W3C home > Mailing lists > Public > www-svg@w3.org > May 2012

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

From: Rik Cabanier <cabanier@gmail.com>
Date: Thu, 31 May 2012 13:43:34 +0200
Message-ID: <CAGN7qDAxVrUqK8yF5dvfP206urejg0Ucnk4sdsGkj1gy5-GLAw@mail.gmail.com>
To: John Daggett <jdaggett@mozilla.com>
Cc: Cameron McCormack <cam@mcc.id.au>, Dirk Schulze <dschulze@adobe.com>, Nikolas Zimmermann <zimmermann@kde.org>, SVG public list <www-svg@w3.org>
On Thu, May 31, 2012 at 8:34 AM, 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.


I agree we should drop it since there is consensus that we're going with
CSS-like capabilities for regular SVG text.
If there is agreement that we should add PDF-like text rendering to SVG,
that feature will always have kerning disabled.

Rik
Received on Thursday, 31 May 2012 11:44:09 GMT

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