Wpf MouseLeftButtonDown - How to know internal processing is finished

Question

As part of some functionality I require in a UserControl I need to capture mouse messages. Capturing part of the screen that is outside of the application. To start the capture initially I had a simple button and it all worked fine.The SetHook works and I can see the WM_xxxx messages and handle them accordingly.

private void Capture_OnClick(object sender, RoutedEventArgs e)
    {
        getLeftClicks = _getLeftClicks.First;
        _hookID = SetHook(_proc);
    }

Now I use clicking on an image to start the capture process but I have to insert a Thread.Sleep statement into the handler for it to work.

    private void Capture_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (_hookID != null)
            UnhookWindowsHookEx(_hookID);
        getLeftClicks = _getLeftClicks.First;

        Thread.Sleep(200);   // need to wait for this mousedown to finish before trying to hook the mouse 
        _hookID = SetHook(_proc);            
    }

What I would like to know is there some Windows property I can examine to see if everything has finished before setting my hook in lieu of the arbitrary 200ms figure I have found that works. If needed I will post more code but the guts of the problem lies here.

Thanks, Jim

Answer 1

Try using the MouseLeftButtonUp event instead of MouseLeftButtonDown.