How to: Create a Custom Formatter to Represent Decimal Values in Binary

• Nov 13, 2018
• 2 minutes to read

This example demonstrates a way of creating a custom formatter object to display decimal values in binary, but only if the format string is supplied as “B”. See the Custom Formatting topic for information on creating custom formatters.

The result is shown in the image below.

C#

// A custom formatter object.
public class BaseFormatter : IFormatProvider, ICustomFormatter {
    // The GetFormat method of the IFormatProvider interface.
    // This must return an object that provides formatting services for the specified type.
    public object GetFormat(Type format) {
        if (format == typeof (ICustomFormatter)) return this;
        else return null;
    }
    // The Format method of the ICustomFormatter interface.
    // This must format the specified value according to the specified format settings.
    public string Format (string format, object arg, IFormatProvider provider) {
        if (format == null) {
            if (arg is IFormattable)
                return ((IFormattable)arg).ToString(format, provider);
            else
                return arg.ToString(); 
        }
        if (format == "B")
            return Convert.ToString(Convert.ToInt32(arg), 2);
        else
            return arg.ToString();
    }
}

// ...
// Assign the custom formatter to the editor.
spinEdit1.Properties.DisplayFormat.FormatType = FormatType.Custom;
spinEdit1.Properties.DisplayFormat.FormatString = "B";
spinEdit1.Properties.DisplayFormat.Format = new BaseFormatter();
spinEdit1.Properties.IsFloatValue = false;
spinEdit1.EditValue = 10;

VB.NET

' A custom formatter object.
Public Class BaseFormatter : Implements IFormatProvider, ICustomFormatter
    ' The GetFormat method of the IFormatProvider interface.
    ' This must return an object that provides formatting services for the specified type.
    Public Function GetFormat(ByVal format As Type) As Object _
    Implements IFormatProvider.GetFormat
        If format.ToString() = GetType(ICustomFormatter).ToString() Then
            GetFormat = Me
        Else
            GetFormat = Nothing
        End If
    End Function

    ' The Format method of the ICustomFormatter interface.
    ' This must format the specified value according to the specified format settings.
    Public Function Format(ByVal formatString As String, ByVal arg As Object, _
    ByVal provider As IFormatProvider) As String Implements ICustomFormatter.Format
        If (formatString = Nothing) Then
            If TypeOf arg Is IFormattable Then
                Format = CType(arg, IFormattable).ToString(formatString, provider)
            Else
                Format = arg.ToString()
            End If
            Exit Function
        End If
        If (formatString = "B") Then
            Format = Convert.ToString(Convert.ToInt32(arg), 2)
        Else
            Format = arg.ToString()
        End If
    End Function
End Class

' ...
' Assign the custom formatter to the editor.
SpinEdit1.Properties.DisplayFormat.FormatType = FormatType.Custom
SpinEdit1.Properties.DisplayFormat.FormatString = "B"
SpinEdit1.Properties.DisplayFormat.Format = New BaseFormatter()
SpinEdit1.Properties.IsFloatValue = False
SpinEdit1.EditValue = 10