KDE 4: Okular Does More Than Just PDFs

by Paul Arnote (parnote)

First came Xpdf, the PDF reader for X-Windows. Then, Kpdf was created for KDE, based off of the efforts of Xpdf. Then, born from Kpdf and the 2005 Google Summer of Code, came Okular, the new universal document reader for KDE 4 SC. During the process, Okular became a lot smarter, and learned how to display a lot more than just PDF files.

Replacing Kpdf, Okular can now view not only PDF files, but also most image files, OpenOffice.org Writer (*.odt) files, postscript files, compiled HTML Help files, EPub e-book files, faxes, and other formats. The chart below, from the KDE 4 Userbase, fills in the details of supported file types that Okular can view.


Remarkably, Okular cannot currently handle displaying simple TXT files, HTML files, or Microsoft Office files. Okular is only capable of displaying OpenOffice.org Writer (*.odt) files, but currently chokes on any of the other OpenOffice.org file formats for the rest of the OpenOffice.org office suite. However, any shortcomings that Okular may currently have with displaying various file formats are likely to be filled in by developers writing additional document format handlers for Okular.


Okular keeps all the same power and abilities as Kpdf, and builds on it by increasing the number of other document files it can handle or display. The screen shot above shows Okular doing what it does best: displaying a PDF file. It can also annotate PDF files, and when you save the annotated document, any other user can open the annotated file using Okular. It can also bookmark your PDF files, which is a handy feature when reading PDF versions of e-books, allowing you to save your current place in the book and to continue reading from where you left off during a previous reading session.


Another cool feature of Okular is it's ability to display multiple pages. You can select for Okular to display "facing pages" in a PDF document, or provide an overview of all the pages (as in the screen capture above of the February 2010 issue of the PCLinuxOS Magazine), to allow you to see how the whole document flows and appears together.

Overall, Okular represents a giant leap forward from Kpdf, which could only display PDF and PS files. With the additional capability of displaying more types of files, Okular is poised to become the one-stop document viewing application in not only Linux, but also every other platform supported by KDE 4 SC. Already made more powerful by it's increased capabilities, Okular will become an unstoppable force in document viewing, once other document format handlers are in place, and a greater variety of file types are supported, especially those file formats specified earlier.