Avoiding InvokeRequired

Introduction

This minor article is an enhancement to the excellent piece of work by Pablo Grisafi.  The goal is to enhance Pablo's code to work in cases where controls are not all created on the same (usually "UI") thread. 

Using the code  

The enhancement is relatively minor and virtually everyone with enough understanding of delegates and generics could easily enhance Pablo's version as I did below.  While Pablo's version works for 95+% cases, in very special circumstances, a control might need to be created on another thread, thus requiring InvokeRequired check on that control's property -- not on the form's.  The idea behind these enhancements is to allow the extension method to handle this type of scenario.  

The code below helps ensure that all controls are updated on the thread on which they were created even when they were created on different threads.  

static class ControlExtensions
{
  public static void InvokeOnOwnerThread<T>(this T control, Action<T> invoker) where T : Control
  {
    if (control.InvokeRequired)
      control.Invoke(invoker, control);
    else
      invoker(control);
  }
}  

The code that uses this extension method would look like this: 

private void UpdateFormTextFromSomeThread(string message)
{
  this.InvokeOnOwnerThread((form) => form.Text = message);  
}

History

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