Zxing sometimes picks up the wrong data from barcode

Question

I know this might be rather a simple issue to ask for and we can also set the barcode format to be scanned by Zxing, like this:

(1)intent.putExtra("SCAN_MODE", "QR_CODE_MODE"); //or any other format

if we do this:

(2)intent.putExtra("SCAN_MODE", "SCAN_MODE"); //for all modes`

While doing the #2 mentioned right above this line, the scanner sometimes seems to scan part of the barcode and picks up wrong information. For example if I try to simply scan a UPC barcode, 98% of the times it works beautifully, but sometimes it just returns me a wrong barcode. I think I know whats happening here, I have an idea up in my head, but what is the exact technical explanation for this? (Anyone familiar with barcodes can help) Thanks in advance guys.

Answer 1

SCAN_MODE is not a valid value. It is ignored and you are scanning for all formats.

It is not reading the wrong information from a barcode; it is finding a 'phantom' barcode among all those white and black lines, of another format. The usual culprit is UPC-E, which is the easiest to accidentally see.

This is why it is far better to restrict the scan to the format you are interested in with a correct value of SCAN_MODE.