DocBook <imagedata/> and scalefit attribute for transforms

[David Nedrow <listbox@nedron.net>]

Is there a [relatively] simple means of defining the viewport size of  
an <imagedata/> tag to the size of another element, possibly the  
enclosing element?

For example, in PDF output, I want the image scaled to fit the size  
of <figure/>, or, at the worst, <para/>. Anyway to handle this for  
the sample shown below?

Code:

    <para>Test
     <figure>
      <title>Static Web</title>
      <mediaobject>
       <imageobject role="html">
        <imagedata fileref="diagrams/static.png"/>
       </imageobject>
       <imageobject role="fo">
        <imagedata format="PDF" fileref="diagrams/static.pdf"/>
       </imageobject>
      </mediaobject>
     </figure>
    </para>

System details: saxon 6.5.3, DocBook XML 4.4, XEP 4.3, DocBook XSL  
Stylesheets 1.68.1

-David