There is a community driven art project in Jacksonville Florida, called Imagination Squared. The idea was to have hundreds of members of the local artist community each contribute a small square that they'd decorated. The squares were all a standardized size, and they were all tiled together in an art installation.
Curious as to what people had sent in, I looked through the site. The art page had hundreds of 100x100 pixel thumbnails, and you had to click on individual ones to get to a larger-resolution 300x300 picture. This struck me as an obvious application for the Microsoft Research PhotoSynth/SeaDragon zooming that was infamously demonstrated at the TED conference by Blaise Aguera y Arcas.
I wondered how the Free Software folks had been faring in creating an open-source variant of SeaDragon. Doing some searching I was pleased to find the OpenZoom project. You can see they have a number of cool examples, and I thought the ImaginationSquared project would be an example that would interest a lot of people (the hundreds who contributed squares, at least!)
So here's the promo video for what I just released the source code to this morning:
Though I'm not going to host the player on hostilefork.com, I pushed the source code out to GitHub today for both the generator (written in Ruby) and the viewer (written in ActionScript 3). I'm also happy to provide built versions of the data and component to individuals who want them:
Neither of those two are languages I've used before. So I'll use the rest of this blog entry to talk about my thoughts on that.
Why Use Ruby?
Using ActionScript was pretty much a given, as all the OpenZoom player code that runs in a browser uses it. But why use Ruby?
I've been meaning to write some actual code in Ruby. I was casually familiar with the language's ideas by looking at small tutorials, but I'd never written anything in it that used any libraries. So installing "gems" or use a library like RMagick was beyond my experience level (basically, I'd never looked at any examples that needed a
The task pulled in a few areas:
Downloading web content - I wanted to get the HTML for the existing grid of images, and use that to get the URLs of the larger images. Then I wanted to get those images via HTTP. This required some basic functionality you can get provided by Ruby's built-in network functionality (files using this will say
DOM parsing and querying - I could have extracted the information I wanted with string processing of the HTML file, but wanted to see Ruby's answer to the DOM. There doesn't seem to be one built-in to the language, but rather (at least) three prominent ones: REXML, Hpricot, libxml-ruby. I chose hpricot because it was jQuery-like and it seemed like it might be more tolerant of HTML that wasn't XML-compatible.
Large image generation - I didn't know if the RMagick library would be very happy about the size of the image I was planning on making. But I figured I'd give it a try. As it turned out, I did have to tweak the virtual memory settings on my virtual machine, but I had it working in virtually no time. :)
You might be wondering why I went through the trouble of web scraping this instead of just asking the Imagination Squared folks for their data. Firstly, because it was an educational exercise in learning Ruby. And secondly, I didn't know if I was going to get this working, or if it started to get difficult if I'd walk away from the project. I didn't want to disappoint anyone if that turned out to be the case, so it was better to just keep it a secret until I actually did the work!
Overall Ruby Impressions
Ruby seems reasonably clean, and appeals to my sensibilities more than Python does. It wasn't too painful to set up and get work done, though what I was writing wasn't precisely rocket science, and I paused any further refinement of it once it produced the files I wanted:
I liked the lack of need for semicolons--code just looks cleaner. But I'm even more extreme than that because I don't like commas in lists. You're always running up against that question in code generation as to whether you're on the last item or not--especially when you're generating code. Putting commas at the ends of lists too is not the answer because if, we, had, to, put, commas, between, every, word, in, English, it, would, get, ugly, right,?
My hopes got up for a moment when I found out about "Ruby Symbols". You can convert from a string to a symbol or a symbol to a string, but you can't modify a symbol directly using string operations... and symbols may be used as keys in hashes/etc. which are unique from their string equivalents. But they're an efficiency trick as opposed to any foundation for symbolic programming.
It seemed that searching Google often found outdated information, or not-very-good advice. What I determined was that the more "noob" your question is, the more likely you are to find documentation from earlier versions or garbage from bloggers who don't know what they're talking about. This made me feel that for basics of a language it's better to start looking on a wiki-like site like StackOverflow.
Something I liked was that Ruby has borrowed Scheme's naming convention for
Ruby does something that Rebol does, which is to have the return value of a code block come from the last expression that gets evaluated. I find myself with the same wish that I could explicitly call that out with something like a "return" when there's a case that the evaluated value is important and you expect it to be used. So I put comments on such lines. But perhaps what I should be doing is ending all code blocks that don't have significant return values with a
Overall OpenZoom SDK Impressions
It seemed to be fairly well organized, and I didn't find it too hard to understand what was going on. More to say on this later.
Overall ActionScript 3 Impressions
As a language, ActionScript just doesn't seem to have a reason for being. Everything I suspected it wouldn't do well it didn't... and those few things I thought it might do well it did not. More to say on this later.