Question

I have Windows Forms application and I need to capture the mouse movements outside my window. My simplified code in my window class is:

private void ButtonOnClick(object sender, EventArgs e)
{
    Capture = true;
    MouseMove += OnMouseMove;
}

private void OnMouseMove(object sender, MouseEventArgs e)
{
    Console.Out.Write("!");
}

As you see, when user presses a button, my program should start tracking mouse (even if it is outside of window – this is a key featue!) But I get really strange behavior. If I move mouse inside the window, everything is great, ! are written to console. But when I move mouse outside of the window, only OnMouseMove is called only once (and the point is really outside). Then if I move mouse anywhere outside of the window it is not called anymore. If I return mouse back to window, everything is perfect. Move away – 1 message, move in the window – OK.

Can anybody help?

Answer 1

You would need a global mouse hook for that. I recommend that you first read something about hooks, eg. on MSDN. An example implementation in C# can be found at the CodeProject.

Hope that helps a bit.