ITypeDescriptorFilterService 接口

public interface class ITypeDescriptorFilterService

public interface ITypeDescriptorFilterService

type ITypeDescriptorFilterService = interface

Public Interface ITypeDescriptorFilterService

派生

System.Windows.Forms.Design.ComponentDocumentDesigner

下面的代码示例演示了一个设计器，该设计器使用 ITypeDescriptorFilterService 筛选任何新设计器或现有 Button 项的属性集合，以便在加载或重新加载按钮的设计器之前为新设计器添加设计器属性。

若要使用此示例，请将代码添加到Windows 窗体项目，并将类库中的组件加载到工具箱中。

另请参阅 演练：使用自定义组件自动填充工具箱。

向窗体添加一些按钮。 将 添加到 ButtonDesignerFilterComponent 窗体，它将显示在组件托盘中。 将ButtonDesignerFilterComponent添加 实现 ButtonDesignerFilterServiceITypeDescriptorFilterService的 作为设计模式服务提供程序。 在 将每个现有和新按钮ColorCycleButtonDesigner的设计器替换为 后ButtonDesignerFilterService，窗体上的现有或Button新对象将开始颜色循环。 将鼠标指针移到按钮上方时，按钮将颜色循环，或者继续循环或重置事件的背景 MouseLeave 和前景颜色。 新 Button 对象将通过已加载 的 ButtonDesignerFilterService 方法提供FilterAttributesColorCycleButtonDesigner，直到 ButtonDesignerFilterComponent 释放并替换原始 ITypeDescriptorFilterService。 ColorCycleButton此示例中的 类是与 ButtonColorCycleButtonDesigner关联的 。

#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.Design.dll>
#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design;
using namespace System::ComponentModel::Design::Serialization;
using namespace System::Drawing;
using namespace System::Reflection;
using namespace System::Timers;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::Design;

// Designer for a Button control which cycles the background color.
public ref class ColorCycleButtonDesigner: public System::Windows::Forms::Design::ControlDesigner
{
private:
   System::Windows::Forms::Timer^ timer1;
   Color initial_bcolor;
   Color initial_fcolor;
   int r;
   int g;
   int b;
   bool ru;
   bool gu;
   bool bu;
   bool continue_;

public:
   ColorCycleButtonDesigner()
   {
      timer1 = gcnew System::Windows::Forms::Timer;
      timer1->Interval = 50;
      timer1->Tick += gcnew EventHandler( this, &ColorCycleButtonDesigner::Elapsed );
      ru = true;
      gu = false;
      bu = true;
      continue_ = false;
      timer1->Start();
   }

private:
   void Elapsed( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      this->Control->BackColor = Color::FromArgb( r % 255, g % 255, b % 255 );
      this->Control->Refresh();
      
      // Updates color.
      if ( ru )
            r += 10;
      else
      if ( r > 10 )
            r -= 10;

      if ( gu )
            g += 10;
      else
      if ( g > 10 )
            g -= 10;

      if ( bu )
            b += 10;
      else
      if ( b > 10 )
            b -= 10;
      
      // Randomly switches direction of color component values.
      Random^ rand = gcnew Random;
      for ( int i = 0; i < 4; i++ )
         switch ( rand->Next( 0, 2 ) )
         {
            case 0:
               if ( ru )
                              ru = false;
               else
                              ru = true;

               break;

            case 1:
               if ( gu )
                              gu = false;
               else
                              gu = true;

               break;

            case 2:
               if ( bu )
                              bu = false;
               else
                              bu = true;

               break;
         }
      this->Control->ForeColor = Color::FromArgb( (this->Control->BackColor.R + 128) % 255, (this->Control->BackColor.G + 128) % 255, (this->Control->BackColor.B + 128) % 255 );
   }

protected:
   virtual void OnMouseEnter() override
   {
      if (  !timer1->Enabled )
      {
         initial_bcolor = this->Control->BackColor;
         initial_fcolor = this->Control->ForeColor;
         r = initial_bcolor.R;
         g = initial_bcolor.G;
         b = initial_bcolor.B;
         timer1->Start();
      }
   }

   virtual void OnMouseLeave() override
   {
      if (  !continue_ )
      {
         continue_ = true;
         timer1->Stop();
      }
      else
            continue_ = false;

      this->Control->BackColor = initial_bcolor;
      this->Control->ForeColor = initial_fcolor;
   }

public:
   ~ColorCycleButtonDesigner()
   {
      timer1->Stop();
      this->Control->BackColor = initial_bcolor;
      this->Control->ForeColor = initial_fcolor;
   }
};

// Provides a TypeDescriptorFilterService to add the
// ColorCycleButtonDesigner using a DesignerAttribute.
public ref class ButtonDesignerFilterService: public System::ComponentModel::Design::ITypeDescriptorFilterService
{
public:
   ITypeDescriptorFilterService^ oldService;
   ButtonDesignerFilterService(){}

   ButtonDesignerFilterService( ITypeDescriptorFilterService^ oldService_ )
   {
      // Stores any previous ITypeDescriptorFilterService to implement service chaining.
      this->oldService = oldService_;
   }

   virtual bool FilterAttributes( System::ComponentModel::IComponent^ component, System::Collections::IDictionary^ attributes )
   {
      if ( oldService != nullptr )
            oldService->FilterAttributes( component, attributes );

      // Creates a designer attribute to compare its TypeID with the TypeID of existing attributes of the component.
      DesignerAttribute^ da = gcnew DesignerAttribute( ColorCycleButtonDesigner::typeid );
      // Adds the designer attribute if the attribute collection does not contain a DesignerAttribute of the same TypeID.
      if ( dynamic_cast<System::Windows::Forms::Button^>(component) && attributes->Contains( da->TypeId ) )
            attributes[ da->TypeId ] = da;

      return true;
   }

   virtual bool FilterEvents( System::ComponentModel::IComponent^ component, System::Collections::IDictionary^ events )
   {
      if ( oldService != nullptr )
            oldService->FilterEvents( component, events );

      return true;
   }

   virtual bool FilterProperties( System::ComponentModel::IComponent^ component, System::Collections::IDictionary^ properties )
   {
      if ( oldService != nullptr )
            oldService->FilterProperties( component, properties );

      return true;
   }
};


// System.Windows.Forms.Button associated with the ColorCycleButtonDesigner.

[Designer(ColorCycleButtonDesigner::typeid)]
public ref class ColorCycleButton: public System::Windows::Forms::Button
{
public:
   ColorCycleButton(){}

};


// Provides a designer that can add a ColorCycleButtonDesigner to each
// button in a design time project using the ButtonDesignerFilterService
// ITypeDescriptorFilterService.
public ref class ButtonDesignerFilterComponentDesigner: public System::ComponentModel::Design::ComponentDesigner
{
private:

   // Indicates whether the service has been loaded.
   bool serviceloaded;

   // Stores any old ITypeDescriptorFilterService to restore later.
   ITypeDescriptorFilterService^ oldservice;

public:
   ButtonDesignerFilterComponentDesigner()
   {
      serviceloaded = false;
   }

   // Loads the new ITypeDescriptorFilterService and reloads the
   // designers for each button.
   virtual void Initialize( System::ComponentModel::IComponent^ component ) override
   {
      ComponentDesigner::Initialize( component );

      // Loads the custom service if it has not been loaded already
      LoadService();

      // Build list of buttons from Container.Components.
      ArrayList^ buttons = gcnew ArrayList;
      IEnumerator^ myEnum = this->Component->Site->Container->Components->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         IComponent^ c = safe_cast<IComponent^>(myEnum->Current);
         if ( c->GetType() == System::Windows::Forms::Button::typeid )
                  buttons->Add( dynamic_cast<System::Windows::Forms::Button^>(c) );
      }

      if ( buttons->Count > 0 )
      {
         // Tests each Button for an existing
         // ColorCycleButtonDesigner;
         // if it has no designer of type
         // ColorCycleButtonDesigner, adds a designer.
         IEnumerator^ myEnum1 = buttons->GetEnumerator();
         while ( myEnum1->MoveNext() )
         {
            Button^ b = safe_cast<Button^>(myEnum1->Current);
            bool loaddesigner = true;

            // Gets the attributes for each button.
            AttributeCollection^ ac = TypeDescriptor::GetAttributes( b );
            for ( int i = 0; i < ac->Count; i++ )
            {
               // If designer attribute is not for a
               // ColorCycleButtonDesigner, adds a new
               // ColorCycleButtonDesigner.
               if ( dynamic_cast<DesignerAttribute^>(ac[ i ]) )
               {
                  DesignerAttribute^ da = dynamic_cast<DesignerAttribute^>(ac[ i ]);
                  if ( da->DesignerTypeName->Substring( da->DesignerTypeName->LastIndexOf( "." ) + 1 )->Equals( "ColorCycleButtonDesigner" ) )
                                    loaddesigner = false;
               }
            }
            if ( loaddesigner )
            {
               // Saves the button location so that it
               // can be repositioned.
               Point p = b->Location;

               // Gets an IMenuCommandService to cut and
               // paste control in order to register with
               // selection and movement interface after
               // designer is changed without reloading.
               IMenuCommandService^ imcs = dynamic_cast<IMenuCommandService^>(this->GetService( IMenuCommandService::typeid ));
               if ( imcs == nullptr )
                              throw gcnew Exception( "Could not obtain IMenuCommandService interface." );

               // Gets an ISelectionService to select the
               // button so that it can be cut and pasted.
               ISelectionService^ iss = dynamic_cast<ISelectionService^>(this->GetService( ISelectionService::typeid ));
               if ( iss == nullptr )
                              throw gcnew Exception( "Could not obtain ISelectionService interface." );
               array<IComponent^>^temp0 = {b};
               iss->SetSelectedComponents( dynamic_cast<ICollection^>(temp0), SelectionTypes::Normal );

               // Invoke Cut and Paste.
               imcs->GlobalInvoke( StandardCommands::Cut );
               imcs->GlobalInvoke( StandardCommands::Paste );

               // Regains reference to button from
               // selection service.
               System::Windows::Forms::Button^ b2 = dynamic_cast<System::Windows::Forms::Button^>(iss->PrimarySelection);
               iss->SetSelectedComponents( nullptr );

               // Refreshes TypeDescriptor properties of
               // button to load new attributes from
               // ButtonDesignerFilterService.
               TypeDescriptor::Refresh( b2 );
               b2->Location = p;
               b2->Focus();
            }
         }
      }
   }


private:

   // Loads a ButtonDesignerFilterService ITypeDescriptorFilterService
   // to add ColorCycleButtonDesigner designers to each button.
   void LoadService()
   {
      // If no custom ITypeDescriptorFilterService is loaded,
      // loads it now.
      if (  !serviceloaded )
      {
         // Stores the current ITypeDescriptorFilterService
         // to restore later.
         ITypeDescriptorFilterService^ tdfs = dynamic_cast<ITypeDescriptorFilterService^>(this->Component->Site->GetService( ITypeDescriptorFilterService::typeid ));
         if ( tdfs != nullptr )
                  oldservice = tdfs;

         // Retrieves an IDesignerHost interface to use to
         // remove and add services.
         IDesignerHost^ dh = dynamic_cast<IDesignerHost^>(this->Component->Site->GetService( IDesignerHost::typeid ));
         if ( dh == nullptr )
                  throw gcnew Exception( "Could not obtain IDesignerHost interface." );

         // Removes standard ITypeDescriptorFilterService.
         dh->RemoveService( ITypeDescriptorFilterService::typeid );

         // Adds new custom ITypeDescriptorFilterService.
         dh->AddService( ITypeDescriptorFilterService::typeid, gcnew ButtonDesignerFilterService );
         serviceloaded = true;
      }
   }

   // Removes the custom service and reloads any stored,
   // preexisting service.
   void RemoveService()
   {
      IDesignerHost^ dh = dynamic_cast<IDesignerHost^>(this->GetService( IDesignerHost::typeid ));
      if ( dh == nullptr )
            throw gcnew Exception( "Could not obtain IDesignerHost interface." );

      dh->RemoveService( ITypeDescriptorFilterService::typeid );
      if ( oldservice != nullptr )
            dh->AddService( ITypeDescriptorFilterService::typeid, oldservice );

      serviceloaded = false;
   }

public:
   ~ButtonDesignerFilterComponentDesigner()
   {
      if ( serviceloaded )
         RemoveService();
   }
};

// Component to host the ButtonDesignerFilterComponentDesigner that loads the
// ButtonDesignerFilterService ITypeDescriptorFilterService.

[Designer(ButtonDesignerFilterComponentDesigner::typeid)]
public ref class ButtonDesignerFilterComponent: public System::ComponentModel::Component
{
public:
   ButtonDesignerFilterComponent( System::ComponentModel::IContainer^ container )
   {
      container->Add( this );
   }

   ButtonDesignerFilterComponent(){}
};

using System;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.ComponentModel.Design.Serialization;
using System.Drawing;
using System.Reflection;
using System.Timers;
using System.Windows.Forms;
using System.Windows.Forms.Design;

namespace ITypeDescriptorFilterSample
{	
    // Component to host the ButtonDesignerFilterComponentDesigner that loads the 
    // ButtonDesignerFilterService ITypeDescriptorFilterService.
    [Designer(typeof(ButtonDesignerFilterComponentDesigner))]
    public class ButtonDesignerFilterComponent : System.ComponentModel.Component
    {		
        public ButtonDesignerFilterComponent(System.ComponentModel.IContainer container)
        {
            container.Add(this);
        }

        public ButtonDesignerFilterComponent()
        {}
    }

    // Provides a designer that can add a ColorCycleButtonDesigner to each 
    // button in a design time project using the ButtonDesignerFilterService 
    // ITypeDescriptorFilterService.
    public class ButtonDesignerFilterComponentDesigner : System.ComponentModel.Design.ComponentDesigner
    {
        // Indicates whether the service has been loaded.
        private bool serviceloaded = false;		
        // Stores any old ITypeDescriptorFilterService to restore later.
        private ITypeDescriptorFilterService oldservice = null;
        
        public ButtonDesignerFilterComponentDesigner()
        {}
        
        // Loads the new ITypeDescriptorFilterService and reloads the 
        // designers for each button.
        public override void Initialize(System.ComponentModel.IComponent component)
        {
            base.Initialize(component);
            
            // Loads the custom service if it has not been loaded already
            LoadService();
            
            // Build list of buttons from Container.Components.
            ArrayList buttons = new ArrayList();
            foreach(IComponent c in this.Component.Site.Container.Components)
                if(c.GetType() == typeof(System.Windows.Forms.Button))
                    buttons.Add((System.Windows.Forms.Button)c);
            if(buttons.Count > 0)
            {		
                // Tests each Button for an existing 
                // ColorCycleButtonDesigner;
                // if it has no designer of type 
                // ColorCycleButtonDesigner, adds a designer.
                foreach(System.Windows.Forms.Button b in buttons)
                {
                    bool loaddesigner = true;
                    // Gets the attributes for each button.
                    AttributeCollection ac = TypeDescriptor.GetAttributes(b);
                    for(int i=0; i<ac.Count; i++)
                    {
                        // If designer attribute is not for a 
                        // ColorCycleButtonDesigner, adds a new 
                        // ColorCycleButtonDesigner.
                        if( ac[i] is DesignerAttribute )
                        {
                            DesignerAttribute da = (DesignerAttribute)ac[i];
                            if( da.DesignerTypeName.Substring(da.DesignerTypeName.LastIndexOf(".")+1) == "ColorCycleButtonDesigner" )
                                loaddesigner = false;
                        }
                    }
                    if(loaddesigner)
                    {
                        // Saves the button location so that it 
                        // can be repositioned.
                        Point p = b.Location;	
                    
                        // Gets an IMenuCommandService to cut and 
                        // paste control in order to register with 
                        // selection and movement interface after 
                        // designer is changed without reloading.
                        IMenuCommandService imcs = (IMenuCommandService)this.GetService(typeof(IMenuCommandService));
                        if( imcs == null )
                            throw new Exception("Could not obtain IMenuCommandService interface.");							
                        // Gets an ISelectionService to select the 
                        // button so that it can be cut and pasted.
                        ISelectionService iss = (ISelectionService)this.GetService(typeof(ISelectionService));
                        if( iss == null)
                            throw new Exception("Could not obtain ISelectionService interface.");
                        iss.SetSelectedComponents(new IComponent[] { b }, SelectionTypes.Auto);						
                        // Invoke Cut and Paste.
                        imcs.GlobalInvoke(StandardCommands.Cut);
                        imcs.GlobalInvoke(StandardCommands.Paste);							
                        // Regains reference to button from 
                        // selection service.
                        System.Windows.Forms.Button b2 = (System.Windows.Forms.Button)iss.PrimarySelection;
                        iss.SetSelectedComponents(null);							
                        // Refreshes TypeDescriptor properties of 
                        // button to load new attributes from
                        // ButtonDesignerFilterService.
                        TypeDescriptor.Refresh(b2);							
                        b2.Location = p;
                        b2.Focus();
                    }
                }
            }
        }

        // Loads a ButtonDesignerFilterService ITypeDescriptorFilterService 
        // to add ColorCycleButtonDesigner designers to each button.
        private void LoadService()
        {
            // If no custom ITypeDescriptorFilterService is loaded, 
            // loads it now.
            if(!serviceloaded)
            {
                // Stores the current ITypeDescriptorFilterService 
                // to restore later.
                ITypeDescriptorFilterService tdfs = (ITypeDescriptorFilterService)this.Component.Site.GetService(typeof(ITypeDescriptorFilterService));
                if( tdfs != null )								
                    oldservice = tdfs;								
                // Retrieves an IDesignerHost interface to use to 
                // remove and add services.
                IDesignerHost dh = (IDesignerHost)this.Component.Site.GetService(typeof(IDesignerHost));
                if( dh == null )
                    throw new Exception("Could not obtain IDesignerHost interface.");				
                // Removes standard ITypeDescriptorFilterService.
                dh.RemoveService(typeof(ITypeDescriptorFilterService));
                // Adds new custom ITypeDescriptorFilterService.
                dh.AddService(typeof(ITypeDescriptorFilterService), new ButtonDesignerFilterService());				
                serviceloaded = true;
            }
        }
        
        // Removes the custom service and reloads any stored, 
        // preexisting service.
        private void RemoveService()
        {
            IDesignerHost dh = (IDesignerHost)this.GetService(typeof(IDesignerHost));
            if( dh == null )
                throw new Exception("Could not obtain IDesignerHost interface.");
            dh.RemoveService(typeof(ITypeDescriptorFilterService));
            if( oldservice != null )
                dh.AddService(typeof(ITypeDescriptorFilterService), oldservice);
            serviceloaded = false;
        }

        protected override void Dispose(bool disposing)
        {
            if(serviceloaded)
                RemoveService();
        }
    }

    // Provides a TypeDescriptorFilterService to add the 
    // ColorCycleButtonDesigner using a DesignerAttribute.
    public class ButtonDesignerFilterService : System.ComponentModel.Design.ITypeDescriptorFilterService
    {
        public ITypeDescriptorFilterService oldService = null;

        public ButtonDesignerFilterService()
        {}

        public ButtonDesignerFilterService(ITypeDescriptorFilterService oldService_)
        {
            // Stores any previous ITypeDescriptorFilterService to implement service chaining.
            this.oldService = oldService_;
        }

        public bool FilterAttributes(System.ComponentModel.IComponent component, System.Collections.IDictionary attributes)
        {
            if(oldService != null)
                oldService.FilterAttributes(component, attributes);
            
            // Creates a designer attribute to compare its TypeID with the TypeID of existing attributes of the component.
            DesignerAttribute da = new DesignerAttribute(typeof(ColorCycleButtonDesigner));
            // Adds the designer attribute if the attribute collection does not contain a DesignerAttribute of the same TypeID.
            if(component is System.Windows.Forms.Button && attributes.Contains(da.TypeId))
                attributes[da.TypeId]=da;
            return true;
        }

        public bool FilterEvents(System.ComponentModel.IComponent component, System.Collections.IDictionary events)
        {
            if(oldService != null)
                oldService.FilterEvents(component, events);
            return true;
        }

        public bool FilterProperties(System.ComponentModel.IComponent component, System.Collections.IDictionary properties)
        {
            if(oldService != null)
                oldService.FilterProperties(component, properties);
            return true;
        }
    }
    
    // Designer for a Button control which cycles the background color.
    public class ColorCycleButtonDesigner : System.Windows.Forms.Design.ControlDesigner
    {
        private System.Windows.Forms.Timer timer1;
        private Color initial_bcolor, initial_fcolor;
        private int r, g, b;
        private bool ru, gu, bu, continue_;

        public ColorCycleButtonDesigner()
        {						
            timer1 = new System.Windows.Forms.Timer();
            timer1.Interval = 50;
            timer1.Tick += new EventHandler(this.Elapsed);
            ru = true;
            gu = false;
            bu = true;			
            continue_ = false;
            timer1.Start();
        }

        private void Elapsed(object sender, EventArgs e)
        {
            this.Control.BackColor = Color.FromArgb(r%255, g%255, b%255);
            this.Control.Refresh();

            // Updates color.		
            if(ru)
                r+=10;
            else if(r>10) 
                r-=10;
            if(gu)
                g+=10;
            else if(g>10)
                g-=10;
            if(bu)
                b+=10;
            else if(b>10)
                b-=10;

            // Randomly switches direction of color component values.
            Random rand = new Random();
            for(int i=0; i<4; i++)			
                switch(rand.Next(0, 2))
                {
                    case 0:
                        if(ru)
                            ru=false;
                        else
                            ru=true;
                        break;
                    case 1:
                        if(gu)
                            gu=false;
                        else
                            gu=true;
                        break;
                    case 2:
                        if(bu)
                            bu=false;
                        else
                            bu=true;
                        break;
                }

            this.Control.ForeColor = Color.FromArgb((this.Control.BackColor.R+128)%255, (this.Control.BackColor.G+128)%255, (this.Control.BackColor.B+128)%255);
        }

        protected override void OnMouseEnter()
        {
            if(!timer1.Enabled)
            {
                initial_bcolor = this.Control.BackColor;
                initial_fcolor = this.Control.ForeColor;
                r = initial_bcolor.R;
                g = initial_bcolor.G;
                b = initial_bcolor.B;			
                timer1.Start();
            }
        }

        protected override void OnMouseLeave()
        {
            if(!continue_)
            {
                continue_ = true;
                timer1.Stop();
            }
            else
            {
                continue_ = false;
            }

            this.Control.BackColor = initial_bcolor;
            this.Control.ForeColor = initial_fcolor;			
        }

        protected override void Dispose(bool disposing)
        {
            timer1.Stop();
            this.Control.BackColor = initial_bcolor;
            this.Control.ForeColor = initial_fcolor;
            base.Dispose(disposing);
        }
    }

    // System.Windows.Forms.Button associated with the ColorCycleButtonDesigner.
    [Designer(typeof(ColorCycleButtonDesigner))]
    public class ColorCycleButton : System.Windows.Forms.Button
    {
        public ColorCycleButton()
        {}
    }
}

Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.ComponentModel.Design.Serialization
Imports System.Drawing
Imports System.Reflection
Imports System.Timers
Imports System.Windows.Forms
Imports System.Windows.Forms.Design

Namespace ITypeDescriptorFilterSample

    ' Component to host the ButtonDesignerFilterComponentDesigner that loads the 
    ' ButtonDesignerFilterService ITypeDescriptorFilterService.
    <Designer(GetType(ButtonDesignerFilterComponentDesigner))> _
    Public Class ButtonDesignerFilterComponent
        Inherits System.ComponentModel.Component

        Public Sub New(ByVal container As System.ComponentModel.IContainer)
            container.Add(Me)
        End Sub

        Public Sub New()
        End Sub
    End Class

    ' Provides a designer that can add a ColorCycleButtonDesigner to each 
    ' button in a design time project using the ButtonDesignerFilterService 
    ' ITypeDescriptorFilterService.
    Public Class ButtonDesignerFilterComponentDesigner
        Inherits System.ComponentModel.Design.ComponentDesigner

        ' Indicates whether the service has been loaded.
        Private serviceloaded As Boolean = False
        ' Stores any old ITypeDescriptorFilterService to restore later.
        Private oldservice As ITypeDescriptorFilterService = Nothing

        Public Sub New()
        End Sub

        ' Loads the new ITypeDescriptorFilterService and reloads the 
        ' designers for each Button.
        Public Overrides Sub Initialize(ByVal component As System.ComponentModel.IComponent)

            MyBase.Initialize(component)

            ' Loads the custom service if it has not been loaded already.
            LoadService()

            ' Build list of buttons from Container.Components.
            Dim buttons As New ArrayList()
            Dim c As IComponent
            For Each c In Me.Component.Site.Container.Components
                If TypeOf c Is System.Windows.Forms.Button Then
                    buttons.Add(CType(c, System.Windows.Forms.Button))
                End If
            Next c
            If buttons.Count > 0 Then
                ' Tests each Button for an existing 
                ' ColorCycleButtonDesigner;
        ' if it has no designer of type 
                ' ColorCycleButtonDesigner, adds a designer.
                Dim b As System.Windows.Forms.Button
                For Each b In buttons
                    Dim loaddesigner As Boolean = True
                    ' Gets the attributes for each button.
                    Dim ac As AttributeCollection = TypeDescriptor.GetAttributes(b)
                    Dim i As Integer
                    For i = 0 To ac.Count - 1
                        ' If designer attribute is not for a 
                        ' ColorCycleButtonDesigner, adds a new 
                        ' ColorCycleButtonDesigner.
                        If TypeOf ac(i) Is DesignerAttribute Then
                            Dim da As DesignerAttribute = CType(ac(i), DesignerAttribute)
                            If da.DesignerTypeName.Substring((da.DesignerTypeName.LastIndexOf(".") + 1)) = "ColorCycleButtonDesigner" Then
                                loaddesigner = False
                            End If
                        End If
                    Next i
                    If loaddesigner Then
                        ' Saves the button location so that it 
                        ' can be repositioned.
                        Dim p As Point = b.Location

                        ' Gets an IMenuCommandService to cut and 
                        ' paste control in order to register with 
                        ' selection and movement interface after 
                        ' designer is changed without reloading.
                        Dim imcs As IMenuCommandService = CType(Me.GetService(GetType(IMenuCommandService)), IMenuCommandService)
                        If imcs Is Nothing Then
                            Throw New Exception("Could not obtain IMenuCommandService interface.")
                        End If 

                        ' Gets an ISelectionService to select the 
                        ' button so that it can be cut and pasted.
                        Dim iss As ISelectionService = CType(Me.GetService(GetType(ISelectionService)), ISelectionService)
                        If iss Is Nothing Then
                            Throw New Exception("Could not obtain ISelectionService interface.")
                        End If
                        iss.SetSelectedComponents(New IComponent() {b}, SelectionTypes.Auto)

                        ' Invoke Cut and Paste.
                        imcs.GlobalInvoke(StandardCommands.Cut)
                        imcs.GlobalInvoke(StandardCommands.Paste)

                        ' Regains reference to button from 
                        ' selection service.
                        Dim b2 As System.Windows.Forms.Button = CType(iss.PrimarySelection, System.Windows.Forms.Button)
                        iss.SetSelectedComponents(Nothing)

                        ' Refreshes TypeDescriptor properties of 
                        ' button to load new attributes from 
                        ' ButtonDesignerFilterService.
                        TypeDescriptor.Refresh(b2)
                        b2.Location = p
                        b2.Focus()
                    End If
                Next b
            End If
        End Sub 

        ' Loads a ButtonDesignerFilterService ITypeDescriptorFilterService 
        ' to add ColorCycleButtonDesigner designers to each button.
        Private Sub LoadService()
            ' If no custom ITypeDescriptorFilterService is loaded, 
            ' loads it now.
            If Not serviceloaded Then
                ' Stores the current ITypeDescriptorFilterService 
                ' to restore later.
                Dim tdfs As ITypeDescriptorFilterService = CType(Me.Component.Site.GetService(GetType(ITypeDescriptorFilterService)), ITypeDescriptorFilterService)
                If (tdfs IsNot Nothing) Then
                    oldservice = tdfs
                End If 
                
                ' Retrieves an IDesignerHost interface to use to 
                ' remove and add services.
                Dim dh As IDesignerHost = CType(Me.Component.Site.GetService(GetType(IDesignerHost)), IDesignerHost)
                If dh Is Nothing Then
                    Throw New Exception("Could not obtain IDesignerHost interface.")
                End If 

                ' Removes the standard ITypeDescriptorFilterService.
                dh.RemoveService(GetType(ITypeDescriptorFilterService))
                ' Adds the new custom ITypeDescriptorFilterService.
                dh.AddService(GetType(ITypeDescriptorFilterService), New ButtonDesignerFilterService())
                serviceloaded = True
            End If
        End Sub

        ' Removes the custom service and reloads any stored, 
        ' preexisting service.
        Private Sub RemoveService()
            Dim dh As IDesignerHost = CType(Me.GetService(GetType(IDesignerHost)), IDesignerHost)
            If dh Is Nothing Then
                Throw New Exception("Could not obtain IDesignerHost interface.")
            End If
            dh.RemoveService(GetType(ITypeDescriptorFilterService))
            If (oldservice IsNot Nothing) Then
                dh.AddService(GetType(ITypeDescriptorFilterService), oldservice)
            End If
            serviceloaded = False
        End Sub

        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If serviceloaded Then
                RemoveService()
            End If
        End Sub

    End Class

    ' Provides a TypeDescriptorFilterService to add the 
    ' ColorCycleButtonDesigner using a DesignerAttribute.
    Public Class ButtonDesignerFilterService
        Implements System.ComponentModel.Design.ITypeDescriptorFilterService

        Public oldService As ITypeDescriptorFilterService = Nothing

        Public Sub New()
        End Sub 

        Public Sub New(ByVal oldService_ As ITypeDescriptorFilterService)
            ' Stores any previous ITypeDescriptorFilterService to implement service chaining.
            Me.oldService = oldService_
        End Sub 

        Public Function FilterAttributes(ByVal component As System.ComponentModel.IComponent, ByVal attributes As System.Collections.IDictionary) As Boolean Implements ITypeDescriptorFilterService.FilterAttributes
            If (oldService IsNot Nothing) Then
                oldService.FilterAttributes(component, attributes)
            End If
            ' Creates a designer attribute to compare its TypeID with the TypeID of existing attributes of the component.
            Dim da As New DesignerAttribute(GetType(ColorCycleButtonDesigner))
            ' Adds the designer attribute if the attribute collection does not contain a DesignerAttribute of the same TypeID.
            If TypeOf component Is System.Windows.Forms.Button And attributes.Contains(da.TypeId) Then
                attributes(da.TypeId) = da
            End If
            Return True
        End Function 

        Public Function FilterEvents(ByVal component As System.ComponentModel.IComponent, ByVal events As System.Collections.IDictionary) As Boolean Implements ITypeDescriptorFilterService.FilterEvents
            If (oldService IsNot Nothing) Then
                oldService.FilterEvents(component, events)
            End If
            Return True
        End Function 

        Public Function FilterProperties(ByVal component As System.ComponentModel.IComponent, ByVal properties As System.Collections.IDictionary) As Boolean Implements ITypeDescriptorFilterService.FilterProperties
            If (oldService IsNot Nothing) Then
                oldService.FilterProperties(component, properties)
            End If
            Return True
        End Function 

    End Class   

    ' Designer for a Button control which cycles the background color.
    Public Class ColorCycleButtonDesigner
        Inherits System.Windows.Forms.Design.ControlDesigner

        Private timer1 As System.Windows.Forms.Timer
        Private initial_bcolor, initial_fcolor As Color
        Private r, g, b As Integer
        Private ru, gu, bu, continue_ As Boolean

        Public Sub New()
            timer1 = New System.Windows.Forms.Timer()
            timer1.Interval = 50
            AddHandler timer1.Tick, AddressOf Me.Elapsed
            ru = True
            gu = False
            bu = True
            continue_ = False
            timer1.Start()
        End Sub 

        Private Sub Elapsed(ByVal sender As Object, ByVal e As EventArgs)
            Me.Control.BackColor = Color.FromArgb(r Mod 255, g Mod 255, b Mod 255)
            Me.Control.Refresh()

            ' Updates color.			
            If ru Then
                r += 10
            Else
                If r > 10 Then
                    r -= 10
                End If
            End If
            If gu Then
                g += 10
            Else
                If g > 10 Then
                    g -= 10
                End If
            End If
            If bu Then
                b += 10
            Else
                If b > 10 Then
                    b -= 10
                End If
            End If 

            ' Randomly switches direction of color component values.
            Dim rand As New Random()
            Dim i As Integer
            For i = 0 To 3
                Select Case rand.Next(0, 2)
                    Case 0
                        If ru Then
                            ru = False
                        Else
                            ru = True
                        End If
                    Case 1
                        If gu Then
                            gu = False
                        Else
                            gu = True
                        End If
                    Case 2
                        If bu Then
                            bu = False
                        Else
                            bu = True
                        End If
                End Select
            Next i
            Me.Control.ForeColor = Color.FromArgb((Me.Control.BackColor.R + 128) Mod 255, (Me.Control.BackColor.G + 128) Mod 255, (Me.Control.BackColor.B + 128) Mod 255)
        End Sub 

        Protected Overrides Sub OnMouseEnter()
            If Not timer1.Enabled Then
                initial_bcolor = Me.Control.BackColor
                initial_fcolor = Me.Control.ForeColor
                r = initial_bcolor.R
                g = initial_bcolor.G
                b = initial_bcolor.B
                timer1.Start()
            End If
        End Sub 

        Protected Overrides Sub OnMouseLeave()
            If Not continue_ Then
                continue_ = True
                timer1.Stop()
            Else
                continue_ = False
            End If
            Me.Control.BackColor = initial_bcolor
            Me.Control.ForeColor = initial_fcolor
        End Sub 

        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            timer1.Stop()
            Me.Control.BackColor = initial_bcolor
            Me.Control.ForeColor = initial_fcolor
            MyBase.Dispose(disposing)
        End Sub 

    End Class 

    ' System.Windows.Forms.Button associated with the ColorCycleButtonDesigner.
    <Designer(GetType(ColorCycleButtonDesigner))> _
    Public Class ColorCycleButton
        Inherits System.Windows.Forms.Button

        Public Sub New()
        End Sub 
    End Class 

End Namespace

接口 ITypeDescriptorFilterService 提供一个接口，允许在设计时修改组件的属性、事件和类级属性。 此修改通过组件通过 提供 TypeDescriptor的描述符集进行。 类型描述符将查询组件的站点以获取 ITypeDescriptorFilterService 服务，如果存在，类型描述符会将它收集的所有元数据传递到此服务。 然后，该服务可以通过添加、删除和更改组件的现有特征来修改元数据。

例如，可以通过调用 FilterProperties 方法修改组件的属性。 筛选器服务获取一个字典，其中包含属性名称及其类型的 PropertyDescriptor属性描述符。 修改是使用以下逻辑实现的。

的 FilterProperties 返回值确定这组属性是否是固定的。 如果此方法返回 true， TypeDescriptor 则此组件的 可以缓存结果。 在对组件进行垃圾回收或 Refresh 调用类型描述符的方法之前，将一直保留此缓存。

若要筛选 由 TypeDescriptor公开的成员描述符，请在组件上实现此接口，并重写 FilterAttributes(IComponent, IDictionary)此类的 、 FilterEvents(IComponent, IDictionary)或 FilterProperties(IComponent, IDictionary) 方法，以分别筛选属性、事件或属性。

• TypeDescriptor
• EventDescriptor
• PropertyDescriptor
• Attribute
• IDictionary