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ISelectionService Interface

Provides an interface for a designer to select components.

For a list of all members of this type, see ISelectionService Members.

[Visual Basic]
<ComVisible(True)>
Public Interface ISelectionService
[C#]
[ComVisible(true)]
public interface ISelectionService
[C++]
[ComVisible(true)]
public __gc __interface ISelectionService
[JScript]
public
   ComVisible(true)
interface ISelectionService

Remarks

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

Example

[Visual Basic, C#, C++] The following example demonstrates use of the ISelectionService to handle the SelectionChanged and SelectionChanging events.

[Visual Basic] 
Imports System
Imports System.Drawing
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Windows.Forms
Imports Microsoft.VisualBasic

'  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 'New

        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 Not (selectionService Is 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 Not (selectionService Is 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 'OnSelectionChanged

        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 'OnSelectionChanging

        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 Not (selectionService Is Nothing) Then
                RemoveHandler selectionService.SelectionChanging, AddressOf OnSelectionChanging
                RemoveHandler selectionService.SelectionChanged, AddressOf OnSelectionChanged
            End If
            MyBase.Dispose(disposing)
        End Sub 'Dispose
    End Class 'SelectionComponent

End Namespace 'ISelectionServiceExample

[C#] 
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 );
        }
    }
}

[C++] 
#using <mscorlib.dll>
#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 __gc class SelectionComponent : public System::Windows::Forms::UserControl 
{        
private:
    System::Windows::Forms::TextBox* tbox1;
    ISelectionService* selectionService;

public:
    SelectionComponent() 
    {
        // Initialize control
        this->SuspendLayout();            
        this->Name = S"SelectionComponent";
        this->Size = System::Drawing::Size(608, 296);                                    
        this->tbox1 = new System::Windows::Forms::TextBox();            
        this->tbox1->Location = System::Drawing::Point(24, 16);
        this->tbox1->Name = S"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* get_Site() 
    {
        return UserControl::get_Site();
    }
    __property void set_Site( ISite* value ) 
    {
        // The ISelectionService is available in design mode 
        // only, and only after the component is sited.
        if (selectionService != 0) 
        {
            // 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(this, &SelectionComponent::OnSelectionChanged);
            selectionService->SelectionChanging -= new EventHandler(this, &SelectionComponent::OnSelectionChanging);
        }

        // Establish the new site for the component.
        UserControl::set_Site( value );

        if( UserControl::Site == 0 )
            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(__typeof(ISelectionService)));

        // If an instance of the ISelectionService was obtained, 
        // attach event handlers for the selection 
        // changing and selection changed events.
        if (selectionService != 0)
        {
            // Add an event handler for the SelectionChanging 
            // and SelectionChanged events.
            selectionService->SelectionChanging += new EventHandler(this, &SelectionComponent::OnSelectionChanging);                    
            selectionService->SelectionChanged += new EventHandler(this, &SelectionComponent::OnSelectionChanged);    
        }
    }

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

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

    String* GetSelectedComponents()
    {
        String* selectedString = String::Empty;
        Object* components[] = new 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 = String::Concat( selectedString, S"&& " );
            if( (dynamic_cast<IComponent*>(selectionService->PrimarySelection)) == (dynamic_cast<IComponent*>(components[i])) )
                selectedString = String::Concat( selectedString, S"PrimarySelection:" );
            selectedString = String::Concat( selectedString, (dynamic_cast<IComponent*>(components[i]))->Site->Name, S" " );
        }
        return selectedString;
    }

    // Clean up any resources being used.
protected:
    void Dispose( bool disposing )
    {
        // Detach the event handlers for the selection service.
        if( selectionService != 0 )
        {
            selectionService->SelectionChanging -= new EventHandler(this, &SelectionComponent::OnSelectionChanging);
            selectionService->SelectionChanged -= new EventHandler(this, &SelectionComponent::OnSelectionChanged);
        }

        UserControl::Dispose( disposing );
    }
};
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.ComponentModel.Design

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System (in System.dll)

See Also

ISelectionService Members | System.ComponentModel.Design Namespace

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