ConvertEventArgs.Value 属性
获取或设置 ConvertEventArgs 的值。
**命名空间:**System.Windows.Forms
**程序集:**System.Windows.Forms（在 system.windows.forms.dll 中）
语法
声明
Public Property Value As Object
用法
Dim instance As ConvertEventArgs
Dim value As Object
value = instance.Value
instance.Value = value
public Object Value { get; set; }
public:
property Object^ Value {
Object^ get ();
void set (Object^ value);
}
/** @property */
public Object get_Value ()
/** @property */
public void set_Value (Object value)
public function get Value () : Object
public function set Value (value : Object)
属性值
ConvertEventArgs 的值。
备注
Value 属性包含的值取决于在其中返回 ConvertEventArgs 的事件。在 Format 事件或 Parse 事件中均可返回 ConvertEventArgs。
在 Format 事件中返回 ConvertEventArgs 时，Value 属性包含数据源的未格式化的属性值。在 Format 事件中，可以读取属性值、格式化该值以及将 Value 属性重置为新的（格式化的）值，从而设置数据绑定控件中显示的值。
在 Parse 事件中返回 ConvertEventArgs 时，该属性包含数据绑定控件的自定义格式化值。在 Parse 事件中，必须读取格式化值，分析它并将其转换回与数据源相同的数据类型。然后可将 Value 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。
示例
下面的代码示例创建一个 Binding，向 Parse 事件和 Format 事件添加 ConvertEventHandler 委托，并使用 DataBindings 属性向 TextBox 控件的 BindingsCollection 添加 Binding。添加到 Format 事件的 DecimalToCurrencyString 事件委托，使用 ToString 方法将绑定值（Decimal 类型）格式化为货币。添加到 Parse 事件的 CurrencyStringToDecimal 事件委托，将控件所显示的值回转为 Decimal 类型。
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 'DecimalToCurrencyString
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 'CurrencyStringToDecimal
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 'BindControl
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:
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.get_DesiredType().Equals(String.class.ToType()))) {
return ;
}
// Use the ToString method to format the value as currency ("c").
cevent.set_Value(((System.Decimal)cevent.get_Value()).ToString("c"));
} //DecimalToCurrencyString
private void CurrencyStringToDecimal(Object sender, ConvertEventArgs cevent)
{
// The method converts back to decimal type only.
if (!(cevent.get_DesiredType().Equals(System.Decimal.class.ToType()))) {
return ;
}
// Converts the string back to decimal using the static Parse method.
cevent.set_Value(Decimal.Parse(cevent.get_Value().ToString(),
NumberStyles.Currency, null));
} //CurrencyStringToDecimal
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.add_Format(new ConvertEventHandler(DecimalToCurrencyString));
b.add_Parse(new ConvertEventHandler(CurrencyStringToDecimal));
text1.get_DataBindings().Add(b);
} //BindControl
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0
请参见
参考
ConvertEventArgs 类
ConvertEventArgs 成员
System.Windows.Forms 命名空间
Binding 类