How to process PropertyGrid changes with Invoke on InvokeRequired?

Question

I'm working with COM object provided by Activator.

It also provide events when properties is changed there but my PropertyGrid can't update them in-time because it comes from another thread and I'm getting :

A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll
A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll
A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

How to automate invoking property update when internal onChange is caused by external thread?

possible fix is: CheckForIllegalCrossThreadCalls = false;

But is it possible to handle this situation in proper way?

Answer 1

Let's say you are binding your object to a PropertyGrid, whenever a Property of your object get changed, it should fire a PropertyChanged event in the GUI thread, in order for the PropertyGrid to update properly.

It is your duty to marshal a Property setter to GUI thread. If you can have a link to any Control, use that Control to invoke. Otherwise, a general solution is create a dummy control at the beginning and use it for invoking.

public partial class ControlBase : UserControl
{
    /// <summary>
    /// Dummy control, use for invoking
    /// </summary>
    public static Control sDummyControl = null;

    /// <summary>
    /// Constructor
    /// </summary>
    public ControlBase()
    {
        InitializeComponent();

        if (sDummyControl == null)
        {
            sDummyControl = new Control();
            sDummyControl.Handle.ToString(); // Force create handle
        }
    }
}

In your parent object:

    public event PropertyChangedEventHandler PropertyChanged;
    protected void RaisePropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (PropertyChanged == null)
        {
            return;
        }
        Control c = ControlBase.sDummyControl;
        if (c == null)
        {
            PropertyChanged(sender, e);
        }
        else
        {
            if (c.InvokeRequired)
            {
                c.BeginInvoke(new PropertyChangedEventHandler(RaisePropertyChanged), new object[] { sender, e });
            }
            else
            {
                PropertyChanged(sender, e);
            }
        }
    }

In your object:

    public string Name
    {
        get { return _name; }
        set { _name = value; RaisePropertyChanged(this, new PropertyChangedEventArgs("Name")); }
    }

HTH, Huy