Chicago Development Roadmap

Introduction

The goal of this document, is to plan the development of an open-source library for reading and writing Excel files.

Background

Currently there are several projects are working on reading and/or writing the Excel file format. However, they are all at different stages. If they joined forces and created a reusable open-source library, much time and effort could be saved.

The code for this library will be based on code from xlhtml. xlhtml is a program which allows you to take Microsoft Excel files, and convert them to:

HTML
CSV
XML
Ascii

However xlhtml is a stand alone program, and was not designed to be used by other programs. The idea is to take the xlhtml code, and turn it into an API for parsing Excel spreadsheets. That way it can be used from Gnumeric and other open-source spread sheets.

Here is a list of what I would like to acomplish with each release of xlhtml.

Current Code - 0.6
Restructure code into a frontend and backend/API. The backend will convert Excel files to XML, for processing by other applications.

The frontend, will turn the XML into HTML/CSV/ASCII.

0.6 - 0.7
Add image support. I think using libwmf, would be the best choice for this.

A way needs to be found to extract all wmf files from an Excel spreadsheet, and turn them into PNG or JPEG format.
0.7 - 0.8
Add support for password protected files. I have written a paper on how Excel encrypts passwords. I hope to use that as a reference for this task.
0.8 - 0.9
Do an extensive search for bugs, and fix them. This includes memory leaks etc.
0.9 - 1.0
Freeze code and release. Version 1.0, will be the version for use in production environments.

References

Other open source Excel converters for inspiration:

Star Calc has an Excel filter for Linux, although the codebase can be difficult to understand.
Gnumeric has code to deal with Excel files.

Feel free to send updates/comments/fixes/whatever. I will keep this
document up-to-date, and post new versions when necessary.