Docbook XSL: Set a default size/scale for imagedata elements?

Question

Writing some stylesheets for DocBook.

Edit: per the comment below: Yes, this means I am writing customizations based on the DocBook-XSL stylesheets, not rewriting existing DocBook stylesheets.

Is it possible, via an XSL stylesheet, to set a default size/scale for imagedata elements, particularly in print output?

Essentially I want to set things up such that if I include scalefit, width and/or contentdepth attributes in an imagedata element, those attributes will be used; however if they aren't included, they will default to scalefit="1" width="100%" contentdepth="100%".

Seems straightforward enough, but I'm an XSLT newbie, and googling has gotten me nowhere. Is this possible? How?

Thanks!

Answer 1

Essentially I want to set things up such that if I include scalefit, width and/or contentdepth attributes in an imagedata element, those attributes will be used; however if they aren't included, they will default to scalefit="1" width="100%" contentdepth="100%".

This transformation:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:template match="node()|@*">
     <xsl:copy>
       <xsl:apply-templates select="node()|@*"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match="imagedata[not(@scalefit|@width|@contentdepth)]">
  <imagedata scalefit="1" width="100%" contentdepth="100%">
   <xsl:copy-of select="@*"/>

   <xsl:apply-templates/>
  </imagedata>
 </xsl:template>
</xsl:stylesheet>

when applied on the following XML document:

<t>
 <imagedata scalefit="1" width="80%" contentdepth="90%"/>
 <imagedata/>
</t>

produces the wanted, correct result:

<t>
   <imagedata scalefit="1" width="80%" contentdepth="90%"/>
   <imagedata scalefit="1" width="100%" contentdepth="100%"/>
</t>

Explanation: Overriding the identity rule for any imagedata that has none of the scalefit, width and contentdepth attributes.