C# WinForms – How to Update a Windows Form GUI from Another Class

c++multithreadingwinforms

how do you update a win forms control (ex. label, progress bar) from another class which created the GUI but not in the creating thread? (for example, an event handler of Program.cs)

I've found several posts regarding updating GUI from another thread using Invoke() method, but what i've found so far only works if the codes are written in the same class as the form

http://www.yoda.arachsys.com/csharp/threads/winforms.shtml

Best Answer

You need to call the Invoke method on the form. For example:

private void someMethod() {
    myOtherForm.Invoke(new MethodInvoker(delegate() {
        // update things in myOtherForm here
    }));
}

If you don't need the updates to be finished before returning back to the method, you should use BeginInvoke instead of Invoke.

Related Solutions

C# – How to Update the GUI from Another Thread

The simplest way is an anonymous method passed into Label.Invoke:

// Running on the worker thread
string newText = "abc";
form.Label.Invoke((MethodInvoker)delegate {
    // Running on the UI thread
    form.Label.Text = newText;
});
// Back on the worker thread

Notice that Invoke blocks execution until it completes--this is synchronous code. The question doesn't ask about asynchronous code, but there is lots of content on Stack Overflow about writing asynchronous code when you want to learn about it.

C# – Update GUI from Another Thread and Class in Windows Forms Application

Check the InvokeRequired of the Control class, and if it's true, then call the Invoke and pass in a delegate (usually an anonymous method) that does what you want to do on the client's thread.

Example:

public void DoWork(Form form)
{
    if (form.InvokeRequired)
    {
        // We're on a thread other than the GUI thread
        form.Invoke(new MethodInvoker(() => DoWork(form)));
        return;
    }

    // Do what you need to do to the form here
    form.Text = "Foo";
}

Best Answer

Related Solutions

C# – How to Update the GUI from Another Thread

C# – Update GUI from Another Thread and Class in Windows Forms Application

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