RE: [xsl] Using Java in XSLT to determine font metrics

Subject: RE: [xsl] Using Java in XSLT to determine font metrics
From: "Ylvisaker, Steve" <steve.j.ylvisaker@xxxxxxxxxxxxx>
Date: Mon, 22 Dec 2008 10:57:28 -0600
Thanks Michael

I think I found the method getFontMetrics(font) in Java class

I added -TJ as a parameter but I'm not convinced <oXygen/> is paying attention
to it.

My error message now seems to be the result of my incorrect use of the

Error in call to extension function {public java.awt.FontMetrics
java.awt.Graphics.getFontMetrics()}: Cannot convert supplied XPath value to
the required type for the extension function.

I have tried several values for $font as well as placing the font name
directly in the parameter list with the same result.

My revised stylesheet is:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="";
    <xsl:output indent="yes"/>
<xsl:template match="/">

<!-- establish a font name -->
<xsl:variable name="font" select="'HelveticaWorld-Regular'"/>

<!-- obtain the metrics for a specified font -->
    <xsl:variable name="metrics" select="FontMetrics:getFontMetrics($font)"/>

<!-- display the result -->
    <xsl:message>result:<xsl:value-of select="$metrics"/></xsl:message>



-----Original Message-----
From: Michael Kay [mailto:mike@xxxxxxxxxxxx]
Sent: Monday, December 22, 2008 10:01 AM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: RE: [xsl] Using Java in XSLT to determine font metrics

As far as I can see the Java class java.awt.FontMetrics does not have a method

Generally, you may find the command line option -TJ useful for debugging this
kind of problem.

Also, please get out of the habit of writing this kind of code:

    <xsl:variable name="metrics">
        <xsl:value-of select="FontMetrics:getFontMetrics()"/>

when you mean

    <xsl:variable name="metrics" select="FontMetrics:getFontMetrics()"/>

This is always highly inefficient, and when you are manipulating external Java
objects it will almost certainly make your code incorrect, because you really
don't want to convert the object to a string.

Michael Kay

> -----Original Message-----
> From: Ylvisaker, Steve [mailto:steve.j.ylvisaker@xxxxxxxxxxxxx]
> Sent: 22 December 2008 15:37
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] Using Java in XSLT to determine font metrics
> This is my first attempt at calling an external Java method to do work
> on behalf of  a stylesheet. I'm not a Java developer so I think I need
> a fairly complete "cookbook"
>  description of how to do this. My objective is to determine the exact
> length, in pixels,  of a given string based on the font and font size
> in play.
>  I'm sure I have two problems here. (1) to properly bind my stylesheet
> to a Java name  space and (2) proper use of the Java methods that
> parse my font and return the  metrics I'm looking for.
>  Following is my failed stylesheet, annotated with comments explaining
> what I am  "trying" to do at each step. I am very certain that I am
> not properly telling whomever  which font I am using.
>  I am working within the <oXygen/> IDE (Saxon8) and have successfully
> gotten the example on  page 134 of Michael's XSLT 2.0 3rd Edition to
> work. This tells me that I am somewhat  successful in using Java
> extensions.
>  When I process this stylesheet I get the following error:
>  Cannot find a matching 0-argument function named
> {ext://java.awt.FontMetrics}getFontMetrics()
>  Unfortunately this error message doesn't tell me if the problem is
> that I'm not finding  the Java method or if I'm finding it but not
> using it properly.
> <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet
> xmlns:xsl=""; version="2.0"
>     xmlns:FontMetrics="ext://java.awt.FontMetrics">
>     <xsl:output indent="yes"/>
> <xsl:template match="/">
>     <xsl:variable name="tstString" select="'Hello World'"/>
> <!-- declair a font and fontsize - not shure who is listening to this
> -->
>     FontMetrics:Font("helveticaWorld", Font.PLAIN, 10)
> <!-- obtain the metrics for the specified font -->
>     <xsl:variable name="metrics">
>         <xsl:value-of select="FontMetrics:getFontMetrics()"/>
>     </xsl:variable>
> <!-- obtain the length in pixels of the test string -->
>     <xsl:variable name="resultStringLength">
>          <xsl:value-of select="metrics.stringWidth($tstString)"/>
>     </xsl:variable>
> <!-- display the result -->
>     <xsl:message>result:<xsl:value-of
> select="$resultStringLength"/></xsl:message>
> </xsl:template>
> </xsl:stylesheet>
> Thanks in advance for you help. Please keep in mind that I am not a
> Java developer at all so nothing is obvious to me.
> Steve Ylvisaker
> Information transmitted by this email is proprietary to Medtronic and
> is intended for use only by the individual or entity to which it is
> addressed, and may contain information that is private, privileged,
> confidential or exempt from disclosure under applicable law. If you
> are not the intended recipient or it appears that this mail has been
> forwarded to you without proper authority, you are notified that any
> use or dissemination of this information in any manner is strictly
> prohibited. In such cases, please delete this mail from your records.
> To view this notice in other languages you can either select the
> following link or manually copy and paste the link into the address
> bar of a web browser:

Current Thread