W3C home > Mailing lists > Public > www-svg@w3.org > January 2006

Re: SVG12: height/width defaults

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Thu, 05 Jan 2006 02:03:35 +0100
To: Bjoern Hoehrmann <derhoermi@gmx.net>
Cc: www-svg@w3.org, WG SVG <w3c-svg-wg@w3.org>
Message-ID: <nkror1dqp62fmh40up4i3o7g6g8g3660kh@hive.bjoern.hoehrmann.de>

* Bjoern Hoehrmann wrote:
>>SVG needs to specify how to calculate some intrinsic sizing properties 
>>to enable inclusion within other languages. The intrinsic width and 
>>height of the viewport of SVG content must be determined from the width 
>>and height attributes. *If these are not specified, the default values 
>>of 100% must be used.*
>>
>>The intrinsic aspect ratio of the viewport of SVG content is necessary 
>>for example, when including SVG from an object tag in XHTML styled with 
>>CSS. The intrinsic aspect ratio must be calculated based upon the 
>>following rules:
>>
>>    * If the width and height of the root SVG element are both specified
>>      in absolute units (in, mm, cm, pt, pc, px) then the aspect ratio
>>      is calculated from the width and height after resolving both
>>      values to the same units.
>>    * If either/both of the width and height of the root svg are in
>>      percentage units, the aspect ratio is calculated from the width
>>      and height of the viewBox. If the viewBox is not present, or set
>>      to 'none', the intrinsic aspect ratio cannot be calculated and is
>>      unspecified.
>
>There are several problems here,
>
>  * the px unit should not be referred to as absolute unit as CSS
>    considers it a relative unit.

This isn't fixed.

>  * the algorithm does not define the result for height and width in
>    user units, em, ex, etc. 

Not fixed.

>  * the prose about the various attribute values is difficult to read
>    (e.g., what is the result if the viewBox attribute is "present" but
>    has an unsupported value and is thus ignored?)

Let's count this as fixed.

>  * "the root SVG element" and "the root svg" seems inconsistent and
>    misleading.

Fixed.

>And the dependency on the view specifications on the root svg element is
>inconsistent with SVG 1.1 where the view specification might be in the
>fragment identifier for the SVG document and authors would expect these
>to be considered when the intrinsic aspect ratio is determined.

Not fixed. This is the most important point really, instead of referring
to the attributes on the <svg> element it should refer to the view that
is established through the view specifications. This is probably the
same in Tiny but not in "Full".

>[...]

These are fixed and/or covered elsewhere. 
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
Weinh. Str. 22 · Telefon: +49(0)621/4309674 · http://www.bjoernsworld.de
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Received on Thursday, 5 January 2006 01:03:08 GMT

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