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1.1     ! root        1: Microsoft Foundation Classes                             Microsoft Corporation
        !             2: Technical Notes                                        
        !             3: 
        !             4: #1 : WNDCLASSes and MFC
        !             5: 
        !             6: This note describes the MFC routines for registering special
        !             7: WNDCLASSes as needed by MS-Windows.  Specific WNDCLASS attributes
        !             8: used by MFC and Windows are discussed.
        !             9: 
        !            10: =============================================================================
        !            11: 
        !            12: The Problem
        !            13: ===========
        !            14: 
        !            15: The attributes of a CWnd object, like an HWND in Windows, are stored
        !            16: in two places, the window object and the WNDCLASS.  A WNDCLASS is different
        !            17: than a C++ class.  The MFC C++ class in Windows still requires that
        !            18: the name of a WNDCLASS be passed to the creation function.  This WNDCLASS
        !            19: must be registered via one of four means:
        !            20: 
        !            21:     * implicitly by MFC
        !            22:     * implicitly by an MS-Windows control (or some other control)
        !            23:     * explicitly by calling the MFC routine AfxRegisterClass
        !            24:     * explicitly by calling the Windows routine RegisterClass
        !            25: 
        !            26: -----------------------------------------------------------------------------
        !            27: WNDCLASSes and MFC
        !            28: ==================
        !            29: 
        !            30: The WNDCLASS structure consists of various fields used to describe a
        !            31: window class.  Here are the fields and how they apply to an MFC app.
        !            32: 
        !            33:     style               -- style of window, see below
        !            34:     lpfnWndProc         -- window proc, must be 'AfxWndProc'
        !            35:     cbClsExtra          -- not used
        !            36:     cbWndExtra          -- not used
        !            37:     hInstance           -- automatically filled with AfxGetInstanceHandle()
        !            38:     hIcon               -- icon for frame windows, see below
        !            39:     hCursor             -- cursor for when mouse is over window, see below
        !            40:     hbrBackground       -- background color, see below
        !            41:     lpszMenuName        -- not used
        !            42:     lpszClassName       -- class name, see below
        !            43: 
        !            44: -----------------------------------------------------------------------------
        !            45: Provided WNDCLASSes
        !            46: ===================
        !            47: 
        !            48: MFC provides 3 standard window classes.
        !            49: 
        !            50:     "AfxWnd" is used for all child windows created with CWnd::Create().
        !            51: 
        !            52:     "AfxFrameWnd" is used for frame windows (both stand-alone CFrameWnds
        !            53:     and CMDIChildWnds).
        !            54: 
        !            55:     "AfxMDIFrameWnd" is used for the MDI frame window (i.e. the parent)
        !            56:     created with CMDIFrameWnd::Create().
        !            57: 
        !            58: 
        !            59: The following table shows the registered attributes:
        !            60: 
        !            61: Class name -->     AfxWnd    AfxFrameWnd          AfxMDIFrameWnd
        !            62: 
        !            63: Attribute
        !            64: ---------
        !            65: style              0         0                    0
        !            66: icon               none      AFX_IDI_STD_FRAME    AFX_IDI_STD_MDIFRAME
        !            67: cursor             arrow     arrow                arrow
        !            68: background color   none      COLOR_WINDOW         n/a
        !            69: 
        !            70: NOTE: if the application provides a resource with the specified 'AFX_ID*'
        !            71: resource ID, MFC will use that resource.  Otherwise the default resource
        !            72: is used.  For the icon, the standard app icon is used (a white box),
        !            73: and for the cursor, the standard arrow cursor is used.
        !            74: 
        !            75: NOTE: we provide two alternative icons for supporting MDI applications
        !            76: with single document types (one icon for the main app, the other icon
        !            77: for iconic document/MDIChild windows).  If you desire an MDI application
        !            78: with multiple document types with different icons, you must register
        !            79: additional WNDCLASSes.
        !            80: 
        !            81: NOTE: the values for background color and cursor for the MDIFrameWnd
        !            82: are not used since the client area of the MDIFrameWnd is completely
        !            83: covered with the "MDICLIENT" window.  We do not support subclassing
        !            84: of the "MDICLIENT" window and you should be sticking to the standard
        !            85: colors and cursor types.
        !            86: 
        !            87: -----------------------------------------------------------------------------
        !            88: Subclassing controls:
        !            89: =====================
        !            90: 
        !            91: If you subclass or superclass a Windows control (eg: CButton) then your class
        !            92: automatically gets the WNDCLASS attributes as provided in the Windows
        !            93: implementation of that control.
        !            94: 
        !            95: -----------------------------------------------------------------------------
        !            96: The AfxRegisterWndClass() Function
        !            97: ==================================
        !            98: 
        !            99: MFC provides a helper routine for registering a window class.
        !           100: Given a set of attributes for: window class style, cursor,
        !           101: background brush and icon, a synthetic name is generated, and
        !           102: the resulting window class registered.
        !           103: 
        !           104: const char* AfxRegisterWndClass(UINT nClassStyle,
        !           105:         HCURSOR hCursor, HBRUSH hbrBackground, HICON hIcon);
        !           106: 
        !           107: This function takes the arguments (all except the first one default
        !           108: to zero) and returns a temporary string of the registered window
        !           109: class.
        !           110: 
        !           111: AfxRegisterWndClass will throw a CResourceException if the window
        !           112: class failed to register (either because of bad parameters, or out of
        !           113: Windows memory).
        !           114: 
        !           115: NOTE: the string returned is a temporary pointer to a static string buffer
        !           116: which is valid until the next call to AfxRegisterWndClass.  If you want
        !           117: to keep this string around, store it in a CString variable.
        !           118: 
        !           119:         CString wndClass = AfxRegisterWndClass(CS_DBLCLK, defaultCursor);
        !           120: 
        !           121:         ...
        !           122:         CWnd wnd;
        !           123:         wnd.Create(wndClass, ...);
        !           124:         ...
        !           125: 
        !           126: -----------------------------------------------------------------------------
        !           127: Last resort: use RegisterClass
        !           128: ==============================
        !           129: 
        !           130: If you want to do anything more sophisticated than what
        !           131: AfxRegisterWndClass provides, you can always call the Windows API
        !           132: 'RegisterClass'.
        !           133: 
        !           134: Most of the MFC window creation routines take a string name for a
        !           135: window class as the first parameter, and any window class name
        !           136: can be used, regardless of how it was registered.
        !           137: 
        !           138: -----------------------------------------------------------------------------

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