12.1. Cocoa and the Art of Graphics

Before jumping head first into graphics, you need to familiarize yourself with a few important Cocoa data types: NSPoint, NSRect, NSSize, and NSColor. You need them to do any type of graphics programming in Cocoa, so they make a good starting point.

12.1.1. Points

Just like in geometry, Cocoa uses points to designate positions on a square grid. To work with points in Cocoa, you use an NSPoint structure. NSPoint is a structure comprised of two floats (x and y, respectively). Quartz, the graphics engine on the Mac OS, defines the bottom-left corner of a view as the origin (0,0). The x value increases as you move to the right. The y value increases as you advance up.