1

Lecture 7Introduction to MFC

Programming:

The Application/Window ApproachWindow Message, WM_LBUTTONDOWN, etc..Menu Message, WM_COMMAND

2 /34

Microsoft Foundation Classes

MFC, is a class library that assists programmers in creating Windows-based applications

Perhaps two of the most important aspects of MFC programming are as follows: MFC adds object-oriented programming capabilities to Windows API

programming MFC encapsulates the Windows API into a logically organized class

hierarchy : Encapsulation means that the C++ class CWnd, for example, contains

HWND m_hWnd: a member variable of type HWND, and BOOL ShowWindow (int nCmdShow) : the class's member functions encapsulate

calls to Win32 functions.

The class member functions typically have the same name as the Win32function they encapsulate. :ShowWindow()

3 /34

MFC Class Library

The MFC class library consists of two major sections:

The MFC class hierarchy

Global functions or variables and macros

If a function or variable is not a member of a class, it is a global function or variable

Most of the MFC classes are defined in the afxwin.h file, must include that file in the header files

4 /34

5 /34

The library’s classes are classified in the following (~10 groups):

Root Class: CObject Most of the classes in the Microsoft Foundation Class (MFC) Library

are derived from a single base class at the root of the class hierarchy.

MFC Application Architecture Classes: CWinApp, CDocument,CView Application and Thread Support Classes Document Classes View Classes Frame Window Classes Document-Template Classes, etc.

Window, Dialog, and Control Classes: CDialog, CEdit, CStatic Dialog Box Classes Control Classes Control Bar Classes, etc.

6 /34

Drawing and Printing Classes: CDC, CBrush, CPen Output (Device Context) Classes Drawing Tool Classes

Simple Data Type Classes: CPoint, CRect Array, List, and Map Classes: CArray, CList, CMap File and Database Classes: CFile, CDatabase

File I/O Classes DAO Classes ODBC Classes OLE DB Classes

The library’s classes are classified in the following: (cont.)

7 /34

The library’s classes are classified in the following: (cont.)

Internet and Networking Classes : CHttpFilter, CSocket ISAPI Classes Windows Sockets Classes Win32 Internet Classes

OLE Classes: COleDocObjectItem (Object Linking and Embedding ) OLE Container Classes OLE Server Classes OLE Drag-and-Drop and Data Transfer Classes OLE Common Dialog Classes OLE Automation Classes OLE Control Classes Active Document Classes OLE-Related Classes

Debugging and Exception Classes: CException Debugging Support Classes Exception Classes

ยกตัวอยาง Word, excelเมนูเปลีย่น

8 /34

2nd Section:MFC Global Functions or Variables and Macros (เรียกใชที่คลาสใดๆ ก็ได) If a function or variable is not a member of a MFC class, it is

Global function : Begin with Afx prefix (Application FrameworKS) or

Global variable : Begin with afx prefix

Macros: all uppercase letters

BEGIN_MESSAGE_MAP() and END_MESSAGE_MAP(), which are used for handling messages

(See Help for more information, เปด MFC reference)

Independent of span MFC class hierarchy

9 /34

The MFC macros and global offer functionality in the following categories:

General MFC: TRY, CATCH, AfxMessageBox() Exception processing CString formatting and message-box display Message maps , etc…

Database:AFX_ODBC_CALL , AfxGetHENV Internet DHTML Event Maps OLE & OLE Controls

10 /34

Some Important Global Functions(2nd Section, cont.)

AfxMessageBox()-- Message boxes are predefined windows

AfxAbort() -- unconditionally terminate an app

AfxBeginThread() -- Create & run a new thread

AfxGetApp() -- Returns a pointer to the application object

AfxGetMainWnd() -- Returns a pointer to application’s main window

AfxGetInstanceHandle() -- Returns handle to applications’s current instance :HINSTANCE

AfxRegisterWndClass() -- Register a custom WNDCLASS for an MFC app

11 /34

To Develop a MFC program

Primary task in writing MFC program— to create Classes: most will be derived from MFC library

classes Member Functions: ShowWindow()--a member of CWnd class TextOut()--a member of CDC LoadBitmap()--a member of CBitmap

data memebers: CWnd::m_hWnd

Apps can also call API functions directly Use Global Scope Resolution Operator(::), for example: ::UpdateWindow(hWnd);

12 /34

MFC Notation

All MFC class names begin with C Additionally, data members of MFC

classes are prefixed with m_

Should begin class names with a C and data members with m_ in order to identify as an MFC program

13 /34

The Application/Window ApproachA Minimal MFC Program

Must contain two classes : An application class derived from CWinApp

encapsulates the initialization, running, and termination of an application

ex. class CApp : public CWinApp {}

A window class usually derived from CFrameWnd Defines the application's main window ex. class CMainWin : public CFrameWnd {}

These & other MFC classes brought in by using#include <afxwin.h>

14 /34

ขั้นตอนการสราง Minimal MFC prog1. สรางคลาส derive จากคลาส CFrameWnd

a) สราง constructor และ destructor ของคลาสที่สรางขึ้นใหมb) ใน constructor ของคลาส ให implement ฟงกชัน Create() เพื่อสราง main

window

2. สรางคลาส derive จากคลาส CWinAppa) สราง constructor และ destructor ของคลาสที่สรางขึ้นใหมb) Override ฟงกชัน InitInstance() และภายใน body ของฟงกชันนี้ตองประกอบดวย

ขั้นตอนดังนี้

i. เซ็ตคา pointer ชี้ไปยังอ็อปเจ็คของคลาสในขอ 1 ใหกับ m_pMainWndii. สั่งแสดง main window ดวยคําสั่ง m_pMainWnd->ShowWindow(m_nCmdShow);

iii. สั่ง update main window ดวยคําสั่ง m_pMainWnd->UpdateWindow();

3. สรางออ็ปเจ็คจากคลาสในขอ 2a) Each application that uses the Microsoft Foundation classes

can only contain one object derived from CWinAppb) Global level

วาด UML

15 /34

// file of prog1.h#include <afxwin.h>class CMainWin : public CFrameWnd{public:

CMainWin(); virtual ~CMainWin();

};

// file of prog1.cpp#include "prog1.h" //declarations

CMainWin::~CMainWin(){}CMainWin::CMainWin(){

Create(NULL, "An MFC pplication Skeleton");

}class CApp : public CWinApp{public:

CApp();virtual ~CApp();virtual BOOL InitInstance();

//must override this fn. };

// Our CApp class function definitionsCApp::CApp(){}CApp::~CApp(){}// Initialize the applicationBOOL CApp::InitInstance(){

m_pMainWnd = new CMainWin(); m_pMainWnd->ShowWindow(m_nCmdShow);m_pMainWnd->UpdateWindow();return TRUE;

}// Instantiate the applicationCApp App;// create a CApp object and // begin execution

CWnd* m_pMainWndเปน inherited data member จากคลาส CWinThread:Holds a pointer to the application’s main window.

CWinApp::m_nCmdShow corresponds to the nCmdShow parameter passed by Windows to WinMain.

16 /34

Sequence of Execution

WinMainCalls

InitInstance

Standard function supplied by framework application

Initializes current instance of the application

Calls

Run Runs the message loop

Calls

ExitInstance Cleans up after the application close

InitInstance, Run, ExitInstance เปน member fns. ของ CWinApp

17 /34

Global functions to access your CWinApp object In addition to the CWinApp member functions, the

Microsoft Foundation Class Library provides the following global functions AfxGetApp Obtains a pointer to the CWinApp object

:CWinApp * (return type) AfxGetInstanceHandle Obtains a handle to the

current application instance :HINSTANCE AfxGetResourceHandle Obtains a handle to the

application's resources. Load the menu specifying the module handle where resource is

to be found & resource ID HMENU hMenu = ::LoadMenu(AfxGetResourceHandle(), MAKEINTRESOURCE(IDR_MENU1));

18 /34

Creating App/Window Application:Win32 Project

File|New|Project|Win32Set to empty Project

19 /34

Project|Add new Items...:Header file(.h) & Declaration file (.cpp)

Visual C++|Code|C++ File(.cpp) or Header File (.h)

20 /34

Enable MFC support in win 32 AppProject|…properties

Use MFC in a Shared DLL

•By default, Win32 Application projects do not support MFC programming•In order to enable MFC support in a Win32 Application project,

•Set “Use MFC in a Shared DLL” or “Use MFC in a Static Library”•If no, compile error•Character set : not set

21 /34

Build|Run

The CFrameWnd class creates a simple window with a frame,title bar, system menu, and control buttons

22 /34

ตองการใหรับ mouse input ได

23 /34

Message Processing under MFC

Like API programs, MFC programs must handle messages from Windows

API mechanism: big switch/case statement

Handle notification messages from child windows.

Child Window Notification Message Handlers

Handles WM_COMMAND messages generated by user menu selections or menu access keys.

WM_COMMAND Message Handlers

Handle WM_ messages, such as WM_LBUTTONDOWN, WM_PAINT.

WM_ Message Handler( Application|Window Approach)

DescriptionMessage Categories

MFC mechanism: "message maps" (lookup tables)

24 /34

Message Handling between Win 32 API & MFC

คลาสที่สามารถจะดักจับเมสเสจไดจะตองเปนคลาสที่ derive มาจากคลาส CCmdTarget ซึ่ง CFrameWnd ก็ derive มาจากคลาสนี้

• Encapsulates the messaging features of the Windows API

CCmdTarget

CFrameWnd

CWnd

CView

CDialog

25 /34

Implement a Message MapTo have your class do something in response to a message:1. Add DECLARE_MESSAGE_MAP statement to the class definition

(header file, *.h). & prototype of function handler2. In implementation file ( *.cpp)

2.1 Identifying the messages between BEGIN_MESSAGE_MAPmacro and END_MESSAGE_MAP macro

• Need to tell it the class name and the superclass name2.2 Add Member Functions to handle the messages

Example: ตองการให app รับเมสเสจจากการกดเมาสปุมซาย- function prototype ใน .h ไฟล:DECLARE_MESSAGE_MAP;afx_msg void OnLButtonDown(UINT nFlags, CPoint point);

- Define message macros ใน .cpp ไฟล:BEGIN_MESSAGE_MAP(CMainWin, CFrameWnd)

ON_WM_LBUTTONDOWN()//ใชชื่ออื่นไมไดเปน Macro มาตรฐานEND_MESSAGE_MAP()void CMainWin::OnLButtonDown(UINT nFlags,CPoint point){…}

ถาตองการให detect การกดเมาสปุมขวาดวยทําอยางไร?

26 /34

Window messaes : WM_ Message Handlers

afx_msg void OnLButtonDown(UINT, CPoint);afx_msg void OnLButtonDblClk( UINT, CPoint );afx_msg void OnMouseMove(UINT, CPoint);afx_msg void OnClose( );afx_msg void OnLButtonUp( UINT, CPoint );etc,...

ON_WM_LBUTTONDOWN()ON_WM_LBUTTONDBLCLK( )ON_WM_MOUSEMOVE()ON_WM_CLOSE()ON_WM_LBUTTONUP( )etc,...

Function prototype member functions of CWndMab Entry

•WM window message

•เปน member function ของคลาส CWnd•CWndCFrameWnd

UINT nFlagsMK_CONTROL Set if CTRL key is down.MK_LBUTTON Set if left mouse button is down.MK_MBUTTON Set if middle mouse button is down.MK_RBUTTON Set if right mouse button is down.MK_SHIFT Set if SHIFT key is down.

CPoint point :

Specifies the x and y coordinates of the cursor.

void CMainWin::OnLButtonDown (UINT nFlags,CPoint point){…}

27 /34

Creating a Message Mapping for a Class Derived from CFrameWnd

// file of prog1.h#include <afxwin.h>class CMainWin : public CFrameWnd{public:CMainWin(); virtual ~CMainWin();

afx_msg void OnLButtonDown(UINT nFlags,CPoint point);DECLARE_MESSAGE_MAP()};

class CApp : public CWinApp{public:

CApp();virtual ~CApp();virtual BOOL InitInstance();

};

// file of prog1.cpp#include "prog1.h" //declarationsCMainWin::~CMainWin(){}CMainWin::CMainWin(){

Create(NULL, "An MFC pplication Skeleton");}// CMainWin's message mapBEGIN_MESSAGE_MAP (CMainWin, CFrameWnd)

ON_WM_LBUTTONDOWN()END_MESSAGE_MAP();void CMainWin::OnLButtonDown(UINT nFlags,

CPoint point){

CDC *pDC = GetDC();pDC->TextOut(point.x, point.y,"Hello");

}// Our CApp class function definitionsCApp::CApp(){}CApp::~CApp(){}// Initialize the applicationBOOL CApp::InitInstance(){

m_pMainWnd = new CMainWin(); m_pMainWnd->ShowWindow(m_nCmdShow);m_pMainWnd->UpdateWindow();return TRUE;

}

// Instantiate the applicationCApp App;

Demo project ;Prog1

if (nFlags & MK_CONTROL) {pDC->TextOut(200, 200,"Bye ");

}

28 /34

WM_COMMAND

Handle notification messages from child windows.

Child Window Notification Message Handlers

Handles WM_COMMAND messages generated by user menu selections or menu access keys.

WM_COMMAND Message Handlers

Handle WM_ messages, such as WM_LBUTTONDOWN, WM_PAINT.

WM_ Message Handler(Application|Window Approach)

DescriptionMessage Categories

Menu• Design• Load• Process

29 /34

Resources A resource is a graphical user interface element that allows a user

to interact with an application

Resources are defined in special files called resource scripts

Resource scripts have an extension of .rc and are written in C preprocessor language

A resource ID is a constant declared with the #define preprocessor directive and is used for programmatically referring to a resource

#include “resource.h”

เนื่องจากสรางภายใต Win 32 Project ดังนั้นการสราง resource ใหกบั Application &window Approach เหมือนใน Win 32 Project

Project|Add Resource…

สมมุติเราจะสรางเมนูให attach กับ main window ทีส่รางขึ้นในสไลดที่ 21

30 /34

Project|Add resource:Design Menu

เกิดไฟลนามสกุล .rc และไฟล resource.h ใหอัตโนมัติ แลวเลือกเมนู เพื่อออกแบบเมนู

31 /34

Attach a menu to the Application:Load Menu

เปลี่ยนแปลงรูปแบบการเรียกใชฟงกชัน Create() ใน Constructor ของคลาสที่ derive จากคลาส CFrameWnd ตัวอยาง:

ใน .cpp ไฟล ตองทําการ #include “resource.h”

สราง message mapping แตละเมนู หรือ resource เพื่อ response เมื่อ user เลือกเมนูนั้นๆ

CMainWin::CMainWin(){

Create(NULL, “Using Menus”, WS_OVERLAPPEDWINDOW, rectDefault, NULL, (LPCTSTR)IDR_MENU1);

}

Demo project ;Prog1

•Create(NULL, "Using Menus", WS_OVERLAPPEDWINDOW, rectDefault, NULL, MAKEINTRESOURCE(IDR_MENU1));

32 /34

Build|Run

Menu does not work.. WHY??ขาด Process

33 /34

afx_msg void memberFxn( );

ParametersId : The control ID.memberFxn: The name of the message-handler function towhich the command is mapped.

ON_COMMAND( id, memberFxn)Menu, toolbar,Accelerator key

Control type Function prototypeMap Entry

Message from :Menu, Toolbar, Accelerator key

อยูใน .cpp ไฟล อยูระหวางmacro:BEGIN_MESSAGE_MAP & END_MESSAGE_MAP

Prototype ในไฟล .hสวน implement ในไฟล .cpp

สวนประกาศของฟงกชนั memberFxn() อยูในไฟล .cppวาจะให response อะไรตอ userDemo Project: Prog1

34 /34

Including a Menu & Responding to Menu SelectionsCMainWin::CMainWin()

{ Create(NULL, “Using Menus”, WS_OVERLAPPEDWINDOW, rectDefault, NULL, (LPCTSTR)IDR_MENU1);

}

BEGIN_MESSAGE_MAP(CMainWin, CFrameWnd)…

ON_COMMAND (ID_SHOW_MESSAGEBOX, OnShowMsg)END_MESSAGE_MAP()

void CMainWin::OnShowMsg(){ AfxMessageBox(200,200, “Bye”);}

.cpp

afx_msg void OnShowMsg(); in .h file