<LinearLayout
	android:orientation="horizontal"
	android:id="@+id/toprow"
	android:weightSum="100"
	android:layout_width="fill_parent"
	android:layout_height="wrap_content">
		<TextView
		  android:id="@+id/text1"
			android:layout_width="0px"
			android:layout_weight="80"
			android:layout_height="wrap_content"/>
		<TextView android:id="@+id/custom_property"
			android:layout_width="0px"
			android:layout_weight="20"
			android:layout_height="wrap_content"/>
</LinearLayout>

In brief, they’re fascinating little 2-dimensional barcodes that can be used to encode up to 2,953 bytes of data. The android app store uses them to encode links to applications, you scan the QR-code and the device pops up a link to the app store for your to download….. Hence my interest!!

I wanted to figure out how to generate these so I decided that combining some of my recent interests (wordpress plugin development and google app engine) and knocking up something to generate QR-codes containing vCard information would be fun and useful.

I’m not going to go into much detail as the source is available and I’m terminally lazy when it comes to explaining code. I used bottle.py as the REST framework (plan on moving it up to GAE, yaml file is there already but because GAE doesn’t have a persistent file system, it’s non trivial to do the permalink) and Uni-Form for the client. Code to generate the QR used pygooglechart and was trivial

from pygooglechart import QRChart
import re
import uuid
import shutil
import os

HEIGHT = 210
WIDTH  = 210

vCardTemplate = '''BEGIN:VCARD
N:{SURNAME};{FIRSTNAME}
TEL;CELL:{TELMOBILE}
TEL;HOME:{TELHOME}
EMAIL:{EMAIL}
URL:{URL}
END:VCARD'''

class QRMaker:
    def __init__(self):
        self._templateData = vCardTemplate

    def createVCard(self, data):
        try:
                chart = QRChart(HEIGHT, WIDTH)
                templateData = ''
                for k, v in data.items():
                    templateData = self._templateData.replace('{%s}' % k, v)
                    self._templateData = templateData

                match = re.sub(r'{\w*\w}', '', templateData)

                chart.add_data(match)
                chart.set_ec('H', 0)
                uid = uuid.uuid1()
                filePath =  '%s/../static/cache/%s.png' % (os.path.dirname(__file__), uid)
                chart.download(filePath)
                return uid
        except ex:
                logging.debug('Unhandled exception')
                logging.exception('Unhandled exception')

    def generatePermalink(self, id):
        shutil.copyfile(
            'static/cache/%s.png' % id,
            'static/images/permalinked/%s.png' % id
        )
        return 'static/images/permalinked/%s.png' % id

Part one of this is to generate the QR-codes and is working (for loose values of work) below

Part two will be to extend it to allow a wordpress plugin to display this QR-code on your site.

:: Demo app is available here
:: Source is available here

::Update::

I’m having mixed success scanning the generate QR-code using a HTC Desire. It seems the more data I add to the QR-code the less accurate it is scanning, despite zxing reading it fine. I’m happy enough though that it’s a valid QR-code and won’t be doing any more work on this side of things unless I hear different, so do let me know your results..

Install cygwin and check all the X’ stuff (I usually just select xterm and let dependency checks do the rest).

run \bin\xwin.exe -multiwindow

Open a putty session, make sure that in Connection\SSH\X11
Enable X11 forwarding is ticked and
X display location is set to IP/hostname of box

Log unto your nix box and try running an xterm…

Put on your awesome pants (or not)..