Thanks Jeremias,

I had a play around with the FOP code and that lead me back to an error in the
servlet I used to stream the image.

----- Original Email -----
From: Jeremias Maerki <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Date: 17-Jun-2003 15:33
Subject: Re: external image provided via servlet - image type not being read

> 
> On 17.06.2003 08:49:21 Brent Snook wrote:
> > I am currently developing a Java servlet that uses embedded FOP 
> > (0.20.5rc3a)under Tomcat 4.1.18 and am having a few problems with
external
> > graphics and PDF generation. 
> > 
> > The external graphics in question are streamed using another servlet,
which is
> > causing a few problems such as FOP not being able to determine the image 
> > type. 
> > 
> > The first problem I had was with using a relative URL. FOP could not find
the
> > 
> > servlet and I thought this was because it was treating the value of the
src 
> > attribute as a relative file rather than URL path. I got around this
> > temporarily by using the full URL although I would ideally not want to
hard 
> > code this. 
> 
> See here for how to set a base URL:
> http://xml.apache.org/fop/servlets.html#cfg
> http://xml.apache.org/fop/embedding.html#config-internal
> 
> You can use an URL, not only a directory as shown in the documentation.
> 
> > The main problem I have is with FOP determining image type properly. The 
> > servlet that streams the image sets the content type of the response
correctly
> > according to the image MIME type (stored in a metadata file). FOP is
finding
> > the servlet but keeps giving me errors: 
> > 
> > Error while creating area : No ImageReader for this type of image 
> > 
> > External graphics work fine when I link to a static file. It is the
dynamic 
> > output from the servlet that is causing the bother. 
> > 
> > I have tried adding servlet mappings to Tomcat such as "fetch/img.jpg" and

> > "fetch.jpg" but FOP still complains that it can not find an ImageReader
for 
> > that image type. Am I wrong in thinking that FOP determines which
ImageReader
> > to use by reading the file extension of the URL? 
> 
> Yes, totally. FOP has ImageReader implementations (package
> org.apache.fop.image.analyser) which actually look into the contents of
> the file being loaded to determine the image format. Neither the file
> extension nor the MIME type are evaluated.
> 
> > I would be gratefull for any suggestions. 
> 
> If you generate such a dynamic image from your servlet and save it to a
> local file and run FOP from the command-line, can FOP then open the
> image? If not, I think you have a strange JPEG format there. If yes, you
> could try to change FopImageFactory so it evaluated the MIME type sent
> by the servlet. But that only helps if the FOP image implementations can
> really load your image.
> 
> Jeremias Maerki
> 
> 
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