通过

ComponentChangedEventArgs 类

  • 项目

为 ComponentChanged 事件提供数据。无法继承此类。

**命名空间:**System.ComponentModel.Design
**程序集:**System（在 system.dll 中）

语法

声明
<ComVisibleAttribute(True)> _
Public NotInheritable Class ComponentChangedEventArgs
    Inherits EventArgs
用法
Dim instance As ComponentChangedEventArgs

[ComVisibleAttribute(true)] 
public sealed class ComponentChangedEventArgs : EventArgs

[ComVisibleAttribute(true)] 
public ref class ComponentChangedEventArgs sealed : public EventArgs

/** @attribute ComVisibleAttribute(true) */ 
public final class ComponentChangedEventArgs extends EventArgs

ComVisibleAttribute(true) 
public final class ComponentChangedEventArgs extends EventArgs

备注

ComponentChangedEventArgs 提供有关 ComponentChanged 事件的数据。ComponentChanged 事件将向 IComponentChangeService 和注册的事件处理程序通知，当前处于活动状态的文档中的特定组件已发生更改。

ComponentChangedEventArgs 提供下列信息：

  • 指示已修改的组件的 Component 属性。

  • 指示已更改的成员的 Member 属性。

  • 指示成员新值的 NewValue 属性。

  • 指示成员旧值的 OldValue 属性。

当添加、移除或修改组件时，组件设计器通常会自动引发 ComponentChanged 事件。在加载和卸载窗体的过程中，由于需要进行更改，将不会引发 ComponentChanged 事件。组件设计器可能会在更改组件属性后引发 ComponentChanged 事件；这将确保“属性”窗口显示经过更新的属性。

提示

应用于此类的 HostProtectionAttribute 属性 (Attribute) 具有以下 Resources 属性 (Property) 值：SharedState。HostProtectionAttribute 不影响桌面应用程序（这些应用程序通常通过双击图标、键入命令或在浏览器中输入 URL 来启动）。有关更多信息，请参见 HostProtectionAttribute 类或 SQL Server 编程和宿主保护属性。

给继承者的说明 如果将此类指定为另一个类的基类，则发生编译器错误。

示例

下面的示例说明如何创建 ComponentChangedEventArgs。

' This example method creates a ComponentChangedEventArgs using the specified arguments.
' Typically, this type of event args is created by a design mode subsystem.            
Public Function CreateComponentChangedEventArgs(ByVal component As Object, ByVal member As MemberDescriptor, ByVal oldValue As Object, ByVal newValue As Object) As ComponentChangedEventArgs
    ' Creates a component changed event args with the specified arguments.
    Dim args As New ComponentChangedEventArgs(component, member, oldValue, newValue)

    ' The component that has changed:              args.Component
    ' The member of the component that changed:    args.Member
    ' The old value of the member:                 args.oldValue
    ' The new value of the member:                 args.newValue
    Return args
End Function

// This example method creates a ComponentChangedEventArgs using the specified arguments.
// Typically, this type of event args is created by a design mode subsystem.            
public ComponentChangedEventArgs CreateComponentChangedEventArgs(object component, MemberDescriptor member, object oldValue, object newValue)
{            
    // Creates a component changed event args with the specified arguments.
    ComponentChangedEventArgs args = new ComponentChangedEventArgs(component, member, oldValue, newValue);

    // The component that has changed:              args.Component
    // The member of the component that changed:    args.Member
    // The old value of the member:                 args.oldValue
    // The new value of the member:                 args.newValue

    return args;            
}

public:
   // This example method creates a ComponentChangedEventArgs using the specified arguments.
   // Typically, this type of event args is created by a design mode subsystem.
   ComponentChangedEventArgs^ CreateComponentChangedEventArgs( Object^ component, MemberDescriptor^ member, Object^ oldValue, Object^ newValue )
   {
      // Creates a component changed event args with the specified arguments.
      ComponentChangedEventArgs^ args = gcnew ComponentChangedEventArgs( component, member, oldValue, newValue );
      
      // The component that has changed:              args->Component
      // The member of the component that changed:    args->Member
      // The old value of the member:                 args->oldValue
      // The new value of the member:                 args->newValue
      return args;
   }

// This example method creates a ComponentChangedEventArgs using 
// the specified arguments.
// Typically, this type of event args is created by a design mode subsystem.            
public ComponentChangedEventArgs CreateComponentChangedEventArgs(
    Object component, MemberDescriptor member, Object oldValue, 
    Object newValue)
{
    // Creates a component changed event args with the specified arguments.
    ComponentChangedEventArgs args = new ComponentChangedEventArgs(component,
        member, oldValue, newValue);
    // The component that has changed:              args.Component
    // The member of the component that changed:    args.Member
    // The old value of the member:                 args.oldValue
    // The new value of the member:                 args.newValue
    return args;
} //CreateComponentChangedEventArgs

继承层次结构

System.Object
   System.EventArgs
    System.ComponentModel.Design.ComponentChangedEventArgs

线程安全

此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。

平台

Windows 98、Windows 2000 SP4、Windows Millennium Edition、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

请参见

参考

ComponentChangedEventArgs 成员
System.ComponentModel.Design 命名空间
ComponentChanged
ComponentChanging
ComponentChangedEventHandler
IComponentChangeService