Question

I’m implementing producer/consumer problem. the code looks like this:

void producer()
{
  // produce item
  // update some control in form
}

void consumer()
{
  // consume item
  // update some control in form
}

producer and consumer methods are executed in different threads from the one that created my form, so I can’t update controls in form. I tried following code:

void producer()
{
  // produce item
  // put the work to be done in a queue
  this.Invalidate();
}

void consumer()
{
  // consume item
  // put the work to be done in a queue
  this.Invalidate();
}

So now I have to detect if the form has been invalidated. I looked in Form’s event list, and the best thing I could find was paint event. I put the code that got the job done, and it works fine. The problem is I somehow doubt I’ve done this the right way although it works. I think paint is not the right place to do the job, as what I’m doing it not just painting. I was wondering if there’s a better way to do this.

Edit — Snippet for Invalidated event handler not working

public Form1()
{
  InitializeComponent();
  this.Invalidated += InvalidateEventHandler;
}
void producer(object o)
{
  // produce
  // put work in queue
  this.Invalidate();
}
public void InvalidateEventHandler(object sender, InvalidateEventArgs e)
{
  // Do Stuff to form -- Where exception raises
}

Answer 1

Invalidate is intended to trigger a Paint.

What you need is to Control.Invoke() your own refresh method on he form.

Edit:

Your non-GUI threads should not even call Invalidate(), they can’t touch the GUI.

You can write your own ProcessData() form-method and from the Prod/Cons call mainForm.Invoke(ProcessData)

Then ProcessData() is responsible for thread-safe access to the data and for Invalidating the GUI