Subject: Re: rendering - how bad is AW font displaying desing?
From: Mike Nordell (tamlin@algonet.se)
Date: Tue Jan 09 2001 - 21:51:53 CST
Tomas Frydrych wrote:
> Unfortunately, rendering is not simply a question of font displaying.
This might have been the first thing I misunderstood. When it comes to WP
and fonts I believed rendering was all *just* about fonts.
> Rendering has to do with the fact that in certain languages a single
> character has got multiple glyphs depending on the character's
> context.
Afther reading a few other comments, and now this, I think I'm finally
beginning to grasp this concept.
> The notion behind rendering is that only a single code is
> used to represent/store/input the character, but the rendering
> engine takes care of displaying the correct glyph based on the
> immediate context.
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?
If I *did* get you right, are there any "engines" available that does this
kind of stuff, or are we breaking new ground?
> Things get further complicated, if your rendering engine is stand-
> alone; you may need two way traffic implemented between it and
> your code. In AW the drawing is done by runs. When you need the
> drawing to be rendered, the text of your run offten will not be
> enough for the engine to work out how to draw it. In that case it will
> have to ask for additional information and you will need to pass it
> back to it. This is further complicated by the fact that a run may
> not contain more than a single character; you may need an
> arbitrary number of runs to be passed to the engine, in one way or
> another, just to accomplish drawing of a single character. And
> there are other issues involved under rendering, not just drawing
> text on screen, such as line breaking.
Wait a minute. Is "line-breaking" *also* a renderer issue?
> The AW back end is not badly designed, only it was not designed
> with the possibility of using a rendering engine in mind (IMHO). So
> you do not need to fix it, but may need to rework it if/when you
> decide you want to use a rendering engine with it; I was hoping to
> look into what exactly it would take once I am done with the BiDi
> patch.
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?
/Mike - please don't ...
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