[openbeos] Re: GSoC: Sub-pixel antialiasing for font rendering

  • From: Stephan Assmus <superstippi@xxxxxx>
  • To: openbeos@xxxxxxxxxxxxx
  • Date: Fri, 04 Apr 2008 09:51:46 +0200

Curtis Wanner wrote:
> Andrej wrote:
> > Hello everybody,
> > 
> > I would like to submit a proposal for the sub-pixel antialiasing 
> > project for GSoC. I know the basics of how sub-pixel antialiasing works 
> > and I think that the most important part of this project would actually 
> > be to get a complex understanding of how text-rendering in Haiku works. 
> > Could you please suggest any materials that would help me familiarize 
> > myself with the structure of Haiku's app_server and font rendering. I 
> > would like to get a more precise idea of what needs to be done before 
> > writing the application.
> 
> Correct me if I'm wrong, but there are potential license issues with this 
> idea that the project may want to avoid.  From my understanding there is 
> disabled sub-pixel code already in FreeType (based on Apple's 
> methodology).

You might confuse this with the hinting algorithm. Freetype offers a 
compile time option to use hinting based on embedded byte code 
interpretation, which is said to be patented by Apple. It is currently 
turned on in our Freetype config.h, because the alternative Freetype "auto 
hinter" used to suck. From what I heard, it has since become much better, 
so we might want to check it out.

As far as sub-pixel anti-aliasing goes, it is controversial. Some people 
say Microsoft has various ClearType related patents. But on another page, I 
read pretty convincingly that these the essence of sub-pixel rendering 
might not be patentable, because there is prior art. Sorry for not 
providing an URL, would need to dig it up.

In any case, patents only apply in certain countries, there is nothing 
wrong with implementing this technology as long as we don't violate any 
licenses and copyrights. Affected people might have to turn off the 
technology in their Haiku builds though, similar to Freetype with the 
hinting algorithm.

Best regards,
-Stephan


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