Subject: Re: rendering
From: Tomas Frydrych (tomas@frydrych.uklinux.net)
Date: Sat Jan 13 2001 - 09:49:59 CST
> So what we *really* need, is some kind of "context sensitive
> glyph-replacer"? Would that suffice, or am I yet again misunderstanding
> something. This "thing" would *not* be part of what we usually see as the
> "renderer", it would be an intermediate (or on-the-side) "helper"-thing?
Yes, rendering engine is a glyph replacer that sits somewhere
between the calls to the GUI rutines and the wordprocessor text.
> If I *did* get you right, are there any "engines" available that does this
> kind of stuff, or are we breaking new ground?
Pango for one. There are others, but the good thing about Pango is
that its open source and in its aims it is trully global. Wheather it is
mature enough for our purposes, I am not entirely sure.
> Wait a minute. Is "line-breaking" *also* a renderer issue?
In principle yes, since the characters on which it is permissible to
break a line may vary from language to language, and you may
need to query the rendering engine about these characters.
> I still fail to see the real distinction you make between a "rendering
> engine" and the kind of "font rendering engine" we currently use. I can see
> we're coming from different camps, but I fail to see how the "rendering
> engine" would be responsible for the "context-sensitive glyph-replacement"
> stuff. Would you please elaborate?
The rendering engine is really a string translator; you pass it a
string in the form you use to store the text and it translates it into a
form that should be drawn on the screen; the rendering engine per
se does not have to deal with fonts at all although it may have
some high-level API that does more than the string translation. I
think the Pango high-level API deals with font isssues, such as
finding which font can be used to display a particular Unicode
character.
Tomas
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