How to differentiate the key event between keyboard and bar code gun.

Question

Hello, I have to set a focus on the text field depending upon the key event I get from BarCode gun instead of keyboard key event.How should I differentiate these key event ?

Answer 1

I would guess that you cannot differentiate simply between a real keypress and a keypress event generated by a barcode gun. The barcode gun I have is an old one which hangs between the keyboard and the pc. The pc is not aware that the barcode gun is even there.

The only suggestion I would have is that you could analyse the input stream and look for barcode-typical strings. Probably not so easy.

Answer 2

In my experience it's not possible.

Not without a little bit wizardry. For example if you scan something with a barcode gun the text gets typed much faster than any human could possible type but still slower than copy/paste.

So analyse the speed and the content.

It gets very easy when you want to scan validatable Barcodes.

last_up = 0
input_cache = ""

key_up(key) {
  if ((time.now() - last_up) > 1) {// seconds
     input_cache = ""
     last_up = 0
  } else {
    input_cache += key
    if (IsValidBarcode(input_cache)) {
      doSomething()
    }
  }
  last_up = time.now()
}

Answer 3

Is it a desktop application?

If it's a web application, the jQuery hotkeys plugin might be useful: http://code.google.com/p/js-hotkeys/

It may not help you isolate the difference in inputs, but I imagine it'd be worth a shot.

Answer 4

Many barcode readers can be configured to send a prefix before the actual content of the barcode. This prefix could either be a string, or specific key strokes (like F12 or Ctrl+B).

You can use this feature to detect an incoming barcode.