Express yourself with Pi, the only painting programme to feature ready made pictures of pie.
Pi is a clone of the Paint programme from Windows with a few additions (and subtractions). The programme features standard tools including pen, brush, fill, spray can, eraser, text and a number of shapes.
You can copy from the image, with a custom shape, although pasting + floating is not supported. The canvas is a fixed size and loaded images are adjusted to fit. A stamp tool is also included which is pre-loaded with pictures of delicious pie.
All tools are implemented with nested event handlers, which forward on events as appropriate. This allows for a lot of code re-used between tools which have common behaviours (e.g. shape drawing). Adding the select region animation requires a timer (to update the crawling ants) which added some complexity.
This was the trickiest part of this app from a performance point of view. Checking pixels directly is far too slow (full-canvas fill time of approx 10 seconds). Most code to achieve this in Python sensibly uses numpy, but I didn't want to introduce a dependency for this alone.
By exporting the image as a bytestring, then down-sampling to a boolean byte-per-pixel (for match/no-match) to simplify the comparison loop, I could get it up to a reasonable speed.
The search-to-fill algorithm is still pretty dumb though.