Re: What's the prerenderer do?

[Lars Clausen <lrclause cs uiuc edu>]

[If this mail looks funny, Gnus knows what it's talking about, and I don't]

On Sat, 2 Mar 2002, Cyrille Chepelov wrote:
> Le Sat, Mar 02, 2002, à 10:22:32AM -0600, Lars Clausen a écrit:
>> 
>> I notice the appearence of a StringPrerenderer thingy.  What's it do?
> 
> Been here for one year (at least). The goal is to make all (UTF-8)
> strings pass at least once through it, so that any special (non-ASCII)
> characters could be noticed and acted upon.
> 
> Currently (that is, before you last commit, which I haven't looked at
> yet), this is used to build on the fly Postscript encoding tables (and
> used also to be used by my Display Postscript experiment for the same
> thing). It also sh/could be used to notice which glyphs we're going to
> need and put them into some kind of prolog. I also use that to lazily
> encode the fonts, instead of bulk-encoding everything (this is normally
> the default now in 0.88.1 and leads to faster EPS/PS). [*]
> 
> Of course, from what I understand of your recent postings, you've sort-of
> re-implemented this in a second, parallel facility.
> 
> Obviously some merging will be necessary.

I thought it looked similar.  As I have an aversion to adding new functions
to the renderers, I instead added an extra mostly empty renderops structure
that can pick out the interesting stuff for the prolog.  This has the
advantage of allowing more than just strings to be examined, for instance
common colors could be predefined, or even common images.  It might be
slightly slower, though, which could be a problem for the DPS renderer.

> [*] building encoding tables is only half the job. Akira TAGOH rightly so
> pointed out that we also need to locate the glyphs the printer is not
> likely to know about, and put them in the prolog. So, your last commit,
> to the extent it is able to download CJK/East-European glyphs, is a big
> step in the right direction. I would have appreciated a lot if some
> public discussion of this had been made before doing duplicate work (I
> deserve 80% of the blame, for not having brought back to the list the
> discussion I had recently with Akira on that topic).

Not too much work on my part, as I didn't touch the Unicode stuff yet.

I know nothing of how FreeType will do non-ASCII glyphs, but from the list
I gather it has no problem with it.  So it's all in the encoding.

I just now got the bounding boxes to do The Right Thing (apart from some
cases where a glyph is larger than it's supposed to be), and got full Type1
printing support.  Pretty, pretty fonts, and in particular, fewer problems
with differing lengths on screen and on paper (though the Courier font
seems to have some issues with zooming).

Still need to look deeper into translating between the standard PS fonts
and FreeType fonts.  There are some hints that can be used, perhaps.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| Hårdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?