条形码阅读器与C＃的集成

Question

I purchased datalogic quickscan QD2430 barcode reader/scanner for the purpose of scanning national identity cards. The purpose is to read the barcode on the id card and display the information in the textbox. Researching over the internet i found out that this scanner acts as a keyboard wedge and fires the keys on the keyboard after the scan. Two issues iam facing here:

1. This system is being built for security purposes as to not allow the guards to make the id editable so i need to disable the textbox and make it non-editable. How can i do this in case of barcode scanner?

2. Secondly mostly apis i came across over the internet said that they decode the barcode from the image files which makes it of no use to me?

PS: is it necessary to have my textbox focused for this kind of scanner?

How can i obtain my desired operation neatly? Detailed guidance would be appreciated!

Answer 1

1. All the barcode scanner is for is speeding the process of hand typing the text in (at least for the model you have). There is nothing wrong with letting a guard type in the box, if the scanner breaks down do you want the guard to not be able to check people in at all or do you want him to be able to hand type in the barcodes in a pinch.

2. Those libraries work with digial cameras, not barcode scanners, it is pretty hard to find a barcode scanner that does not act as a keyboard.

3. (your PS) Yes, you will need to have the text box focused, as I said in 1), the consumer level barcode readers like the one you have are designed to just make data entry faster. (EDIT: see Cory's comment , apparently some low end readers do provide a driver you can work with. If you can find a driver for yours that lets you communicate directly with the scanner you will no longer need to focus on the textbox)

Answer 2

Barcode scanners normally just act as a keyboard and type the scanned code in really fast. In my case I listened to the key-events, instead of using a TextBox, and determined if a valid barcode was entered in a fixed timeframe, and if it was I just executed some code.

1. Because the barcode scanner acts as a keyboard and you have to listen to the key-events it is possible for a human to enter the code manually. But if you choose a small timeframe for the input it is nearly impossible for humans to enter it.

2. The image decoder libraries do not help in this situation because you have no cam.

I listened for a key-event, remembered the time of this event and stored the key in a buffer (if the key is valid). On the next key-event I checked if the last event and this were no more than X milliseconds (you have to determine this value for yourself) apart and if it was (and the key was valid) added it to the buffer. I Repeated this over and over and if the Buffer validates to a complete Barcode, I executed some code.