Re: Sample line drawing app

Around 21 o'clock on May 23, Jorge Valencia wrote:

> correct me if I'm wrong , but XRender seems to handle lines as polygons, how
> will this impact the performance and feasability of line characteristics?
> Can somebody confirm which line characteristics are currently supported by
> XRender when drawing AA lines?

You can draw anything you like with trapezoids, sometimes you just have to 
use a lot of trapezoids :-)

> line style? (solid, onoff, double)
> cap style?  (butt, notlast, projecting, round)
> join style? (bevel, miter, round)
> fill style? (solid, tiled, stippled, opaquestippled)

All of these will be implemented client-side by sending appropriate lists 
of trapezoids.  That's how the current server-side implementation works 
now, it's just hidden behind the Byzantine protocol spec.

Xrender has a polygon tesselation routine, but Carl Worth and I think that 
we should build a separate library (Xr) that would support client-side 
tesselation of the "usual" suspects as well as supporting the image
compositing based underlying pixelization model either with the Render 
extension or using GetImage/PutImage for X servers without Render support.

We should get started on a list of features for Xr; suggestions about the 
content would be welcome -- in particular, we need to pick the various 
primitive elements and a structure for gluing them together.  I'm thinking
of a stateful system like GL or Postscript to reduce the number of 
function parameters, but I don't write graphics apps for a living, so for 
those of you that do, now would be a good time to bring your favorite 
models forward.

Keith Packard        XFree86 Core Team        HP Cambridge Research Lab