ToolboxItemFilterAttribute 类
为工具箱项指定要使用的筛选器字符串和筛选器类型。
**命名空间:**System.ComponentModel
**程序集:**System（在 system.dll 中）
语法
声明
<SerializableAttribute> _
<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple:=True, Inherited:=True)> _
Public NotInheritable Class ToolboxItemFilterAttribute
Inherits Attribute
用法
Dim instance As ToolboxItemFilterAttribute
[SerializableAttribute]
[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true, Inherited=true)]
public sealed class ToolboxItemFilterAttribute : Attribute
[SerializableAttribute]
[AttributeUsageAttribute(AttributeTargets::Class, AllowMultiple=true, Inherited=true)]
public ref class ToolboxItemFilterAttribute sealed : public Attribute
/** @attribute SerializableAttribute() */
/** @attribute AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true, Inherited=true) */
public final class ToolboxItemFilterAttribute extends Attribute
SerializableAttribute
AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=true, Inherited=true)
public final class ToolboxItemFilterAttribute extends Attribute
备注
ToolboxItemFilterAttribute 提供一种机制，通过这种机制，可以将工具箱项标记为只能与具有匹配的属性或者代码的设计器一起使用，这些属性或者代码确定了该项在工具箱中应该启用还是禁用。
可以将 ToolboxItemFilterAttribute 应用到 ToolboxItem 以指示筛选器字符串和筛选器类型，以便指定何时启用或禁用项。还可以将 ToolboxItemFilterAttribute 应用到设计器，以指示在工具箱中启用项的要求。这一类型的属性可以使用来表明，某个工具箱项只有在使用带匹配筛选器字符串的设计器时才能启用。筛选器的类型在 FilterType 属性中由 ToolboxItemFilterType 来指示，它指示是否使用筛选器字符串匹配以及如何使用，或者是否使用自定义代码来确定是否启用项。
示例
下面的代码示例演示如何应用 ToolboxItemFilterAttribute。
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Diagnostics
Imports System.Drawing
Imports System.Drawing.Design
Imports System.Windows.Forms
Imports System.Windows.Forms.Design
' This example contains an IRootDesigner that implements the IToolboxUser interface.
' This example demonstrates how to enable the GetToolSupported method of an IToolboxUser
' designer in order to disable specific toolbox items, and how to respond to the
' invocation of a ToolboxItem in the ToolPicked method of an IToolboxUser implementation.
' This example component class demonstrates the associated IRootDesigner which
' implements the IToolboxUser interface. When designer view is invoked, Visual
' Studio .NET attempts to display a design mode view for the class at the top
' of a code file. This can sometimes fail when the class is one of multiple types
' in a code file, and has a DesignerAttribute associating it with an IRootDesigner.
' Placing a derived class at the top of the code file solves this problem. A
' derived class is not typically needed for this reason, except that placing the
' RootDesignedComponent class in another file is not a simple solution for a code
' example that is packaged in one segment of code.
Public Class RootViewSampleComponent
Inherits RootDesignedComponent
End Class
' The following attribute associates the SampleRootDesigner with this example component.
<DesignerAttribute(GetType(SampleRootDesigner), GetType(IRootDesigner))> _
Public Class RootDesignedComponent
Inherits System.Windows.Forms.Control
End Class
' This example IRootDesigner implements the IToolboxUser interface and provides a
' Windows Forms view technology view for its associated component using an internal
' Control type.
' The following ToolboxItemFilterAttribute enables the GetToolSupported method of this
' IToolboxUser designer to be queried to check for whether to enable or disable all
' ToolboxItems which create any components whose type name begins with "System.Windows.Forms".
<ToolboxItemFilterAttribute("System.Windows.Forms", ToolboxItemFilterType.Custom)> _
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Public Class SampleRootDesigner
Inherits ParentControlDesigner
Implements IRootDesigner, IToolboxUser
' Member field of custom type RootDesignerView, a control that is shown in the
' design mode document window. This member is cached to reduce processing needed
' to recreate the view control on each call to GetView().
Private m_view As RootDesignerView
' This string array contains type names of components that should not be added to
' the component managed by this designer from the Toolbox. Any ToolboxItems whose
' type name matches a type name in this array will be marked disabled according to
' the signal returned by the IToolboxUser.GetToolSupported method of this designer.
Private blockedTypeNames As String() = {"System.Windows.Forms.ListBox", "System.Windows.Forms.GroupBox"}
' IRootDesigner.SupportedTechnologies is a required override for an IRootDesigner.
' This designer provides a display using the Windows Forms view technology.
ReadOnly Property SupportedTechnologies() As ViewTechnology() Implements IRootDesigner.SupportedTechnologies
Get
Return New ViewTechnology() {ViewTechnology.Default}
End Get
End Property
' This method returns an object that provides the view for this root designer.
Function GetView(ByVal technology As ViewTechnology) As Object Implements IRootDesigner.GetView
' If the design environment requests a view technology other than Windows
' Forms, this method throws an Argument Exception.
If technology <> ViewTechnology.Default Then
Throw New ArgumentException("An unsupported view technology was requested", "Unsupported view technology.")
End If
' Creates the view object if it has not yet been initialized.
If m_view Is Nothing Then
m_view = New RootDesignerView(Me)
End If
Return m_view
End Function
' This method can signal whether to enable or disable the specified
' ToolboxItem when the component associated with this designer is selected.
Function GetToolSupported(ByVal tool As ToolboxItem) As Boolean Implements IToolboxUser.GetToolSupported
' Search the blocked type names array for the type name of the tool
' for which support for is being tested. Return false to indicate the
' tool should be disabled when the associated component is selected.
Dim i As Integer
For i = 0 To blockedTypeNames.Length - 1
If tool.TypeName = blockedTypeNames(i) Then
Return False
End If
Next i ' Return true to indicate support for the tool, if the type name of the
' tool is not located in the blockedTypeNames string array.
Return True
End Function
' This method can perform behavior when the specified tool has been invoked.
' Invocation of a ToolboxItem typically creates a component or components,
' and adds any created components to the associated component.
Sub ToolPicked(ByVal tool As ToolboxItem) Implements IToolboxUser.ToolPicked
End Sub
' This control provides a Windows Forms view technology view object that
' provides a display for the SampleRootDesigner.
<DesignerAttribute(GetType(ParentControlDesigner), GetType(IDesigner))> _
Friend Class RootDesignerView
Inherits Control
' This field stores a reference to a designer.
Private m_designer As IDesigner
Public Sub New(ByVal designer As IDesigner)
' Performs basic control initialization.
m_designer = designer
BackColor = Color.Blue
Font = New Font(Font.FontFamily.Name, 24.0F)
End Sub
' This method is called to draw the view for the SampleRootDesigner.
Protected Overrides Sub OnPaint(ByVal pe As PaintEventArgs)
MyBase.OnPaint(pe)
' Draws the name of the component in large letters.
pe.Graphics.DrawString(m_designer.Component.Site.Name, Font, Brushes.Yellow, New RectangleF(ClientRectangle.X, ClientRectangle.Y, ClientRectangle.Width, ClientRectangle.Height))
End Sub
End Class
End Class
using System;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Windows.Forms.Design;
// This example contains an IRootDesigner that implements the IToolboxUser interface.
// This example demonstrates how to enable the GetToolSupported method of an IToolboxUser
// designer in order to disable specific toolbox items, and how to respond to the
// invocation of a ToolboxItem in the ToolPicked method of an IToolboxUser implementation.
namespace IToolboxUserExample
{
// This example component class demonstrates the associated IRootDesigner which
// implements the IToolboxUser interface. When designer view is invoked, Visual
// Studio .NET attempts to display a design mode view for the class at the top
// of a code file. This can sometimes fail when the class is one of multiple types
// in a code file, and has a DesignerAttribute associating it with an IRootDesigner.
// Placing a derived class at the top of the code file solves this problem. A
// derived class is not typically needed for this reason, except that placing the
// RootDesignedComponent class in another file is not a simple solution for a code
// example that is packaged in one segment of code.
public class RootViewSampleComponent : RootDesignedComponent
{
}
// The following attribute associates the SampleRootDesigner with this example component.
[DesignerAttribute(typeof(SampleRootDesigner), typeof(IRootDesigner))]
public class RootDesignedComponent : System.Windows.Forms.Control
{
}
// This example IRootDesigner implements the IToolboxUser interface and provides a
// Windows Forms view technology view for its associated component using an internal
// Control type.
// The following ToolboxItemFilterAttribute enables the GetToolSupported method of this
// IToolboxUser designer to be queried to check for whether to enable or disable all
// ToolboxItems which create any components whose type name begins with "System.Windows.Forms".
[ToolboxItemFilterAttribute("System.Windows.Forms", ToolboxItemFilterType.Custom)]
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
public class SampleRootDesigner : ParentControlDesigner, IRootDesigner, IToolboxUser
{
// This field is a custom Control type named RootDesignerView. This field references
// a control that is shown in the design mode document window.
private RootDesignerView view;
// This string array contains type names of components that should not be added to
// the component managed by this designer from the Toolbox. Any ToolboxItems whose
// type name matches a type name in this array will be marked disabled according to
// the signal returned by the IToolboxUser.GetToolSupported method of this designer.
private string[] blockedTypeNames =
{
"System.Windows.Forms.ListBox",
"System.Windows.Forms.GroupBox"
};
// IRootDesigner.SupportedTechnologies is a required override for an IRootDesigner.
// This designer provides a display using the Windows Forms view technology.
ViewTechnology[] IRootDesigner.SupportedTechnologies
{
get { return new ViewTechnology[] {ViewTechnology.Default}; }
}
// This method returns an object that provides the view for this root designer.
object IRootDesigner.GetView(ViewTechnology technology)
{
// If the design environment requests a view technology other than Windows
// Forms, this method throws an Argument Exception.
if (technology != ViewTechnology.Default)
throw new ArgumentException("An unsupported view technology was requested",
"Unsupported view technology.");
// Creates the view object if it has not yet been initialized.
if (view == null)
view = new RootDesignerView(this);
return view;
}
// This method can signal whether to enable or disable the specified
// ToolboxItem when the component associated with this designer is selected.
bool IToolboxUser.GetToolSupported(ToolboxItem tool)
{
// Search the blocked type names array for the type name of the tool
// for which support for is being tested. Return false to indicate the
// tool should be disabled when the associated component is selected.
for( int i=0; i<blockedTypeNames.Length; i++ )
if( tool.TypeName == blockedTypeNames[i] )
return false;
// Return true to indicate support for the tool, if the type name of the
// tool is not located in the blockedTypeNames string array.
return true;
}
// This method can perform behavior when the specified tool has been invoked.
// Invocation of a ToolboxItem typically creates a component or components,
// and adds any created components to the associated component.
void IToolboxUser.ToolPicked(ToolboxItem tool)
{
}
// This control provides a Windows Forms view technology view object that
// provides a display for the SampleRootDesigner.
[DesignerAttribute(typeof(ParentControlDesigner), typeof(IDesigner))]
internal class RootDesignerView : Control
{
// This field stores a reference to a designer.
private IDesigner m_designer;
public RootDesignerView(IDesigner designer)
{
// Perform basic control initialization.
m_designer = designer;
BackColor = Color.Blue;
Font = new Font(Font.FontFamily.Name, 24.0f);
}
// This method is called to draw the view for the SampleRootDesigner.
protected override void OnPaint(PaintEventArgs pe)
{
base.OnPaint(pe);
// Draw the name of the component in large letters.
pe.Graphics.DrawString(m_designer.Component.Site.Name, Font, Brushes.Yellow, ClientRectangle);
}
}
}
}
继承层次结构
System.Object
System.Attribute
System.ComponentModel.ToolboxItemFilterAttribute
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
ToolboxItemFilterAttribute 成员
System.ComponentModel 命名空间
ToolboxItemFilterType