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ConvertEventHandler Delegate

Represents the method that will handle the Parse and Format events of a Binding object.

[Visual Basic]
<Serializable>
Public Delegate Sub ConvertEventHandler( _
   ByVal sender As Object, _
   ByVal e As ConvertEventArgs _
)
[C#]
[Serializable]
public delegate void ConvertEventHandler(
   object sender,
   ConvertEventArgs e
);
[C++]
[Serializable]
public __gc __delegate void ConvertEventHandler(
   Object* sender,
   ConvertEventArgs* e
);

[JScript] In JScript, you can use the delegates in the .NET Framework, but you cannot define your own.

Parameters [Visual Basic, C#, C++]

The declaration of your event handler must have the same parameters as the ConvertEventHandler delegate declaration.

sender
The source of the event.
e
A ConvertEventArgs that contains the event data.

Remarks

When you create a(n) ConvertEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Events and Delegates.

Example

[Visual Basic, C#, C++] The following example creates a Binding, adds a ConvertEventHandler delegate to both the Parse and Format events, and adds the Binding to the BindingsCollection of a TextBox control through the DataBindings property. The DecimalToCurrency event delegate, added to the Format event, formats the bound value (a Decimal type) as currency using the ToString method. The CurrencyToDecimal event delegate, added to the Parse event, converts the value displayed by the control back to the Decimal type.

[Visual Basic] 
Private Sub DecimalToCurrency(sender As Object, cevent As ConvertEventArgs)
    ' The method converts only to string type. Test this using the DesiredType.
    If Not cevent.DesiredType Is GetType(String) Then
        Return
    End If 
    ' Use the ToString method to format the value as currency ("c").
    cevent.Value = CDec(cevent.Value).ToString("c")
End Sub 


Private Sub CurrencyToDecimal(sender As Object, cevent As ConvertEventArgs)
    ' The method converts only to decimal type. 
    If Not cevent.DesiredType Is GetType(Decimal) Then
        Return
    End If 
    ' Converts the string back to decimal using the static ToDecimal method.
    cevent.Value = Convert.ToDecimal(cevent.Value.ToString())
End Sub 


Private Sub BindControl()
    ' Creates the binding first. The OrderAmount is typed as Decimal.
    Dim b As New Binding("Text", ds, "customers.custToOrders.OrderAmount")
    ' Adds the delegates to the events.
    AddHandler b.Format, AddressOf DecimalToCurrency
    AddHandler b.Parse, AddressOf CurrencyToDecimal
    text1.DataBindings.Add(b)
End Sub 

[C#] 
private void DecimalToCurrency(object sender, ConvertEventArgs cevent)
{
   // The method converts only to string type. Test this using the DesiredType.
   if (cevent.DesiredType != typeof(string)) return;

   // Use the ToString method to format the value as currency ("c").
   cevent.Value = ((decimal) cevent.Value).ToString("c");
}

private void CurrencyToDecimal(object sender, ConvertEventArgs cevent)
{
   // ' The method converts only to decimal type. 
   if (cevent.DesiredType != typeof(decimal)) return;

   // Converts the string back to decimal using the static ToDecimal method.
   cevent.Value = Convert.ToDecimal(cevent.Value.ToString());
}

private void BindControl()
{
   // Creates the binding first. The OrderAmount is typed as Decimal.
   Binding b = new Binding
      ("Text", ds, "customers.custToOrders.OrderAmount");
   // Add the delegates to the events.
   b.Format += new ConvertEventHandler(DecimalToCurrency);
   b.Parse += new ConvertEventHandler(CurrencyToDecimal);
   text1.DataBindings.Add(b);
}


[C++] 
private:
void DecimalToCurrency(Object* /*sender*/, ConvertEventArgs* cevent)
{
   // The method converts only to string type. Test this using the DesiredType.
   if (cevent->DesiredType != __typeof(String)) return;

   // Use the ToString method to format the value as currency ("c").
   cevent->Value = (dynamic_cast<Decimal*> (cevent->Value))->ToString(S"c");
}

private:
void CurrencyToDecimal(Object* /*sender*/, ConvertEventArgs* cevent)
{
   // ' The method converts only to decimal type. 
   if (cevent->DesiredType != __typeof(Decimal)) return;

   // Converts the string back to decimal using the static ToDecimal method.
   cevent->Value = __box(Convert::ToDecimal(cevent->Value->ToString()));
}

private:
void BindControl()
{
   // Creates the binding first. The OrderAmount is typed as Decimal.
   Binding* b = new Binding
      (S"Text", ds, S"customers.custToOrders.OrderAmount");
   // Add the delegates to the events.
   b->Format += new ConvertEventHandler(this, &Form1::DecimalToCurrency);
   b->Parse += new ConvertEventHandler(this, &Form1::CurrencyToDecimal);
   text1->DataBindings->Add(b);
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Windows.Forms

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

See Also

System.Windows.Forms Namespace

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