render improvements

Zack Rusin zack at
Fri Apr 15 14:10:47 PDT 2005

On Friday 15 April 2005 16:18, Owen Taylor wrote:
> The xorg patch above removes all the changes from the xorg tree that
> my patch merges from the xorg tree into the xserver tree ... but
> I think those changes don't have much to do with the bulk of your
> code, which is all about the general case, instead of special
> case optimizations.


> To avoid further confusion, I'll go ahead and commit my changes this
> evening ... hopefully that won't cause you too much pain.

Well, to be honest we removed the mmx code for now. I can add it back 
without any problems, but it shouldn't be necessary. 
Also since now the combining methods operate on scanlines adding code 
that would in a common way accelerate all operations by combining a 
couple of pixels in one pass should be rather easy. 

> I think it would be very good if someone went through and merged up
> the remaining differences in fb/ between xserver and xorg. There's
> no reason that they should differ at all.

I guess I could do it early next week, but...

> If we did that, then we could have a simple way of treating fb/
> changes ... to say that all changes must go first into xserver than
> get merged into xorg.

Before we do that, lets decide what to do about convolution filters. 
Start of them them is in the xserver but not in the xorg or the specs. 
Glitz implements them already. We haven't implemented them in our 
implementation. I wasn't sure whether I should bother quite yet. This 
might be the right moment to figure out what to do with them :)

> In the slightly longer term, the work that needs to be done is to
> make the X server trees use libpixman.

Yeah, that'd be good. One other short-term thing I'd like to see is 
improving the tessellation code in XRenderCompositeDoublePoly, or maybe 
even having one common trapezoidation algorithm that everyone could 
share. I guess even merging back the changes from the Cairo tessellator 
back into Render would be enough for now.


There are two ways to write error-free programs. Only the third one 

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