Buggy window behavior?

[Jerry Hammond]

Using one of the teach-yourself-you-dummie books I entered the following code to creat a window. It compiles just fine, without error or warning. But once I execute it my CPU usage pegs at 100%, the small Icon does not render, and clicking the close button fails to close the window. //Standard wondows include #include //Message Loop CallBack Function Prototype LRESULT CALLBACK fnMessageProcessor (HWND, UINT, WPARAM, LPARAM); //Function called automatically when the program starts int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { HWND hWnd; MSG msg; WNDCLASSEX wndclass; //Set up window class wndclass.cbSize =sizeof(WNDCLASSEX); wndclass.style =CS_HREDRAW | CS_VREDRAW; wndclass.lpfnWndProc =fnMessageProcessor; wndclass.cbClsExtra =0; wndclass.cbWndExtra =0; wndclass.hInstance =hInstance; wndclass.hIcon =LoadIcon(NULL, IDI_APPLICATION); wndclass.hCursor =LoadCursor(NULL, IDC_ARROW); wndclass.hbrBackground=(HBRUSH) GetStockObject (GRAY_BRUSH); wndclass.lpszMenuName=NULL; wndclass.lpszClassName="Window Class"; //Class Name wndclass.hIconSm =LoadIcon(NULL,IDI_APPLICATION); //Register the window class if(RegisterClassEx(&wndclass)==0) { //the program failed, exit exit(1); } //Create the window hWnd=CreateWindowEx( WS_EX_OVERLAPPEDWINDOW, "Window Class", //Class Name "Create Window Example", //Title bar text WS_OVERLAPPEDWINDOW, 0, 0, 400, 600, NULL, NULL, hInstance, NULL); //Display Window ShowWindow(hWnd, iCmdShow); //Process Messages until program is terminated while(GetMessage (&msg,NULL,0,0)); { TranslateMessage(&msg); DispatchMessage(&msg); } return (msg.wParam); } //Message loop callBack function (Required for all windows programs) LRESULT CALLBACK fnMessageProcessor(HWND hWnd, UINT iMsg, WPARAM wParam, LPARAM lParam) { switch(iMsg) { //Called when window is first created case WM_CREATE: return(0); //Called when window is refreshed case WM_PAINT: return(0); //Called when the user closes the window case WM_DESTROY: PostQuitMessage(0); return(0); default: return DefWindowProc(hWnd, iMsg, wParam, lParam); } } Do any of you have any observations about the code and or any suggestion to overcome this buggy behavior? Thanks all. Best, Jerry

[alex barylski]

Everything looks prety good to me :) Maybe try commenting out DefWindowProc() and compiling...see what happens The word of the day is legs, let's go back to my house and spread the word ;P

[Chris Richardson]

I'm pretty sure you need to add the following code to your WM_PAINT case:

     PAINTSTRUCT a\_stPaint;
     BeginPaint( hWnd, &a\_stPaint );
     
     // Do your painting here.
     
     EndPaint( hWnd, &a\_stPaint );

It's been a while since I did raw Win32, so I'm not certain. Chris Richardson

[Monty2]

in WM_CREATE and WM_PAINT ... don't return 0 do a break; and call DefwindowProc might help Live as if your were to die tomorrow. Learn as if you were to live forever. -Mahatma Gandhi

[Jerry Hammond]

This gets weirder and weirder. I created a new solution (workspace). Copy&pasted the code into a new .cpp file, compile and executed and all worked just fine. Can we say, "things that make you go hmmm?" Thanks for all the suggestions and help. Best, Jerry

The only way of discovering the limits of the possible is to venture a little past them into the impossible.--Arthur C. Clark

Toasty0.com

[nema32]

TranslateMessage() and DispatchMessage() are never getting called. Why? Because your while loop does nothing thanks to the common error of an extra semicolon. Your message pump is effectively: while (GetMessage(&msg, NULL, 0, 0)) ;