Quartz, also known as Core Graphics, is the native graphics API for OS X. Now, that QuickDraw has been deprecated, it has become more important to learn and master Quartz. Quartz is a superset of Adobe PDF 1.4. Next Step and now Cocoa are also based on Quartz.
Quartz uses floats in point and rectangle structures so it can represent more accurate values during scaling, rotation, and other transforms.
By default, Quartz uses a coordinate system with 0.0, 0.0 as the lower, left corner, as opposed to QuickDraw with 0,0 on the top, left. However, the HIView system for drawing in composited windows uses a transformed coordinate system with 0.0, 0.0 as the top, left corner of a view.
Draw Image in Window Using QuickTime
There is now a new and excellent book on Quartz available Programming with Quartz
Another new Quartz Book Quartz 2D Graphics for Mac OS X Developers by Scott Thompson
Quartz Programming Articles by Scott Thompson