How to prevent specific keyboard inputing into TextBox in WPF

Question

I have a system with two HID keyboards (actually, one's a barcode scanner.). I Register the device('barcode scanner') for reading raw input data.

I set the RIDEV_NOLEGACY | RIDEV_INPUTSINK to the dwFlags of the RAWINPUTDEVICE. Then I can read and process raw input data in my code.

But, because I set the RIDEV_NOLEGACY dwFlags, another generial keyboard cannot input anything into the TextBox on XAML. That's not what I want. I just want to prevent the barcode scanner from entering directly into the text box， instead of all keyboards.

The following is the code sample(you need to install the nuget package 'sharplibhid'):

private SharpLib.Hid.Handler iHidHandler;
    
    private void Window1_Loaded(object sender, RoutedEventArgs e)
    {
        HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
        source.AddHook(WndProc);

        RAWINPUTDEVICE[] rid = new RAWINPUTDEVICE[1];
        rid[0].usUsagePage = 0x01;

        rid[0].usUsage = 0x06;

        rid[0].dwFlags = RawInputDeviceFlags.RIDEV_INPUTSINK | RawInputDeviceFlags.RIDEV_NOLEGACY;

        rid[0].hwndTarget = source.Handle;

        iHidHandler = new SharpLib.Hid.Handler(rid);

        iHidHandler.OnHidEvent += HandleHidEventThreadSafe;
    }

    public void HandleHidEventThreadSafe(object aSender, SharpLib.Hid.Event aHidEvent)
    {
        if (aHidEvent.IsStray)
        {
            //Stray event just ignore it
            return;
        }
        else
        {
            // do something...
            if (aHidEvent.Device.ProductId == xxx && aHidEvent.Device.VendorId == xxx)
            {
                Debug.WriteLine(aHidEvent.VirtualKey.ToString());
            }
        }
    }

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        Message message = Message.Create(hwnd, msg, wParam, lParam);

        switch (msg)
        {
            case Const.WM_INPUT:

                iHidHandler.ProcessInput(ref message);
                handled = true;
                break;
        }

        return IntPtr.Zero;
    }

This might help: https://stackoverflow.com/questions/587840/how-to-distinguish-between-multiple-input-devices-in-c-sharp. — anonymousCoder, Feb 24 '22 at 14:27
In my application I used a prefix and suffix to surround the barcode input to distinguish from the keyboard input. Once you've determine the source you can decide whether or not to toss it or keep it in the textbox — anonymousCoder, Feb 24 '22 at 14:31
@anonymousCoder Unfortunately, my barcode scanner recognized by the system as HID keyboard. So, the UWP API may not work. — Xie Steven, Feb 25 '22 at 02:03
Have a look at my answer, https://stackoverflow.com/questions/56619941/how-can-i-hook-only-hid-keyboard-to-read-keys-like-a-keylogger-barcode-scanne/56620266#56620266 the problem you are facing are very similar I guess if your barcode reader supports prefix and suffix key downs — Gurhan Polat, Feb 27 '22 at 12:15
@GurhanPolat I could not programm my barcode scaner. I can only think of it as an generic keyboard. — Xie Steven, Feb 28 '22 at 02:53

score 0 · Answer 1 · answered Mar 05 '22 at 13:34

0

I suggest using simple textBox to read all kinds of keyboards and in barcode reader device active to pass Enter after decoding the barcode So you can read both of them keyboard and barcode reader data.

answered Mar 05 '22 at 13:34

Arash Ghazi

633
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How to prevent specific keyboard inputing into TextBox in WPF

1 Answers1