Ivor Horton's Beginning Visual C++ 2012

THE MFC DOCUMENT/VIEW CONCEPT

When you write applications using the MFC, it implies acceptance of a specific structure for your program, with application data being stored and processed in a particular way. This may sound restrictive, but it really isn’t for the most part, and the benefits in speed and ease of implementation you gain far outweigh any conceivable disadvantages. The structure of an MFC program incorporates two application-oriented entities — a document and a view — so let’s look at what they are and how they’re used.

What Is a Document?

A document is a collection of data in your application with which the user interacts. Although the word document seems to imply something of a textual nature, it isn’t limited to text. It could be data for a game, a geometric model, a text file, a collection of data on the distribution of orange trees in California, or, indeed, anything you want. The term document is just a convenient label for the application data in your program, treated as a unit.

You won’t be surprised to hear that a document is defined as an object of a document class. Your document class is derived from the CDocument class in the MFC library, and you add your own data members to store items that your application requires, and member functions to support processing of that data. Your application is not limited to a single document type; you can define multiple document classes when there are several different kinds of documents involved in your application.