Inside Macintosh: Imaging with QuickDraw
Color QuickDraw is a collection of system software routines that your application can use to display hundreds, thousands, even millions of colors on capable screens. Color QuickDraw is available on all newer models of Macintosh computers; only those older computers based on the Motorola 68000 processor provide no support for Color QuickDraw.
Color QuickDraw performs its operations in a graphics port called a color graphics port , which is based on a data structure of type CGrafPort . As with basic graphics ports (which are based on a data structure of type GrafPort ), each color graphics port has its own local coordinate system. All fields in a CGrafPort record are expressed in these coordinates, and all calculations and actions that Color QuickDraw performs use its local coordinate system.
As described in the chapter "QuickDraw Drawing," you can draw into a basic graphics port using eight predefined colors. With a color graphics port, however, you can define your own colors with which to draw. With Color QuickDraw, your application works in an abstract color space defined by three axes of red, green, and blue (RGB). Although the range of colors actually available to your application depends on the user's computer system, Color QuickDraw provides a consistent way for your application to deal with color, regardless of the characteristics of your user's screen and software configuration.