Ok, here is my remarks (I know, it's an Alpha version).
There are not criticisms, just remarks.
1/ There are some hard coded strings in the xoopsPDF class
for example in line 88 : trigger_error( 'Library not set' );
2/ In the method setOptions() why are you using variable arguments whereas you can just pass one parameter ?
That's a just a question of curiosity
3/ If I use your example (pdftest.php), I don't have the same render if I just swith from ezpdf to tcpdf.
For example $xoopsPDF->setSlogan uses the slogan that is given to him when you are using ezpdf but it is not used wiht tcpdf
I suppose taht you worked more time on ezPdf than on TPCDF.
4/ As many PDFs will be created from html content, you'll have html entities.
For example, Hervé is converted to Hervé and this is exactly what you see in the PDF.
If you want, I have a function to revert html entities to their original value (adapted to PDF)
5/ In the file xoopspdf.php you are using (line 80) : public function setLibrary()
I'm not sure that the "public" keyword will be recognized by Php 4.
But if you want to go the Php5 way, that's ok for me
I tought that XOOPS 2.3 was compatible with Php 4 ?
6/ function load_library()
May I can suggest to test the value of library (or to set it a default value in the constructor) ?
7/ file pdf.library.php, you use a Php5 constructor
8/ File xoopspdf.php, function setContent()
The function calls pdfStrip() which remove some html tags.
That's ok but some PDF libraries are capable to recognize some html tags.
For example, TPCDF is capable to treat the LI tag
9/ With TCPDF, you can output the PDF to the screen but you can also output it to a local file.
Is it possible to have the same behaviour with the xoopsPDF::render() (or with a property) ?
10/ The version of TCPDF is the one used for Php5