Cannot decode qr images with Qtqr in UbuntuStudio 16.04.1

Asked by Nosphky

I installed qtqr and its listed dependencies (python-qrtools, pyton-qt4) using Synaptic Package Manager in a clean installation of UbuntuStudio 16.04.1.

I can make qr code images by typing into the qtqr gui. These images appear to be good (they scan correctly in my smartphone) but I can't get anything to happen when I try to decode using the gui.

There is in the gui an invitation to drop image files in the gui. I click and slide a file into the gui and expect to see the hidden data revealed. This does nothing at all - not even a sign of the file being accepted..

There is a dropdown box in the lower right side of the gui which invites me to decode a file. I navigate to the qr.png file and click to open. The selection box closes but apart from that absolutely nothing happens in the gui.

I have seen an old reference to python-zbar not being in old (10.04) versions of ubuntu. That is present in my installation.

I imagine I must be missing something simple somewhere. Any suggestions would be welcome.

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Solved by:
Manfred Hampl
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Launchpad Janitor (janitor) said :

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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Nosphky (philip-jackson) said :

I am disappointed not to have received any response to this question. While waiting, I also placed the question on Ubuntu's General Help forum but that produced the same lack of response.

Perhaps nobody uses Qtqr or does not have the problem I have described.

At present, the only way I have to read a qr code is via a smartphone.

So, please, if anyone can help I would like a reply before the next time out.

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Manfred Hampl (m-hampl) said :
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Nosphky (philip-jackson) said :

Thank you Manfred - but I'm afraid you've provided a circular link. My question is already placed on the site you link to. Your posting was on the same page and this reply adds to that page.

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Nosphky (philip-jackson) said :

Sorry - my mistake - didn't see the "+source" bit - I'll have a look.

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Manfred Hampl (m-hampl) said :

There is an area for "QR tools", and one for "qr-tools on Ubuntu". Slightly different.

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Nosphky (philip-jackson) said :

Hi Manfred, after searching around, I decided to install the Daily PPA and got the latest update for Xenial 16.04.1.
This didn't improve matters.

I looked at man qtqr which is a masterpiece of nothingness but did inspire me to try running from the command line.
In the terminal, qtqr started the gui - I made a couple of qr codes but couldn't get to read them.
When I looked back in the terminal, I found a few lines of output ending with -

"Exception: tostring() has been removed. Please call tobytes() instead."

and it seemed to me that I had seen that on one of the Launchpad pages. Sure enough it is part of bug 1589965 so I clicked on that to say I too was affected.

Bad news but a bit of progress nevertheless.

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Best Manfred Hampl (m-hampl) said :

Comment #3 in bug #1589965 suggest a simple editing of one of the files as workaround:

sudo gedit /usr/lib/python2.7/dist-packages/

scroll to line 181 and replace 'tostring()' by 'tobytes()'.

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Nosphky (philip-jackson) said :

Thanks, that solves the problem and qr codes now decode nicely in the gui br drag and drop and by decode > file

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Nosphky (philip-jackson) said :

Thanks Manfred Hampl, that solved my question.

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Warren (wseverin) said :

Thanks, Manfred. That solved it for me, too.