WPF Command-Canexecute-Revalidation

Question

I've just written a little game using wpf. There is a matrix of cells I can click. The click events are working through a DelegateCommand. The problem is that the canexecute method is not called. I always have to click somewhere on the window first. I never had problems with my commandclass because I was using this:

event EventHandler ICommand.CanExecuteChanged
{
    add { CommandManager.RequerySuggested += value; }
    remove { CommandManager.RequerySuggested -= value; }
}

I also tried to call CommandManager.InvalidateRequerySuggested(); but that also does not work. The Cells are clickable if the currentuser that is allowed to click it, is the local user of my pc(it is multiplayer). So I called InvalidateRequerySuggested after I get the Message from the network that I am the "currentplayer" now.

private void SetTurn(TurnMessage message)
{
    CurrentPlayer = GetPlayer(message.PlayerID);
    System.Windows.Input.CommandManager.InvalidateRequerySuggested();
}

That will have this affect:

    public bool HasTurn
    {
        get { return CurrentPlayer != null && CurrentPlayer.PlayerID == Player.PlayerID; }
    }

My Command Can-Execute looks like this:

private bool CanMatrixClick(Object param)
{
    return Main.PlayerViewModel.HasTurn;
}

So has anyone a clean and easy solution for this problem? I really could not find anything which I had not tried already.

Answer 1

DelegateCommand have method RaiseCanExecuteChanged() which you can call manually to fire the CanExecute Event -

private void SetTurn(TurnMessage message)
{
    CurrentPlayer = GetPlayer(message.PlayerID);
    YourCommand.RaiseCanExecuteChanged();
}

Answer 2

Only for others, who get maybe into this problem: Be carefull where you call InvalidateRequerySuggested. You have to call it in the UI-Thread.

For me the dispatcher solved the problem

                Application.Current.Dispatcher.BeginInvoke ((Action) (() =>
                {
                    CommandManager.InvalidateRequerySuggested();
                }));