Dompdf, HTML to PDF for PHP5

We’ve recently had a first approach to PDF on-the-fly generation, using a nice and efficient free class for PHP, FPDF.

With this short review we’ll deal with another nice piece of software, designed to translate entire HTML documents into PDF files: dompdf.

To make things short, dompdf is somewhat a rendering engine written in PHP5 (no chance to see it run under PHP4, sorry folks!), and designed to operate on HTML document to be converted procedurally into PDF documents, with a nice level of compliance with the CSS 2.1 rules. It’s a so called style-driven engine: it downloads and reads external style sheets, inline style tags and most of the html’s presentation attributes.

Dompdf can operate through PDFLib if available on your system with a working licence. As alternative, dompdf is bundled with the R&OS CPDF class written by Wayne Munro, a slightly slower but free class with no dependencies on external libraries.

To summarize dompdf’s features, we can read straight from the official documentation and know that:

• handles most CSS2.1 properties, including @import, @media & @page rules
• supports most presentational HTML 4.0 attributes
• supports external stylesheets, either on the local machine or through http/ftp (via fopen-wrappers)
• supports complex tables, including row & column spans, separate & collapsed border models, individual cell styling, multi-page tables (no nested tables yet however)
• image support (png, gif & jpeg)
• no dependencies on external PDF libraries, thanks to the R&OS PDF class
• inline PHP support.

The last one is a very interesting features for us, because is the key to versatile implementations such as real-time reporting, database-to-pdf charts, and so on. To embed PHP code into the HTML document to be translated, you must enclose the scripts within a script declaration tags, as following:

Dompdf can be used through an usual PHP script, maybe summoned to translate a dinamically generated HTML document, or via command line if you have rights to access your host’ shell.

The PHP script must invoke the dompdf program by passing its parameters via one of the following GET variables:

Here is a little snippet:

$file_to_pdf = rawurlencode("http://www.mysite.com/docs/$new_html_file");
$destination = "http://www.mysite.com/dompdf/dompdf.php?input_file=" . $file_to_pdf . "&output_file=" . $custom_filename . ".pdf";
header("Location:$destination");

For a quick usage, just the input_file and the save_file parameters must be passed, the first one to locate the actual file to be translated, the second one to set up a right filename, thus avoiding the default which is mostly useless in a customized environment. Don’t forget to apply the rawurlencode() PHP’s function to the paths passed to dompdf as GET variables!

Dompdf distribution is bundled also with many samples you can easily disassemble in order to see how the program works.

If you like this software, as I do, take a minute and drop a line or two to the Author, just to make him know your mind. Perhaps he’ll find a new start in development of this beautiful PDF rendering engine.