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Re: ligature formation across text chunks

From: Glenn Adams <glenn@skynav.com>
Date: Fri, 13 May 2011 08:33:07 -0600
Message-ID: <BANLkTi=iNGFvbXB0jwLYPKiXjwaNqCT=Rg@mail.gmail.com>
To: Alex Danilo <alex@abbra.com>
Cc: Cameron McCormack <cam@mcc.id.au>, Vincent Hardy <vhardy@adobe.com>, "public-svg-wg@w3.org" <public-svg-wg@w3.org>
Alex,

In my message, by glyph index I did not mean the glyph identifier or code
used in the font, but rather the index in the sequence of glyphs in the
example I referenced. In any case, it does seem that SVG can support
referring to glyph identifiers via the glyphRef attribute or element.

Part of the point of my email was also to remind the group that one can have
a discontiguous set of characters in the original input character sequence
that maps to a single ligature glyph. One can also have one character
mapping to multiple discontiguous glyphs. In the general case, one has an M
to N mapping from characters to glyphs, where both M and N may be
non-discontiguous.

Regards,
Glenn

On Thu, May 12, 2011 at 11:50 PM, Alex Danilo <alex@abbra.com> wrote:

> Hi Guys,
>
>        I raised this a while back. It's tracked as an issue:
>
> http://www.w3.org/Graphics/SVG/WG/track/issues/2332
>
>        I think the behaviour described by Vincent is more likely to be
> useful
> to authoring tools.
>
>        For example, HP's PCL-XL explicitly positions each glyph for
> printing. Microsoft's XPS does the same. The usefulness of the X,Y
> positions
> is more than likely for accurate glyph placement when seriallizing output
> from
> some tool (like SVGMaker for example). In such cases, the ligatures are
> more
> than likely wanted.
>
>        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.
>
>        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.
>
>        There are tests in the test suite to check this behaviour IIRC.
>
> Alex
>
>
>
Received on Friday, 13 May 2011 14:33:55 GMT

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