Update WinForm interface from a different thread

NicolD — Sat, 29 Dec 2007 20:56:00 GMT

Well, this is a typical issue when you have a thread that works (i.e. a Workflow) and a UI that needs to be updated.

Let assume that you have a WinFom and you need to update its windows Title from another thread. The other thread needs to call "UpdateTitle" public method of current Form instance. If you write the following code:

public class MainForm : Form
{
   ...
   
   void UpdateTitle(string newTitle)
   {
      this.Text = newTitle;         
   }

   ...
}

UpdateTitle will work only if you call the method from the UI thread.

In order to make this call thread safe, I found two ways, choose the one that fits your needs:-)

Method ONE: Using a delegate

public class MainForm : Form
{
   ...
   
   private delegate void UpdateTitleDelegate(string s);
   void UpdateTitle(string newTitle)
   {
   if (this.InvokeRequired)             
      this.Invoke(new UpdateTitleDelegate                 
         (this.UpdateTitle), newTitle);         
   else         
      {             
      this.Text = newTitle;         
      }
   }

   ...
}

Method TWO: using MethodInvoker

public class MainForm : Form
{
   ...
      
   void UpdateTitle(string newTitle)
   {
   if (this.InvokeRequired)             
      this.Invoke(new MethodInvoker(delegate()
      {
      this.Text = newTitle;    
      }));
   else         
      {             
      this.Text = newTitle;         
      }
   }
   ...
}

For more information have a look to Control.InvokeRequired property on MSDN.

Avoid threads deadlock

NicolD — Wed, 03 Oct 2007 16:28:00 GMT

On this month's issue of MSDN Magazine, Stephen Toub describe the class DdMonitor. DdMonitor implements almost all interfaces exposed by .NET System.Threading.Monitor class but includes deadlock detection capabilities too.

With the objective to make available a lock(...) keyword replacement, a static DdMonitor.Lock(...) is implemented too.

A System.Threading.Monitor replacement to avoid threads deadlocks

NicolBlog : Threading

Update WinForm interface from a different thread

Method ONE: Using a delegate

Method TWO: using MethodInvoker

Avoid threads deadlock