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y-axis reversal (was: Re: Agenda for Sept 25th call)

From: Robin Berjon <robin@berjon.com>
Date: Fri, 26 Sep 2008 13:06:51 +0200
Cc: public-svg-ig@w3.org
Message-Id: <A4B61995-AA41-4649-9F7D-3CF2133FA367@berjon.com>
To: rindahl@lrcwe.com

HI Bruce,

On Sep 25, 2008, at 16:43 , Bruce Rindahl wrote:
> However, I would like to bring up for discussion the possibility of  
> a new feature/attribute for SVG.  I am constantly fighting with the  
> SVG default of the Y-direction is positive downward on the screen.   
> It is opposite of all GIS application as well as graphs and  
> PostScript/PDF.  Appling a transform="scale(1,-1)" inverts the text.  
> What do you think about an additional attribute in the <svg> tag  
> that allows the y direction to be reversed? say y- 
> direction="inverted" ?

That feature has been requested quite a few times, I'm sure there must  
be some discussion of it somewhere in the group's private archives  
(I'd look but I don't have access anymore). Before trying to make a  
case for this I'd look there first to document the counter-arguments.

If you seriously intend to float this proposal, you need more than  
just the attribute's syntax (which is the easy part, really) but a  
normative description of how it would work. That would include  
describing the transformation applied to the root element, but also  
the converse transformation applied to text, what happens when you  
include an external SVG document that has a different y-axis from the  
origin document, what happens when you link to external resources  
(e.g. gradients, filters...) that have a different y-axis from the  
origin document, do foreignDocuments get their y-axis reversed too, etc.

Once options for all those issues are outlined, it boils down to  
looking at the implementation cost, and whether the use case justifies  
it. One big question there will be whether doing this in the UAs is  
justified, or whether creating a tool to handle coordinates inversion  
automatically (for instance in XSLT) would be simpler.

Robin Berjon - http://berjon.com/
     Feel like hiring me? Go to http://robineko.com/
Received on Friday, 26 September 2008 11:07:29 UTC

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