Saturday, 6 August 2011

PDF Viewer has colors and speed but lacks text reflow and pinch-to-zoom

Adobe may have invented the PDF format, but does anyone still use Adobe PDF Reader on their computers? With alternative viewers like Foxit Reader and Sumatra it doesn't make sense to use the bloatware from Adobe on a PC.

What about Android? There are plenty of PDF viewers on the Android Market, and now we have another one: PDF Viewer (a.k.a. Android PDF Viewer or APV).

It's not really new, though. It's an updated version of the open source app PDF Viewer by Maciej Pietrzak. The new edition made by Alexander Pruss is faster, displays page numbers, and has some other improvements.

What sets PDF Viewer apart from other PDF apps is its colors. Black on white is not nice for your eyes unless you're out in the sun or in a brightly lit office. PDF Viewer lets you invert the colors of your pdf, or force it to black on yellow, white on black, green on black, and red on black. Of course plain old black on white is also an option. Reversing colors is not only for looks, but it can save a bit of power on AMOLED screens where darker means less battery drain.

PDF Viewer renders one page ahead, so scrolling down is smooth unless you try to jump too many pages at once. You can speed it up a bit more by skipping the images. If you don't like swiping through your files you can scroll through the pages with the volume buttons. PDF Viewer does a pretty good job of zooming pictures, albeit a bit slow.

There are a few major shortcomings, though. Searching for PDFs in the built-in file browser of PDF Viewer is ugly and inefficient. The back button doesn't move you back to the previous folder, but just exits the app (we already have the home button for that). And in contrast to Adobe Reader, PDF Viewer can't find your PDF files by itself so you really have to navigate all the way through your folder structure. On the bright side, the app remembers your position in the file, which can be useful when you read long eBooks.

PDF Viewer doesn't have pinch-to-zoom, so you'll have to use the zoom buttons instead.

Another flaw is lack of text reflow.

At first glance, text reflow is against the idea behind the PDF format. PDFs were meant to look exactly the way the author intended them to look, without giving a damn about what the reader wants to see.

But when the PDF was invented its makers didn't foresee the invention of the smartphone. The format was originally designed for printers and big computer screens, but what works on a large monitor doesn't work on a small phone display. The typical PDF in its original layout requires lots of horizontal scrolling on a phone, unless you zoom out so far that you need a microscope to read the text.

So reflowing text to fit your screen is essential on a tiny phone display. Unfortunately the only free PDF viewer for Android that gets it right is Adobe Reader.

But the speed, preservation of detail when zooming, and color options are a good reason to give PDF Viewer a try. It may get a lot better in future updates. If you think you can make it better, just do what Alex Pruss did: grab the source code, improve it, and post it back for others to build on.

The latest update is not on the Market (yet), but you can grab a copy from Google Code.

PDF Viewer (Google Code)
PDF Viewer by arpruss (xda forum)
PDF Viewer by Maciej (Android Market)

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