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Re: Is the px unit equivalent to user units?

From: Ian Hickson <ian@hixie.ch>
Date: Wed, 4 Jan 2006 19:03:23 +0000 (UTC)
To: Jonathan Watt <jonathan.watt@strath.ac.uk>
Cc: www-svg@w3.org, Dean Jackson <dino@w3.org>
Message-ID: <Pine.LNX.4.62.0601041855450.2856@dhalsim.dreamhost.com>

On Wed, 4 Jan 2006, Jonathan Watt wrote:
> Will you also be saying that the presentation attributes should add a 'px' to
> unitless length values before they are mapped into the CSS style system?

It isn't necessary to say this. The CSS style system is strongly typed -- 
the values are not strings, but lengths. Any length, once parsed, is a 
length. It is no longer a number followed by a unit identifier.

> I think this is important to make sure the value inherited or returned 
> by getPresentationAttribute is consistent across implementations.

getPresentationAttribute() returns objects implementing the poorly 
designed CSSValue interface, which has its own problems, including the 
ambiguity regarding exactly what it represents. The CSSWG announced some 
years ago that these interfaces were to be considered deprecated, and that 
new interfaces would be forthcoming. Unfortunately we then got distracted 
with making CSS2 match the real world, so the new interfaces aren't done 
yet. The CSSValue problems need to be fixed independently of the unitless 
length issue at hand.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 4 January 2006 19:15:56 UTC

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