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RE: ligature formation across text chunks

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Sun, 15 May 2011 14:15:52 -0700
To: Rik Cabanier <cabanier@adobe.com>, "'Alex Danilo'" <alex@abbra.com>, Cameron McCormack <cam@mcc.id.au>
CC: Vincent Hardy <vhardy@adobe.com>, "public-svg-wg@w3.org" <public-svg-wg@w3.org>
Message-ID: <D23D6B9E57D654429A9AB6918CACEAA98060741F71@NAMBX02.corp.adobe.com>
This is also one of the places where the (defunct) Adobe Mars/PDFXML project had to extend SVG in order to provide a richer glyph<->character(s) mapping along with absolute positioning.


-----Original Message-----
From: public-svg-wg-request@w3.org [mailto:public-svg-wg-request@w3.org] On Behalf Of Rik Cabanier
Sent: Friday, May 13, 2011 11:35 AM
To: 'Alex Danilo'; Cameron McCormack
Cc: Vincent Hardy; public-svg-wg@w3.org
Subject: RE: ligature formation across text chunks

> 	As a case of how to do things properly(;-) XPS defines a set of glyph
> indices with matching X, Y positional information - then provides the raw
> Unicode string as another attribute so that character copy/paste etc. can
> work using the content in the file.

This is similar to how PDF works.
It has an N-to-M mapping so N number of glyphs can map to M number of Unicode characters.

> 	SVG does not have the concept of glyph indices, so we're stuck with
> the character string only. So, to get precise glyph positioning (including
> ligatures), it must be done via X,Y or dx, dy.

Adobe's apps leave it up to the designer if they want ligatures are not. It seems that SVG is in a mode to always create them which might not be the desired effect.
Many ligatures have Unicode representations. Maybe we should rely on those instead...

If SVG wants to have robust Asian text support or support for discretionary ligature, the concept of glyph indices will be needed.

Received on Sunday, 15 May 2011 21:16:24 UTC

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