Question

I want to create a window and show some image display (like animation based on SetTimer()) on window created using CreateWindow() function. But it should be created on separate thread and should remain alive until user closes this. I tried but was unsuccessful.

EDITED

I just googled I found this link How To Create Windows in a Multithreaded Application but one thing i want to know when Window Procedure get invoked. if it is invoked by system then how i can call it from my child thread.

Answer 1

Windows (represented by HWNDs) in Windows have a thread affinity. Their WindowProc is always invoked in the context of the thread they are created with.

As such, they are a convenient way to serialize calls between threads as the PostMessage and SendMessage APIs can be called from any thread in the application, but the WindowProc will get executed in the context of the original creating thread.

Because WM_TIMER messages posted to message queues are the mechanism by which SetTimer works, again you need to be careful when calling SetTimer in a multithreaded app – The timer messages will be processed by the calling thread (if the hwnd parameter is NULL) or the window’s thread.

You also, as a result, have to be careful to put a message loop on every thread that might create windows, or want to process timers.