Use and understanding of message-map along with message

1. Use and Understanding Of
MESSAGE_MAP along with Message
Handlers
Presented By :
Sheth Shraddha(50)
Tamhane Vaidehi(54)

2. Use of MESSAGE_MAP
 Windows Operating Systems – A Message
Driven System
 Example : Mouse click, Printer signal
 MESSAGE_MAP supports Message Driven
Programming in MFC.
 Class Member Functions are used.

3. Role Of Class Member Functions
 To execute commands
 Messages are directed to class member
functions by the use of macros in MFC.
 Convenience

4. Components Of MESSAGE_MAP
 Declaration
 Beginning
 Termination

5. Declaration
 DECLARE_MESSAGE_MAP
– Declared in the class which allows to respond to messages.
– A class is eligible to execute a message map if it is derived
from CCmdTarget or a class which is derived from
CCmdTarget.
– A class can have only one message map.
– It should be the last member declared within a class.
– If not then next member should be preceded by an access
specifier.

6. BEGINNING
 BEGIN_MESSAGE_MAP
– Parameters
 Class name which implements the message map.
 Base class
– Succeeded by macros which represent
messages.

7. Termination
 END_MESSAGE_MAP
– Messages macros are succeeded by
END_MESSAGE_MAP

8. Message Handlers
 To respond to a message one must add a
message handler.
 Members of CWnd class.
 Can be overridden.

9. Naming Pattern Of Message Handlers
 Start with “On”.
 Succeeded by message name.
 Should be in camel case.
 Ex:
– Macro: WM_SIZE
– Handler: OnSize()

10. ExampleExample

11. References

12. Thank You!!