ConvertEventArgs 类

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

提供有关 Format 和 Parse 事件的数据。

public ref class ConvertEventArgs : EventArgs

public class ConvertEventArgs : EventArgs

type ConvertEventArgs = class
    inherit EventArgs

Public Class ConvertEventArgs
Inherits EventArgs

继承

Object

EventArgs

ConvertEventArgs

派生

System.Windows.Forms.DataGridViewCellFormattingEventArgs

System.Windows.Forms.DataGridViewCellParsingEventArgs

System.Windows.Forms.ListControlConvertEventArgs

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

ConvertEventArgs用于格式化和取消格式化由通过 Binding 对象绑定到数据的Windows 窗体控件显示的值。 Format每当控件属性绑定到值时，将发生事件，Parse每当绑定值更改时，该事件就发生。

Format和 Parse 事件允许你创建自定义格式来显示数据。 例如，如果表中的数据的类型为 Decimal，则可以通过在 事件中Format将 的 ConvertEventArgs 属性设置为Value格式化值，指定应以本地货币格式显示数据。 因此，必须在 事件中 Parse 取消显示的值格式。

有关处理事件的详细信息，请参阅 处理和引发事件。

构造函数

ConvertEventArgs(Object, Type)

初始化 ConvertEventArgs 类的新实例。

属性

DesiredType	获取所需值的数据类型。
Value	获取或设置 ConvertEventArgs 的值。

方法

Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ToString()	返回表示当前对象的字符串。 (继承自 Object)

另请参阅

• Binding
• BindingManagerBase
• BindingsCollection
• DataBindings