Easy QR Code Generation With Google Charts API

When I found about the ability to create QR codes using the Google Charts API I decided to sit down and create a little tool that would generate QR codes for me. I've had this tool for a while and I recently noticed that the QR code mechanism has become deprecated. The API will still work for a couple of years so I thought it was worth posting this. Creating a static QR code using Google Charts is quite easy, all you need to do is create an image. For instance, to create a QR code for the #! code address I would do the following.

<img src="https://chart.googleapis.com/chart?chs=177x177&cht=qr&chl=http://www.hashbangcode.com/&choe=UTF-8" />

Which creates the following image.

A QR code for the domain www.hashbangcode.com

To add a little bit of automation to this I created a HTML page with a textarea and an image. This forms the basis of the tool that will create QR codes.

<textarea cols="100" id="inputtext"></textarea>
<img id="qrcode" src="" />

To keep things easy I decided to use jQuery to interact with the elements on the page, so I created an include for that using another Google service for including JavaScript frameworks called Google Ajax. I then wrote a little function that would update the source of the image every time text was entered into the textarea.

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> 
<script type="text/javascript">
$(document).ready(function(){
  $('textarea#inputtext').keydown(function(e) {
    $('img#qrcode').attr('src', 'https://chart.googleapis.com/chart?chs=177x177&cht=qr&chl=' + $('textarea#inputtext').val() + '&choe=UTF-8');
  });
});
</script>

This code works, but if you are tying in anything into the textarea a lot of requests are made to Google and the image is updated lots of times. To stop this I introduced a small timeout so that the image update function would only be run every second, rather than immediately.

<script type="text/javascript">
$(document).ready(function(){
  var timeout;
  $('textarea#inputtext').keydown(function(e) {
    if (timeout) {
      window.clearTimeout(timeout);
    }
    timeout = window.setTimeout(function() {
      $('img#qrcode').attr('src', 'https://chart.googleapis.com/chart?chs=177x177&cht=qr&chl=' + $('textarea#inputtext').val() + '&choe=UTF-8');
    }, 1000);
  });
});
</script>

After this, I extended the tool to allow for the size of the QR code to be changed. This involved adding a simple select element to the form so that I now had the following.

<textarea cols="100" id="inputtext"></textarea>
<select id="qrsize"><option value="29">29</option><option value="57">57</option><option selected="selected" value="177">177</option><option value="500">500</option>
</select>
<img id="qrcode" src="" />

I then incorporated this select element into the jQuery so that the size is incorporated into the QR code call. I also added a clause that runs the keydown() event on the textarea so that the QR code gets updated when a new size is selected.

<script type="text/javascript">
$(document).ready(function(){
  var timeout;
  $('textarea#inputtext').keydown(function(e) {
    if (timeout) {
      window.clearTimeout(timeout);
    }
    timeout = window.setTimeout(function() {
      var qrsize = $('select#qrsize').val();
      $('img#qrcode').attr('src', 'https://chart.googleapis.com/chart?chs=' + qrsize + 'x' + qrsize + '&cht=qr&chl=' + $('textarea#inputtext').val() + '&choe=UTF-8');
    }, 1000);
  });
  $('select#qrsize').change(function(e) {
    $('textarea#inputtext').keydown();
  });
});
</script>

If you want to view the tool in action have a look at the QR Code Generator Tool.

Comments

Is there an easy EAN13 generation with Google Charts API? Sounds like an article that worths writing :)
Permalink

Hii,

Seriously this post was damn awesome, one thing that strikes me the most  is your style of writing… Whoa you explain stuffs so elegantly, I could understand the concept behind this very well just by reading it once, very well written.

Thanks for sharing this wonderful Article.

Permalink

Add new comment

The content of this field is kept private and will not be shown publicly.
CAPTCHA
2 + 1 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.