HPGS - HPGL Script open source HPGL/2 interpreter

Introduction

The HPGL/2 interpreter HPGS was written by EV-i Informationstechnologie GmbH in 2004 as a component of a closed internet platform for document exchange.

In the beginning we thought, that it should not be necessary to reinvent the wheel and to write an own HPGL/2 interpreter. After evaluating several alternatives we came to the conclusion, that it would be feasible to have an open source code basis, which provides the following features:

• Interpretation of all modern HPGL/2 features.
• Handling of all paper formats.
• Processing of vector data through a Postscript like API.
• Output to native vector graphics formats such as eps.
• State of the art rendering to pixmaps including anti-aliasing.
• Processing of inlined PCL images.

So after two weeks of intensive hacking, the first running version of hpgs was available and since then the program has evolved to meet the above mentioned goals. In order to achieve a reasonable quality of the parser we keep a testsuite of real-world HPGL/2 files, which at the moment is not part of hpgs, because these files may contain sensible data of our customers.

Going public

After a couple of month using hpgs on our document exchange platform, we recognized several shortcoming of a closed source solution. There are still lacking features and a program performing such a basic task as parsing a standarized file format could never ever receive enough testing efforts. So we decided to publish hpgs under the lesser GNU public license (LGPL) for the following reasons:

• We like to donate a free HPGL/2 interpreter to the public.
• We'd like to receive feedback such as the interpretation mixed content files consisting of HPGL and PCL.
• We aim at further augmenting hpgs' capabilities to render almost any real-world HPGL/PCL file.

To achieve these goals we are explicitly inviting commercial software developers to use the code in their own products and on the other hand to contribute to the hpgs code basis.

Status of the project

As of February, 2005 we included preliminary support for inlined PCL images. We are still searching co-workers, which do more testing and propably send in patches for further improving hpgs.