.NET Windows Forms in a Nutshell

The Form Class

All windows in a Windows Forms application are represented by objects of some type deriving from the Form class. Of course, Form derives from Control, as do all classes that represent visual elements, so we have already seen much of what it can do in the previous chapter. But we will now look at the features that the Form class adds.

You will rarely use the Form class directly—any forms you define in your application will be represented by a class that inherits from Form. Adding a new form in Visual Studio .NET simply adds an appropriate class definition to your project. We will examine how it structures these classes when generating new forms, and we will look at how it cleans up any resource used by the form when it is destroyed. Then, we will consider the different types of forms. Finally, we will look at extender properties. These provide a powerful way of extending the behavior of all controls on a form to augment the basic Control functionality.

The Forms Designer

Most forms are designed using the Forms Designer in Visual Studio .NET. This is not an essential requirement—the designer just generates code that you could write manually instead. It is simply much easier to arrange the contents of a form visually than it is to write code to do this.

When you add a new form to a project, a new class definition is created. The Designer always uses the same structure for the source code of these classes. They begin with private fields in C# and Friend fields in VB to ...