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Subject: RE: Re[6]: [cgmo-webcgm] ISSUE: what does 'get..' return? [2 of 2]
Hi Benoit,
see inline
> -----Original Message-----
> From: Benoit Bezaire [mailto:benoit@itedo.com]
> Sent: Thursday, April 28, 2005 5:07 PM
> To: cgmo-webcgm@lists.oasis-open.org
> Subject: Re[6]: [cgmo-webcgm] ISSUE: what does 'get..' return? [2 of 2]
>
>
> Hi Dieter,
>
> See inline...
>
> Thursday, April 28, 2005, 10:22:15 AM, Dieter wrote:
>
> DW> Hi Benoit,
>
> DW> First of all, I agree that an empty string should be returned.
> DW> If I then follow your comments, I see the following challenges:
>
> >> DW> How do I return to the initial state?
> >> DW> I can delete the attribute, no problem.
> >> We've made 'visibility' and 'interactivity' WebCGM APS attribute as
> >> oppose to style attributes (like stroke, intensity, stroke-width
> >> etc...), so the clearStyle() method doesn't work.
> >>
> >> You have to either:
> >> - reload the file.
> >> - remove the attribute.
> >> - or your script has to remember the previous value.
>
> DW> I can not set the previous value it was not "on" or "off", right?
> What do you mean?
I mean that "" is not an allowed value in a set call. You show this
below by using removeAppStructureAttr instead.
>
> var prev = obj.getAppStructureAttr( "visibility" );
> obj.setAppStructureAttr( "visibility", "off" );
> if( prev == "" )
> obj.removeAppStructureAttr( "visibility" );
> else
> obj.setAppStructureAttr( prev );
>
> DW> Or is an empty string also a legal value for a set call?
> No, empty string is not a legal value for a set call. (Note: there has
> been numerous issues raised about this on multiple mailing lists, DOM,
> SVG etc... I advise that we stay away from this).
Understood.
>
> DW> For an XCF value?
> We have not defined what should happen.
That's what we need to do.
>
> DW> If this is the case then I have everything I need.
> If this is what case?
If "" would have been an allowed value we could have used it for both
the set call and the XCF value. Since it is not a legal value, we
can use removeAppStructureAttr in a script, however,
we don't have a solution for the XCF case, i.e. I have no way to
set this state using an XCF, because I can not remove an attribute
using the XCF.
>
> DW> Otherwise we would need a value "inherit" to do this.
> DW> There are use cases for this, e.g.
>
> DW> - Make everything invisible on a layer by setting its
> visibility to "off"
> DW> - Make one object on this layer visibible by setting it to "on"
> DW> - after some other operations, I want to restore the previous state.
> Are you talking of achieving this with xcf only or with scripts? Is
> this not ok?
XCF only.
>
> var layerPrev = l.getAppStructureAttr( "visibility" );
> var objPrev = o.getAppStructureAttr( "visibility" );
>
> l.setAppStructureAttr( "visibility", "off" );
> o.setAppStructureAttr( "visibility", "on" );
>
> if( layerPrev == "" )
> l.removeAppStructureAttr( "visibility" );
> else
> l.setAppStructureAttr( layerPrev );
>
> if( objPrev == "" )
> o.removeAppStructureAttr( "visibility" );
> else
> o.setAppStructureAttr( objPrev );
This is perfectly fine if DOM calls can be used. I think we are down to
looking for a solution for the XCF attribute value only.
Regards,
Dieter
>
> DW> Reloading the file is not a good option, since you would lose
> all changes
> DW> applied by one/multiple XCFs and/or DOM calls.
> Understood.
>
> --
> Benoit mailto:benoit@itedo.com
>
> DW> Regards,
> DW> Dieter
>
>
>
>
>
> >> -----Original Message-----
> >> From: Benoit Bezaire [mailto:benoit@itedo.com]
> >> Sent: Thursday, April 28, 2005 3:21 PM
> >> To: cgmo-webcgm@lists.oasis-open.org
> >> Subject: Re[4]: [cgmo-webcgm] ISSUE: what does 'get..' return? [2 of 2]
> >>
> >>
> >> Hi all,
> >>
> >> This thread is not using the right terminology and that's confusing
> >> me. I don't like the word "undefined", there is no such word in the
> >> DOM getAttribute() method. An attribute is either 'specified'
> >> (explicitly written in the file, attName="value") or has a default
> >> value (from a schema or DTD, ex: version="2.0").
> >>
> >> The DOM getAttribute() method returns an empty string if the attribute
> >> is not specified or assigned a default value in the DTD. Not
> >> "undefined".
> >>
> >> Question: Is there a big different between returning an empty string
> >> or returning the "inherit" string?
> >>
> >> To me there isn't since they both mean that the attribute is not
> >> specified on the object.
> >>
> >> More inline.
> >>
> >> Thursday, April 28, 2005, 5:38:04 AM, Dieter wrote:
> >>
> >> DW> Hi Lofton,
> >>
> >> DW> we are close.
> >>
> >> LH>> Here is our conceptual disagreement. Because the 3.2.2.9
> >> model (above)
> >> LH>> says "Inherited: yes", you are interpreting that as
> meaning that the
> >> LH>> initial value for an unspecified attribute must be
> >> 'inherit'. I don't
> >> LH>> think that necessarily follows. IMO, our model currently works
> >> LH>> fine this way:
> >> LH>>
> >> LH>> 1.) if explicitly set value on particular node, that is it for
> >> LH>> both display and DOM query (no dispute here);
> >> DW> Agreed.
> >>
> >> LH>> 2.) if no explicitly set value on particular node,
> including on any
> >> LH>> ancestors, then "Initial value" is used for display ("Initial
> >> LH>> value: on" rules);
> >> DW> Agreed.
> >>
> >> LH>> 3.) if no explicitly set value on particular node, but
> explicit on an
> >> LH>> ancestor, then that ancestor value used for display
> ("Inherited: yes"
> >> LH>> rules, overrides initial value);
> >> DW> see comment below.
> >>
> >> LH>> 4.) if no explicitly set value on particular node, DOM
> query returns
> >> LH>> "undefined" (standard DOM rule)
> >> LH>>
> >> DW> agreed. The behavior is inherit then, though.
> >> I don't think we should re-invent an inheritance model with 1,2,3,4.
> >> It is already defined in the spec, please read: 5.4.1.1 Specified
> >> values. That particular wording talks about the CSS style attribute
> >> which should be replaced to WebCGM Style attributes (or something
> >> equivalent), but the concept is there.
> >>
> >> DW> I guess my confusion is based on my lack of understanding,
> >> what "initial
> >> DW> value" means. I have no problem with 4.), a programmer then knows
> >> DW> that he has to walk up the tree to compute the actual behavior, if
> >> DW> there is any specified on ancestors.
> >>
> >> DW> Questions:
> >> DW> - initial value is used until an explicit value is set using
> >> a DOM call,
> >> DW> right?
> >> Yes but note that initial value will not be used if the attribute
> >> value is inherited.
> >>
> >> DW> - assume the following situation:
> >> DW> BEGAPS 'first'
> >> DW> 'visibility' on
> >> DW> BEGAPS 'second'
> >> DW> ENDAPS;
> >> DW> ENDAPS;
> >>
> >> DW> first is visible, second as well.
> >> Yes.
> >>
> >> DW> DOM get call on second returns "undefined" according to 4.)
> >> I don't like that, I think it should return an empty string.
> >>
> >> DW> Now assume a "set" call on "second" set visibility to "off"
> >> Ok.
> >>
> >> DW> DOM get call on second now returns "off".
> >> Yes.
> >>
> >> DW> How do I return to the initial state?
> >> DW> I can delete the attribute, no problem.
> >> We've made 'visibility' and 'interactivity' WebCGM APS attribute as
> >> oppose to style attributes (like stroke, intensity, stroke-width
> >> etc...), so the clearStyle() method doesn't work.
> >>
> >> You have to either:
> >> - reload the file.
> >> - remove the attribute.
> >> - or your script has to remember the previous value.
> >>
> >> DW> Then there may be one out of two situations:
> >> DW> - ancestor has set value and controls visibility of
> >> "second" from there on
> >> DW> - no ancestor with set value.
> >>
> >> DW> Does the latter case imply that "initial value" will be used,
> >> DW> - after opening the file without modifications
> >> Yes.
> >>
> >> DW> - after deleting a previously set attribute on the
> APS AND no
> >> DW> ancestor has a set value
> >> Yes.
> >>
> >> DW> - after deleting an attribute read from the WebCGM
> file AND no
> >> DW> ancestor has a set value
> >> Yes.
> >>
> >> DW> - how do I set the "undefined" state from within an XCF?
> >> DW> BEGAPS 'first'
> >> DW> 'visibility' on
> >> DW> ENDAPS;
> >> You cannot (not at the moment). Is this something you believe users
> >> will want to do?
> >>
> >> DW> I can set visibility="on" or visibility="off". How do I delete the
> >> DW> attribute, or in other words, how do I set this APS to inherit its
> >> DW> behavior from its ancestors?
> >> We would need the "inherit" value for that.
> >>
> >> --
> >> Benoit mailto:benoit@itedo.com
>
>
>
>
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