Win32 Button

newguy194

Why am I unable to produce a button with this Win32 program? All I have been able to produce is the empty window.

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 #include <windows.h>
 
// Declare WndProcedure

LRESULT CALLBACK WndProcedure(HWND hWnd, UINT uMsg,

               WPARAM wParam, LPARAM lParam);
 
INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,

               LPSTR lpCmdLine, int nCmdShow)

{

    HWND       button;

    MSG        Msg;

    HWND       hWnd;

    HRESULT       hRet;

    WNDCLASSEX WndClsEx;
 
    // Populate the WNDCLASSEX structure

    WndClsEx.cbSize        = sizeof(WNDCLASSEX);

    WndClsEx.style         = CS_HREDRAW | CS_VREDRAW;

    WndClsEx.lpfnWndProc   = WndProcedure;

    WndClsEx.cbClsExtra    = 0;

    WndClsEx.cbWndExtra    = 0;

    WndClsEx.hIcon         = LoadIcon(NULL, IDI_APPLICATION);

    WndClsEx.hCursor       = LoadCursor(NULL, IDC_ARROW);

    WndClsEx.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

    WndClsEx.lpszMenuName  = NULL;

    WndClsEx.lpszClassName = "GlowdotWin32TutorialPartI";

    WndClsEx.hInstance     = hInstance;

    WndClsEx.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);
 
    // Register the class

    RegisterClassEx(&WndClsEx);
 
    // Create the window object

    hWnd = CreateWindow("GlowdotWin32TutorialPartI",

              "Glowdot Win32 Tutorial - Part I",

              WS_OVERLAPPEDWINDOW,

              CW_USEDEFAULT,

              CW_USEDEFAULT,

              CW_USEDEFAULT,

              CW_USEDEFAULT,

              NULL,

              NULL,

              hInstance,

              NULL);
 
    button = CreateWindow( 

    "BUTTON",                                    // predefined class

    "OK",                                        // button text

    WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON,    // styles 

                                                 // Size and position values are given 

                                                 // explicitly, because the CW_USEDEFAULT 

                                                 // constant gives zero values for buttons. 

    100,                                          // starting x position

    100,                                          // starting y position 

    200,                                         // button width 

    200,                                         // button height 

    hWnd,                                        // parent window 

    NULL,                                        // No menu 

    hInstance,                                   // Our apps HINSTANCE 

    NULL                                         // pointer not needed 

);
 
    if ( !button)

       return 0;

    // Verify window creation

    if( !hWnd ) // If the window was not created,

        return 0; // stop the application
 
    // Show the window

    ShowWindow(hWnd, SW_SHOWNORMAL);

    ShowWindow(button, SW_SHOWNORMAL);

    UpdateWindow(hWnd);

    UpdateWindow(button);

    // our message pump

    while( (hRet = GetMessage( &Msg, NULL, 0, 0 )) != 0)

    { 

        if (hRet == -1)

        {

        // handle the error and possibly exit

        }

        else

        {

            TranslateMessage(&Msg); 

            DispatchMessage(&Msg); 

        }

    }

}
 
//////////////////

// WndProcedure //

//////////////////
 
LRESULT CALLBACK WndProcedure(HWND hWnd, UINT Msg,

               WPARAM wParam, LPARAM lParam)

{

    switch(Msg)

    {

    case WM_DESTROY:

        // user wants to exit

        PostQuitMessage(WM_QUIT);

        break;

    default:

        // Hand off unprocessed messages to DefWindowProc

        return DefWindowProc(hWnd, Msg, wParam, lParam);

    }
 
    return 0;

}

Studlyami

what compiler are you using?

That program fails to create anything on visual studios 2005. I added
if(!hWnd)
{
return 0;
}

and i get a return 0. two tired to try and figure out why.

newguy194

Quote:

Originally Posted by Studlyami

what compiler are you using?

That program fails to create anything on visual studios 2005. I added
if(!hWnd)
{
return 0;
}

and i get a return 0. two tired to try and figure out why.

My compiler is gcc

The program creates a window for me, but does not generate or display the button, and the check I added for the button is telling me it is not created.

newguy194

Something really, really, really, really weird. On the PC which I do most of my programming on the program fails to run correctly and nothing appears, but on my Vista pc the program runs fine, generates a button and doesn't fail any of the checks.

Studlyami

LOL! Alright on my home pc (Vista, Visual Studios 2005 (latest updates)) this program wouldn't even generate the original window. At work (XP, Visual Studios 2003(Uknown updates)) this program loads fine and creates the button. I would say this would of been an issue with Vista, but newguy built it fine on vista. Newguy what program did you use to compile it? maybe we can narrow the problem down that way.

newguy194

Sorry, my compiler is gcc, not Dev silly me.

Cucumber

You can use this function to show what was the last error at any point within your win32 program. You may use it after creating or showing the button to see what the operating system that is not showing the button has to say about it.

void ShowLastError( )
{
TCHAR *buffer;
int errorcode = ::GetLastError();
if ( errorcode )
{
::FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|FOR MAT_MESSAGE_FROM_SYSTEM,
NULL,errorcode,MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPTSTR)&buffer,0,NULL);
::MessageBox(HWND_DESKTOP, buffer, 0,0);
::LocalFree( buffer );
}
}

By the way, using UpdateWindow with the button seems a bit awkward to me, the Win32 protocol says you should call UpdateWindow for the parent Window, not for the child controls.
I would also avoid calling ShowWindow for the control too.

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