.NET Windows Forms in a Nutshell

GDI+

GDI+ is the name of the drawing API in .NET. It is exposed through classes defined in the System.Drawing namespace and its descendants, System.Drawing.Drawing2D, System.Drawing.Imaging, and System.Drawing.Text. It provides a simple but powerful set of tools for drawing text, bitmaps, and vector graphics.

GDI+ Naming

None of the GDI+ classes have the name “GDI+” in them anywhere. The API is named after its predecessor, GDI (the Graphics Device Interface), which was the Win32 drawing API. GDI+ is not in fact a part of .NET—all the same facilities are available to Win32 programs on Windows XP (or older versions of Windows if GDI+ has been installed; GDI+ is put in automatically on these platforms when the .NET Framework is installed). The System.Drawing namespaces are the managed interface to GDI+.

There is a small group of classes that are crucial for drawing anything—some represent fundamental concepts such as colors, coordinates, and drawing styles, others represent entities that can be drawn into, such as bitmaps or windows. We will start by seeing what each of these classes is for, and how they relate to each other. Then, we will look at the various drawing facilities supplied by GDI+ and how to use them. Finally, we will look at some of the advanced support for changing the coordinate system used for drawing.

Essential GDI+ Classes

There are certain classes defined in the System.Drawing namespace that are used in almost all drawing code. This is because they represent concepts ...