RE: XSLT and SVG

["Chris Bayes" <Chris@xxxxxxxxxxx>]

>Hi,
>
>I was wondering if anyone on the list had been able to get XSLT to
>successfully produce altered SVG i.e. transform an SVG source
>document to an
>SVG output document. For example, altering the value of some attributes.
>
>I am not asking about transforming XML source documents to SVG
>output using
>XSLT. That is fairly straightforward.
>
>However, I can't seem to get SVG to SVG transformations working at all. I
>would appreciate any suggestions, or even a simple working code sample.
>
>By the way, I am using Instant Saxon 5.4.1.

Andrew,
Your question prompted me to play around with this a little. I decided that
one of the difficult things to do was to change a css property within a
style attribute. Normally I would do my styling solely within my xslt
stylesheet and ignore any styling in the xml document but with SVG you have
your styling in the source document so it is not that easy. i.e.
<polyline id="polyline-03"
          style="fill:blue; stroke:#00FF00; stroke-width:4"
          points="310,80,335,180,360,80,385,180,410,80,435,180" />
<text style="font-family:Helvetica;font-size:12;" x="340" y="202">filled
&amp; stroked</text>
So I decided to write an xslt that would change one css property of the xml
in the stylesheet. If you want to change more than one or two then it is
probably easier to just replace the style attribute but they can get quite
large so you wouldn't want to do that for just say the fill or stroke
colour. I came up with this
<xsl:template match="polyline">
	<xsl:copy>
		<xsl:apply-templates select="@*[name() != 'style']"/>
		<xsl:attribute name="style">
			<xsl:call-template name="changecssproperty">
				<xsl:with-param name="style" select="@style" />
				<xsl:with-param name="cssproperty">stroke:red</xsl:with-param>
			</xsl:call-template>
		</xsl:attribute>
		<xsl:apply-templates select="node()"/>
	</xsl:copy>
</xsl:template>
The stylesheet will be available some time tomorrow at
www.bayes.co.uk/xml/index.xml?/xml/utils/changecssproperty.xml
and an explanation at
www.bayes.co.uk/xml/index.xml?/xml/tutorial/changecssproperty.xml
This raised a lot of problems. The SVG viewer often would not display
anything even though it looked like i had produced a valid SVG document.
With MSXML2 it insisted on outputting

<?xml version="1.0" encoding="UTF-16" standalone="yes"?>

even though i had

<xsl:output method="xml" encoding="UTF-8" indent="yes"
doctype-system="-//W3C//DTD SVG 20000303 Stylable//EN"
doctype-public="http://www.w3.org/TR/2000/03/WD-SVG-20000303/DTD/svg-2000030
3-stylable.dtd" standalone="yes" />

in my stylesheet which caused an error

encoding specified in XML declaration is incorrect: line1, column 30

If you remove the encoding then it works fine.

As I was working on this I was checking against saxon as usual. Everything
looked fine but I couldn't get it to do the actual replace. When I checked
the output instead of getting a copy of the style attribute I was getting
spaces. i.e.
style="font-family:Helvetica;font-size:12;"
became
style="font-family:Helvetica; font-size:12;"

and was not getting the property replaced.
I changed my test to normalize-space but this still wouldn't change
anything. I still got the same output as input.

So what looked like a simple answer to a simple problem *isn't*. Maybe Ms
and Mike can shed some light on this

Ciao Chris

XML/XSL Portal
http://www.bayes.co.uk/xml


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