This sample code introduces some of the concepts and features of Quartz. It contains code that:

* fills then strokes a rectangle and strokes then fills a rectangle
* creates a CGPath object and then paints that path with varying degrees of alpha transparency
* draws the contents of a TIFF file using Quartz
* draws the contents of a TIFF file using Quartz clipped by an elliptical shape
* caches content using a CGLayer object and then draws using that cache
* exports any of the above drawing to a PDF file
* exports any of the above drawing as a PNG file

This is a translation of the Cocoa version of the ADC example with the same name.