First of all, you have to have a look to the scanner manufacturer and see how it works. It can be very different process depending on which scanner, i.e. RS232 serial, USB, TCP/IP, Bluetooth...
Bringing the barcode to the WPF should be more easy.
Sorry if this is not exactly what you were expecting, but the question is a bit too wide to be answered in "Quick Answers".
When you start trying and have a concrete issue, then feel free to come back.
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