Raw Input for Barcode Reader

I have successfully accomplished what you are looking for here. I have an application that receives all barcode character data from a Honeywell/Metrologic barcode scanner. No other application on the system receives the data from the scanner, and the keyboard continues to function normally.

My application uses a combination of raw input and the dreaded low-level keyboard hook system. Contrary to what I've read in numerous online resources, I found that the wm_input raw input message is received before the keyboard hook function is called. My code to process the wm_input message basically sets a boolean variable to specify whether or not the received character is from the scanner. The keyboard hook function, called immediately after the wm_input is processed, swallows the scanner’s pseudo-keyboard data, preventing the data from being received by other applications.

The keyboard hook function has to be placed in an dll since you want to intercept all system keyboard messages. Also, a memory mapped file has to be used for the wm_input processing code to communicate with the dll.