ISelectionService Interface

Definition

Namespace:

System.ComponentModel.Design

Assembly:

System.ComponentModel.TypeConverter.dll

Provides an interface for a designer to select components.

public interface class ISelectionService

public interface ISelectionService

type ISelectionService = interface

Public Interface ISelectionService

Examples

The following example demonstrates use of the ISelectionService to handle the SelectionChanged and SelectionChanging events.

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

using namespace System;
using namespace System::Drawing;
using namespace System::Collections;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design;
using namespace System::Windows::Forms;

/*  This sample demonstrates using the ISelectionService
interface to receive notification of selection change events.  
The SelectionComponent control attempts to retrieve an instance 
of the ISelectionService when it is sited. If it can, it attaches 
event handlers for events provided by the service that display
a message when a component is selected or deselected.

To run this sample, add the SelectionComponent control to a Form and
then select or deselect components in design mode to see the behavior 
of the component change event handlers. */
namespace ISelectionServiceExample
{
   public ref class SelectionComponent: public System::Windows::Forms::UserControl
   {
   private:
      System::Windows::Forms::TextBox^ tbox1;
      ISelectionService^ selectionService;

   public:
      SelectionComponent()
      {
         // Initialize control
         this->SuspendLayout();
         this->Name = "SelectionComponent";
         this->Size = System::Drawing::Size( 608, 296 );
         this->tbox1 = gcnew System::Windows::Forms::TextBox;
         this->tbox1->Location = System::Drawing::Point( 24, 16 );
         this->tbox1->Name = "listBox1";
         this->tbox1->Multiline = true;
         this->tbox1->Size = System::Drawing::Size( 560, 251 );
         this->tbox1->TabIndex = 0;
         this->Controls->Add( this->tbox1 );
         this->ResumeLayout();
      }

      property ISite^ Site 
      {
         virtual ISite^ get() override
         {
            return __super::Site;
         }

         virtual void set( ISite^ value ) override
         {
            // The ISelectionService is available in design mode 
            // only, and only after the component is sited.
            if ( selectionService != nullptr )
            {
               // Because the selection service has been 
               // previously obtained, the component may be in 
               // the process of being resited. 
               // Detatch the previous selection change event 
               // handlers in case the new selection
               // service is a new service instance belonging to 
               // another design mode service host.
               selectionService->SelectionChanged -= gcnew EventHandler( this, &SelectionComponent::OnSelectionChanged );
               selectionService->SelectionChanging -= gcnew EventHandler( this, &SelectionComponent::OnSelectionChanging );
            }

            // Establish the new site for the component.
            __super::Site = value;
            if ( __super::Site == nullptr )
                        return;

            // The selection service is not available outside of 
            // design mode. A call requesting the service 
            // using GetService while not in design mode will 
            // return null.
            selectionService = dynamic_cast<ISelectionService^>(this->Site->GetService( ISelectionService::typeid ));

            // If an instance of the ISelectionService was obtained, 
            // attach event handlers for the selection 
            // changing and selection changed events.
            if ( selectionService != nullptr )
            {
               // Add an event handler for the SelectionChanging 
               // and SelectionChanged events.
               selectionService->SelectionChanging += gcnew EventHandler( this, &SelectionComponent::OnSelectionChanging );
               selectionService->SelectionChanged += gcnew EventHandler( this, &SelectionComponent::OnSelectionChanged );
            }
         }
      }

   private:
      void OnSelectionChanged( Object^ /*sender*/, EventArgs^ /*args*/ )
      {
         tbox1->AppendText( String::Format( "The selected component was changed.  Selected components:\r\n    {0}\r\n", GetSelectedComponents() ) );
      }

      void OnSelectionChanging( Object^ /*sender*/, EventArgs^ /*args*/ )
      {
         tbox1->AppendText( String::Format( "The selected component is changing. Selected components:\r\n    {0}\r\n", GetSelectedComponents() ) );
      }

      String^ GetSelectedComponents()
      {
         String^ selectedString = String::Empty;
         array<Object^>^components = gcnew array<Object^>((dynamic_cast<ICollection^>(selectionService->GetSelectedComponents()))->Count);
         (dynamic_cast<ICollection^>(selectionService->GetSelectedComponents()))->CopyTo( components, 0 );
         for ( int i = 0; i < components->Length; i++ )
         {
            if ( i != 0 )
                        selectedString = selectedString + "&& ";

            if ( (dynamic_cast<IComponent^>(selectionService->PrimarySelection)) == (dynamic_cast<IComponent^>(components[ i ])) )
                        selectedString = selectedString + "PrimarySelection:";

            selectedString = selectedString + (dynamic_cast<IComponent^>(components[ i ]))->Site->Name + " ";

         }
         return selectedString;
      }

      // Clean up any resources being used.
   public:
      ~SelectionComponent()
      {
         // Detach the event handlers for the selection service.
         if ( selectionService != nullptr )
         {
            selectionService->SelectionChanging -= gcnew EventHandler( this, &SelectionComponent::OnSelectionChanging );
            selectionService->SelectionChanged -= gcnew EventHandler( this, &SelectionComponent::OnSelectionChanged );
         }
      }
   };
}

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms;

/*  This sample demonstrates using the ISelectionService
    interface to receive notification of selection change events.  
    The SelectionComponent control attempts to retrieve an instance 
    of the ISelectionService when it is sited. If it can, it attaches 
    event handlers for events provided by the service that display
    a message when a component is selected or deselected.

    To run this sample, add the SelectionComponent control to a Form and
    then select or deselect components in design mode to see the behavior 
    of the component change event handlers. */

namespace ISelectionServiceExample 
{
    public class SelectionComponent : System.Windows.Forms.UserControl 
    {		
        private System.Windows.Forms.TextBox tbox1;
        private ISelectionService selectionService;
        
        public SelectionComponent() 
        {
            // Initialize control
            this.SuspendLayout();			
            this.Name = "SelectionComponent";
            this.Size = new System.Drawing.Size(608, 296);									
            this.tbox1 = new System.Windows.Forms.TextBox();			
            this.tbox1.Location = new System.Drawing.Point(24, 16);
            this.tbox1.Name = "listBox1";
            this.tbox1.Multiline = true;
            this.tbox1.Size = new System.Drawing.Size(560, 251);
            this.tbox1.TabIndex = 0;
            this.Controls.Add(this.tbox1);
            this.ResumeLayout();
        }
        
        public override ISite Site 
        {
            get 
            {
                return base.Site;
            }
            set 
            {
                // The ISelectionService is available in design mode 
                // only, and only after the component is sited.
                if (selectionService != null) 
                {
                    // Because the selection service has been 
                    // previously obtained, the component may be in 
                    // the process of being resited. 
                    // Detatch the previous selection change event 
                    // handlers in case the new selection
                    // service is a new service instance belonging to 
                    // another design mode service host.
                    selectionService.SelectionChanged -= new EventHandler(OnSelectionChanged);
                    selectionService.SelectionChanging -= new EventHandler(OnSelectionChanging);
                }

                // Establish the new site for the component.
                base.Site = value;				

                if( base.Site == null )
                    return;

                // The selection service is not available outside of 
                // design mode. A call requesting the service 
                // using GetService while not in design mode will 
                // return null.
                selectionService = (ISelectionService)this.Site.GetService(typeof(ISelectionService));

                // If an instance of the ISelectionService was obtained, 
                // attach event handlers for the selection 
                // changing and selection changed events.
                if (selectionService != null)
                {
                    // Add an event handler for the SelectionChanging 
                    // and SelectionChanged events.
                    selectionService.SelectionChanging += new EventHandler(OnSelectionChanging);					
                    selectionService.SelectionChanged += new EventHandler(OnSelectionChanged);	
                }
            }
        }
        
        private void OnSelectionChanged(object sender, EventArgs args)
        {						
            tbox1.AppendText("The selected component was changed.  Selected components:\r\n    " + GetSelectedComponents() + "\r\n");
        }
        
        private void OnSelectionChanging(object sender, EventArgs args)
        {
            tbox1.AppendText("The selected component is changing. Selected components:\r\n    " + GetSelectedComponents() + "\r\n");			
        }
        
        private string GetSelectedComponents()
        {
            string selectedString = String.Empty;
            object[] components = new object[((ICollection)selectionService.GetSelectedComponents()).Count];
            ((ICollection)selectionService.GetSelectedComponents()).CopyTo(components, 0);

            for(int i=0; i<components.Length; i++)
            {
                if( i != 0 )
                    selectedString += "&& ";
                if( ((IComponent)selectionService.PrimarySelection) == ((IComponent)components[i]) )
                    selectedString += "PrimarySelection:";				
                selectedString += ((IComponent)components[i]).Site.Name+" ";
            }
            return selectedString;
        }
        
        // Clean up any resources being used.
        protected override void Dispose( bool disposing )
        {
            // Detatch the event handlers for the selection service.
            if( selectionService != null )
            {
                selectionService.SelectionChanging -= new EventHandler(this.OnSelectionChanging);
                selectionService.SelectionChanged -= new EventHandler(this.OnSelectionChanged);
            }

            base.Dispose( disposing );
        }
    }
}

Imports System.Drawing
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Windows.Forms

'  This sample demonstrates using the ISelectionService
'  interface to receive notification of selection change events.  

'  The SelectionComponent control attempts to retrieve an instance 
'  of the ISelectionService when it is sited. If it can, it attaches 
'  event handlers for events provided by the service that display
'  a message when a component is selected or deselected.
'  To run this sample, add the SelectionComponent control to a Form and
'  then select or deselect components in design mode to see the behavior 
'  of the component change event handlers. 

Namespace ISelectionServiceExample

    Public Class SelectionComponent
        Inherits System.Windows.Forms.UserControl
        Private tbox1 As System.Windows.Forms.TextBox
        Private selectionService As ISelectionService        

        Public Sub New()
            ' Initialize control
            Me.SuspendLayout()
            Me.Name = "SelectionComponent"
            Me.Size = New System.Drawing.Size(608, 296)
            Me.tbox1 = New System.Windows.Forms.TextBox()
            Me.tbox1.Location = New System.Drawing.Point(24, 16)
            Me.tbox1.Name = "listBox1"
            Me.tbox1.Multiline = True
            Me.tbox1.Size = New System.Drawing.Size(560, 251)
            Me.tbox1.TabIndex = 0
            Me.Controls.Add(Me.tbox1)
            Me.ResumeLayout()
        End Sub

        Public Overrides Property Site() As ISite
            Get
                Return MyBase.Site
            End Get
            Set(ByVal Value As ISite)
                ' The ISelectionService is available in design mode 
                ' only, and only after the component is sited.
                If (selectionService IsNot Nothing) Then
                    ' Because the selection service has been 
                    ' previously obtained, the component may be in 
                    ' the process of being resited. 
                    ' Detatch the previous selection change event 
                    ' handlers in case the new selection
                    ' service is a new service instance belonging to 
                    ' another design mode service host.
                    RemoveHandler selectionService.SelectionChanged, AddressOf OnSelectionChanged
                    RemoveHandler selectionService.SelectionChanging, AddressOf OnSelectionChanging
                End If

                ' Establish the new site for the component.
                MyBase.Site = Value

                If MyBase.Site Is Nothing Then
                    Return
                End If

                ' The selection service is not available outside of 
                ' design mode. A call requesting the service 
                ' using GetService while not in design mode will 
                ' return null.
                selectionService = Me.Site.GetService(GetType(ISelectionService))

                ' If an instance of the ISelectionService was obtained, 
                ' attach event handlers for the selection 
                ' changing and selection changed events.
                If (selectionService IsNot Nothing) Then
                    ' Add an event handler for the SelectionChanging and SelectionChanged events.
                    AddHandler selectionService.SelectionChanging, AddressOf OnSelectionChanging
                    AddHandler selectionService.SelectionChanged, AddressOf OnSelectionChanged
                End If
            End Set
        End Property

        Private Sub OnSelectionChanged(ByVal sender As Object, ByVal args As EventArgs)            
            tbox1.AppendText("The selected component was changed.  Selected components:" + Microsoft.VisualBasic.ControlChars.CrLf + "    " + GetSelectedComponents() + Microsoft.VisualBasic.ControlChars.CrLf)
        End Sub

        Private Sub OnSelectionChanging(ByVal sender As Object, ByVal args As EventArgs)                        
            tbox1.AppendText("The selected component is changing.  Selected components:" + Microsoft.VisualBasic.ControlChars.CrLf + "    " + GetSelectedComponents() + Microsoft.VisualBasic.ControlChars.CrLf)
        End Sub

        Private Function GetSelectedComponents() As String
            Dim selectedString As String = String.Empty
            Dim components(CType(selectionService.GetSelectedComponents(), ICollection).Count - 1) As Object
            CType(selectionService.GetSelectedComponents(), ICollection).CopyTo(components, 0)

            Dim i As Integer
            For i = 0 To components.Length - 1
                If i <> 0 Then
                    selectedString += "&& "
                End If
                If CType(selectionService.PrimarySelection, IComponent) Is CType(components(i), IComponent) Then
                    selectedString += "PrimarySelection:"
                End If
                selectedString += CType(components(i), IComponent).Site.Name + " "
            Next i

            Return selectedString
        End Function 'GetSelectedComponents

        ' Clean up any resources being used.
        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            ' Detatch the event handlers for the selection service.
            If (selectionService IsNot Nothing) Then
                RemoveHandler selectionService.SelectionChanging, AddressOf OnSelectionChanging
                RemoveHandler selectionService.SelectionChanged, AddressOf OnSelectionChanged
            End If
            MyBase.Dispose(disposing)
        End Sub
    End Class

End Namespace 'ISelectionServiceExample

Remarks

When a component is selected, its viewable or editable properties are shown in the Properties window.

Properties

PrimarySelection	Gets the object that is currently the primary selected object.
SelectionCount	Gets the count of selected objects.

Methods

GetComponentSelected(Object)	Gets a value indicating whether the specified component is currently selected.
GetSelectedComponents()	Gets a collection of components that are currently selected.
SetSelectedComponents(ICollection, SelectionTypes)	Selects the components from within the specified collection of components that match the specified selection type.
SetSelectedComponents(ICollection)	Selects the specified collection of components.

Events

SelectionChanged	Occurs when the current selection changes.
SelectionChanging	Occurs when the current selection is about to change.