D-event Oriented Window Programming & MFC (Microsoft Foundation Class) Liberaries

Windows programs are event driven.  This means that such programs respond to user actions called events.  Such as clicking the mouse striking a key and so on.

      Each time such an event occurs, the corresponding method is called in our program.  Such a method is known as Event Handler.  In this way, the whole program is broken up into bite sized methods responding to various windows events.

For example :-  The OnDraw() method handles the case in which the client area.  The Onchar() method handles the case the user presses a key on the keyboard.

The LButtonDown() method handles the case when the user clicks the left mouse button.

Method

i) OnLButtonDblclk :- called when the user double clicks left mouse button.

ii) OnLButtonDown :- called when the user presses the left mouse button.

Microsoft provides a library that makes the programmer's job easier called the Microsoft Foundation Class library(MFC).  It is an extraordinary package of pre-written, ready to use code.  It greatly reduces the amount of code that must be written to create to a windows program.  For Example Instead of having to write all the code (and that's a huge amount of code) to support a new window.  We can just rely the MFC Cwnd code package, which handles all the details for us.

     It also provides all the advantages normally found in C++ programming.  Such as inheritance and encapsulation.  The visual C++ application development environment is specifically tuned to MFC, so by learning MFC and visual C++ together one can significantly increase its power as an application developer.  The library's primary advantages is its efficiency.

Some of the basic MFC's are :->

1) CDC :  This handles device context for viewing on screen or printer.

2) Cstring : This handles text string for us.

3) Cwnd :  This handles window functioning.

4) CFile :  This handles all the work related to file i.e opening, closing, writing etc.

5) CDialog :  This handles all the work related to dialog box.

6) CButton :  This handles work related to Button.

7) CPen :  This handles drawing with pen in particular color.

8) CSlider :  This handles slider work where value is taken from the user.

9) ChttpConnection :  This executes HTTP requests.

10) CObject :  This handles work related to serialization in file handling.

       To develop a windows applications in VC++, we use MFC AppWizard.  The AppWizard creates a great deal of code in our program for us.  We just need to modify the code according to our requirement.