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PaintWeb code refactoring and more
Article published on:14 May 2009, 11:09
Hello everyone!
I have been working on the PaintWeb code refactoring and now I am nearing completion. The initial PaintWeb 0.5 alpha code was more of a demo - it was all in a single big script. I have now added jsdoc comments almost everywhere and I did split the code into multiple files - per tools, per extensions, per language, and more. I have also made important changes to the API. Now any external code can easily add/remove tools, extensions and keyboard shortcuts.
For more developer-related information please read the latest forum thread I posted on the Moodle forums.
For teachers and potential users of PaintWeb inside Moodle, I have prepared a list of questions on how you would use the paint tool in Moodle.
Martin, my mentor, suggested early in my GSOC application process to also apply for the OLPC Contributors program. So I did, and my project was accepted.
Even if the OLPC XO has a slow CPU by today's expectations, it's only 400 Mhz, the system works quite nicely. It has 256 MB of RAM and 1GB of disk capacity. The Sugar interface and the activities provided are amazing. People who hear about these laptops do not know to appreciate the numerous doors such laptops open, doors to knowledge, for all those children who receive them. They help a lot in learning about computing, maths, music, and more.
The Sugar interface is quite well thought-out. I like the concept of having the neighbourhood, group, home and activity views.
The default browser, is some Python application embedding Gecko - on par with Firefox 3.0. The performance of the browser is lacking. Opera 10 alphas start much faster and feel snappier. The paint tool feels sluggish as well.
The Gnash plugin is more of a problem rather than a solution. I installed Flash Player 10, which is sluggish, but at least it works. The system can play Youtube high-quality videos and even uncompressed DVD videos, with Mplayer over the wireless connection. Flash Player cannot play Youtube videos.
Battery life is good - I can use it about three hours without any problems.
Since last week I have been working on the performance of the PaintWeb application, with the OLPC XO-1 laptop. After several tests, I have managed to improve things sufficiently such that the paint tool is now usable in Opera 10 on the XO. Unfortunately, in Browse.xo it's not, at least not by default.
The main performance culprit affecting PaintWeb on the XO is their use of layout.css.dpi. Gecko allows users to change the DPI used for rendering Web pages, in order to makes fonts and images smaller or bigger. So, on the XO the browser is set to use DPI 134, instead of DPI 96. This makes the fonts and images render bigger - with DPI 96 they would all be way too small. PaintWeb and all the pages feel much slower because Gecko performs bilinear image resampling.
When I set layout.css.dpi to 96, drawing in PaintWeb becomes real-time. I was amazed to see it works so well. It's like on my desktop computer. And ... it's even faster than in Opera 10. ;)
If you want, check out the
performance tests yourself. Spoiler: Webkit is the fastest and Gecko is the slowest when running synthetic tests. Obviously, more performance
tests will come - these are only limited to the pencil tool and to the main ev_canvas() event handler from
PaintWeb.
Next on my of list things to do is a new GUI and a packager for the entire code. Loading PaintWeb is now slower due to the amount of code comments and the increasing number of files. The packager will compress/minify all the files into a single one.
That's all for now. Any feedback is welcome!