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Questions tagged [invokerequired]

InvokeRequired refers to the .NET WinForms Control.InvokeRequired method, which needs to be checked before UI updates are made.

In .NET WinForms Control.InvokeRequired needs to be checked before UI updates are made.

It will be True when the handle has been created and the current thread is not the thread on which the control was created.

When it is True, you need to perform the UI update using a delegate call through Control.Invoke which will marshal the delegate onto the UI thread.

MSDN link - Note that other frameworks can implement this concept using the System.ComponentModel.ISynchronizeInvoke interface (though something is still needed to actually marshal the calls back to another thread).

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Winforms data-binding to business objects in a multi-threaded scenario without InvokeRequired?

For example, I've got a business object Person: class Person : INotifyPropertyChanged { string Name { get; set; } DateTime DateOfBirth { get; set; } } // ^ abbreviated for better legibility; implementation would be trivial And I've got some…
stakx - no longer contributing
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Trying to setup tomcat to use servlets

I'm following instructions found in Java All in one for Dummies 3rd edition I downloaded tomcat and followed all the steps for setting it up, step 6 says. "Modify the web.xml file to enable the invoker servlet" It says to find the lines of code…
user3527058
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Multiple Invokes and thread safety

Lets assume that I have worker threads that increment a value on some control. Since an invoke is required, all the increments need to be done on the GUI thread. For that I use BeginInvoke. My question is: Can a race condition break the increment of…
Dennis Kuypers
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How can I ensure that InvokeRequired will not aborted?

This is my code: foreach (var pathCartella in folderList) { try { // some operation if (txtMonitor.InvokeRequired) { txtMonitor.BeginInvoke(new MethodInvoker(delegate { txtMonitor.AppendText(pathCartella…
markzzz
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Why is a value copy of MainForm created when method is called or invoked cross thread?

Update: I think it has something to do with lazy instantiation of the window handle for MainForm - but haven't been able to work out quite how that would result in the behavior seen here. The application requests data via 3rd party COM interface…
Pauli Price
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Updating a label from multiple background threads

I'm working on a football simulator and i have 9 matches in backgroung on separate threads. And in the method what's in the heart of each thread, there is an event. And when that even occurs (when a goal is "kicked"), I want to update a label (named…
user1852051
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Progressbar on separate form freezes/crashes when updating

I have a weird exception that I can't seem to debug. For anyone about to suggest worker threads I am prohibited from using them at my work... I asked why not myself and received a vague answer and clear directions to avoid it... anyways... I decided…
Goat
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Invoke without Func in Property's getter for .Net 2.0

I would like to use Invoke in getter, how to do it when using .Net 2.0 not e.g. 4.0? For .Net > 2.0 we can use Func and what is replacement for .Net 2.0? Here is example for .Net 4.0 (from link) public ApplicationViewModel SelectedApplication { …
jotbek
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What happen with my InvokedRequired?

What wrong with my code ?? Why it not go to true statement ?
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How do I use Control.Invoke if I need to pass in a mixture of reference and value types?

How do I do something like the following? private delegate void RenameOperation(string name, string uniqueName, int position); private void AssignColumnNames(string name, string uniqueName, int position) { …
Richard1987
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Why does the StatusBar.Invoke method not work for a ToolStripProgressBar?

I have recently been working on an application where I wanted to display the progress of another thread in the status bar via the ToolStripProgressBar control that is contained in the StatusBar control. Before I attempted to add this code I…
JRSofty
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InvokeRequired returns false when the form has been created

This question is about how to get execution back on the UI thread - InvokeRequired is returning false when I think it should be returning true. I have a simple Windows Forms app for testing and Debug.Writeline messages to the output window in…
Kevin
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C# Winform hangs on Invoke() due to InvokeRequired() acting on opening Form from non UIThread

I have a parallel thread requiring to open a form using Form.Show() or, worst case, Form.ShowDialog(owner). I use the classic WinForm pattern as: if (owner != null && owner.InvokeRequired) owner.Invoke(new Action(() => { xForm.Show(owner); })); …
Federico Ballan
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Removing Text with an Invoke?

So, the documentation that I've found online so far regarding the Invoke property doesn't seem to be particularly good, which is actually kind of annoying, believe it or not. I understand what Invoke does - you can't safely access the GUI directly,…
Kulahan
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Datagridview InvokeRequired works slow

I'm developing software for logging data from RS232. There is a lot of data received each millisecond. Received data is stored in datagridview, you can see on attached picture. For filling data I use dataGridView1.InvokeRequired from…
uriy
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