Apparently, when the TrafficCam flash program was released, Justin was opening a can of worms that was bigger than I could have imagined.
After my example of quick development on the Python app, I got a lot of interest in my own TrafficCam application. Suddenly, there was a London version. And a Dubai version. And every time I mentioned it, someone else wanted to create their own version and load it in so that they could use the same nifty features. If there’s one thing that I do right, it’s listen to what my users are telling me. So, this afternoon, upon the arrival about my new Nokia 6600, I got to work.
First step: Build a file loader. This function should take a file of predefined format and read it in over the web, letting you specify some parameters to the program. This data should then be returned in a way that the application can use. We can’t make the file format too complex: the default Python install comes with no XML support, remember, so we’re using a very basic, tab delimited layout for this. The format is pretty simple: It’s described in the TrafficCam Format Documentation, for those of you who may want to use it.
Step two: Build the app around the data. Given a specific URL, construct the entire application setup, from the tabs to the title to listings, from that returned data. Not too hard: required a little bit of changing how I did things so that it could be reloaded easily, but as always, Python was cooperative.
Step Three: Build a frontend to choosing URLs to load data from. Store a title an a URI, and let people choose which to load. Not too bad: using the popup_menu that symbian provides, can easily associate the resulting choice with your earlier list.
Step Four: Add support for reloading. Once I’m done with one set of cameras, I want to view another without having to exit and restart. This is a bit more complex: it requires me to move some of the logic around so that the application flow stays mostly the same. In the end, I ended up cleaning up some ugly repetition of the code this way, which was useful.
Step Five: Make it more user friendly. Add an “Other” for choosing their own URLs, add progress meters and information boxes, put in exception support for when a URI doesn’t load correctly, and in general, make the app work better.
All in all, I spent six hours yesterday working on the application, and basically rewrote it from top to bottom. It’s now easy to use, and extendable to do whatever people want. I can admit that it’s probably the single most user-friendly application I’ve ever written: almost all my work in the past has been command line based, but this is truly a cool application.
If you have a phone which supports Python, I highly recommend this application. Although I’m sure there are better apps out there, this one is my personal favorite: lets you get a glimpse of the world through your phone. Of course, you should be aware that this is not a low bandwidth application: the camera listings are only about 3-4k apiece, but each camera image can be anywhere from 10-15k, sometimes more depending on the cameras you’re using. Yesterday, while doing development, I used up a megabyte of GPRS bandwidth - luckily, I have unlimited GPRS through my provider.
If you live in an area where there are traffic cameras, and you’d like to see them added, simply construct a file according to the format documentation, and drop me a line.
Have I mentioned lately that I love Python?
Now, to get working on that contact database export I had in mind…