Debugging from a different thread

Question

I have a progress bar which is bound to the "CurrProgress" and "Total" fields as follows:

    <ProgressBar Height="29" HorizontalAlignment="Left" Margin="12,32,0,0" Name="pbSendingData" VerticalAlignment="Top" Width="346"">
        <ProgressBar.Value>
            <Binding ElementName="this" Path="CurrProgress" />
        </ProgressBar.Value>
        <ProgressBar.Maximum>
            <Binding ElementName="this" Path="Total" />
        </ProgressBar.Maximum>
    </ProgressBar>

I also have a "Worker thread" that is doing the heavy lifting while trying to keep the UI responsive:

    private void worker_DoWork(object sender, DoWorkEventArgs e)
    {          
        const int sizeOfPacket = 30;
        Total = allEntries.Count();

        var arrayOfEntries = Split(allEntries, sizeOfPacket); //Split array into small arrays

        //Send parts to server separately:
        foreach (var entries in arrayOfEntries)
        {
            svc.ProcessPMData(Globals.username, Globals.password, entries.ToArray());
            CurrProgress += sizeOfPacket;
            Thread.Sleep(100);
        }

        Thread.Sleep(100);
    }

I have ensured that the "Total" and "CurrProgress" dependency properties are thread safe (though I may have not done it correctly):

    //Dependency properties:
    public int CurrProgress
    {
        get
        {
            return (int)this.Dispatcher.Invoke(
                DispatcherPriority.Background,
                (DispatcherOperationCallback)delegate
                {
                    return GetValue(CurrProgressProperty);
                }, CurrProgressProperty);

        }

        set
        {
            this.Dispatcher.BeginInvoke(DispatcherPriority.Background,
                (SendOrPostCallback)delegate { SetValue(CurrProgressProperty, value); },
                value);
        }
    }


    public static readonly DependencyProperty CurrProgressProperty =
        DependencyProperty.Register("CurrProgress", typeof(int), typeof(DataSender), new PropertyMetadata(0));


    public int Total
    {
        get
        {
            return (int)this.Dispatcher.Invoke(
                DispatcherPriority.Background,
                (DispatcherOperationCallback)delegate
                {
                    return GetValue(TotalProperty);
                }, TotalProperty);

        }

        set
        {
            this.Dispatcher.BeginInvoke(DispatcherPriority.Background,
                (SendOrPostCallback)delegate { SetValue(TotalProperty, value); },
                value);
        }
    }

    public static readonly DependencyProperty TotalProperty =
        DependencyProperty.Register("Total", typeof(int), typeof(DataSender), new PropertyMetadata(0));

When trying to debug, I first tried to check what was the value of the progress bar from the immediate window:

pbSendingData.Value

I was greeted with this error message...

The error made sense, so I tried another way:

this.Dispatcher.Invoke((Action)(() =>      {   MessageBox.Show(pbSendingData.Minimum);     }));

At this point I discovered the immediate window does not support lambda expressions.

The watch window was also unhelpful:

While debugging, I want to get the value of a UI components from the immediate/watch window from a different thread. Is this possible? As a sidenote, if there is anything scandalous in my code, I'm open to suggestions. I'm a bit new to WPF.

Answer 1

1. What element is this "this" element you are referring to in the Bindings of the progress bar properties?

2. Most code I see uses the dispatcher and delegates from the worker thread and not within the property getters/setters as this might result in some ugly race conditions and deadlocks or similar nasty stuff.

3. The "DoWork" method seems to belong to a BackGroundWorker class. Why not using the "ReportProgress" feature? It includes thread synchronization...