Wednesday, June 8, 2011

Calendar Update



What a crazy couple of months it's been. I have been back in San Francisco since late February, but not found the motivation or time to post until now. Among other things, I've been to racing school, and I've taken up drumming as a new hobby. I also attended the meego conference here, where I was showing off my QML GES demo (another post about this is still in progress).

I thought I'd take some time to write about the work I've done on my desktop calendar application over the past several months. This will stop me from pestering my friends about it, which will make them a lot happier.

  • Major cosmetic face-lift.
  • Added an infinite-scrolling month view.
  • Added support for all-day events, which are displayed in a pane along the top row.
  • Added support for recurring events via a natural-ish language parser which supports english-like recurrence expressions such as "every two days from now until october", or "the 3rd wednesday of every month except this wednesday"
  • You can easily shift the entire recurrence pattern by dragging a single occurrence with the mouse
  • Possible to select the same block of time across multiple days.
  • Added support for editable event text.
  • Removed dependency on goocanvas. Since all the drawing code is custom, and the entire widget is re-painted on every expose, there really is no point in using goocanvas.




I am considering making an initial release, but would like to address the following issues:
  • I need to come up with a name. As my music teacher once told me, "Name your children." Anything is better than cal.py.
  • Adopt some system for installation, most likely distutils.
  • Currently the calendar widget leaks about 100kb of memory for every expose event. After a few minutes of scrolling and dragging it's pushing 100mb. It's obviously a bug, and I've narrowed it down to the functions I wrote to simplify drawing text. Disabling these functions reduces the memory consumption to a much more reasonable 15-ish mb, Either I am doing something memory inefficient in python, or I've found a leak in pango / cairo. I would very much like to understand that better.
  • I recently added all-day events. You can create an event as an all-day event, or you can drag an existing event to the all-day area. But you can't drag an all-day event back into the timed area.
I did some "usability testing" on a hapless friend of mine, and the results were encouraging but showed there was a great deal of room for improvement. Unfortunately, my select-then-add paradigm of creating new events is confusing for those used to applications like google calendar and evolution. In evolution I find the click-to-create behaviour frustrating. Google calendar, on the other hand, seems to get it right.

After the release
This post is getting long enough already. I've also got some ideas for subsequent improvements, which I will summarize here. TTFN

  • A better grammar
  • A mouse-driven way to add recurrence exceptions.
  • Integration with other calendars
  • Event alarms

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