Library: Barcodes of Type UPC-A gets decoded incorrectly

[ilinkMat]

While decoding a barcode of type UPCA, the library adds a extra 0 to the decoded results. So the decoded result has 13 digits instead of 12
Please find the decoded results

{ format:7 numBits:0 rawBytes:null resultMetadata:null resultPoints: [ResultPoint, ResultPoint] text:"0885909934096" timestamp:1536309792565 ... }

[github-actions[bot]]

Stale issue message

[odahcam]

This issue was not resolved yet.

[sam2332]

This is still an issue?! I will investigate if i can but i have not played around with development on this library at all. i am looking for a solid barcode reader in js and this is the only working example i can find.

[odahcam]

I believe it is. I did not work on this since I had other priorities, also I never really used UPC-A, this is entirely community sourced. Lately we begin to experience some of these strange errors as the library grows, so I had no time to go back and fix everything. Give it a try, let me know what you found. _Fun fact: I was just looking at this issue today as I had saved it to take a look later, months ago, hehe._

[sam2332]

I will give it a look over tomorrow thanks!

[sam2332]

The reason it is returning 13 char is due to EAN13Reader being the decoder that decodes it.
I am looking into it

/src/oned/MultiFormatUPCEANReader.ts has a comment: // todo add UPC_A, UPC_E

I have to figure out how to add one in.
Im going to attempt to copy the EAN13Reader to a UPC_A file and wire it up.

[odahcam]

You can take a look at the Java version source code to help you.

Here we have the multi-format ONE-D, which is already used by our multi-format reader: https://github.com/zxing/zxing/blob/3c96923276dd5785d58eb970b6ba3f80d36a9505/core/src/main/java/com/google/zxing/oned/MultiFormatOneDReader.java#L37

It uses the multi-format UPC EAN reader:

This reader then checks if UPCA format is given in the hints map and then adds the reader:

So, for our code, the only thing left is check if the UPCA format hint is there and then add, this can be done in this piece of code:

https://github.com/zxing-js/library/blob/e01576b8fe812a754cdb043c15cd5ae2170e1ac3/src/core/oned/MultiFormatUPCEANReader.ts#L42-L51

With something like this:

The only problem is that we don't have none of those readers (UPCA, UPCE) ported yet.

Some would have to port one of them so it can work properly.

I hope it helps. 🙂

[sam2332]

I see, you are a godsend! Thank you for the java code to use as reference! I believe I can make some progress with this, ill see what i can come up with.

[sam2332]

OMG! its just EAN13Reader();
all i have to do is strip off the 0 at the beginning, I think i got this :P

https://github.com/zxing/zxing/blob/3c96923276dd5785d58eb970b6ba3f80d36a9505/core/src/main/java/com/google/zxing/oned/UPCAReader.java#L36

if (text.charAt(0) == '0') {
      Result upcaResult = new Result(text.substring(1), null, result.getResultPoints(), BarcodeFormat.UPC_A);
      if (result.getResultMetadata() != null) {

Edit: added file name

[odahcam]

~Holly forking shit.~ Now who is the god sent. 😄

That's probably due to some EAN13 rule, as we can see the lib does put a zero in the start of the string in here for example: https://github.com/zxing/zxing/blob/3c96923276dd5785d58eb970b6ba3f80d36a9505/core/src/main/java/com/google/zxing/oned/EAN13Reader.java#L103

UPC can't be too hard to port, since almost everything is already in here. Anyone interested: be my guest! PRs are very welcome.

[sam2332]

https://github.com/sam2332/library/tree/GHI-88_Barcodes-of-Type-UPC-A-gets-decoded-incorrectly

I am working on a pr over here

[odahcam]

Feel free to open a draft PR If you need any help.

[sam2332]

I will submit a draft PR tomorrow I'm sorry I spelled on this but I got
most of the code implemented I'm just not sure where I'm going wrong on it

On Sun, May 17, 2020, 11:11 PM Luiz Machado [e-mail]
wrote:

Feel free to open a draft PR If you need any help.

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[odahcam]

No worries, open it and I'll take a look ASAP. I just can't promise we will be done this week, as I have lots of important work stuff to work on, but we'll get it working soon.

[sam2332]

https://github.com/zxing-js/library/pull/304 I have created the draft pr

[sam2332]

its not in working order but this is my first time using typescript.

[odahcam]

Feel free to ask if you have any difficulties. Also, this and this can help.