In this article I want to tell you about two Linux native, open source PDF viewers that can match almost all of their Windows counterparts (and have quirkier names too!).
The Contenders
If you use Ubuntu, you must have come across Evince (below left)—if not necessarily by that name. The rather sterile sounding Document Viewer that Ubuntu ships with is also known as Evince. According to Carlos Gracia Campos, the current project lead, Evince was,”created by Red Hat to provide a consistent way to read any kind of paginated documents”. Evince's tagline reads—”Simply a Document Viewer.”
Okular (below right), KDE's counterpart to Evince, however, came into being from KPDF—as the name suggests a KDE PDF viewer. The change of name to Okular was both logical and pragmatic. When I asked Albert Astals Cid, the project lead, about the switch, he told me,”KPDF 'has' to be a PDF viewer because of the name, while Okular not so; we could support more file formats like we do now.” Indeed, Okular's tagline proudly boasts that it is “More than a reader.”
So, Evince and Okular, though part of the same large family that is FOSS, are driven by starkly different philosophies. However, do these philosophies actually dictate the development? Or are they merely descriptions of the team's vision? I decided to fire up both and load the same document (incidentally a back issue of FCM) to find out more.
The User Interface
The screenshots below show the file opened in the two different readers.
At first glance, some things are evidently clear. Evince—which belongs to the GNOME project—is perfectly at home in Ubuntu. It has Global Menu support and its appearance compliments the Ambiance theme on my setup. The menu bar is simple and intuitive, it includes up and down arrows for navigating the document. The current page number and total number of pages are also shown—they help you get your bearings and are useful in large documents. The other important option included is the “Zoom” percentage. “Fit Page Width” and “Best Fit” are handy options that save you the effort of estimating the right percentage. The menu bar also has an option to show the parent folder to which the document belongs, which can be surprisingly useful for certain use cases (eg: browsing the FCM archive on my hard drive).
Evince has a two-column UI, the first column is extremely unobtrusive and the focus is clearly on the document—extremely clever design. The first column though serves an important purpose other than just thumbnails, it also shows the bookmarks and annotations (you have to select these from a drop-down menu).
Now to Okular. A perfunctory glance at the screenshot and you would think that Okular acquits itself well in strange waters (it's part of the KDE project, remember). Sure, the UI isn't as elegant or as simple as Evince's UI, but it’s still fairly straightforward. The navigation bar has the standard “previous” and “next” buttons, a small difference from Evince—they're horizontal. And that tiny detail makes a significant difference, somehow browsing doesn't seem as intuitive as it did on Evince. The rest of the items on the navigation bar more or less match Evince's. There's a “Zoom” option with “Fit width” and “Fit page.” An added advantage are the simple “Zoom in” and “Zoom out” buttons that allow you to circumvent the percentage dilemma and simply go on clicking till you're comfortable. There's a “Browse” button that doesn't do much in particular. There's also a “Selection” tool that is simply awesome. But more about that later, let me first complete the UI description.
Okular's UI can be referred to as a three-column interface. The first column has four buttons—”Contents,” “Thumbnails,” “Reviews” and “Bookmarks.” Choosing one of the four determines the contents of the next column, which, uhh, shows the thumbnails, bookmarks or annotations. The final column shows the document, again it's larger than the other two but perhaps places slightly less emphasis on the document than Evince. Having said that, the three-column view has its advantages—it makes accessing annotations and bookmarks much easier, avoiding the drop-down complication of Evince.
Performance
Just as we shouldn't judge a PDF by its cover page (sorry but I love bringing familiar sayings to the 21st Century), we can't be satisfied merely by analyzing the GUI of both Evince and Okular. The question is how do they perform with a large, picture-filled PDF file like an FCM edition? But, before I answer that question, a short detour.
Okular, under “Settings,” has an option called “Configure Okular.” And under that there is a “Performance” tab. And in that tab lies Okular's hidden (literally) ace—memory usage modes. You can choose “low” memory usage if your machine is slow, “Normal” is the default. But if your computer is fairly modern and has RAM greater than 512 MB, choose “Aggressive.” Congratulations, you now have a PDF reader on steroids. In the comparison that follows my Okular was in “Aggressive” mode.
I loaded FCM, edition #63. I then started browsing rapidly. Evince didn't much care for my style of reading, after a few pages it would show blank pages and display a rather apologetic looking yellow loading sign, accompanied by a spinning progress wheel. The delay was only a few seconds, but irritating nonetheless. In sharp contrast, Okular on opening the PDF informed me in a business-like gray message box that it had loaded the 59 page document. And it really had. I could browse through as fast as I wanted. The searches in Okular were sniper like, Google-esque—super accurate and super fast. It managed to find my name in the magazine (sorry for ego surfing) literally within seconds.
Annotations and other Goodies
Things go downhill for Evince from here. PDFs are quickly replacing books and traditional paper documents; you want to be able to make annotations on them. Evince scored very poorly in this category. The only annotation possible is adding a small note. And in case you typed that note wrong, you can't delete it. Yes you heard me right, Evince informs you that it can't delete annotations as of now. In a nutshell, it is simply a document viewer.
Okular, on the other hand, really is more than a reader. Its annotation tools prove that its boast was not an empty one. Press F6 or “Review” under “Tools,” and a plethora of icons shows up on the left-hand side of the document. Each icon depicts an annotation operation. You can make a note, make an in-line note, draw freehand, highlight, make ellipses and rectangles, and even put a stamp (Okular logo with your name) on the document. Further, the “Selection” tool in the navigation bar makes selecting text or images a snap. After you select them, you can either copy to the clipboard or directly save them in a file. It works flawlessly and is one of the most efficient ways of extracting data from a PDF that I have seen so far.
Both document viewers had a “Presentation” mode that would certainly come in handy, Evince's offering was again a tad better designed.
Conclusion
In the end however, there can only be one default PDF viewer. And that is Okular! Despite Evince's better, slicker UI, Okular's superior feature list and blazingly fast “Aggressive mode” makes it the PDF viewer of choice for FOSS fans.
However..
Having said that, I would like to put forward a small addendum. While interviewing the project leads of both Evince and Okular, I realized that the projects share a close relationship. In fact they both work together on “poppler” the PDF rendering library that powers both viewers.
Mr. Cid told me, “Most of the 'bad attitude' comes from user(s) than from developers.” While Mr. Campos pointed out that advanced annotations may be lacking in Evince as of now, but only because of “lack of manpower” and to remember, “that all Evince contributors are volunteers.”
Whichever document viewer you choose, don't forget that a lot of effort goes into developing and maintaining both Evince and Okular. More importantly, both belong to the FOSS family and deserve appreciation—no matter what their shortcomings. Show your gratitude by dropping them an email (or even better, offering to contribute) at okular-devel@kde.org (Okular) and evince-list@gnome.org (Evince).
Summary – Evince The Good • Intuitive, simple and elegant user interface • A great professional looking Presentation mode • A great guide to using Evince under 'Help' > 'Contents' The Bad • Lackluster performance with large PDF files • Lack of annotation features and the inability to delete a simple note • Issues while selecting text, which the guide itself describes as a hit and trial procedure Website - http://projects.gnome.org/evince/
Summary – Okular The Good • Efficient and fast performance especially on a large PDF file • Amazing annotation options • Great text or image selection tool, in fact the best I've ever seen on any OS • Extremely powerful searches especially in the 'Aggressive' mode • The option to choose memory management modes makes it adaptable to computers of all types The Bad • A bit clunky User Interface • Sometimes the menu options don't work • May take up a lot of memory on GNOME environments as it needs the KDE dependencies Website - http://okular.kde.org/
The Winner is: Okular!