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HID Device Detection

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  • S Offline
    S Offline
    stevedorries
    wrote on last edited by
    #1

    I have a need to detect if data is coming from a real keyboard or a barcode reader that reports itself as a keyboard and sends keystrokes and react differently to that input versus the real keyboard or a virtual keyboard.

    From my googling I've reached the understanding that this will have to be accomplished in a different manner on different platforms, my first concern is Linux, and I haven't been able to find anything that would point me in the right direction to accomplish my goal.

    How do I tell my application to listen to the keyboards differently?

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #2

      Hi,

      Since we are talking about linux and without diving too deep in Qt's internals you could create an object that reads directly from the correct input device in /dev. Your widget would have to ignore all key events and get feed from that special keyboard reader.

      Hope it helps

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • S Offline
        S Offline
        stevedorries
        wrote on last edited by
        #3

        https://github.com/bimetek/QUSB

        I followed your advice to read the device directly from /dev/foo, to figure out what subdirectory I need to be reading from I found the linked wrapper for libUSB. I'm almost positive there is a way to use that wrapper to do the actual reading so I don't have to open a device file, but I'm not sure how yet. I just thought it may be of some interest to other developers using Qt that there is a prettier way than directly calling libUSB functions.

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #4

          You can also setup your system to give a specific name to that device so you don't have to search with special means

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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          • S Offline
            S Offline
            stevedorries
            wrote on last edited by
            #5

            Can multiple different devices be assigned the same friendly name?

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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #6

              If they are not connected at the same time it should be possible. It depends on what you are using on your target distribution to handle devices.

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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