ConvertEventHandler Delegate
Definition
Important
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public delegate void ConvertEventHandler(System::Object ^ sender, ConvertEventArgs ^ e);
public delegate void ConvertEventHandler(object sender, ConvertEventArgs e);
public delegate void ConvertEventHandler(object? sender, ConvertEventArgs e);
type ConvertEventHandler = delegate of obj * ConvertEventArgs -> unit
Public Delegate Sub ConvertEventHandler(sender As Object, e As ConvertEventArgs)
Parameters
- sender
- Object
The source of the event.
A ConvertEventArgs that contains the event data.
Examples
The following code
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.
private:
void DecimalToCurrency( Object^ /*sender*/, ConvertEventArgs^ cevent )
{
// The method converts only to string type. Test this using the DesiredType.
if ( cevent->DesiredType != String::typeid )
{
return;
}
// Use the ToString method to format the value as currency ("c").
cevent->Value = ( (Decimal^)(cevent->Value) )->ToString( "c" );
}
void CurrencyToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
{
// ' The method converts only to decimal type.
if ( cevent->DesiredType != Decimal::typeid )
{
return;
}
// Converts the string back to decimal using the static ToDecimal method.
cevent->Value = Convert::ToDecimal( cevent->Value->ToString() );
}
void BindControl()
{
// Creates the binding first. The OrderAmount is typed as Decimal.
Binding^ b = gcnew Binding(
"Text",ds,"customers.custToOrders.OrderAmount" );
// Add the delegates to the events.
b->Format += gcnew ConvertEventHandler(
this, &Form1::DecimalToCurrency );
b->Parse += gcnew ConvertEventHandler(
this, &Form1::CurrencyToDecimal );
text1->DataBindings->Add( b );
}
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);
}
Private Sub DecimalToCurrency(sender As Object, cevent As ConvertEventArgs)
' The method converts only to string type. Test this using the DesiredType.
If cevent.DesiredType IsNot 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 cevent.DesiredType IsNot 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
Remarks
When you create a 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 Handling and Raising Events.
Extension Methods
GetMethodInfo(Delegate) |
Gets an object that represents the method represented by the specified delegate. |