在Win32API中注册窗口类

尽管在网上阅读了大量信息，以及Petzold的书《Windows API编程》，并且几乎从书中复制了完全相同的方法，以及关于如何初始化OpenGL上下文的文档，但我还没能建立并运行Window class。

我试过在VC++和MinGW上编译（我使用的是QtCreator），看看这是否可行。我已经尝试将WNDCLASSEXA作为指针，并在堆栈上分配它。两者都没有骰子。

因此，我很不确定该怎么办。有时，类只是无法注册，而其他时候，从CreateWindowExA返回的HWND根本不起作用，并返回NULL。在尝试继续这个程序之后，尽管发生了这些事件，但我最终得到了一个无法绘制窗口的应用程序。

想法很简单：我有一个结构，用来简单地存储所有使用的数据（DEVMODEA、WNDCLASSEXA、HGLRC等）。

从那里，我使用该结构创建一个Window，然后将其传递回函数的调用方。

我真正想做的就是使用GLSL/ONGGL3.3在OpenGL中编写一个简单的类似乒乓球的游戏。要做到这一点，我显然首先需要一个上下文，但我无法判断问题是否是Qt Creator、Windows或其他什么。

那么，我可能做错了什么？

GameData结构

typedef struct
{
    HGLRC        hrc;
    HDC          hdc;
    HWND         hwnd;
    HINSTANCE    hInstance;
    UINT         numFormats;
    WNDCLASSEXA* winClass;
    DWORD        dwExStyle;
    DWORD        dwStyle;
    RECT         winRect;
    DEVMODEA     screenSettings;
    bool         fullscreen;
    const char*  winClassName;
    int          pixelFormat;
    bool         keys[ 256 ];
    bool         active;
}
GameData;

initPong()功能

static GameData* initContextAndWindow( void )
{
    GameData* dat = new GameData;
    const int width     = 640;
    const int height    = 480;
    const int bitsPerPixel = 32;
    dat->winRect.left   = ( long )0;
    dat->winRect.right  = ( long )width;
    dat->winRect.top    = ( long )0;
    dat->winRect.bottom = ( long )height;
    dat->fullscreen     = false;
    dat->hInstance              = GetModuleHandleA( NULL );
    dat->winClass = ( WNDCLASSEXA* )calloc( sizeof( WNDCLASSEXA ), 1 );
    if( !dat->winClass )
        MessageBoxA( NULL, "Something wrong!", "ERROR", MB_OK | MB_ICONINFORMATION );
    dat->winClass->style         = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
    dat->winClass->lpfnWndProc   = ( WNDPROC ) eventHandler;
    dat->winClass->cbClsExtra    = 1;
    dat->winClass->cbWndExtra    = 1;
    dat->winClass->cbSize        = sizeof( WNDCLASSEXA );
    dat->winClass->hInstance     = dat->hInstance;
    dat->winClass->hIcon         = LoadIcon( NULL, IDI_WINLOGO );
    dat->winClass->hCursor       = LoadCursor( NULL, IDC_ARROW );
    dat->winClass->hbrBackground = ( HBRUSH ) GetStockObject( WHITE_BRUSH );
    dat->winClass->lpszMenuName  = NULL;
    dat->winClass->lpszClassName = "PongDH";
    if ( !RegisterClassExA( dat->winClass ) )
    {
        MessageBoxA( NULL, "Failed to register class.", "ERROR", MB_OK | MB_ICONINFORMATION );
        exit( 1 );
    }
    if ( dat->fullscreen )
    {
        memset( &dat->screenSettings, 0, sizeof( dat->screenSettings ) );
        dat->screenSettings.dmSize          = sizeof( dat->screenSettings );
        dat->screenSettings.dmPelsWidth     = width;
        dat->screenSettings.dmPelsHeight    = height;
        dat->screenSettings.dmBitsPerPel    = bitsPerPixel;
        dat->screenSettings.dmFields        = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;
        if ( ChangeDisplaySettingsA( &dat->screenSettings, CDS_FULLSCREEN ) != DISP_CHANGE_SUCCESSFUL )
        {
            dat->fullscreen = false;

            const int continuePlaying = MessageBoxA(
                NULL,
                "Could not implement fullscreen. Please check your drivers. Do you plan to continue?",
                "ERROR",
                MB_YESNO | MB_ICONEXCLAMATION
            );
            if ( continuePlaying == IDYES )
            {
                MessageBoxA( NULL, "Will revert back to fullscreen.", "Notifcation", MB_OK );
                dat->fullscreen = false;
            }
            else
            {
                MessageBoxA( NULL, "The program will now close", "Notification", MB_OK );
                exit( 1 );
            }
        }
    }
    if ( dat->fullscreen )
    {
        dat->dwExStyle = WS_EX_APPWINDOW;
        dat->dwStyle = WS_POPUP;
        ShowCursor( FALSE );
    }
    else
    {
        dat->dwExStyle  = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
        dat->dwStyle    = WS_OVERLAPPEDWINDOW;
    }
    AdjustWindowRectEx( &dat->winRect, dat->dwStyle, FALSE, dat->dwExStyle );
    dat->hwnd = CreateWindowExA(
                    dat->dwStyle,
                    dat->winClass->lpszClassName,
                    "PongDH",
                    WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
                    CW_USEDEFAULT, CW_USEDEFAULT,
                    dat->winRect.right,
                    dat->winRect.bottom,
                    NULL,
                    NULL,
                    dat->hInstance,
                    NULL
                );

    if ( dat->hwnd == NULL )
    {
        MessageBoxA( NULL, "Failed to create window; exiting program.", "ERROR", MB_OK | MB_ICONEXCLAMATION );
        exit( 1 );
    }
    const int attrList[] =
    {
        WGL_DRAW_TO_WINDOW_ARB  , GL_TRUE,
        WGL_SUPPORT_OPENGL_ARB  , GL_TRUE,
        WGL_DOUBLE_BUFFER_ARB   , GL_TRUE,
        WGL_PIXEL_TYPE_ARB      , WGL_TYPE_RGBA_ARB,
        WGL_COLOR_BITS_ARB      , 32,
        WGL_DEPTH_BITS_ARB      , 24,
        WGL_STENCIL_BITS_ARB    , 8,
        0,
    };
    wglChoosePixelFormatARB( dat->hdc, attrList, NULL, 1, &dat->pixelFormat, &dat->numFormats );
    const int contextList[] =
    {
        WGL_CONTEXT_MAJOR_VERSION_ARB, 3,
        WGL_CONTEXT_MINOR_VERSION_ARB, 3,
        0,
    };
    dat->hrc = wglCreateContextAttribsARB( dat->hdc, NULL, contextList );
    if( !wglMakeCurrent( dat->hdc, dat->hrc ) )
    {
        MessageBoxA( NULL, "Error making OpenGL Rendering Context current.", "ERROR", MB_OK | MB_ICONEXCLAMATION );
        exit( 1 );
    }
    ShowWindow( dat->hwnd, SW_SHOW );
    SetForegroundWindow( dat->hwnd );
    SetFocus( dat->hwnd );
    resizeScene( width, height );
    UpdateWindow( dat->hwnd );
    glEnable( GL_DEPTH_TEST );
    return dat;
}

更新

在这里，我将发布我所做的程序：

我第一次尝试将cbClsExtra设置为1，而之前是0。然后我将cbWndExtra设置为1。之后，我尝试将cbSize设置为sizeof( WNDCLASSEXA )。

我还尝试了在VC++和MinGW下进行编译；在VC++中，类只是无法注册，而在MinGW中，类会注册，但实际上不会创建所需的hwnd。

我还尝试通过将WNDCLASSEXA（即dat->winClass）作为指针来编辑代码，而不是使用堆栈分配的变量。

我还在if检查中注释了我的exit函数，看看类是否没有注册，或者hwnd是不是创建。这在尝试用wglChoosePixelFormatARB渲染OpenGL上下文时会产生分段错误。

更新2

这是我的WndProc:

LRESULT CALLBACK eventHandler( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
    return DefWindowProcA( hwnd, uMsg, wParam, lParam );
}