Overview

mPDF is a PHP class which generates PDF files from UTF-8 encoded HTML. It is based on FPDF and HTML2FPDF, with a number of enhancements. mPDF was written by Ian Back and is released under the GNU GPL v2 licence.
mPDF is manually installable in Tiki since Tiki 15.2. Since Tiki18 you can install mPDF with the new Packages feature from the Tiki admin panel in a few clicks.

More info

Github	https://github.com/mpdf/mpdf
Documentation	https://mpdf.github.io/

PDF Output of Tiki content with 'mPDF'

All Free / Libre / Open Source PDF generation solutions were analyzed and mPDF was selected as the overall best solution for deep integration in Tiki. The main reasons are:

Vast feature set: The mpdfmanual.pdf (8 megs download) is over 600 pages!
It's written in PHP (like Tiki) so it eases deployment, facilitates integration and makes it easier for the Tiki community to contribute.
The approach is to convert HTML to PDF (other approaches would have been more complex / less suitable for the Tiki context)
Strong multilingual support: Some of the other good solutions didn't support all languages. And thus, it would have forced us to have a second solution for these languages, which would have fragmented the efforts.

Since the GNU GPL v2 licence is not compatible with Tiki's LGPL licence, we cannot ship mPDF with the source code as part of Tiki. Integration code has been added to Tiki, and you can install mPDF via Packages in Tiki18.

Installation

Enable mPDF in Tiki: login to your Tiki and go to example.org/tiki-admin.php?page=print and set the following preference: PDF from URL: mPDF
If mPDF is not installed, you can install mPDF via the Composer Web Installer

Configuration

mPDF works well with Tiki out-of-the-box even on average shared hosting. There are many options at tiki-admin.php?page=print, most of which can be overridden page by page via PluginPDF

If you are programmer, you may want to look in */mpdf/config.php for additional configuration options.

Collection of References on doc.tiki.org

Print general info about printing
PDF general overview about PDF creation in Tiki
mPDF create PDFs from Tiki content (advanced library that works even on shared hosting). Recommended for Tiki18+
PluginPDF alter default settings of mPDF per wiki page
PluginPDFPageBreak add a page break for PDFs created with mPDF
PluginMediaPlayer display PDF file from file gallery
PDF.js viewer PDF.js from Mozilla
ViewerJS: a script to view PDFs and ODFs, which bundles WebODF
PluginArchiveBuilder Generate a zip file, including PDFs from wiki pages
WeasyPrint A PDF generation option in Python
wkhtmltopdf create PDFs from Tiki content (needs root installation)
dompdf once used for PDF print of slideshows