ConvertEventArgs.Value 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置 ConvertEventArgs 的值。

public:
 property System::Object ^ Value { System::Object ^ get(); void set(System::Object ^ value); };

public object? Value { get; set; }

member this.Value : obj with get, set

Public Property Value As Object

属性值

Object

ConvertEventArgs 的值。

示例

下面的代码示例创建 一个 Binding，将委托ConvertEventHandler添加到 Parse 和 Format 事件，并使用 DataBindings 属性将 BindingsCollection 添加到Binding控件的 TextBox 。 DecimalToCurrencyString添加到 Format 事件的事件委托使用 ToString 方法将绑定值格式化 (Decimal类型) 为货币。 CurrencyStringToDecimal添加到 事件的事件Parse委托将控件显示的值转换回 类型Decimal。

private:
   void DecimalToCurrencyString( 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 CurrencyStringToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      // The method converts back to decimal type only. 
      if ( cevent->DesiredType != Decimal::typeid )
      {
         return;
      }
      
      // Converts the string back to decimal using the static Parse method.
      cevent->Value = Decimal::Parse( cevent->Value->ToString(),
         NumberStyles::Currency, nullptr );
   }

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

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

   // Converts the string back to decimal using the static Parse method.
   cevent.Value = Decimal.Parse(cevent.Value.ToString(),
   NumberStyles.Currency, null);
}

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

Private Sub DecimalToCurrencyString(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 CurrencyStringToDecimal(sender As Object, cevent As ConvertEventArgs)
   ' The method converts back to decimal type only. 
   If Not cevent.DesiredType Is GetType(Decimal) Then
      Return
   End If 
   ' Converts the string back to decimal using the shared Parse method.
   cevent.Value = Decimal.Parse(cevent.Value.ToString, _
   NumberStyles.Currency, nothing)

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 DecimalToCurrencyString
   AddHandler b.Parse, AddressOf CurrencyStringToDecimal
   text1.DataBindings.Add(b)
End Sub

注解

属性包含 Value 的值取决于返回 的事件 ConvertEventArgs 。 ConvertEventArgs可以在 事件或 Parse 事件中Format返回 。

ConvertEventArgs在 事件中Format返回 时，Value属性包含数据源的未格式化属性值。 在 事件中 Format ，可以读取属性值、设置值格式，并将属性重置 Value 为新 (格式化) 值，从而设置数据绑定控件中显示的值。

ConvertEventArgs在 事件中Parse返回 时， 属性包含数据绑定控件的自定义格式值。 在 事件中 Parse ，必须读取格式化值，对其进行分析，然后将其转换回与数据源相同的数据类型。 然后， Value 可以将 属性重置为未格式化的值，从而设置数据源的值。 若要确定数据源的类型，请检查 DesiredType 属性值。

另请参阅

• Binding