A PostScript-like API for the X Render Extension

Pivot writes: "Carl Worth and Keith Packard have started building a PostScript-like API for drawing using the X Render extension. There are two modules, called 'Xr' (the "rendering part") and 'Xc' (the "compositing part", which is a layer on top of Render which will eventually grow to a client-side Render emulator). The API supports only cubic Bezier splines, leaving other splines out of the library, similar to PostScript. Check out the initial announcement on the Render mailing list, and some example shots. Shurely this will remind some of NeWS, cowritten by another well known character."

Comments

Re:I don't understand

[dmiller]

In addition to the already-mentioned resolution independance. This API would allow an X server to implement hardware acceleration of the rendering. I don't know if any cards support acceleration of spline decompisition, but just about everyone supports hardware-assisted polygon filling, which means many fewer pixels go over the wire (or SHM segment).

Now if only they would implement true multi-window tranparency and complete affine transformation support, then X would begin to catch up to OS X :)

Re:Is this a security hole?

[rjw57]

This is a common misconception. With this you don't literally throw PostScript at the X-server. Instead this library presents a drawing and compositing API with similar semantics to PostScript (i.e. it is a stack-based protocol with elementary drawing commands such as 'MoveTo' and 'DrawTo'). All commands are issued via function calls however not by parsing PostScript (which would introduce a) a huge overhead and b) security questions as you said).

True Display Postscript can be thought of as a rich-text version of the X11 protocol, there is little protocol-based computation which can be initiated on the server by the client, instead it simply encapsulates a set of vector and bitmap srawing commands within a consistant protocol.