WPF/C# Don't block the UI

Question

I\'ve an existing WPF application, which has several sections. Every section is a UserControl, that implements an interface.

The interface specify two methods:

Answer 1

You should implement a dependency property "IsBusy" of type bool, that you set to TRUE before starting the BackgoundWorker, and then to FALSE when the work is complete.

On the UI, you bind to that property whatever functionality you want disabled during the processing(like the button for loading the next view, etc.); or maybe showing a "Cancel" button.

You should not "wait" for the operation to complete, you can retrieve the result in an additional variable, that the BackgroundWorker will set:

    BackgroundWorker _bw;
    bool _returnValue = false;

    private void button_Click(object sender, RoutedEventArgs e)
    {  // if starting the processing by clicking a button
        _bw = new BackgroundWorker();

        IsBusy = true;

        _bw.DoWork += new DoWorkEventHandler(_bw_DoWork);

        _bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(_bw_RunWorkerCompleted);

        _bw.RunWorkerAsync();
    }

    void _bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        IsBusy = false;

        // retrieve the result of the operation in the _returnValue variable
    }


    void _bw_DoWork(object sender, DoWorkEventArgs e)
    {
        _returnValue = UnloadData();
    }

    private bool UnloadData()
    {
        if (...)
        {
            LaunchTimeConsumingMethod();
            return true;
        }
        else
            return false;

        //etc ...
    }

    public bool IsBusy
    {
        get { return (bool)GetValue(IsBusyProperty); }
        set { SetValue(IsBusyProperty, value); }
    }

    // Using a DependencyProperty as the backing store for IsBusy.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty IsBusyProperty =
        DependencyProperty.Register( ... )