I am using PHPJasperXML 0.8d to generate a JasperReport pdf file. I am using Jaspersoft Studio 5.1.0. The first time I ran the php script, the pdf was blank. Now every time I run it, I get this error message: "1TCPDF ERROR: Some data has already been output, can't send PDF file."
I just took a peek at the phpjasperxml-08d class, it looks like is in a very alpha stage and tries to render the JRXML files in PDF only. I will look further into this. But if you are trying to embed reporting into your PHP application check out the Japser PHP client http://community.jaspersoft.com/project/php-client.
I actually have a full working sample of that here: https://github.com/marianol/JasperServer-for-PHP and there is a techtalk / webinar that goes over the topic oif integrating Jasper and PHP applications: http://www.jaspersoft.com/embedding-jaspersoft-into-your-php-application
Hope this helps..