output ( macro/python )
The Cairo driver offers PNG as a raster output. This output is intended for use on web pages. PNG output has two extra feature compared to the other outputs: possible transparent background and the return of meta information about the plot inside the PNG. Both features are intended for when PNGs are used for web pages. The transparent overlay allows overlays of multiple images. The meta information generated by Magics++ allows JavaScript developer navigate the PNG and implement interactions on top of the PNGs content.
This driver uses the Cairo graphics library to generate various output formats. The library is quite new and might not be installed on older or non-mainstream systems. However the situation is improving with Firefox and Inkscape requiring Cairo being installed. Cairo works internally with vectors and produces high quality output.
For more information on Cairo, see the documentation at Cairo home page