Erroneous Mouse Coordinates Returned from Low Leve

Question

I'm building a WPF application with some hackery involved to embed Form elements on the same render layer. Essentially what I do is I render the form off-screen and have a mock-up of the form in a WPF image. I also have a low level mouse hook which steals events from the WPF application if they are destined for the Form mock-up and instead use PostMessage(...) to send the events off to the hidden form element.

If I return a non-zero value from my hook procedure indicating to eat the event (even if I still call all the mouse hooks in the queue), the cursor gets stuck in one position. I'm assuming this is because the cursor position gets handled in some sort of WPF application layer that the event isn't reaching.

I figured that it was fine to prevent the WPF application from knowing about the event at all because I could just set the cursor position myself-- there are coordinates attached to a mouse event after all. Unfortunately, it seems that these mouse coordinates are horribly incorrect. In fact, no matter where my cursor is located, I always receive the same coordinates.

Here is my code:

if (nCode >= 0){
    MOUSEHOOKSTRUCT_LL mousehookstruct_ll1 =
                    ((MOUSEHOOKSTRUCT_LL)Marshal.PtrToStructure(((IntPtr)lParam), typeof(MOUSEHOOKSTRUCT_LL)));
    if (mousehookstruct_ll1 != null) {
        if ((user != null) && user.SystemMouseHookProc(nCode, wParam, lParam, new Point(mousehookstruct_ll1.pt_x, mousehookstruct_ll1.pt_y), mousehookstruct_ll1.dwExtraInfo)) {
            return new IntPtr(1);// CallNextHookEx(this.MessageHookHandle, 1, wParam, lParam);// It doesn't matter that I don't call CallNextHook here.
         }
     }
 }
 GC.KeepAlive(this);
 return CallNextHookEx(this.MessageHookHandle, nCode, wParam, lParam);

}

Then in user.SystemMouseHookProc(...) I print out the correct cursor position followed by the coordinates pulled by the mouse hook, and the output is always something like the following:

Cursor: 523,578

{X=1985777551,Y=1985777602} //This coordinate never changes

That output is clearly wrong. What can I do to get the correct mouse coordinates from a mouse hook?

Thank you.

P.S. This solution is derived from a popular one online. Unfortunately, that solution didn't meet my needs so I've had to alter it to this form.

Answer 1

Any reason the static property System.Windows.Forms.Control.MousePosition won't work?