Package ‘Cairo’：Title R graphics device using cairo graphics library for creating high-quality bitmap (PNG, JPEG, TIFF), vector (PDF, SVG,PostScript) and dis-play (X11 and Win32) output.
Author Simon Urbanek <Simon.Urbanek@r-project.org>, Jeffrey Horner
<jeff.horner@vanderbilt.edu>

Description：This package provides a Cairo graphics device that can be use 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 environemnts (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.