Saturday, August 21, 2010

Setting the turtle free with Sikuli

Have you played with turtle graphics? I enjoyed Logo ages and ages ago. Nowadays there's a turtle module in Python's standard library, plus several other implementations.

But all the implementations I know of keep the poor little turtle stuck inside a dull little window. Last night I realized that, with Sikuli, I can set the turtle free! It can roam freely beyond one little window and have adventures in the big, wide world. Here it is marching right past the edge of TuxPaint and onto GNU Paint.

Note that this is an invisible turtle. But you can see its effects.

For the new free-range turtle, "penDown" and "penUp" are actually "mouse button down" and "mouse button up". If it's walking across a drawing program with a paintbrush turned on, it will paint a line like a traditional Logo turtle. Otherwise, it will click and drag its way across your desktop and your other applications. This turtle can be mischievous!

What really pleased me was just how easy it was to implement with Sikuli. Here's the code in an .skl bundle - it's a zipfile that Sikuli can use directly.

import math

class Turtle(object):
def __init__(self):
self.heading = 0
self.loc = Env.getMouseLocation()
def forward(self, distance):
sin = math.sin(math.radians(self.heading))
cos = math.cos(math.radians(self.heading))
endpoint = (int(self.loc.x + cos * distance),
int(self.loc.y + sin * distance))
if self.down:
dragDrop(self.loc, endpoint)
self.loc = Location(*endpoint)
def backward(self, distance):
self.forward(distance * -1)
def right(self, degrees):
self.heading = (self.heading + degrees) % 360
def left(self, degrees):
self.right(-1 * degrees)
def penUp(self):
self.down = False
def penDown(self):
self.down = True
def circle(self, radius, extent=360., steps=20):
circ = 2 * math.pi * radius
fraction = extent / 360.
step_length = (circ * fraction) / steps
for i in range(steps):
self.left(360. * fraction / steps)

def zigzag(startHeading, size, angle, steps):
t = Turtle()
t.heading = startHeading
t.left(angle * 0.5)
for i in range(steps):

Tuesday, August 17, 2010

gmail filter appender with Sikuli

Gmail filters are great, but I've got some filters that apply to a hundred different senders - and I'm always adding new senders to them. I've wished for an automated way to add the sender of the message I'm currently viewing to one of my filters.

I'm sure this could be done in Greasemonkey, Selenium, etc., but Sikuli is my tool of interest for the moment - and, after some fumbling, I'm really happy with it.

A partial screenshot, just to give you the idea:

View the Sikuli code, or download it and run it with /path/to/your/ spammy.skl - except you'll probably want to edit the keywords identifying your filter, and possibly recreate the graphics to match your own Firefox theme. Mostly, it's there as an example to learn from.

I'm learning plenty that will go into my Ohio LinuxFest talk, but the big lesson for today is to rely on keyboard-based and text-based techniques rather than picture-finding whenever they're available. For instance, how should I click a button that might have scrolled off the bottom of the screen? There are lots of ways - I could embed find() in a loop with type(Key.PAGE_DOWN), for example - but it's more reliable to piggyback off Firefox's "Find" to zoom in on the text on (or near) the button and then find it.

Wednesday, August 11, 2010

Sikuli at Ohio LinuxFest

And now, for my next trick, one month from today, I shall demonstrate how to script virtually any program with a GUI... without touching an API! (audience gasps)

If You Can See It, You Can Automate It: Sikuli
Your computer should save you from doing tedious and repetitive tasks yourself, but automation programming has been too difficult for casual uses. MIT's Project Sikuli changes that. It fuses traditional text-base scripts with actual screenshots of targets on your screen, making programming simple, versatile, and useful. If you've ever told a friend, "Go here, now click on this, then on that", you know enough to start using Sikuli. Let Project Sikuli shake up your notions of what programming is like.

I'll be spending most of this month using Sikuli to build a test suite for a complex GUI app at work, recording the pain points as I go. I'd also appreciate your questions and comments about Sikuli - I may be able to work them into my talk (or at least be prepared when they're asked from the audience.)

Ohio Linux Fest, Sep. 10 - 12.

Sunday, August 08, 2010

"Many Eyeballs" - HA!

Oh, yes, I feel I should record this little incident from PyOhio 2010, for the sake of evidence during Nick's trial.

I used PyOhio's Lightning Talks to give away our swag prizes; and, in the spirit of open-source, I put the code on the projector for everyone to see.

import csv
import random

regfile = open('registrations.csv')
reader = csv.DictReader(regfile)
registrants = list(reader)

def pick():
winner = random.choice(registrants)
return '%s %s' % (winner['First Name'],
winner['Last Name'])

Then I realized that I didn't have the Lightning Talk sign-up board, so I went out into the hall to get it. I was gone maybe 60 seconds. When I got back, I called pick() and got... Nick Bastin!

The room giggled. Nick said, "Wow, that's the first time I've written bug-free code on the first try!" I didn't get it, so he said, "Why don't you pick another winner?"

Nick Bastin!

The nice thing is, my code was intact. However, this was lurking in my directory.

$ cat
def choice(foo):
return {"First Name" : "Nick", "Last Name" : "Bastin"}

The lesson here is: Many eyeballs can help protect you from malicious code... unless they're all in on it!

PyOhio 2010 review

My own PyOhio 2010 wrap-up post is highly suspect, because I'm probably not one to deliver an unbiased opinion. So, when I say that


you can be forgiven for being a little skeptical. In fact, one of my few regrets is that I didn't collect firm, objective data on just how awesome it was. I don't have accurate numbers on attendance yet - our sign in sheets are, um, somewhere around here. We had 179 pre-registrations; subtract some no-shows, add some walk-ins, and you get... I don't know. But the place was bustling!

The talks were good, and more importantly, they stimulated some excellent informal activity. The Open Space activity was stronger than ever this year; some of them packed our Open Space rooms to the walls. There were a fair number of Python newcomers there - yay! - and I was glad that we had a good Beginners' Track for them. An After-Hours Board helped people coordinate some evening fun together. Overall, it was not at all just "a place to see talks", but a full immersion in the awesomeness of Python people. Of course, the sprints were the big after-hours event, but they deserve their own post (soon to follow).

OSU's new Ohio Union was a great locale. It helps a lot that it has a design and a staff specialized in holding meetings and conferences, and it's just fantastic that the OSU Open Source club was able to provide the space at incredibly good rates. We look forward to using virtually the same space next year, with just some minor tweaks.

And, for everybody who wondered how we put on a great show at no charge... thank our sponsors!
  • Microsoft
  • Intellovations
  • AGInteractive
  • Dayton Microcomputer Association
Anyway, I'm delighted. I had fun and learned a ton. I hope you did, too! Thanks so much to everybody who took part!

Here are a couple other wrap-up posts I've happened across. Let me know about others you find.

Alex Gaynor
William Chambers
Richard Harding