Question

Possible Duplicate:
How To Start And Stop A Continuously Running Background Worker Using A Button

I have 2 buttons the first one it’s name “Continuous” .. the second one “Stop”

I want to call a method when press the continuous button :

private void continuous_Click(object sender ,EvantArgs e) 

      {   

     // continuous taking pictures ...

      }

my question is : how can I stop the execution by pressing the stop button ??

I’ve written a code to take a picture and I’ve succeeded to take pictures …
now I want the camera to take continuous snapshots … but if I press stop button the camera should stop taking pictures …

I’ve used BackGroundWorker but the code does not work !!!

this is the code :

private void ContinousSnaps_Click(object sender, EventArgs e)
    {

        Contiguous.DoWork += Contiguous_DoWork;
        Contiguous.RunWorkerCompleted += Contiguous_RunWorkerCompleted;
        Contiguous.RunWorkerAsync();
    }

    private void Contiguous_DoWork(object sender, DoWorkEventArgs e)
    {
        for (int i = 0; ; i++) TakeSnapShotCommand();
    }

    private void Contiguous_RunWorkerCompleted(object sender,
                                   RunWorkerCompletedEventArgs e)
    {
        MessageBox.Show("complete");
    }

    //------------------------------------------------------------------//

    private void Stop_Click(object sender, EventArgs e)
    {
        Contiguous.CancelAsync();


    }

  //--------------------------------------------------------------------//

how can I achieve the result that I want ?!

Answer 1

Try and see if this is going to work:
In your _DoWork event:

    private void Contiguous_DoWork(object sender, DoWorkEventArgs e)
    {
        for (int i = 0; ; i++)
        {
            if (Contiguous.CancellationPending)
            {
                e.Cancel = true;
                return;
            }
            TakeSnapShotCommand();
        }
    }

And in the Stop_Click to the following:

    private void Stop_Click(object sender, EventArgs e)
    {
        if (Contiguous.WorkerSupportsCancellation)
            Contiguous.CancelAsync();
    }

Also make sure you allow cancellation (and if you want to take my advice here – move these event registrations in a the form load, so they will be executed once, not every time the button is clicked – leave just the Continuous.RunWorkerAsync()):

    // your form load <---
    private void Form1_Load(object sender, EventArgs e)
    {
        Contiguous.DoWork += Contiguous_DoWork;
        Contiguous.RunWorkerCompleted += Contiguous_RunWorkerCompleted;
        Contiguous.WorkerSupportsCancellation = true; // allowing cancellation
    }

    private void ContinousSnaps_Click(object sender, EventArgs e)
    {
        // not a bad idea if you disable the button here at this point
        Contiguous.RunWorkerAsync();
    }