如何加载简单的位图文件win32

Question

我想测试一些使用位图的简单Win32。这是我从谷歌搜索获得的代码。

#include <windows.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
void DisplayError(DWORD, const char*);

/*  Make the class name into a global variable  */
char szClassName[ ] = "WindowsApp";

int WINAPI WinMain (HINSTANCE hThisInstance,
                HINSTANCE hPrevInstance,
                LPSTR lpszArgument,
                int nFunsterStil)

{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
       0,                   /* Extended possibilites for variation */
       szClassName,         /* Classname */
       "Windows App",       /* Title Text */
       WS_OVERLAPPEDWINDOW | SS_BITMAP,
       CW_USEDEFAULT,       /* Windows decides the position */
       CW_USEDEFAULT,       /* where the window ends up on the screen */
       544,                 /* The programs width */
       375,                 /* and height in pixels */
       HWND_DESKTOP,        /* The window is a child-window to desktop */
       NULL,                /* No menu */
       hThisInstance,       /* Program Instance handler */
       NULL                 /* No Window Creation data */
       );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nFunsterStil);
    UpdateWindow(hwnd);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }
    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}

/*  This function is called by the Windows function DispatchMessage()  */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    HBITMAP g_hbitmap = NULL;
    switch (message)                  /* handle the messages */
    {
        case WM_CREATE: {
            g_hbitmap = (HBITMAP)LoadImage(GetModuleHandle(NULL),
                                       "D:\\zhbackground.bmp",
                                       IMAGE_BITMAP,
                                       LR_DEFAULTSIZE,
                                       LR_DEFAULTSIZE,
                                       LR_LOADFROMFILE);
            if(!g_hbitmap) {
                DisplayError(GetLastError(), "Error loading bitmap");
            }
            break;
        }
        case WM_PAINT: {
            HDC dc;
            HDC memdc;
            HGDIOBJ old;
            PAINTSTRUCT ps;
            BITMAP bm;
            dc = BeginPaint(hwnd, &ps);
            DisplayError(GetLastError(), "BeginPaint");
            memdc = CreateCompatibleDC(dc);
            DisplayError(GetLastError(), "CreateCompatibleDC");
            old = SelectObject(memdc, g_hbitmap);
            DisplayError(GetLastError(), "SelectObject");
            GetObject(g_hbitmap, sizeof(bm), &bm);
            DisplayError(GetLastError(), "GetObject");
            BitBlt(dc, 0, 0, bm.bmWidth, bm.bmHeight, memdc, 0, 0, SRCCOPY);
            DisplayError(GetLastError(), "BitBlt");
            SelectObject(memdc, old);
            DisplayError(GetLastError(), "SelectObject");
            DeleteDC(memdc);
            DisplayError(GetLastError(), "DeleteDC");
            EndPaint(hwnd, &ps);
            DisplayError(GetLastError(), "EndPaint");
            break;
        }
        case WM_DESTROY:
            DeleteObject(g_hbitmap);
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

void DisplayError(DWORD dw, const char* szFuncName)
{
     LPSTR buff;
     FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER,
              NULL,
              dw,
              LANG_NEUTRAL,
              (LPSTR)&buff,
              0,
              NULL);
     MessageBox(NULL, buff, szFuncName, MB_OK);
}

问题是窗口什么也没显示，所以我调用GetLastError（）并试着看看发生了什么。从那里，我得到文件已加载（我猜为g_hbitmap！= NULL），另一个DisplayError（）显示操作已成功完成。

有什么想法吗？谢谢你提前！