Vfrdtyky

Requirement:-
To create a Windows application to read barcode which has control characters/invisible characters in it.(using c# and wpf)

I have attached a sample solution which I tried but I have the following issue:-

The solution works fine for barcode without control characters and also for barcodes having ESC or Enter as control characters.
But for control characters like [TAB] , [SHIFT] , [DEL] ,[BACKSPACE] it doesn’t works correctly.

For example:-

If I manually put : 1234[ALT]009[RELEASE ALT]5678[ENTER]: simulates the invisible character
But if I try reading the same via bar code(see attachment for bar code) the entire things gets cleared out. (Check in sample solution)
When I tried to figure out the reason on my end, I found ‘PreviewTextInput’ event is not raised for the invisible character(tab control).

Please can anyone suggest an alternative solution or what changes to be made in the solution I shared so
that I achieve the functionality required.

Sample Solution and Barcode uploaded

Thanks in advance!

Your TextBox does not accept Tabs use

AcceptsTab="True"

to make it accept this instead jump to next tabstop. In WPF it is better to use Binding instead CodeBehind, so I created a ViewModel for you handling the Input.

So as first step I created a ViewModel for you:

public class ViewModel: INotifyPropertyChanged

{

    private String _inputText;

    private ObservableCollection<String> _resultList = new ObservableCollection<string>();

    private String _resultText;



    public string InputText

    {

        get => _inputText;

        set

        {

            if (value == _inputText) return;

            _inputText = value;

            ProcessInput();

            OnPropertyChanged();

        }

    }



    private void ProcessInput()

    {

        ResultList.Clear();

        ResultText = GetUiFriendlyBarCode(InputText);

    }



    public ObservableCollection<string> ResultList

    {

        get => _resultList;

        set

        {

            if (Equals(value, _resultList)) return;

            _resultList = value;

            OnPropertyChanged();

        }

    }



    public string ResultText

    {

        get => _resultText;

        set

        {

            if (value == _resultText) return;

            _resultText = value;

            OnPropertyChanged();

        }

    }





    private string GetUiFriendlyBarCode(String input)

    {

        StringBuilder barCodeToDisplay = new StringBuilder();

        foreach (char character in input.ToString())

        {

            var uiFriendlyCharCode = GetUiFriendlyCharCode((int)character);

            barCodeToDisplay.Append(uiFriendlyCharCode);

            ResultList.Add(uiFriendlyCharCode);

        }

        return barCodeToDisplay.ToString();

    }



//... implement GetUiFriendlyCharCode and INotifyPropertyChnaged

Add the Bindings in Xaml

    <Label Target="{Binding ElementName=Scan}">_Scan</Label>

    <TextBox AcceptsTab="True" Grid.Column="1" x:Name="Scan" Height="50" Text="{Binding InputText, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />



    <!-- List all characters separately -->

    <ListBox Grid.Row="2" Grid.ColumnSpan="2" x:Name="Log" ItemsSource="{Binding ResultList}"/>

    <!-- 

        Show a string to the user that clearly shows any invisible characters.

    -->

    <TextBlock Grid.Row="3">Result</TextBlock>

    <TextBox Grid.Row="3" Grid.Column="1" x:Name="Result" Text="{Binding ResultText}"/>

And than add the DataSource in MainWindow

public MainWindow()

    {

        InitializeComponent();         

        DataContext = new ViewModel();

    }