Common Graphics The Common Graphics (CG) subsystem can be divided into two sets of classes: • The core Common Graphics classes • Classes comprising Common Graphics Image Support This document first describes the core Common Graphics classes and later describes the Image Support classes. The core Common Graphics classes and methods enable programmers to do the following: • Define drawing attributes, such as line widths or styles, through the use of graphics contexts • Perform drawing operations, such as drawing lines, arcs, text strings, and polygons • Manipulate fonts • Manipulate two-color bitmaps and multicolor pixmaps Common Graphics Image Support also enables programmers to do the following: • Specify a palette of colors to use in drawing operations • Create, manipulate, and draw bitmap images in a platform-independent and device-independent format • Create and draw icons • Load and unload images and icons using standard file formats This chapter describes how the core system is based on the X Window System's graphics library, shows the class hierarchy, and explains the basic process for building an application. It summarizes resource management, describing when and how to free graphics resources that have been allocated. Classes in the Common Graphics hierarchy are prefixed by the letters 'Cg;' for example, CgRGBColor or CgFont.
