MSDN中给出的“消息映射”宏的说明

宏名：DECLARE_MESSAGE_MAP

使用方式：DECLARE_MESSAGE_MAP( )

Remarks

Each CCmdTarget-derived class in your program must provide a message map to handle messages.
Use the DECLARE_MESSAGE_MAP macro at the end of your class declaration.
Then, in the .CPP file that defines the member functions for the class, use the BEGIN_MESSAGE_MAP
macro, macro entries for each of your message-handler functions, and the END_MESSAGE_MAP macro.
Note   If you declare any memberafter DECLARE_MESSAGE_MAP, you must specify a new access type
(public, private, or protected) for them.

For more information on message maps and the DECLARE_MESSAGE_MAP macro,
see Message Handling and Mapping Topics in Visual C++ Programmer's Guide.

Example

// example for DECLARE_MESSAGE_MAP
class CMyWnd : public CFrameWnd
{
    // Member declarations
    
    DECLARE_MESSAGE_MAP( )
};


---------------------------------------------------------
BEGIN_MESSAGE_MAP
BEGIN_MESSAGE_MAP( theClass, baseClass )
Parameters
theClass          //指定：这是哪个类的消息映射
Specifies the name of the class whose message map this is.
baseClass         //指定：要进行消息映射的这个类的父类是谁
Specifies the name of the base class of theClass.
Remarks
Use the BEGIN_MESSAGE_MAP macro to begin the definition of your message map.
In the implementation (.CPP) file that defines the member functions for your class, 
start the message map with the BEGIN_MESSAGE_MAP macro, then add macro entries for 
each of your message-handler functions, and complete the message map with the 
END_MESSAGE_MAP macro.For more information on message maps and the BEGIN_MESSAGE_MAP macro, 
see Adding a Dialog Box in Visual C++ Tutorials.
Example
// example for BEGIN_MESSAGE_MAP
BEGIN_MESSAGE_MAP( CMyWindow, CFrameWnd )
   //{{AFX_MSG_MAP( CMyWindow )
    ON_WM_PAINT()
    ON_COMMAND( IDM_ABOUT, OnAbout )
   //}}AFX_MSG_MAP
END_MESSAGE_MAP( )
--------------------------------------------------------------------
END_MESSAGE_MAP
END_MESSAGE_MAP( )
Remarks
Use the END_MESSAGE_MAP macro to end the definition of your message map.
For more information on message maps and the END_MESSAGE_MAP macro, 
see Message Handling and Mapping Topics in Visual C++ Programmer's Guide.
--------------------------------------------------------------
Message Maps
This section of the reference lists all message mapping macros and all CWnd 
message-map entries along with the corresponding member function prototypes:
Category
Description
WM_COMMAND Message Handler
Handles WM_COMMAND messages generated by user menu selections or menu access keys.
Child Window Notification Message Handlers
Handle notification messages from child windows.
WM_ Message Handlers
Handle WM_ messages, such as WM_PAINT.
User-Defined Message Handlers
Handle user-defined messages.
(For an explanation of the terminology and conventions used in this reference, 
see How to Use the Message Map Cross-Reference.) 
Since Windows is a message-oriented operating system, a large portion of programming for 
the Windows environment involves message handling. Each time an event such as a keystroke 
or mouse click occurs, a message is sent to the application, which must then handle the 
event.
The Microsoft Foundation Class Library offers a programming model optimized for 
message-based programming. In this model, "message maps" are used to designate which 
functions will handle various messages for a particular class. Message maps contain one 
or more macros that specify which messages will be handled by which functions. For example,
a message map containing an ON_COMMAND macro might look something like this: 
BEGIN_MESSAGE_MAP( CMyDoc, CDocument )
    //{{AFX_MSG_MAP( CMyDoc )
    ON_COMMAND( ID_MYCMD, OnMyCommand )    // ... More entries to handle additional commands
    //}}AFX_MSG_MAP
END_MESSAGE_MAP( )
The ON_COMMAND macro is used to handle command messages generated by menus, buttons, 
and accelerator keys. Macros are available to map the following:
Windows Messages
Control notifications

User-defined messages 
Command Messages
Registered user-defined messages

User-interface update messages 
Ranges of Messages
Commands

Update handler messages

Control notifications 
Although message-map macros are important, you generally won't have to use them directly. 
This is because ClassWizard automatically creates message-map entries in your source files 
when you use it to associate message-handling functions with messages. Any time you want 
to edit or add a message-map entry, you can use ClassWizard.




Note   ClassWizard does not support message-map ranges. You must write these message-map 
entries yourself.
However, message maps are an important part of the Microsoft Foundation 
Class Library. You should understand what they do, and documentation is provided for them.