Skip to main content

MFC - Microsoft Foundation Classes, GUI Development


Are you ready to start programming? No you are not. You don't want me to teach you a stupid 'hello world' application, do you? If you want to make the most of Visual C++ you have to use Microsoft Foundation Classes (MFC). These classes are great because they wrap all of those handles we talked about in the first lesson with easy to use classes. The most important to you right now is the class CWnd. This wraps the functions which needed a window handle (HWND). Remember that PostMessage function I mentioned?

PostMessage(your_HWND, WM_PAINT, 0,0);

Well now we can take our windows class and call it's member function.

MyCWnd.PostMessage(WM_PAINT, 0,0);

This does the same thing, but now we don't have to keep track of the window handles. But don't be fooled, they are still there. We can still use them too. They are now just member variables of the class. The handle to the window a CWnd is associated with in the member variable m_hWnd. We can call the old post message this way:

::PostMessage(MyCWnd.m_hWnd, WM_PAINT, 0,0);

Those colons (::) are used to tell MFC that we are calling the old fashioned versions of the function. You can get away without using them most of the time, but I put them here so you won't be too confused when you see them in microsoft's code.

The CWnd class is the base for several other classes. Like CButton and CDialog which I hope the names make self explanatory. From CButton you can access the windows handle also. (You'd be surprised how many things are windows.. Scroll bars, edit boxes, tree views, the desktop...) Got all that?

Good.

The next most important class, though you won't explicitly use it much, is CWinApp. This class is the backbone of all of your future MFC applications. This is the class that does the main dirty work under the hood. Your program will have a CWinApp class, which when created, starts the program execution. The main function called when the CWinApp is constructed is InitInstance(). In this
function windows are created and the application is set up. Think of the InitInstance() function in CWinApp as the main() section in a C program.

Let's move on to one last very useful MFC class that you will surely use: CString. This is one of microsoft's support classes. It is used to make string manipulation easier. Since CString overrides many of the common operators, like = and +, you can do things like this:

CString strMyString;
strMyString="May the Force be with you";
strMyString+=" young Jedi."
printf("%s", strMyString);
//output will be "May the Force be with you young Jedi.";

Labels:

Comments

Post a Comment

Popular posts from this blog

Explain Polymorphism and Flavors of Polymorphism...

Polymorphism is the ability of different objects to react in an individual manner to the same message. This notion was imported from natural languages. For example, the verb "to close" means different things when applied to different objects. Closing a door, closing a bank account, or closing a program's window are all different actions; their exact meaning is determined by the object on which the action is performed. Most object-oriented languages implement polymorphism only in the form of virtual functions. But C++ has two more mechanisms of static (meaning: compile-time) polymorphism: Operator overloading. Applying the += operator to integers or string objects, for example, is interpreted by each of these objects in an individual manner. Obviously, the underlying implementation of += differs in every type. Yet, intuitively, we can predict what results are. Templates. A vector of integers, for example, reacts differently from a vector of string objects when it receives ...
17 comments
Read more

Function name mangling for C++ and Java

G++ internals - Mangling Both C++ and Jave provide overloaded function and methods, which are methods with the same types but different parameter lists. Selecting the correct version is done at compile time. Though the overloaded functions have the same name in the source code, they need to be translated into different assembler-level names, since typical assemblers and linkers cannot handle overloading. This process of encoding the parameter types with the method name into a unique name is called name mangling . The inverse process is called demangling . It is convenient that C++ and Java use compatible mangling schemes, since the makes life easier for tools such as gdb, and it eases integration between C++ and Java. Note there is also a standard "Jave Native Interface" (JNI) which implements a different calling convention, and uses a different mangling scheme. The JNI is a rather abstract ABI so Java can call methods written in C or C++; we are concerned he...
5 comments
Read more