Chapter 4: Creating a UML Class Diagram Editor

This chapter presents a drawing application that can create a Unified Modeling Language (UML) class diagram, save it to a disk file, and then retrieve it. The main goal of this project is to illustrate the .NET Framework's Application Programming Interface (API), which enables the use of graphics and text on the video display and the printer. This API is called Graphics Device Interface Plus (GDI+). GDI+ is an improvement on the GDI, the underlying technology of Windows graphics used by programmers prior to the .NET Framework era. The project is a pure drawing application. For example, do not expect to generate code once you finish your class diagram.

Overview of the Chapter

Like in other projects in this book, you need to understand a number of underlying technologies before developing this application. Each of these technologies gets its own section. Afterward, you will develop the project. These are the main sections:

• "Drawing in the .NET Framework": This section describes various members of the System.Drawing namespace used for drawing in the .NET Framework.

• "Creating a Simple Drawing Application": This section presents an application that lets the user to draw simple shapes. This section demonstrates the use of the classes in the System.Drawing namespace.

• "Understanding Object Serialization for Persisting the Graphics Objects": This section explains how to persist graphics objects such as lines and rectangles into the file system to be retrieved later when the user needs them.

• "Understanding the Memento Design Pattern": This section explains how you can use the Memento pattern to help with object serialization.

• "Exploring the UML Class Diagram": This section introduces the UML class diagram.

• "Implementing the Project": This section explains how the project works and describes each class in detail.