Hello, I have some screen coordinates that refuse to be converted to client coordinates and I don't know why. Here is my code: POINT p; GetCursorPos(&p); if(ScreenToClient(hwndMain,&p)) do something The GetCursorPos works and gets me the screen coordinates for my mouse clicks. However, the ScreenToClient will not covert them. Any ideas why? Thanks

Hi,

I don't know how it would fail, exept if hwndMain is not a valid window handle. Anyway, try using GetLastError() when it fails to get the error code. Once you have it, you can look it up using the "Visual C++ Error Lookup" tool, or MSDN states that it is possible to use FormatMessage() to get a string corresponding to the error...

Good luck!

Thanks for your help. I've never heard of either of those methods but they will greatly ease my debugging :)


Turns out you were right. It was an invalid window handle.