How the VC handles custom messages

ClassWizard does not allow the addition of user-defined messages, so you have to enter them manually. Once typed, ClassWizard will be able to process your custom messages just like any other message.

Here are the steps to add a custom message:

Step 1: Define the message. When developing Windows 95 applications, Microsoft recommends that user-defined messages be at least WM User+100, as many new controls also use WM User messages.

Step 2: Implement the message handler. The function uses the wpram and lparam arguments and returns lpesult.

lpesult cmainframe::onmymessage(wparam wparam, lparam lparam)

todo: Handles user-defined messages.

return 0;

Step 3: Describe the message handling function in the afx msg block of the class header file

class cmainframe:public cmdiframewnd

General message mapping functions.

protected:

afx_msg

declare_message_map()

Step 4: In the message block of the user class, use the on message macro to map the message to the message handler.

begin_message_map(cmainframe, cmdiframewnd)

afx_msg_map

end_message_map()

If you need a message that is unique to the entire system, you can call the SDK function RegisterWindowMessage and use the On Register Message macro instead of the On Message macro, and the rest of the steps are the same as above.

It's hard to say here.

It's up to you to figure it out.

It's not realistic.

Define a global constant in the header file.

Define global constants in the header file.

A statement sends a custom message to a window or control, and the window or control that receives the message executes the corresponding response function.

In a simple case, if the syntax allows, it is equivalent to the sender directly calling the receiver's response function.

For example, if a::fun1() sends a message to window b, b responds to the message and executes b::fun2();

People who don't know how to customize the message can remove the pointer to b in a::fun1() and use b->fun2(); Invoke the implementation.

However, in some cases, when this direct call is not allowed (e.g. between two threads), you can only use custom messages to communicate and execute functions.

By passing a custom message, a custom message handler is called. It can not conflict with system messages.

This is a bug of VC itself, to solve this problem, you need to manually add the message function between }afx msg, otherwise VC may delete the message you added without giving any prompt.

The message is thrown to ctestdlg, but you are processed in cresultdlg, which is not received. With: postmessage().

Pass the handle of the receiving window in, and it's done.