Problems in C++ (WIN32 API)

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Original post by Deyja The 'window long' is just an arbitrary bit of data that the application can set when creating the window. In your case, when you create the window, you cast a pointer to that window to long and store it there. Later, you can retreive it using the handle your message handler receives and cast it back into a pointer.

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Original post by santonel OK i've figured out that it isn't just the function pointer. Any attempt to call a member function from the wccwindow::message_proc crashes the program. Does the fact that the wccwindow::message_proc function itself was called by a static function?(wccwindow::message_route). And if so, how can i get around this problem?

SetWindowLong(window,GWL_USERDATA, reinterpret_cast<long>(this));RegisterClassEx(&wnd);window = CreateWindowEx(exstyle,windowname,windowtitle,windowstyle,x,y,xlen,ylen,parent,(HMENU)menu,instance,NULL);}

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Original post by rmsimpson Quote: Original post by santonel OK i've figured out that it isn't just the function pointer. Any attempt to call a member function from the wccwindow::message_proc crashes the program. Does the fact that the wccwindow::message_proc function itself was called by a static function?(wccwindow::message_route). And if so, how can i get around this problem? You do realize you're reinventing the wheel, right? ATL/WTL has a phenomenally powerful set of windowing template classes without the MFC bloat, and has taken care of just about every scenario you might dream up. ATL provided the base window templates, and WTL is built on top of them. You are going to have a lot of problems implementing your class, for many reasons. Here's a few problems I saw immediately: *** Source Snippet Removed *** First, you're calling SetWindowLong() on a window that doesn't exist until CreateWindowEx() is called. Second, even if you called SetWindowLong() after creating the window, the windowproc has already received about 10-20 messages and dispatched them. Of course, when you receive any message in your windowproc, you must call GetWindowLong() to get the pointer to wccwindow, and if it is NULL (which it MAY BE) you must call the DefWindowProc without trying to dispatch the message. The fundamental problem you'll face is that the static windowproc doesn't have any decent way of getting a pointer to the window's wccwindow instance when the window is being created -- and there are literally dozens of messages that need dispatching during the creation process before control ever returns to you from CreateWindowEx(). There are lots of ways to do this, some of them more technical than others. Some involve extending the WNDCLASSEX struct, some involve WM_NCCREATE, but most all boil down to storing the wccwindow pointer with the window's data via SetWindowLong. ATL/WTL takes a different approach entirely, and a very cool one, but you'll hurt your head trying to figure it out -- it involves some clever inline assembly. I'll give you credit for wanting to figure this stuff out for yourself (I wrote straight C windows for years before switching to WTL) but I just hate seeing someone hammering away with a chisel to make a wheel when there's a perfectly good Ferrari in their garage. You said you didn't want to learn MFC, which I can't blame you for ... so give WTL a try. To use the Ferarri analogy: It will take you longer to build the wheel than it will to learn how to drive a stick. Robert

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Original post by santonel I called the set window long before the createwindowex because i figured it would catch these 10-20 messages that the createwindowex generates. Also for now since I want this to be really basic I'm not interested in most of the events generated by CreateWindowEx. Just the basic stuff like WM_MOVE or WM_SIZE and the like. What I need to figure out is why the program crashes when I call a member function in either the message_route or message_proc functions. Anywhere else it works fine.

LRESULT CALLBACK WndProc(...){  AWindowClass pwin = (AWindowClass*)GetWindowLong(hwnd, GWL_USER);  switch (msg)  {    case WM_CREATE: // or WM_NCCREATE      {        AWindowClass * pwin = new AWindowClass(...);        SetWindowLong(hwnd, GWL_USER, (long)pwin);        pwin->OnCreate(...);      }      return 0;    case WM_PAINT:      {        pwin->OnPaint(...);      }      //...       return 0;  }  return DefWindowProc(...);}

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Original post by rmsimpson Quote: Original post by santonel I called the set window long before the createwindowex because i figured it would catch these 10-20 messages that the createwindowex generates. Also for now since I want this to be really basic I'm not interested in most of the events generated by CreateWindowEx. Just the basic stuff like WM_MOVE or WM_SIZE and the like. What I need to figure out is why the program crashes when I call a member function in either the message_route or message_proc functions. Anywhere else it works fine. In your window proc you must do several things: 1. Call GetWindowLong() to get a pointer to the window class 2. If the pointer is null, which it can be sometimes, you must call DefWindowProc() and exit (unless you receive WM_NCCREATE, in which case proceed to #4) 3. If it is not null, you cast the pointer to a wccwindow* and call the method on the pointer that you want. 4. The last parameter of CreateWindowEx() should be a pointer to the wccwindow instance. When your wndproc receives WM_NCCREATE, you must store the LPARAM value using SetWindowLong() -- this is your pointer to the class instance.