Question

I am using vlc to capture a video and audio stream and display it in a picture box. The new libvlc api no longer supports the double click/fullscreen in windows and I need to have that functionality. I don’t have a problem creating a new form, adding a picture box to it and showing the video in that, but I do have a problem capturing the double click event in the vlc window in order to tell the app to make the video feed fullscreen. I found out that I need to use a hook. I have the hook installed and all of that. My only problem is, I only want to handle the message if it is a click in one of my pictureboxes. So, from my callback method, here is what I need:

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0 &&  MouseMessages.WM_LBUTTONDOWN == (MouseMessages)wParam)
        {
            //Here I need to grab the Handle of the control that the mouse was clicked in.
            //Now I need to cast the Control.FromHandle() as PictureBox.
            // then if(control != null)
            // send the event to the form via. form.on_double_click or whatever.


        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

Any ideas?

Ubdate:

Here is what I’ve got now, look good?

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0 &&  MouseMessages.WM_LBUTTONDOWN == (MouseMessages)wParam)
        {
            MOUSEHOOKSTRUCT msg = (MOUSEHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MOUSEHOOKSTRUCT));

            PictureBox control = Control.FromHandle(msg.hwnd) as PictureBox;

            if (control != null)
            {
                PreviewForm.pbox_MouseDoubleClick(control, new MouseEventArgs(MouseButtons.Left, 2, msg.pt.x, msg.pt.y, 0));
            }                
        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

Update

Another little gotcha for those coming in from Google. In Windows 7, If you attach your debugger to the callback, it will appear to be broken. There is a timeout value on hook responses, if that timeout ever expires, your hook will never fire again for the life of the hook. From my reading, it appears that this is a Windows 7 issue while it works on Windows Vista and less. The break point in your debugger will most certainly force this timeout to expire and as a result, your callback will only be called once. However, it will work fine without the break point.

Answer 1

Your lParam is a pointer to a MOUSEHOOKSTRUCT which will contain the window handle.

You can use the definition a Pinvoke.net and marshal lParam to that type.