Steps for customizing messages in VC and methods for intercepting messages

To customize a message, follow these steps:
1. Define a message.

1. # Define wm_mymessage (wm_user+ 100)

Microsoft recommends that you customize the message at least wm_user + 100, because many new controls also use wm_user messages.

2. Declare the message processing function in the afx_msg block in the. h file

1. Afx_msg lresult onmymessage (wparam, lparam );

As follows:

1. Protected:
2. // {Afx_msg (...)
3. Afx_msg int oncreate (maid );
4. Afx_msg void ontimer (uint nidevent );
5. Afx_msg lresult onmymessage (wparam, lparam );
6. //} Afx_msg
7. Declare_message_map ()

3. Add a message ing macro to the. cpp file.

1. On_message (wm_my_message, onmymessage)

As follows:

1. Begin_message_map (...)
2. // {Afx_msg_map (...)
3. On_wm_create ()
4. On_wm_timer ()
5. On_message (wm_mymessage, onmymessage)
6. //} Afx_msg_map
7. End_message_map ()

4. Edit the message processing function in the. cpp File

1. Lresult yourclass: onmymessage (wparam, lparam)
2. {
3. Return 0;
4. }

Message Interception Method
Use sendmessage (wm_mymessage) or postmessage (wm_mymessage) to send messages to the Message Queue where you need to use the message processing function.
The differences between the two are as follows:
Sendmessage: After a message is sent to the message queue, it is returned only after the message is processed. continue to run the code.
Postmessage: After a message is sent to the message queue, the message is returned immediately without waiting for message processing, and the code is executed.