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

From: Erik Dahlstrom <ed@opera.com>
Date: Thu, 31 May 2012 10:21:15 +0200
To: "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: <op.we5ytpwzgeuyw5@localhost.localdomain>
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 08:22:27 GMT

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