R graphics device using cairographics library that can be used to create
high-quality vector (PDF, PostScript and SVG) and bitmap output
(PNG,JPEG,TIFF), and high-quality rendering in displays (X11 and Win32).
Since it uses the same back-end for all output, copying across formats is
WYSIWYG. Files are created without the dependence on X11 or other external
programs. This device supports alpha channel (semi-transparent drawing)
and resulting images can contain transparent and semi-transparent regions.
It is ideal for use in server environments (file output) and as a
replacement for other devices that don't have Cairo's capabilities such as
alpha support or anti-aliasing. Backends are modular such that any subset
of backends is supported.
