A barcode does not contain the stock balance
The code normally identifies a product record. Quantity, location and transaction history live in the stock system. That distinction keeps the scan fast while leaving the user in control of whether the event is a sale, delivery, transfer or correction.
Phone camera or dedicated scanner?
A camera may suit a small shop and moderate volume without extra hardware. A dedicated scanner can be quicker for continuous use, damaged printing or difficult warehouse conditions. Decide after testing the handling rate and products, not from the word “barcode” alone.
Include glossy packets, curved containers, small labels and older print in the sample.
Keep each code unambiguous
One code should resolve to the intended product. Reusing a code across several records makes any scanner unreliable. If no match appears, inspect the digits before creating another product so a formatting difference does not produce a duplicate.
Test the business consequence
Set a test product to ten, scan it into a sale, enter two and complete the operation. Check that the chosen location now shows eight and that the sale appears in movement history. Then cancel it and inspect the reversal. The result matters more than how quickly the camera animation appears.