Gadgets, maemo, project, SoftwareEngineering

Witter - a basic python twitter client for Maemo

So I wrote last week about developing a basic twitter client. And this week I got the main stuff done, and wanted to share the code example here. In my looking for help developing apps for Maemo from a start of basically no GTK knowledge or python knowledge I found the examples either too trivial, or way over engineered. So I wrote this intending it to be useful (to me), contain only enough capability to basically read my timeline and tweet. I've intentionally not added bells and whistles (yet) and it's a single 'monolithic' app. By which I mean it's all in a single python file, there is no separation of gui and logic, no nice engineered constructs etc etc.

I hope that it does show an intermediate level example of writing an application for Maemo using Python. This is what it looks like in action

Witter
Witter

This was taken full screen. The app supports switching in and our of full screen. And it adjusts the width of the displayed text to fit. As you can see the shot was taken not long after completing the application.

It also sorts the tweets using the ListStore ability to just tell it which column to sort on. This is very useful as it means I don't have to mess around myself. Originally I had it sorting on created_at, but since I was loading that as a String it would order Thursday below Wednesday. Rather than cast the string into a meaningful date object of some form, I just used ID instead, which is a Long. Still comparing as a string, but the number always increments so newer tweets always appear t the top.  Obviously if you prefer newer tweets at the bottom, just flip the sort order to Ascending.

So here is the code, it's a little under 300 lines, but I've commented it pretty well (I think) to explain what it's all doing.

# ============================================================================ # Name : witter.py # Author : Daniel Would # Version : 0.1 # Description : Witter # ============================================================================ #This is the bunch of things I wound up importing #I think I need them all..

import gtk import pygtk import hildon import urllib2 import urllib import base64 import urlparse import simplejson import socket

#Initially I found I'd hang the whole interface if I was having network probs #because by default there is an unlimited wait on connect so I set #the timeout to 10 seconds afterwhich you get back a timeout error # timeout in seconds

timeout = 10 socket.setdefaulttimeout(timeout)

#the main witter application

class Witter(hildon.Program):

#first an init method to set everything up

def __init__(self): hildon.Program.__init__(self)

#being lazy this just uses basic auth and I am not doing anything #yet to store uid/pwd so for the moment just put info here

self.username = "YOUR_USERNAME" self.password = "YOUR_PASSWORD"

#This being a hildon app we start with a hildon.Window

self.window = hildon.Window()

#connect the delete event for closing the window

self.window.connect("delete_event", self.quit)

#add window to self

self.add_window(self.window)

#For this app I wanted a scrollable area for the tweets to show up #so I create a gtk ScrolledWindow

self.scrolled_window = gtk.ScrolledWindow(hadjustment=None, vadjustment=None)

# as well as somewhere to show the tweets we need somewhere to write a tweet # this being twitter we cap the input at 140 chars

self.tweetInput = gtk.Entry(max=140)

# we also want a couple of control buttons to load up tweets and submit a tweet

self.buttonloadTweets = gtk.Button(label="Load Tweets",stock=None, use_underline=None );

# we connect out load tweets button to the getTweets method

self.buttonloadTweets.connect("clicked", self.getTweets) self.buttonnewTweet = gtk.Button(label="Tweet",stock=None, use_underline=None );

#we connect the Tweet button to the newTweet method

self.buttonnewTweet.connect("clicked", self.newTweet, self.tweetInput)

# a vertical box to set the scrollable window and the button box # in the display

self.box1 = gtk.VBox(False, 0)

#a horizontal box to put our tweet input box and two control buttons in

self.buttonBox = gtk.HBox()

# add the Vbox to the window

self.window.add(self.box1)

# create a menu object by calling a method to deine it

menu = self.create_menu(self.scrolled_window)

# add the menu to the window

self.window.set_menu(menu)

# define a liststore we use this to store our tweets and some associated data # the fields are : Name,nameColour,Tweet+timestamp,TweetColour,Id

self.liststore = gtk.ListStore(str, str, str, str, str)

# create the TreeView using treestore this is the object which displays the # info stored in the liststore

self.treeview = gtk.TreeView(self.liststore)

# create the TreeViewColumn to display the data, I decided on two colums # one for name and the other for the tweet

self.tvcname = gtk.TreeViewColumn('Name') self.tvctweet = gtk.TreeViewColumn('Tweet')

# add the two tree view columns to the treeview

self.treeview.append_column(self.tvcname) self.treeview.append_column(self.tvctweet)

# we need a CellRendererText to render the data

self.cell = gtk.CellRendererText()

# add the cell renderer to the columns

self.tvcname.pack_start(self.cell, True) self.tvctweet.pack_start(self.cell,True)

# set the cell "text" attribute to column 0 - retrieve text # from that column in liststore and treat it as the text to render # in this case it's the name of a tweeter

self.tvcname.add_attribute(self.cell, 'text', 0)

# we then use the second field of our liststore to hold the colour for # the 'name' text

self.tvcname.add_attribute(self.cell, 'foreground', 1)

# next we add a mapping to the tweet column, again the third field # in our list store is the tweet text

self.tvctweet.add_attribute(self.cell, 'text',2)

# and the fourth is the colour of the tweet text

self.tvctweet.add_attribute(self.cell, 'foreground', 3)

# we start up non-fullscreen, and we want the tweets to appear without # scrolling left-right (well I wanted that) so I set a wrap width for # the text being rendered

self.cell.set_property('wrap-width', 500)

# make it searchable (I found this in an example and thought I might use it # but currently I make no use of this setting

self.treeview.set_search_column(0)

# Allow sorting on the column. This is cool because no matter what order # we load tweets in, we always get a view which is sorted by the tweet id which # always increments, so we get them in order

self.liststore.set_sort_column_id(4,gtk.SORT_DESCENDING)

# I don't want to accidentally be dragging and dropping rows out of order

self.treeview.set_reorderable(False)

#with all that done I add the treeview to the scrolled window

self.scrolled_window.add(self.treeview)

# Then just 'pack# the scrolled window and a Hbox into the # V box

self.box1.pack_start(self.scrolled_window, True, True, 0) self.box1.pack_start(self.buttonBox, False, True,0)

#and pack the hbox with input field and buttons

self.buttonBox.pack_start(self.tweetInput, True,True,0) self.buttonBox.pack_start(self.buttonnewTweet, False, False,0) self.buttonBox.pack_start(self.buttonloadTweets, False, False,0)

#setup some urllib things to use to fetch twitter feeds

self.last_id=None def quit(self, *args):

#this is our end method called when window is closed

print "Stop Wittering" gtk.main_quit() def create_menu(self, widget):

#a fairly standard menu create #I put in the same options as I have buttons # and linked to the same methods

menu = gtk.Menu() menuItemGetTweets = gtk.MenuItem("Get Tweets") menuItemGetTweets.connect("activate", self.getTweets ) menuItemTweet = gtk.MenuItem("Tweet") menuItemTweet.connect("activate",self.newTweet) menuItemSeparator = gtk.SeparatorMenuItem() menuItemExit = gtk.MenuItem("Exit") menuItemExit.connect("activate", self.quit); menu.append(menuItemGetTweets) menu.append(menuItemTweet) menu.append(menuItemSeparator) menu.append(menuItemExit) menuItemFile = gtk.MenuItem("File") menuItemFile.set_submenu(menu) return menu def run(self):

#this is the main execution method # we set things visible, connect a couple of event hooks to methods # specifically to handle switching in and our of fullscreen

self.window.show_all() self.window.connect("key-press-event", self.on_key_press) self.window.connect("window-state-event", self.on_window_state_change)

#this starts everything up

gtk.main() def getTweets(self, *args):

#Now for the main logic...fetching tweets #at the moment I'm just using basic auth. #urllib2 provides all the HTTP handling stuff

auth_handler = urllib2.HTTPBasicAuthHandler()

#realm here is important. or at least it seemed to be #this info is on the login box if you go to the url in a browser

auth_handler.add_password(realm='Twitter API', uri='http://twitter.com/statuses/friends_timeline.json', user=self.username, passwd=self.password)

#we create an 'opener' object with our auth_handler

opener = urllib2.build_opener(auth_handler)

# ...and install it globally so it can be used with urlopen.

urllib2.install_opener(opener)

#switch on whether this is an refresh or a first download

if self.last_id == None: json = urllib2.urlopen('http://twitter.com/statuses/friends_timeline.json') else:

#basically the twitter API will respond with just tweets newer than the ID we send

json = urllib2.urlopen('http://twitter.com/statuses/friends_timeline.json?since_id='+str(self.last_id)+'L')

#JSON is awesome stuff. we get given a long string of json encoded information #which contains all the tweets, with lots of info, we decode to a json object

data = simplejson.loads(json.read())

#then this line does all the hard work. Basicaly for evey top level object in the JSON #structure we call out getStatus method with the contents of the USER structure #and the values of top level values text/id/created_at

[self.getStatus(x['user'],x['text'], x['id'], x['created_at']) for x in data] def getStatus(self, user,data, id, created_at):

#at this point user is another JSON structure of lots more values of which we are currently #only interested in screen_name #append to our list store the values from the JSON data we've been passed for a tweet # the funny #NXNXNX type values are colours I chose a slightly blue for the name # and black for the tweet. At some point I intend to do some alternating colours for # cell backgrounds to make the display clearer

self.liststore.append([ user['screen_name'],"#2E00B8",data+"\nposted on: "+created_at,"#000000", id])

#now we process the id, this is so we can do a refresh with just the posts since the latest one we have #if we haven't stored the most recent id then store this one

if self.last_id == None: self.last_id=id else:

#if we have an id stored, check if this one is 'newer' if so then store it

if long(self.last_id) < long(id): self.last_id=id def newTweet(self, widget, text_widget,*args):

#The other main need of a twitter client #the ability to post an update #get the tweet text from the input box

tweet = text_widget.get_text()

#see if we have just an empty string (eg eroneous button press)

if (tweet == ""): return

#we get the text in the input box then we construct the outbound tweet #first we need to encode for utf-8

tweet = unicode(tweet).encode('utf-8')

#then we need to urlencode so that we can use twitter chars like @ without #causing problems

post = urllib.urlencode({ 'status' : tweet })

#build the request with the url and our post data

req = urllib2.Request('http://twitter.com/statuses/update.json', post)

#setup the auth stuff

auth_handler = urllib2.HTTPBasicAuthHandler() auth_handler.add_password(realm='Twitter API', uri='http://twitter.com/statuses/update.json', user=self.username, passwd=self.password) opener = urllib2.build_opener(auth_handler)

# ...and install it globally so it can be used with urlopen.

urllib2.install_opener(opener) json = urllib2.urlopen(req) data = simplejson.loads(json.read())

#message sent, I'm assuming a failure to send would not continue #in this method? so it's safe to remove the tweet line # what I don't want is to lose the tweet I typed if we didn't # sucessfully send it to twitter. that would be annoying (I'm looking # at you Mauku)

text_widget.set_text(""); def on_window_state_change(self, widget, event, *args):

#this just sets a flag to keep track of what state we're in

if event.new_window_state & gtk.gdk.WINDOW_STATE_FULLSCREEN: self.window_in_fullscreen = True else: self.window_in_fullscreen = False def on_key_press(self, widget, event, *args):

#this picks up the press of the full screen key and toggles #from one mode to the other

if event.keyval == gtk.keysyms.F6:

# The "Full screen" hardware key has been pressed

if self.window_in_fullscreen: self.window.unfullscreen ()

#when we toggle off fullscreen set the cell render wrap #to 500

self.cell.set_property('wrap-width', 500) else: self.window.fullscreen ()

#when we toggle into fullscreen set the cell render wrap #wider

self.cell.set_property('wrap-width', 630) if __name__ == "__main__":

#this is just what initialises the app and calls run

app = Witter() app.run()

And that's it. I used esbox to develop and just had it using SCP/SSH to copy accross to my n810 and execute directly there, which was a pretty easy way to develop.

There are lots of things I will now go on to add to this client. Things like checking for replies/DMs. Being able to make easy reference to an URLs in tweets, and reply to people etc etc. But I wanted to show the code of the bare bones working in case it helped anyone else get started with developing apps for Maemo.