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POCreateWindowEx failing
 

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  1. POCreateWindowEx failing
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    <p>I'm following the NeHe gamedev tutorials (while altering them to be OO) and I've run into a problem with the CreateWindowEx demo (http://nehe.gamedev.net/tutorial/creating_an_opengl_window_(win32)/13001/).</p> <p>I'm trying to pass the WndProc a pointer to my Window object via the lpParam (as detailed here: <a href="http://web.archive.org/web/20051125022758/www.rpi.edu/~pudeyo/articles/wndproc/" rel="nofollow">http://web.archive.org/web/20051125022758/www.rpi.edu/~pudeyo/articles/wndproc/</a>) but if I attempt to do so, CreateWindowEx fails with GetLastError returning 1400 - ERROR_INVALID_WINDOW_HANDLE.</p> <p>I'm a complete beginner at the windows API and have exhausted every method I know of resolving this, please could you point out my mistake here? Relevant code below:</p> <pre><code>LRESULT CALLBACK cog::WindowProc(HWND window, UINT msg, WPARAM wParam, LPARAM lParam) { // Member method as windowproc: http://web.archive.org/web/20051125022758/www.rpi.edu/~pudeyo/articles/wndproc/ if(msg == WM_NCCREATE) { LPCREATESTRUCT cs = (LPCREATESTRUCT)lParam; SetWindowLong(window, GWL_USERDATA, (long)cs-&gt;lpCreateParams); } cog::Window* w = (cog::Window*)GetWindowLong(window, GWL_USERDATA); if(w) { return w-&gt;windowProc(msg, wParam, lParam); } else { return DefWindowProc(window, msg, wParam, lParam); } } cog::Window::Window(int width, int height, int bits, bool fullscreen) : fullscreen(fullscreen), appInstance(GetModuleHandle(NULL)), active(FALSE) { // Generate a rectangle corresponding to the window size RECT winRect = {0, 0, width, height}; WNDCLASS winClass; winClass.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window. winClass.lpfnWndProc = (WNDPROC) cog::WindowProc; // WndProc Handles Messages winClass.cbClsExtra = 0; // No Extra Window Data winClass.cbWndExtra = sizeof(this); // Window Data - pointer to Window object winClass.hInstance = this-&gt;appInstance; // Set The Instance winClass.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon winClass.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer winClass.hbrBackground = NULL; // No Background Required For GL winClass.lpszMenuName = NULL; // We Don't Want A Menu winClass.lpszClassName = TEXT("OpenGL"); if(!RegisterClass(&amp;winClass)) { throw cog::WindowException(std::string("Failed to register class")); } if(this-&gt;fullscreen) { DEVMODE screenSettings; memset(&amp;screenSettings, 0, sizeof(DEVMODE)); screenSettings.dmSize = sizeof(DEVMODE); screenSettings.dmPelsWidth = width; screenSettings.dmPelsHeight = height; screenSettings.dmBitsPerPel = bits; screenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT; if(DISP_CHANGE_SUCCESSFUL != ChangeDisplaySettings(&amp;screenSettings, CDS_FULLSCREEN)) { if(MessageBox(NULL, "Cannot start in full screen mode - start in windowed mode instead?", "OpenGL", MB_YESNO | MB_ICONEXCLAMATION)) { this-&gt;fullscreen = FALSE; } else { throw cog::WindowException(std::string("Refused to launch program in windowed mode")); } } } DWORD winExStyle; DWORD winStyle; if(fullscreen) { winExStyle = WS_EX_APPWINDOW; winStyle = WS_POPUP; ShowCursor(FALSE); } else { winExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; winStyle = WS_OVERLAPPEDWINDOW; } AdjustWindowRectEx(&amp;winRect, winStyle, FALSE, winExStyle); /* * !! BLOWS UP AT THIS CALL - WindowException triggered */ if(!(this-&gt;window = CreateWindowEx( winExStyle, TEXT("OpenGL"), TEXT("OpenGL Testing"), winStyle, 0, 0, winRect.right - winRect.left, winRect.bottom - winRect.top, NULL, NULL, this-&gt;appInstance, this))) { throw cog::WindowException(std::string("Failed to create window")); } // ... cut here ... } int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE lPrevInstance, LPSTR lpCmdLine, int nCmdShow) { MSG msg; cog::Window* w = NULL; try { w = new cog::Window(100, 100, 16, TRUE); // ... cut here ... } catch(cog::Exception e) { MessageBox(NULL, e.what(), "Exception Raised", MB_OK | MB_ICONEXCLAMATION); } if(w) { delete w; } } </code></pre> <p>The member windowProc:</p> <pre><code>LRESULT CALLBACK cog::Window::windowProc(UINT msg, WPARAM wParam, LPARAM lParam) { switch(msg) { case WM_ACTIVATE: if(HIWORD(wParam)) { this-&gt;active = FALSE; } else { this-&gt;active = TRUE; } return 0;; case WM_SYSCOMMAND: switch(wParam) { case SC_SCREENSAVE: case SC_MONITORPOWER: return 0; } break; case WM_CLOSE: PostQuitMessage(0); return 0; case WM_KEYDOWN: this-&gt;keys[wParam] = TRUE; break; case WM_KEYUP: this-&gt;keys[wParam] = FALSE; break; case WM_SIZE: this-&gt;resize(LOWORD(lParam), HIWORD(lParam)); return 0; default: break; } return DefWindowProc(this-&gt;window, msg, wParam, lParam); } </code></pre>
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    1. COcan you post your declaration of your static WindProc and the Class member WndProc in your header file?
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    2. COThe static WindowProc was already there, but I've edited in the member windowProc now
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      1. USAlex Jeffrey
    3. COdo you have a declaration of the static WndProc in a header file in the cog namespace? if not, try without the namespace in the cpp file
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