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Re: proposal for text layout with positioned glyphs, anchoring and bidirectionality

From: Rik Cabanier <cabanier@gmail.com>
Date: Fri, 3 Jun 2011 13:50:19 -0700
Message-ID: <BANLkTinm_scU8ZrRHum_tO-=5CahPbjm-g@mail.gmail.com>
To: www-svg@w3.org
Hi Cameron,

I believe that there are 2 approaches:
1. Let SVG do the layout of the text including generation of ligatures.
2. Have the authoring application do the layout and select what ligatures to

Currently, SVG has a hybrid approach that leans mostly towards step 1. Your
proposal goes towards giving the authoring application somewhat more control
but it ends up creating a syntax with many rules (as witnessed by your
example of '<text x="30 15" direction="ltr">ABCdef</text>').

For SVG 2.0, we should clear up this distinction and implement the 2
different approaches.
We can simplify the current spec and call it approach 1. David's proposal
for alignment to a common baseline would be incorporated here.

For post-layout text, we can look at what other implementations have done
(such as Flash, PDF or XPS) and introduce a new text tag.
It should be able to do things such as:
- exact positioning of a glyph
- set default word and letter spacing
- select what ligature you want to use
- attach unicode data to glyphs
but it will not:
- create ligatures automatically
- be aware of different writing directions


On Thu, May 19, 2011 at 8:31 PM, Cameron McCormack <cam@mcc.id.au> wrote:

> SVG text with positioned glyphs, anchoring and bidirectionality is
> greatly non-interoperable and somewhat underspecified.  We have
> discussed some aspects of this in a couple of threads on the WG mailing
> list over the last week or so:
>  http://lists.w3.org/Archives/Public/public-svg-wg/2011AprJun/0062.html
>  http://lists.w3.org/Archives/Public/public-svg-wg/2011AprJun/0082.html
> I want to make a proposal for defining text layout behaviour in these
> cases.  Comments and suggestions (particularly any suggested
> simplifications) are welcome.
>  http://www.w3.org/Graphics/SVG/WG/wiki/Proposals/Text_layout
> (Apologies for the general illegibility of the WG wiki; I figured it’s
> better for refining the proposal to have it up there than in a plain
> text email.)
> --
> Cameron McCormack ≝ http://mcc.id.au/
Received on Friday, 3 June 2011 20:50:49 UTC

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