[Xsltforms-support] Experimental Component control (Was: A couple of questions about subforms)

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Hi Eric,

I have implemented a new component control in XSLTForms. It is named 
"xf:component" and has two attributes named "@ref" and "@resource".

There are still restrictions within a component: ids cannot be used if 
the component is to be instantiated more than once. The default instance 
is local to each instantiated component and the subform-instance() 
function can be used to get the document element of it.

 From the main form to the component, a binding with a special mip named 
"changed" is defined. The subform-context() allows to reference the node 
bound to the component control in the main form.

The corresponding build has been committed to repositories: 
http://sourceforge.net/p/xsltforms/code/ci/master/tree/build/

Performance can surely be optimized (component source is currently 
loaded as many time as instantiated...) and this new control has been 
tested only in this limited test case:

figures.xml:

<?xml-stylesheet href="xsltforms/xsltforms.xsl" type="text/xsl"?>
<xh:html xmlns:xh="http://www.w3.org/1999/xhtml" 
xmlns:xf="http://www.w3.org/2002/xforms" 
xmlns:ev="http://www.w3.org/2001/xml-events">
     <xh:head>
         <xh:title>Figures</xh:title>
         <xf:model>
             <xf:instance id="main">
                 <figures>
                     <rectangle height="10in" width="4em"/>
                     <circle radius="8%"/>
                 </figures>
             </xf:instance>
         </xf:model>
     </xh:head>
     <xh:body>
         <xf:repeat ref="*">
             <xf:output value="name()"/>
             <ul>
                 <xf:repeat ref="@*">
                     <li>
                         <xf:component ref="." resource="size.xml"/>
                         <xf:output value="concat(' = ',.)"/>
                     </li>
                 </xf:repeat>
             </ul>
         </xf:repeat>
     </xh:body>
</xh:html>

size.xml:

<?xml-stylesheet href="xsltforms/xsltforms.xsl" type="text/xsl"?>
<xh:html xmlns:xh="http://www.w3.org/1999/xhtml" 
xmlns:xf="http://www.w3.org/2002/xforms" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:ev="http://www.w3.org/2001/xml-events">
     <xh:head>
         <xh:title>Size</xh:title>
         <xf:model>
             <xf:instance>
                 <size>
                     <value xsi:type="xsd:decimal">2</value>
                     <unit>cm</unit>
                 </size>
             </xf:instance>
             <xf:bind ref="subform-instance()/value" 
changed="translate(subform-context(), '%incmptxe', '')"/>
             <xf:bind ref="subform-instance()/unit" 
changed="translate(subform-context(), '0123456789', '')"/>
         </xf:model>
     </xh:head>
     <xh:body>
         <xf:input ref="subform-instance()/value" incremental="true">
             <xf:label><xf:output 
value="local-name(subform-context())"/>: </xf:label>
             <xf:setvalue ev:event="xforms-value-changed" 
ref="subform-context()" value="concat(subform-instance()/value, 
subform-instance()/unit)"/>
         </xf:input>
         <xf:select1 ref="subform-instance()/unit">
             <xf:label/>
             <xf:item>
                 <xf:label>pixels</xf:label>
                 <xf:value>px</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>font size</xf:label>
                 <xf:value>em</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>font height</xf:label>
                 <xf:value>ex</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>inches</xf:label>
                 <xf:value>in</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>centimeters</xf:label>
                 <xf:value>cm</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>millimeters</xf:label>
                 <xf:value>mm</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>points</xf:label>
                 <xf:value>pt</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>picas</xf:label>
                 <xf:value>pc</xf:value>
             </xf:item>
             <xf:item>
                 <xf:label>%</xf:label>
                 <xf:value>%</xf:value>
             </xf:item>
             <xf:setvalue ev:event="xforms-value-changed" 
ref="subform-context()" value="concat(subform-instance()/value, 
subform-instance()/unit)"/>
         </xf:select1>
     </xh:body>
</xh:html>

Thank you for your feedbacks!

-Alain

> 2) My subform has a local instance and I need to move data between the
> current node in the main form and the subform local instance. The
> context node appears to be available in the XForms controls (I can write
> <xf:output ref="."/> and the current node in the main form is displayed)
> but I don't know how to access this node in actions in the subform. Is
> there a function I can use for that?
>
> For this use case we need:
>
>        * A way to access the context node to which the "component" is
>          bound in the caller form. An extension function would be fine
>          for that.
>        * A way to define and access a local instance "private" to the
>          component. In this specific case the component needs only one
>          instance but I am sure we can find more complex cases where
>          several instances would be more convenient in which case
>          anonymous instances wouldn't work.
>        * We also need to receive events such as xforms-ready in the
>          component.
>
> In don't know if you're familiar with Orbeon's XBL implementation [1]
> but this component would be defined as:
>
> [1]
> http://wiki.orbeon.com/forms/doc/developer-guide/xbl-components-guide
>
> <xbl:xbl script-type="application/xhtml+xml">
>     <xbl:binding id="my-dimension" element="my|dimension" xxbl:mode="lhha
> binding value">
>        <xbl:handlers>
>           <xbl:handler event="xforms-enabled xforms-value-changed">
>              <xf:setvalue ref="instance('my-dimension-instance')/value"
> value="translate(xxf:binding('my-dimension'), '%incmptxe', '')"/>
>              <xf:setvalue ref="instance('my-dimension-instance')/unit"
> value="translate(xxf:binding('my-dimension'), '0123456789', '')"/>
>           </xbl:handler>
>        </xbl:handlers>
>        <xbl:implementation>
>           <xf:model id="my-dimension-model">
>              <xf:instance id="my-dimension-instance">
>                 <dimension>
>                    <value/>
>                    <unit/>
>                 </dimension>
>              </xf:instance>
>              <xf:setvalue ev:event="xforms-value-changed"
> ev:observer="my-dimension-value-control"
> ref="xxf:binding('my-dimension')"
> value="concat(instance('my-dimension-instance')/value,
> instance('my-dimension-instance')/unit)"/>
>              <xf:setvalue ev:event="xforms-value-changed"
> ev:observer="my-dimension-unit-control"
> ref="xxf:binding('my-dimension')"
> value="concat(instance('my-dimension-instance')/value,
> instance('my-dimension-instance')/unit)"/>
>           </xf:model>
>        </xbl:implementation>
>        <xbl:template>
>           <xf:input ref="value" id="my-dimension-value-control"/>
>           <xf:select1 ref="unit" id="my-dimension-unit-control">
>              <xf:label/>
>              <xf:item>
>                 <xf:label>pixels</xf:label>
>                 <xf:value>px</xf:value>
>              </xf:item>
>              .../...
>           </xf:select1>
>        </xbl:template>
>     </xbl:binding>
> </xbl:xbl>
>
> I won't go into the details, but see how:
>
>        * The bound node in the caller form instance is accessed through
>          "xxf:binding('my-dimension')" (where "my-dimension" is the
>          component's id)
>        * Local (private) instances can have ids and are accessed through
>          the standard instance() function
>          ("instance('my-dimension-instance')" in our case)
>        * A handler section is used to define event handlers for events
>          coming "from the external".
>
>