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Re: Fwd: Proposed changes for units.

From: Erik Dahlstrom <ed@opera.com>
Date: Tue, 20 Jul 2010 15:36:59 +0200
To: public-svg-wg@w3.org
Message-ID: <op.vf49fvxjgeuyw5@localhost>
On Tue, 20 Jul 2010 13:09:56 +0200, Erik Dahlstrom <ed@opera.com> wrote:

> Forwarded on Tav's behalf for ISSUE-2351.
>
> ------- Forwarded message -------
> From: "Tavmjong Bah" <tavmjong@gmail.com>
> Subject: Proposed changes for units.
> Date: Fri, 16 Jul 2010 20:20:29 +0200
>
> Re: ISSUE-2351: Clarify that units are required on <length>s in style
> attribute; fix examples in text.  [SVG 1.1 F2  Last Call
>
>
> First an update on the issue:
>
>           After some discussion on the www-svg mailing list, it can be
>           concluded that the examples in 6.6 are correct as the parameter
>           in question ('stroke-width') is not a CSS defined property and
>           thus does not need a unit. The example in 7.10 is wrong as
>           'font-size' is a CSS defined property and its use in a 'style'
>           attribute requires a unit.
>
> Second, a proposal to clarify when units are required follows. Part of
> the proposal is based on suggested text from Doug Schepers.
>
>                                           Tav
>
> Proposed changes:
>
> 4.2 Basic data types
>
> Change <angle> section to:
>
>       Angles are specified in one of two ways, depending upon whether
>       they are used in CSS property syntax or SVG presentation attribute
>       syntax:
>
>       * When an <angle> is used in a stylesheet or with a property in a
>         'style' attribute, the syntax must match the following pattern:
>
>         angle ::= number (~"deg" | ~"grad" | ~"rad")?
>
>         where deg indicates degrees, grad indicates grads and rad
>         indicates radians. The unit identifier may be in lower
>         (recommended) or upper case.
>
>         For properties defined in CSS2 [CSS2], an angle unit identifier
>         must be provided. For angle values in SVG-specific properties
>         the angle unit identifier is optional. If a unit is not
>         provided, the angle value is assumed to be in degrees.
>
>       * When an <angle> is used in an SVG attribute, the syntax must
>         match the following pattern:
>
>         angle ::= number ("deg" | "grad" | "rad")?
>
>         The unit identifier must be in lower case.
>
>       In the SVG DOM, <angle> values are represented using SVGAngle or
>       SVGAnimatedAngle objects.

Would be nice to get a test for this. The only two properties defined in  
the svg spec that use <angle> are 'glyph-orientation-vertical' and  
'glyph-orientation-horizontal'.

...
> 6.12 The 'style' attribute
>
> Add period to end of sentence in first paragraph, followed by:
>
> "Property declarations must follow CSS style rules thus CSS defined
> properties (e.g. 'font-size') with a <length> value must include a
> unit (for non-zero values). See 6.1 for a list of CSS defined
> properties."

I don't understand the first sentence of this new paragraph.

> 7.10 Units:
>
> Change first line from:
>
> All coordinates and lengths in SVG can be specified with or without a
> unit identifier.
>
> to:
>
> "All coordinates and lengths in SVG can be specified with or without a
> unit identifier. (Note that CSS defined properties used in a CSS style
> sheet or the 'style' attribute require units for lengths, see 6.1.)"

That's not entirely true. You can specify '0' without a unit in CSS.  
That's the only exception though AFAIK.
...

Cheers
/Erik

-- 
Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
Received on Tuesday, 20 July 2010 13:37:35 GMT

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