CairoGraphicsLibrary http://cairographics.org/

''Cairo is a 2D graphics library with support for multiple output devices. Currently supported output targets include the X Window System, Win32, image buffers, PostScript, PDF, and SVG file output. Experimental backends include OpenGl (through glitz), Quartz, and XCB.''

''Cairo is designed to produce consistent output on all output media while taking advantage of display hardware acceleration when available (eg. through the X Render Extension).''

See RubyShoes.