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CSS and XForms - Style and Instance Data

From: T. V. Raman <tvraman@us.ibm.com>
Date: Fri, 25 Oct 2002 11:50:30 -0700
Message-ID: <15801.37494.458573.236458@bubbles.almaden.ibm.com>
To: Mark Birbeck <Mark.Birbeck@x-port.net>
Cc: "'www-forms@w3.org'" <www-forms@w3.org>, "'www-style@w3.org'" <www-style@w3.org>

What you bring up is a
very useful CSS design point.

To summarize what you're saying, it would be nice to be able to
specify  a mapping between CSS styles and the type of a value (here
type == schema type)
and further to attain this mapping via a CSS pseudo class.

I think the right thing to do might be to have CSS recognize "type" or
"datatype" as a pseudo class,
in which case this mechanism would work with XForms, 
but also provide a framework for styling XML  documents for which
there is a XML Schema available via CSS.

 >>>>> "Mark" == Mark Birbeck <Mark.Birbeck@x-port.net> writes:

    Mark> Hello all,

    Mark> I have tried to see if I am resurrecting an old discussion
    Mark> on CSS, and can't find it. Apologies if I am.
    Mark> The issue I'm raising concerns the selection criteria for
    Mark> CSS, when used with XForms.

    Mark> INTRO For those on the CSS list who are not familiar with
    Mark> XForms, a quick intro. With XForms we can have some data in
    Mark> an XML document that is then bound to a set of UI controls,
    Mark> using XPath statements. The data might be like this:

    Mark> 	<person> <firstName>Mark</firstName>
    Mark> <surname>Birbeck</surname> </person>

    Mark> and the UI part of the form might be like this:

    Mark> 	<xforms:input ref="person/firstName"> <caption>Please
    Mark> enter the first name</caption> </xforms:input> <xforms:input
    Mark> ref="person/surname"> <caption>Please enter the
    Mark> surname</caption> </xforms:input>

    Mark> In the main, a lot of things from CSS work quite well. For
    Mark> example, you can do the following, and the syntax copes
    Mark> fine:

    Mark> 	@namespace xforms "http://www.w3.org/2002/01/xforms";

    Mark> 	xforms|input { display: block; }

    Mark> This sets all of our input controls to blocks. We can also
    Mark> set the style on the captions that appear inside input
    Mark> controls:

    Mark> 	xforms|input > xforms|caption { font-weight: bold;
    Mark> width: 50%; color: white; background-color: #cfd7df }

    Mark> All pretty much as you would expect. However, we are trying
    Mark> to find a consistent way of solving two issues at the
    Mark> moment, and unless we have missed something, we can't seem
    Mark> to do it within the CSS framework at present:

    Mark> * ensuring that a particular piece of data is displayed
    Mark> consistently throughout a site

    Mark> * ensuring that a particular *type* of data is displayed
    Mark> consistently throughout a site

    Mark> CONSISTENT DATA If we wanted all surnames in our system to
    Mark> be displayed with a red background, we would either have to
    Mark> add a class attribute to all such xforms:input statements,
    Mark> or we could use an attribute selector:

    Mark> 	xforms|input[ref="person/surname"] { background-color:
    Mark> #ff0000; }

    Mark> The problem is that the following input statement refers to
    Mark> exactly the same node in the instance data:

    Mark> 	<xforms:input ref="//surname"> <caption>Please enter
    Mark> the surname</caption> </xforms:input>

    Mark> We would now need to add another attribute selector for this
    Mark> different syntax. Alternatively we could use:

    Mark> 	ref$="/surname"

    Mark> but in other situations this would match elements
    Mark> incorrectly.

    Mark> It would be better if there were some way of tying the style
    Mark> to the source data. One simple possibility would be to have
    Mark> a pseudo-attribute that takes an XPath statement:

    Mark> 	*:bound="person/surname" { background-color: #ff0000;
    Mark> }

    Mark> This would affect the style of *any* XForms control that is
    Mark> bound to a 'surname' element that is a child of a 'parent'
    Mark> element.

    Mark> Another possibility is to put the onus back onto XForms. In
    Mark> CSS we would just use the normal syntax to say that any
    Mark> element of type 'surname' that appears underneath an element
    Mark> of type 'person' is to be shown with a red background:

    Mark> 	person > surname { background-color: #ff0000; }

    Mark> There would never be an element 'surname' in the actual UI
    Mark> part of the form, but what we could then do is modify the
    Mark> styling part of XForms and say that the style of a control
    Mark> is a combination of the style of the control elements *and*
    Mark> the style of the underlying data elements. These two would
    Mark> both be applied to our surname control:

    Mark> 	xforms\:input { display: block; } person > surname {
    Mark> background-color: #ff0000; }

    Mark> Although this takes the burden off CSS, I think ultimately
    Mark> that it is the weaker solution.

    Mark> CONSISTENT DATA TYPES A related issue concerns the type of
    Mark> the underlying data that is being bound to. It should be
    Mark> possible to say that all controls that bind to a date are
    Mark> shown in one way, all integers in another. For example:

    Mark> 	*:dataType="xsd:integer" { background-color: #ff0000;
    Mark> }

    Mark> All UI controls that have as their underlying data an
    Mark> integer will now be shown with a red background.

    Mark> If XForms is set to become the 'forms module' for XHTML,
    Mark> then it seems to me that CSS will need some way of handling
    Mark> the link between underlying data and the user interface used
    Mark> to manipulate that data.

    Mark> Best regards,

    Mark> Mark

    Mark> Mark Birbeck Co-author Professional XML and Professional XML
    Mark> Meta Data, both by Wrox Press

    Mark> See x-port's XForms plug-in for IE, at
    Mark> http://www.FormsPlayer.com/

    Mark> Managing Director x-port.net Ltd. 4 Pear Tree Court London
    Mark> EC1R 0DS

    Mark> E: Mark.Birbeck@x-port.net W: www.x-port.net T: +44 (20)
    Mark> 7689 9232

Best Regards,
T. V. Raman:  PhD (Cornell University)
IBM Research: Human Language Technologies
Architect:    Conversational And Multimodal WWW Standards
Phone:        1 (408) 927 2608   T-Line 457-2608
Fax:        1 (408) 927 3012     Cell: 1 650 799 5724
Email:        tvraman@us.ibm.com
WWW:      http://www.cs.cornell.edu/home/raman
AIM:      TVRaman
PGP:          http://emacspeak.sf.net/raman.asc
Snail:        IBM Almaden Research Center,
              650 Harry Road
              San Jose 95120
Received on Friday, 25 October 2002 14:50:32 UTC

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