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Re: ligature formation across text chunks

From: Cameron McCormack <cam@mcc.id.au>
Date: Tue, 17 May 2011 16:01:06 +1200
To: Glenn Adams <glenn@skynav.com>
Cc: Vincent Hardy <vhardy@adobe.com>, "public-svg-wg@w3.org" <public-svg-wg@w3.org>
Message-ID: <20110517040106.GD11461@wok.mcc.id.au>
Glenn Adams:
> I probably shouldn't throw this in, but I wonder how these semantics would
> handle situations like Example 1 under "Examples [of] Devanagari syllables"
> in [1], where a sequence of 12 Unicode characters maps to a sequence of 4
> glyphs, and where the inverse association from glyph to generating character
> indices are as follows:
> 
> Glyph  Char
> Index  Indices
> 
> 0   <- {10}
> 1   <- {2,3,4}
> 2   <- {5,6,7,8,9}
> 3   <- {0,1,11}
> 
> The semantics of associating x offsets (and similar properties) with
> characters as opposed to glyphs seems rather disconnected to me.

What I would expect from the above example is that if you have

  <text x="10 20 30 40 50 60 70 80 90 100 110 120 130 140">
    azzzzzzzzzzzzb
  </text>

where the zs are the 12 characters mapping to the single glyph that you
mention, then you would get the “a” glyph at x = 10, the Devanagari
glyph at x = 20 and the b glyph at x = 140.  That’s what the rules in
http://www.w3.org/TR/SVG/text.html#TSpanElement say to do (the third
bullet beneath “The following additional rules apply …”).

> One can certainly talk about associating x offsets with the output
> glyphs, but attempting to associate such properties with input
> characters that may be subjected to a complex, non-continuous,
> disjoint mapping to glyphs seems questionable, except in the special
> case of 1:1 continuous mappings.

Yes, the x="" attribute there shouldn’t break up the complex glyph.

-- 
Cameron McCormack ≝ http://mcc.id.au/
Received on Tuesday, 17 May 2011 04:01:41 GMT

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