VC++ (2) win32 显示图片

#include <windows.h>
#include"resource.h"

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
    PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] = TEXT ("Bricks") ;
    HWND         hwnd ;
    MSG          msg ;
    WNDCLASS     wndclass ;

    wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
    wndclass.lpfnWndProc   = WndProc ;
    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 (WHITE_BRUSH) ;
    wndclass.lpszMenuName  = NULL ;
    wndclass.lpszClassName = szAppName ;

    if (!RegisterClass (&wndclass))
    {
        MessageBox (NULL, TEXT ("This program requires Windows NT!"), 
            szAppName, MB_ICONERROR) ;
        return 0 ;
    }

    hwnd = CreateWindow (szAppName,                  // window class name
        TEXT ("LoadBitmap"), // window caption
        WS_OVERLAPPEDWINDOW,        // window style
        CW_USEDEFAULT,              // initial x position
        CW_USEDEFAULT,              // initial y position
        CW_USEDEFAULT,              // initial x size
        CW_USEDEFAULT,              // initial y size
        NULL,                       // parent window handle
        NULL,                       // window menu handle
        hInstance,                  // program instance handle
        NULL) ;                     // creation parameters

    ShowWindow (hwnd, iCmdShow) ;
    UpdateWindow (hwnd) ;

    while (GetMessage (&msg, NULL, 0, 0))
    {
        TranslateMessage (&msg) ;
        DispatchMessage (&msg) ;
    }
    return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static HBITMAP hBitmap;
    static int cxClient, cyClient, cxSource ,cySource;
    BITMAP bitmap;
    HDC         hdc, hdcMem ;
    HINSTANCE   hInstance ;
    int         x, y;
    PAINTSTRUCT ps ;
    

    switch (message)
    {
    case WM_CREATE:

        hInstance = ((LPCREATESTRUCT) lParam)->hInstance ;

        hBitmap = LoadBitmap (hInstance, MAKEINTRESOURCE (IDB_BITMAP1)) ;

        GetObject (hBitmap, sizeof (BITMAP), &bitmap) ;

        cxSource = bitmap.bmWidth ;
        cySource = bitmap.bmHeight ;

        return 0 ;

    case WM_SIZE:
        cxClient = LOWORD (lParam) ;
        cyClient = HIWORD (lParam) ;
        return 0 ;

    case WM_PAINT:
        hdc = BeginPaint (hwnd, &ps) ;

        hdcMem = CreateCompatibleDC (hdc) ;
        SelectObject (hdcMem, hBitmap) ;
        
        BitBlt (hdc, 100, 100, cxSource, cySource, hdcMem, 0, 0, SRCCOPY) ;
        
        DeleteDC (hdcMem) ;

        EndPaint (hwnd, &ps) ;
        return 0 ;

    case WM_DESTROY:
        PostQuitMessage (0) ;
        return 0 ;
    }
    return DefWindowProc (hwnd, message, wParam, lParam) ;
}