogging silverlight 2, i thought id mention an oft forgotten little class in silverlight and in wpf called the dispatcher. However, a consequence is that under the silverlight threading model, the separate worker thread cannot directly access the objects on the ui thread. Upon reinstalling i was told i could not reinstall because a newer version of silverlight was already installed.
Need help silverlight gauges in ui for silverlight general. To get the dispatcher for an application before the rootvisual has been assigned, use the. Getting the data set back onto the ui is then done using deployment. With this release, there are a lot of changes to the way microsoft is doing things and behind the scenes if you read into some of the posts how things are going to shape up for the rtm release. A user clicks a link icon, image, and video on a web page and is offered an application that in many instances can be executed within the confines of a web browser as well. Wiring the ui with radpdfviewer commands the navigation panel is separated from the control to provide better customization options. Raddiagram exposes a set of properties that allow you to customize the graph layout and operations. If they are inside a class that is not a gui component then you need to invoke against something else. With silverlight 4 and the entity framework you get a lot of work done on your behalf in terms of standard ui crudstyle operations. Silverlight contextmenu getting started telerik ui for. Every control class has the dispatcher property, which can be used to render changes from any thread. Silverlight application with dispatcher and asynchronous wcf.
You dont stuff data into controls like we did in the goold old days. Note that you should be marshalling your data call out on the ui thread. Therefore, when creating assemblies using this technique you will need to reference the system. To get the dispatcher for an application before the rootvisual has. Handle the click event on a button create a new thread. Jun 27, 2009 in silverlight 3, as with winforms and wpf, we need to be careful about cross thread communication. One way to mitigate a ui threadblock situation is to create a separate thread and do work on it. Everything seems like it is installing ok, it gets 99% done and then the message comes up. This code can be improved, but i dont think you can easily make ui more responsive. Invoke suspended i have a somewhat complex wpf application which seems to be hanging or getting stuck in a wait call when trying to use the dispatcher to invoke a call on the ui thread. Jim jackson using the backgroundworker in a silverlight. It checks if i am running in the designer or if i am already on the ui thread. Get the silverlight main dispatcher before the rootvisual. Keep the ui thread responsive uwp applications microsoft docs.
The proper way to deal with this situation is to dispatch the requested uirelated operation to the ui thread using the dispatcher class. Dec 16, 2009 fortunately, silverlight makes it very easy to find your dispatcher, because it is a property on any uielement that exists, including your own user control. One of the beauties of silverlight is that is has or is a web based software delivery mechanism. Well create a simple wpf silverlight application that covers these fundamentals. Oct 16, 2012 in silverlight the main thread is incorporated with the dispatcher, and we can use the begininvoke method of the dispatcher class to update the ui from a different thread. I want to call a javascript function from a thread that is handling an async web request. Programming, web development, and devops news, tutorials and tools for beginners to experts. Invoke calls which means it is using the current class to determine which dispatcher to use. If those calls are inside a form then it should work. The simple way to fix this is to simply do all the processing in the ui thread, but mostly that is not a practical solution. As radrichtextbox does not have a dependency on richtextboxui, the assemblies are not normally copied to the shell project by prism and are not included in the xap, if the view containing the richtextbox is in another project. I had a invalid cross thread access issue, but a little research and i managed to fix it by using the dispatcher. Remember that ui elements may only be accessed from the ui thread. Solution in case of wpf silverlight, it can be resolved by using the system.
You can access the dispatcher object for the ui thread through the dependencyobject. Begininvoke to invoke some arbitrary code on the ui thread. Additionally, the first look example demonstrates how it can be used. Dispatching operations to ui thread in silverlight jernej virag. From the dispatcher we are able to create a dispatchersynchronizationcontext, which allows us to perform synchronous actions on the ui thread. However dispatcher is not available in windows forms. Silverlight 4 binding does not work on enum types of poco objects. Threading considerations for binding and change notification.
If you would like to use the control with a radribbonview, which shows the full potential of the control, you can refer to the sdk repository. Microsoft silverlight will reach end of support after october 2021. The major investments of microsoft on making silverlight to work out of. Begininvoke marshals the work that has to be done from whatever thread youre running on to the user interface thread. Users expect an app to remain responsive while it does computation, regardless of the type of machine. I understand that the response thread is going to be a background worker thread and i. In silverlight 3, as with winforms and wpf, we need to be careful about cross thread communication. Controls namespace, to bind the check state of the checkbox to the visibility of the chart series. Hundreds of free publications, over 1m members, totally free.
You can easily add nested filter criteria by clicking on the button for adding nested operators. Silverlight richtextbox troubleshooting common problems. Sep 27, 2011 here i am going to explain about dispathcertimer class in silvelright with help of a sample applicaiton. But execution picks up in that handler again after computenextmove which executes on a background thread completes. If the current thread is the user interface thread, the dispatcher if not used and the.
The checkaccess method on the dispatcher associated with the button is called to verify access to the thread. It allows you to create complex filter criteria within unlimited number of filter conditions combined by logical operators. Silverlight hour glass hangs at 100% in ui for silverlight. Silverlight 4 synchronous wcf service calls or how to avoid. Sometimes called as dispatcher thread is actually a. If you attempt to get the currentdispatcher for the current thread and a dispatcher is not associated with the. Backgroundworker class is one of the most convenient way to do this. Silverlight install failed at 99% i uninstalled previous silverlight but still getting an install failed message. In silverlight, background threads can influence the ui asynchronously. Raddatafilter is a control that allows you to filter your data. For example, you can set up the active mouse tool, specify if a cut, copy, paste or delete operation is allowed, and customize the background color, the cells height and width as well as the gridline thickness of the drawing canvas. Even the flash and silverlight activex controls are not yet. I had to make another dispatcher call within my object. If i need to make sure a thread executes on the ui thread, i simply do something like this.
If an addin gets stuck in native code or merely runs a message loop on some thread that gets no user input presumably different from the hosts ui thread, appdomain unloading is guaranteed to fail. The items collection of radtabcontrol can contain any uielement. Threading namespace, which is used to process a task at specified interval of time and at a specified priority. Crossprocess ui isolation is the strongest, largely because its supported at the os level. Silverlight 4 synchronous wcf service calls or how to. Secondly on button click items get selected in listbox which are get fetched by making asynchronous wcf service call and ui get updated by dispatcher. Use the ui thread to access ui elements before launching the background work andor use coredispatcher. This fails because descriptioncallback is trying to access ui while executing in a background thread. Understanding the silverlight dispatcher stack overflow. Before reading this tutorial you should get familiar with the visual structure of the standard. Radspreadsheet is easy to integrate with all kinds of ui thanks to the commanding mechanism that it employs. In silverlight the main thread is incorporated with the dispatcher, and we can use the begininvoke method of the dispatcher class to update the ui from a different thread. Invoking through the dispatcher on windows phone and metro. Dispathchertimer has start and stop methods to start the timer and stop the timer.
Updatebuttonuithebutton else this thread does not have access to the ui thread. I am using these things in my silverlight application but i am stuck some. Things get a little more tricky if you are trying to. Silverlight spreadsheet getting started telerik ui for. This may apply for hostedifd crm environments as well. Silverlight diagram getting started telerik ui for. However, if you do not wrap it manually into a radtabitem control, the tab control will do it automatically. Wcf ria services sample, hr application 4004 exception. The following example uses checkaccess to determine whether a thread has access to a button. Controls instantiated in the xaml dom belong to the ui thread and only the ui thread can update them. Creation of a thread this way is expensive there are three alternatives which are faster, but you did not report any observable delay before the. These are instance methods, but instances of these types are frequently inaccessible from non ui threads. Dispatcherhelper for mvvm framework monotoshs blog. Microsoft silverlight is stuck in an infinite loop.
Silverlight pdfviewer getting started telerik ui for. I removed all files from my computer and went to reinstall. May 08, 2011 this silverlight project is not a full featured video player, but it actually works, and hopefully demonstrates a nontrivial example of a view model style silverlight project. Feb 22, 2012 note that you should be marshalling your data call out on the ui thread. The ui thread, dispatchers, background workers and async network programming pete brown 23 april 2010 im starting a occasional series of postings on top things every silverlight and wpf developer should know. Hosting wpf ui crossthread and crossprocess diaries of. Silverlight datafilter getting started telerik ui for. The key to simplifying calling the ui thread is the dispatcher class.
When a dispatcher is created on a thread, it becomes the only dispatcher that can be associated with the thread, even if the dispatcher is shut down. Examples of such containers are scrollviewer, stackpanel or grid with row height and column width set to auto wiring the ui with radpdfviewer commands. As i mentioned before this was not enough to satisfy silverlight. The dispatcher class currently provides support only for running code on the user interface ui thread from a non ui thread. This class supports a static or shared interface for executing code on the ui thread. Microsoft seems to only provide help for windows users. The remaining code in the handler updates the ui with the results. Validations and io are pretty easy to accommodate out of the box. Something funky happens in silverlight where when you make a call in the background thread the cookies arent shared all the time so it actually loses your authentication to crm. The call to this method is within a dispatcher like so. An example of work that can be performed on a background thread is the calculating of computer ai in a game. Selected container problem in ui for silverlight treelistview. Although you will probably end up doing most of your ui design with a draganddrop tool such as expression blend, knowing the internals gives you a leg up in making the final tweaks to ensure an excellent user experience. How set legend items and display horizontaly from code behind.
Radtabcontrol with several radtabitems defined in its items collection. Dispatching operations to ui thread in silverlight. This tutorial will walk you through the creation of a radcontextmenu and will show you how to. To open a document, you need to import it and the export. Here i am going to explain about dispathcertimer class in silvelright with help of a sample applicaiton. This can be done on application startup or in the constructor of your page, just before initializecomponent. Invoke to create a delegate for updating ui elements. This can be a problem because many legacy components are not available in 64bit form. The dispatcher maintains a prioritized queue of work items for a specific thread. Certain functions such as the pause button, full screen support, and skip ahead were left out to simplify the example code as much as possible.
But sometimes you need to perform some long running tasks either on the client or on the server via service calls. Legacyinvokeimpl nullreferenceexception in ui for wpf. Ui of the silverlight page in the page list of item item page listbox get filled with the help of dispatcher and by calling wcf service asynchronous. If you would like to use the control with a radribbonview, which shows the full potential of the control, you can refer to the sdk repository opensave documents. This call will only succeed if the current thread is the ui thread. May 21, 2010 with silverlight 4 and the entity framework you get a lot of work done on your behalf in terms of standard ui crudstyle operations. According to the msdn documentation dispatcher in silverlight is intended for the ui updates.
Use silverlight in the 32bit internet explorer process on x64 systems. Im using a dummy method which returns a string reversed of its input. Most browser plugins including silverlight, flash, java and almost all activex controls only work in 32bit browsers currently. How to use dispatchertimer in silverlight syed amjads blog. When you create a radpdfviewer, ensure that the control is not placed in a container that measures its children in infinity as this could lead to unexpected behavior of the viewer. Additionally, the first look example demonstrates how it can be used with radbusyincicator. To see this, try updating the ui from a different thread, public mainpage initializecomponent. Checkaccess then this thread has access so it can update the ui thread.
Dispatcher property is used to retrieve the system. This is why synchronizationcontext is best practice for most scenarios. Silverlight install failed at 99% microsoft community. In fact, this is one area where it would have been fun to go into great detail in my book, but there simply wasnt the space.
Place the update method on the dispatcher of the ui thread. In order to add a panel in your application, you can use radtoolbar, which has the command descriptors of the viewer as a datacontext. I use visibilitytobooleanconverter which is provided in telerik. Silverlight shows up in programs so ive tried to uninstall and then install again with the same outcome. If either is true, i just run the action since there is no need to use the dispatcher. We discussed some of the reasons, but i felt this would be a good topic to share with everyone. Threading considerations for binding and change notification in silverlight 5 pete brown 10 january 2012 a reader of my silverlight 5 book recently reached out to me about threading and why i create some objects on the ui thread in the examples. A reader of my silverlight 5 book recently reached out to me about threading and why i create some objects on the ui thread in the examples. Silverlight tabcontrol getting started telerik ui for. Silverlight application with dispatcher and asynchronous. The proper way to deal with this situation is to dispatch the requested ui related operation to the ui thread using the dispatcher class. So recently i created this class with a single method, begininvoke. Fortunately, silverlight makes it very easy to find your dispatcher, because it is a property on any uielement that exists, including your own user control.