Introduction to Microsoft Windows MFC Programming: the Application/Window Approach

1. Introduction to MicrosoftWindows MFC Programming:the Application/WindowApproach Lecture 4

2. MFC Windows Programming(App/Window Approach) • MFC stands for “The Microsoft Foundation Class Library” • Object oriented interface to windows. • A Hierarchy of C++ classes designed to facilitate Windows programming • An alternative to using Win32 API functions • A Visual C++ Windows application can use either Win32 API, MFC, or both Lecture 4

3. Relationship between Windows MFC and Win32API Programming Lecture 4

4. Microsoft Foundation Classes • About 200 MFC classes (versus 2000+ API functions ) • Also called “Application Frame work” • Provide a framework upon which to build Windows applications • Encapsulate most of the Win32 API in a set of logically organized classes • MFC organizes the WIN32 API. • it groups related functionality into a class. • Wraps the windows API and windows objects with classes Lecture 4

5. MFC Characteristics 1. Convenience of reusable code: • Many tasks common to all Windows apps are provided by MFC • Our programs can inherit and modify this functionality as needed • We don't need to recreate these tasks 2. Produce smaller executables: • Typically 1/3 the size of their API counterparts Lecture 4

6. MFC Characteristics (contd) 3. Can lead to faster program development: • Make creation of windows application with C++ easy • Make access to Windows API features easier 4. MFC Programs must be written in C++ • require the use of classes • Programmer must have good grasp of: • How classes are declared, instantiated, and used • Encapsulation • Inheritance • Polymorphism--virtual functions Lecture 4

7. MFC Notations • Classes names begins with ‘C’ • CFrameWnd • CView • Variable names begin with ‘m_’ • m_pFrameWnd • Functions name begins with Afx • AfxMessageBox() Lecture 4

8. MFC Class Hierarchy • Two categories of classes • Derived from CObject • Not Derived from CObject • CObject • At top of hierarchy ("Mother of all classes") • Provides features like: • Serialization • Streaming object’s persistent data to or from a storage medium (disk reading/writing) • Diagnostic & Debugging support • All its functionality is inherited by any classes derived from it Lecture 4

9. Important Derived Classes— • CFile: Support for file operations • CDC: Encapsulates the device context (Graphical Drawing) • CGdiObject: Base class for various drawing objects (brushes, pens, fonts, etc.) • CMenu: Encapsulates menu management Lecture 4

10. CCmdTarget: Encapsulates message passing process& is parent of: • CWnd: Encapsulates many important windows functions and data members • Example: m_hWnd stores the window’s handle • Base class all windows are derived from • Most common: • CFrameWindow: Can contain other windows • ("normal" kind of window we've used) • CView: Encapsulates process of displaying and interacting with data • CDialog: Encapsulates dialog boxes Lecture 4

11. CCmdTarget also parent of: • CWinThread: Defines a thread of execution and is the parent of: • CWinApp: Most important class dealt with in MFC applications: • Encapsulates an MFC application • Controls following aspects of Windows programs: • Startup, initialization, execution, shutdown • An application should have one CWinApp object • When instantiated, application begins to run • CDocument • Encapsulates the data associated with a program Lecture 4

12. Not Derived from CObject • Provide valuable additional services for MFC: • OLE Classes • Simple Data Type Classes • CImage • CRect • CString etc. • Synchronization classes • CSemaphore • CMutex Lecture 4

13. Applications can also call API functions directly • Use Global Scope Resolution Operator, for • example: • ::UpdateWindow(hWnd); • Usually more convenient to use MFC member functions Lecture 4

14. A Minimal MFC Program • Simplest MFC programs must contain two classes derived from hierarchy: 1. An application class derived from CWinApp • Defines the application • provides the message loop • Three common methods are • InitApplication(); • InitInstance(); • Run(); These methods created automatically when object is created. Lecture 4

15. 2. A window class usually derived from CFrameWnd • Defines the application's main window • Referred as frame window • Tasks: • Creation of window • Management of window It creates window and attach it to our program • These & other MFC classes brought in by using #include <Afxwin.h> Lecture 4

16. #include <afxwin.h> class CMyApp : public CWinApp { public: virtual BOOL InitInstance(); }; Lecture 4

17. class CMainFrame : public CFrameWnd { public: CMainFrame() { Create(NULL, "MFC Fundamentals"); } }; BOOL CMyApp::InitInstance() { m_myWnd * CMainFrame ; m_myWnd = new CMainFrame; m_myWnd ->ShowWindow(SW_NORMAL); m_pMainWnd= m_myWnd ; return TRUE; } CMyApp a; Lecture 4

18. Message Processing under MFC • Like API programs, MFC programs must handle messages from Windows • API mechanism: big switch/case statement • MFC mechanism: "message maps" (lookup tables) Lecture 4

19. Messages in an application can be send in 2 ways • Directly • Queued • Directly • Message queue and message loop both are by passed • Windows directly call WndProc() • ::SendMessage • Queued • ::PostMessage Lecture 4

20. System Defined Messages • Windows uses these messages • Each of the system defined messages has • unique numeric identifier • Corresponding identifier macro definition • System defined message macro prefix • BM Button control Messages • CB Combo Box control Messages • EM Edit Box control Messages • LB List Box control Messages • WM General Window Messages Lecture 4

21. Message Handler • Message handler methods receive notification from the application object when some event occurs • Three types of messages processed in Message handler • Windows Messages • Control Notification Messages • Command Messages • Windows Messages • Send by window to application • Starts with WM_* • WM_COMMAND exception Lecture 4

22. Control Notification Messages • Send from child window • Control has no message queue and loop • Whatever activity notify directly to parent • Use message loop and queue of parent • Command Messages • Include WM_COMMAND • Notification from user interface object like • menu buttons • toolbar buttons Lecture 4

23. Message Maps • Mechanism for handling messaging with in a process • Object Oriented alternative to “switch-case” of window procedure • Table entries: • Message number • Pointer to a derived class member message-processing function • These are members of CWnd • You override the ones you want your app to respond to • Known as “Message handler” Lecture 4

24. Message Mapping • Programs must: • Declaration • DECLARE_MESSAGE_MAP() • Implementation • BEGIN_MESSAGE_MAP( FC_Tutorial_Window, CFrameWnd)      ON_WM_LBUTTONDOWN() //Macro to map the left button click to the handlerEND_MESSAGE_MAP() Lecture 4

25. Message Mapping • Programs must: • Declare message-processing functions • e.g., OnWhatever() for WM_WHATEVER message • Map them to messages app is going to respond to • Mapping done by "message-mapping macros” • Bind a message to a handler function • e.g., ON_WM_WHATEVER() • Most MFC application windows use a window procedure, WndProc(), supplied by the library • Message maps enable library window procedure to find the function corresponding to the current msg. Lecture 4

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