Evince is a free software document viewer developed for the GNOME desktop environment. The goal of Evince is to replace the multiple document viewers that exist on GNOME, like GGV, GPdf, and xpdf, with a single, simple application
Evince began as a rewrite of the gpdf code, which most people thought was getting unwieldy to maintain. In a short period of time it surpassed the functionality of gpdf. Evince is being actively maintained and developed.
Evince has been included in GNOME since GNOME 2.12, released on September 7, 2005. It is written mainly in the C programming language, with a small part (the code that interfaces with poppler) written in C++.
Evince supports image file formats including PDF, DJVU, TIFF, PostScript (using an additional library) and DVI. Of that list, it seems that DJVU should be the number one addition to the basic XML/HTML support in Sugar. DJVU adds the ability to use scanned book pages without the bloat of PDF. The DJVU compression format is specifically designed for scanned text and achieves better result than general image compression techniques. See choosing image formats.
The Evince version currently used by the Read activity in Sugar is based on version 2.20, but slightly modified to support building it in a form that allows embedding in a Python program. It comes from the git repo http://dev.laptop.org/git?p=users/rwh/evince;a=summary The Read activity does not include the libraries required to view PostScript and EPS files.