Thierry Kormann wrote:
>
> On Tuesday 26 June 2001 14:34, Peter Becker wrote:
> > Jon Bråtøymyr wrote:
> > > Hi,
> > >
> > > I'm having problems with creating an image from a plain
> > > org.w3c.dom.Document. I was told that I could use
> > > DOMUtilities.deepCloneDocument to convert a w3c-Document to a
> > > SVGDocument, but when I run the transcoding I get a ClassCastException.
> > > Apparently when the ImageTranscoder tries to cast the root element to
> > > org.apache.batik.dom.GenericElement.
>
> I think you might have used the method with an appropriate argument.
> You must give the original document and then the DOMImplementation you want
> to use.
>
> The document is the one you have (that can be from xerces, generic DOM or
> whatever) then the DOMImplementation must be the SVGDOMImplementation.
>
> DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
Even if this repeats Jons code more or less exactly, here is my try:
<code>
org.jdom.adapters.DOMAdapter domAdapter = new
org.jdom.adapters.XercesDOMAdapter();
org.jdom.output.DOMOutputter out = new
org.jdom.output.DOMOutputter();
org.w3c.dom.Document w3cdoc = domAdapter.createDocument();
org.w3c.dom.Node root = w3cdoc.importNode( out.output(
_svgElement ), true );
w3cdoc.appendChild( root );
org.w3c.dom.DOMImplementation impl =
org.apache.batik.dom.svg.SVGDOMImplementation.getDOMImplementation();
org.w3c.dom.Document svgDoc =
org.apache.batik.dom.util.DOMUtilities.deepCloneDocument(w3cdoc, impl);
ImageTranscoder t;
if( target.toString().endsWith( ".jpg" ) ||
target.toString().endsWith( ".jpeg" ) )
{
// create a JPEG transcoder
t = new JPEGTranscoder();
// set the transcoding hints
t.addTranscodingHint(
JPEGTranscoder.KEY_XML_PARSER_CLASSNAME,
"org.apache.crimson.parser.XMLReaderImpl" );
t.addTranscodingHint( JPEGTranscoder.KEY_QUALITY,
new Float(.8) );
}
else if( target.toString().endsWith( ".png" ) )
{
// create a PNG transcoder
t = new PNGTranscoder();
// set the transcoding hints
t.addTranscodingHint(
PNGTranscoder.KEY_XML_PARSER_CLASSNAME,
"org.apache.crimson.parser.XMLReaderImpl" );
}
else
{
throw new ImageGenerationException( "Image '" +
target.toString() +
"' could not be generated: unknown
extension" );
}
// create the transcoder input
TranscoderInput input = new TranscoderInput( svgDoc );
// create the transcoder output
OutputStream ostream = new FileOutputStream( target );
TranscoderOutput output = new TranscoderOutput( ostream );
// save the image
t.transcode( input, output );
// flush and close the stream
ostream.flush();
ostream.close();
</code>
(sorry about all the package names, but I knew I would have to remove it
later ;-) )
and here is the result:
<output>
java.lang.ClassCastException: org.apache.batik.dom.GenericElementNS
at
org.apache.batik.dom.svg.SVGOMDocument.getRootElement(SVGOMDocument.java:519)
at
org.apache.batik.transcoder.image.ImageTranscoder.transcode(ImageTranscoder.java:142)
at
org.apache.batik.transcoder.XMLAbstractTranscoder.transcode(XMLAbstractTranscoder.java:126)
at
net.sourceforge.xweb.backend.images.SVGImageGenerator.createImageFileInternal(SVGImageGenerator.java:176)
at
<skip/>
</output>
Exactly Jon's problem and what I wrote some time ago.
> BTW: We could not rely on a generic DOM implementation at least for building
> and rendering SVG documents because SVG is complex and needs special hooks.
> The best example is to implement external <use> element with the correct
> cascading algorithm for the CSS properties.
As said in the other thread: then either don't claim to accept the
generic interfaces or just fall back into a less performant mode, e.g.
like this:
<code implemented="false">
public TranscoderInput(Document document) {
if( document instanceof SVGDocument ) {
this.document = document;
}
else {
this.document = DOMUtilities.deepCloneDocument(document,
impl);
}
}
</code>
where impl is an instance of your DOMImplementation and the
deepCloneDocument works. This should be easy to do (if the cloning
works), you can add a hint on the performance problem to the JavaDoc.
Jon, you and I would have saved hours.
So currently I have to stick with my temp files which sometimes just
won't get deleted but otherwise are not a big issue for me, but surely
are if you want to use a dynamic environment and not the more
compilerlike approach of XWeb.
BTW: I finished the first version of my Java rant *g* See:
http://www.peterbecker.de/texts/javacritique.html
Batik has many of the flaws mentioned there :-(
HTH,
PeterB
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