Display Ghostscript (DGS) is functionally upward-compatible with Adobe Display PostScript, but it has been written independently. The Display Ghostscript System provides a device-independent imaging model for displaying information on a screen. The imaging model uses the PostScript language which has powerful graphics capabilities and frees the programmer from display-specific details like screen resolution and color issues. DGS is an integral part of the GNUstep Development Environment.
GNUstep is a cross-platform, object oriented environment composed of frameworks, tools, and servers (daemons). It is very similar to the Cocoa frameworks from Apple, and tries to maintain compatibility with Cocoa wherever it is desired and possible. The frameworks provide classes for containers, distributed objects, object archiving, file management, text system, font management, image composition, WYSIWYG PostScript graphics, and more.