How HID devices work when programming?

Question

I have a barcode scanner works as HID device. Everytime a barcode scans it goes directly to windows keyboard, for example if I open notepad I can see the barcode typed there.

As far as I know programmatically is it possible to to read HID data from your HID devices.

But what happens if the user is already on a form with a text edit control? The scanned code will go inside the text box.

Can you block incoming text and make a background-only processing?

Can you explain the theory please?

Answer 1

You can set up your scanner to use USB-HID(POS) setting. Your datasheet of barcode settings for the scanner device should have it. I use this project to test my scanners. http://www.codeproject.com/Articles/18099/A-USB-HID-Component-for-C

Answer 2

See if your barcode scanner can emulate a serial port and just read the data directly from the the serial port into your app.

That is cleaner and less expensive then a global keyboard hook. When I was looking into this awhile ago I found that most USB barcode scanners can emulate a serial port, it's a cinch to read serial port data in most programming languages. I happened to be doing mine in Java, I posted an example in answer to this question actually.