Code
//风格类型枚举
enum EWALLPAPERSTYLE
{
    EWPS_TILE,
    EWPS_CENTER,
    EWPS_STRETCH
};
//设置图片函数
bool SetWallpaper(LPCTSTR fileName,int iStyle)
{
    HKEY regKeyRoot;
    CFileFind ffind ;
    //判断图片文件是否存在
    CString filestr = fileName;
    if(!ffind.FindFile(filestr))
    {
        return false;
    }
    //打开注册表 ".DEFAULT"为默认的桌面  如果是其他用户要用SID
    if(ERROR_SUCCESS==RegOpenKey(HKEY_USERS,
        ".DEFAULT\\Control Panel\\Desktop",
        &regKeyRoot))
    {
        char datas[2];
        datas[1]='\0';
        switch (iStyle)
        {
        case EWPS_CENTER:
            {
                datas[0]='0';
                RegSetValueEx(regKeyRoot,"WallpaperStyle",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                RegSetValueEx(regKeyRoot,"TileWallpaper",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                break;
            }
        case EWPS_STRETCH:
            {
                datas[0]='2';
                RegSetValueEx(regKeyRoot,"WallpaperStyle",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                datas[0]='0';
                RegSetValueEx(regKeyRoot,"TileWallpaper",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                break;
            }
        case EWPS_TILE:
            {
                datas[0]='0';
                RegSetValueEx(regKeyRoot,"WallpaperStyle",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                datas[0]='1';
                RegSetValueEx(regKeyRoot,"TileWallpaper",NULL,REG_SZ,(unsigned char*)datas,sizeof(datas));
                break;
            }
        default:
            {
                RegCloseKey(regKeyRoot);
                return false;
            }
        }
        RegSetValueEx(regKeyRoot,"Wallpaper",NULL,REG_SZ,(unsigned char*)filestr.GetBuffer(0),filestr.GetLength());
        RegCloseKey(regKeyRoot);
    }
    return true;
    
}