Visual C++ 6 Unleashed

By MICKEY WILLIAMS and David Bennett

• Table of Contents
  • Copyright
  • About the Authors
  • About the Contributors
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • How to Use This Book
  • What You Need to Use This Book
  • What's New in Visual C++ 6.0
  • Contacting the Main Author
  • Part I: Introduction
  • Chapter 1. The Visual C++ 6.0 Environment
  • Part II: MFC Programming
  • Chapter 2. MFC Class Library Overview
  • Chapter 3. MFC Message Handling Mechanism
    • Message Categories
    • Message Handling in MFC
    • Message Dispatching
    • Message Handling with ClassWizard
    • Creating Your Own Message Maps
    • A Common Problem with MFC Message Maps
    • Summary
  • Chapter 4. The Document View Architecture
  • Chapter 5. Creating and Using Dialog Boxes
  • Chapter 6. Working with Device Contexts and GDI Objects
  • Chapter 7. Creating and Using Property Sheets
  • Chapter 8. Working with the File System
  • Chapter 9. Using Serialization with File and Archive Objects
  • Part III: Internet Programming with MFC
  • Chapter 10. MFC and the Internet Server API (ISAPI)
  • Chapter 11. The WinInet API
  • Chapter 12. MFC HTML Support
  • Part IV: Advanced Programming Topics
  • Chapter 13. Using the Standard C++ Library
  • Chapter 14. Error Detection and Exception Handling Techniques
  • Chapter 15. Debugging and Profiling Strategies
  • Chapter 16. Multithreading
  • Chapter 17. Using Scripting and Other Tools to Automate the Visual C++ IDE
  • Part V: Database Programming
  • Chapter 18. Creating Custom AppWizards
  • Chapter 19. Database Overview
  • Chapter 20. ODBC Programming
  • Chapter 21. MFC Database Classes
  • Chapter 22. Using OLE DB
  • Chapter 23. Programming with ADO
  • Part VI: MFC Support for COM and ActiveX
  • Chapter 24. Overview of COM and Active Technologies
  • Chapter 25. Active Documents
  • Chapter 26. Active Containers
  • Chapter 27. Active Servers
  • Chapter 28. ActiveX Controls
  • Part VII: Using the Active Template Library
  • Chapter 29. ATL Architecture
  • Chapter 30. Creating COM Objects Using ATL
  • Chapter 31. Creating ActiveX Controls Using ATL
  • Chapter 32. Using ATL to Create MTS and COM+ Components
  • Part VIII: Finishing Touches
  • Chapter 33. Adding Windows Help
  • Part IX: Appendix

Message Handling in MFC

MFC provides a framework for handling windows messages that can be much easier to work with than the web of switches and ifs that are used in traditional Windows programs to control the handling of messages. This is based on the capability of classes derived from CCmdTarget of having their own message maps. MFC uses the message maps of your classes to decide how any given message should be handled, allowing you to take full advantage of the benefits of the C++ language to encapsulate functionality in your classes so that other classes derived from them don't have to reinvent the wheel.

To further expand on reusability, MFC provides default handlers for a wide range of commands used in most Windows applications. Most of the commands that have default handlers are also included in the default menus generated by AppWizard. The following are menu commands that have default handlers in MFC:

• File menu commands: New, Open, Close, Save, Save As, Page Setup, Print Setup, Print, Print Preview, Exit, and the most recently used files list.
• Edit menu commands: Clear, Clear All, Copy, Cut, Find, Paste, Repeat, Replace, Select All, Undo, and Redo.
• View menu commands: Toolbar and Status Bar.
• Window menu commands: New, Arrange, Cascade, Tile Horizontal, Tile Vertical, and Split.
• Help menu commands: Index, Using Help, and About.

The menus created by AppWizard generate messages for the standard commands defined in AFXRES.H. For example, the File | New menu item generates a message with the command ID of ID_FILE_NEW. The other standard commands are similarly named, with ID_, the menu name, and the command name.

If you wish to perform one of these standard actions, you can send one of the predefined command messages from anywhere in your application that will be handled by MFC's default handlers. Of course, you can also implement your own handlers for these commands, but you will explore that later. For more information on the default commands, see Technical Note 22 (TN022) in the online help.

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