RE: [cgmo-webcgm] XCF and "inherit" value

[Dieter Weidenbruck <dieter@itedo.com>]

Hi Lofton,

> -----Original Message-----
> From: Lofton Henderson [mailto:lofton@rockynet.com]
> Sent: Tuesday, May 24, 2005 3:05 AM
> To: cgmo-webcgm@lists.oasis-open.org
> Subject: [cgmo-webcgm] XCF and "inherit" value
>
>
> On 11-may, we resolved to add "inherit" value to 'interactivity' and
> 'visibility' APS Attributes.  The minutes say something about
> "...require a
> change to the XCF DTD".
>
> I'm editing now.  Just to be clear, "inherit" will be allowed in
> the WebCGM
> 2.0 metafile instance, in the applicable DOM places, and in the
> XCF, correct?
yes.

>
> Next, while editing the XCF, this interesting question came up.  Is
> "inherit" a valid value for visibility and interactivity on the 'layer'
> element?
yes.

>
> Recall that the WebCGM content model requires layer (if present) is the
> top-level object within a picture.  So there is no APS above a 'layer',
> from which to inherit.  (As shown in figure 5.1b, above 'layer'
> is Picture
> and Metafile, neither of which carry these attributes, AFAIK.) So if the
> value (visibility and/or interactivity) are not specified for a
> layer, they
> would seem to take the Initial Value, "on".
>
> We could stop there, and make some such ad hoc specification to solve the
> layer question.  But the same question pops up if there are one or more
> top-level (just below Picture) 'grobject' in the picture.  Which leads to
> the real question, about the inheritance model...
>
> When I turned to the inheritance stuff of 5.4 to try to sort it out ...
> more questions than answers.  The inheritance discussion of 5.4.1.1 (et
> al), talks about going up the branch to look for values, if the node is
> "..not the root of the document tree".  Neither layers nor top-level APSs
> can be the "root" of the document tree -- there can be multiple sibling
> layers, and we need a single "root".   So aside from whether or not
> "inherit" is valid for these attributes on layer, what is the "root" for
> the purposes of the inheritance discussion?
>
> It seems to me that the parentNode attribute on a layer or a
> top-level APS
> would be the Picture, right?  So for the purposes of the
> inheritance model
> discussion, do we need to say that it is a "virtual APS" that has the
> Initial Value of the ApsAttrs in question?  (And if "yes", then ... well
> the Picture isn't the root yet, is it?  The Picture's parentNode
> attribute
> is the Metafile, right?  Same question there.)
>
> Thoughts?  How can we deal with this cleanly?
the "root" should be the metafile IMO, and it needs to be treated as a
virtual
APS as far as visibility, interactivity, and style properties are concerned.

Dieter