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RE: should we remove the kerning property in favour of font-kerning?

From: David Dailey <ddailey@zoominternet.net>
Date: Thu, 31 May 2012 08:35:16 -0400
To: "'David Dailey'" <ddailey@zoominternet.net>, "'Erik Dahlstrom'" <ed@opera.com>, "'Cameron McCormack'" <cam@mcc.id.au>, "'John Daggett'" <jdaggett@mozilla.com>
Cc: "'Dirk Schulze'" <dschulze@adobe.com>, "'Nikolas Zimmermann'" <zimmermann@kde.org>, "'SVG public list'" <www-svg@w3.org>
Message-ID: <001301cd3f29$d51318e0$7f394aa0$@net>
By the way there are instances in which illustrators have set kerning to negative numbers for certain pairs of glyphs to intentionally overlap certain characters for artistic effect. That would be a nice addition.

D

-----Original Message-----
From: David Dailey [mailto:ddailey@zoominternet.net] 
Sent: Thursday, May 31, 2012 7:52 AM
To: 'Erik Dahlstrom'; 'Cameron McCormack'; 'John Daggett'
Cc: 'Dirk Schulze'; 'Nikolas Zimmermann'; 'SVG public list'
Subject: RE: should we remove the kerning property in favour of font-kerning?

In addition to the cases that Cameron found on the web, we also have various instructional materials that were written relying on the spec including books and other materials such as http://www.w3.org/Graphics/SVG/IG/resources/svgprimer.html#text . Future authors will be using kerning since that is what the spec said and hence what the instructional materials say.

Losing the ability to do character by character kerning, which apparently is included in the proposal to deprecate would represent a step backward for authors abilities to mimic effects used in advertising and logos and, accordingly, for accessibility, by forcing authors to use bitmaps instead of fonts to convey stylistic effects such as in http://cs.sru.edu/~ddailey/svg/GeometricAccessibility.html -- the world is replete with such examples, I believe. Allowing CSS to dictate the terms for SVG graphics harms accessibility, art and sensibility.

Regards
David

-----Original Message-----
From: Erik Dahlstrom [mailto:ed@opera.com]
Sent: Thursday, May 31, 2012 4:21 AM
To: Cameron McCormack; John Daggett
Cc: Dirk Schulze; Nikolas Zimmermann; SVG public list
Subject: Re: should we remove the kerning property in favour of font-kerning?

On Thu, 31 May 2012 08:34:11 +0200, John Daggett <jdaggett@mozilla.com>
wrote:

> Cameron McCormack wrote:
>
>> > Not sure what you're kvetching about here.  The CSS 'font-kerning'
>> > property enables or disables metrics-based kerning based on kerning 
>> > data in the font.  It does not take a length value.  So the two 
>> > properties are not equivalent.
>> >
>> > The SVG 'kerning' feature seems designed to allow 
>> > character-by-character tweaking.  One sets the 'letter-spacing' for 
>> > an entire text span and tweaks individual pairs of letters by 
>> > wrapping a span around each pair of characters and applying the 
>> > appropriate
>> relative
>> > adjustment via 'kerning'.  My guess is that this was designed to 
>> > allow PDF-like layout where an app spits out a set of characters 
>> > with positions.
>> >
>> > The CSS property is only designed to enable/disable font-based 
>> > kerning.  It's not designed to support character-by-character 
>> > tweaking nor do I think it should.
>>
>> Do you think it is reasonable to use "letter-spacing: 3px; font-kerning:
>> none" in place of "kerning: 3px" for SVG content?  If we are in the 
>> situation where we could drop "kerning" in favour of authors using a 
>> combination of font-kerning and letter-spacing, should we do that?
>> Or is letter-spacing something different enough from kerning 
>> adjustment that it should be kept separate?
> Right, most of the time that's all that would be needed. The only 
> thing you wouldn't be able to do without the 'kerning' property around 
> is to be able to use the combined effect of letter-spacing + kerning 
> with a fixed length. So the question is whether there's content that 
> relies on that use case.
>
> The SVG kerning property is just an odd thing to me.  Kerning 
> adjustments are typically made to pairs of letters (e.g. Ta, To, AV,
> etc.) and that's what font kerning data has, adjustments based on 
> glyph combinations.  Generic span-wide adjustments to spacing are 
> never called "kerning".
>
> I would suggest dropping the 'kerning' property.
>
> John Daggett

Dropping 'kerning' is fine with me.

--
Erik Dahlstrom, Core Technology Developer, Opera Software Co-Chair, W3C SVG Working Group Personal blog: http://my.opera.com/macdev_ed
Received on Thursday, 31 May 2012 12:35:54 GMT

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