Bug with Barcode Scanner

Getting Started Newbie Questions
1

Hi,

I have a problem with QR Scanner Plugin

The Problem is, when you scan a barcode, you don’t always get the same value

first i thought this is because i’m using too many barcode types, which gave so many errors

but right now i’m only using ean13 barcode type

and i’m reading the same barcode whether from a webpage or from a plain paper

and sometimes it gives a wrong value

This is function i’m using:

local function listener3(event) print(event.message) end local function barImg\_Tap() qrscanner.show{ topbar = { text = 'Barcode Scanner', }, symbols = {'ean13'}, overlays = { searching = { filename = 'images/home/searching.png', baseDir = system.ResourceDirectory }, found = { filename = 'images/home/found.png', baseDir = system.ResourceDirectory } }, listener = listener3 } end barImg\_Tap()

you can test it yourself

just go to https://barcode.tec-it.com/en/EAN13?data=6251158770107

and scan the barcode many times and see for yourself

2

Is the checksum valid for the misreads?

3

i used the same website to generate the mis-read barcodes and they are correct

this website will not generate the barcode if it is written in a wrong way (bad checksum)

https://barcode.tec-it.com/en/EAN13?data=0081121000087

https://barcode.tec-it.com/en/EAN13?data=0065363000067

This one for example is a wrong barcode (manually created):

https://barcode.tec-it.com/en/EAN13?data=0065363000064

4

How often are the reads coming in via the listener? Just wondering if you could keep track of reported codes, and when you have maybe 4 or 5 choose the one that occurs most often. 

5

i’m not sure i understand your question, but in general my app is used to scan barcodes of medicine boxes, so users click a button to scan the barcode… most of the times it is correct … but sometimes it is totally wrong

so as a test we scanned the same box for many times … and you can say there is a 30% chance to get the barcode wrong … and this happens for any barcode even if it looked crystal clear and large enough in size

i’m not sure why hardware barcode scanners never make mistakes … they either read or not

i thought barcode detection through software would be the same… but seems not!

i read an article about this and i can see why this might happen … but not sure why it does not happen with hardware scanners

i noticed that most bad readings has 3 or 4 zeros inside the barcode … so i will do further tests and check if this is real … i will let the software scan again if the 3 zeros occur … but i hope that real time universal barcodes do not have 3 or 4 adjacent zeros

6

I don’t know how the plugin behaves,so I was asking if you just get one barcode in the listener or a constant stream until you dismiss it? If you get a series of readings for the same barcode then you can ignore those that don’t match the ones around them.

In Xamarin I use the Zxing scanner library for a POS app and haven’t noticed any false readings so far.