Limitations on Win32 API functions

Hi friends, completely new on the Win32 API programming. I've learned two functions and their use in C [WndProc() & WinMain()]. I believe that one develop in this environment if they need to write programs which will have windows, dialog boxes, buttons, i/o (mouse, keyboard, etc). My question is, can i use some of the API functions in my own development tools/environment? I'm busy learning learning to write programs using QUEST (a Computer Based Training tool) which has it's own frame windows where one can insert/draw objects (pictures/boxes/etc). My first task is to draw a line using a mouse, or a shape. So there only solution i have in my mind is to use MoveToEx(), and LineTo() functions to draw markers and use the WinAPI functions to handle mouse or window messages.

... Usually, one has to first define WndProc() function to handle messages and then use WinMain() to create a window. In my case, there's no need to create a new window in the WinMain() function, QUEST has a function GetFrameWindow() which return a handle (HWND). Can i use the WinMain() function but eliminate all the code which creates a new windows, perhaps leave the following lines...

Code:

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ShowWindow(hWnd,iCmdShow);
UpdateWindow(hWnd);
while (GetMessage(&msg,NULL,0,0))
{
    TranslateMessage(&msg);
    DispatchMessage(&msg);
}

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CreateWindow() is what actually creates the window. ShowWindow() displays it. that while loop is the message loop that actually handles displatching the messages to the window procedure (WindProc) for the window you specify. In yoru case you are specifying NULL which means the window for the callign thread. If you want ot manipulate the window that is already created by the application, you need to retrieve a handle to that window, and use that handle in the API calls.

Quote:

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Originally Posted by abachler

CreateWindow() is what actually creates the window. ShowWindow() displays it. that while loop is the message loop that actually handles displatching the messages to the window procedure (WindProc) for the window you specify. In yoru case you are specifying NULL which means the window for the callign thread. If you want ot manipulate the window that is already created by the application, you need to retrieve a handle to that window, and use that handle in the API calls.

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That's exactly what i though Abachler. There's is a function GetFrameHandle() which returns HWND, meaning i can then use it in WinMain()... But then my concern is the function ShowWindow(). When i run QUEST (the tool am developing in) it automatically runs the windows/frames anyway... Someone said i need to override or replace the WndProc() function with the one QUEST uses (apparently tools which have their on windows/frames should have their own Windows Procedure function to run frames..?). Topic under "Subclassing using SetWindowLong()....

Yes, it's possible to specify a new WindowProc using SetWindowLong. It's called subclassing.
But what is need of such a thing? Is there some behavior you need to override?

Quote:

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Originally Posted by Elysia

Yes, it's possible to specify a new WindowProc using SetWindowLong. It's called subclassing.
But what is need of such a thing? Is there some behavior you need to override?

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I need to have control over my frames (draw objects, animate them, listen to messages, etc). But this has to be done on existing frame windows (no need to CreateWindow() in WinMain() )... QUEST tool i'm using uses its own frames

I see. In that case, you can specify your own WindowProc using SetWindowLong. It will returns the previous WindowProc function, so you can also use a function pointer and call the old windowproc for any messages your own function doesn't handle.