Canvas basics

Caveat: every time the width and height attributes of a canvas are changed the canvas is cleared.

Caveat: The memory used by a canvas is width * height * 4 bytes. So if you create a 10,000px by 10,000px canvas, it will use 400MB of RAM, not to mention causing issues for effective hardware acceleration. Try to avoid doing that sort of thing.

      void arc(in double x, in double y, in double radius,
               in double startAngle, in double endAngle,
               in optional boolean anticlockwise);