Export (0) Print
Expand All
This topic has not yet been rated - Rate this topic

IComponentDiscoveryService Interface

Enables enumeration of components at design time.

Namespace: System.ComponentModel.Design
Assembly: System (in system.dll)

'Declaration
Public Interface IComponentDiscoveryService
'Usage
Dim instance As IComponentDiscoveryService

public interface IComponentDiscoveryService
public interface IComponentDiscoveryService
Not applicable.

The default implementation of the IComponentDiscoveryService interface enables design-time enumeration of components in the Toolbox.

You could provide a custom implementation that enumerates across other types available at design time. For example, your implementation could enumerate the components that are present in a particular designer.

The following code example demonstrates how to use IComponentDiscoveryService to find all the types that derive from the ScrollableControl type.

' This class defines the smart tags that appear on the control
' that is being designed.

Friend Class DemoActionList
    Inherits System.ComponentModel.Design.DesignerActionList
    ' Cache a reference to the designer host.
    Private host As IDesignerHost = Nothing

    ' Cache a reference to the control.
    Private relatedControl As DemoControl = Nothing

    ' Cache a reference to the designer.
    Private relatedDesigner As DemoControlDesigner = Nothing

    'The constructor associates the control 
    'with the smart tag list.
    Public Sub New(ByVal component As IComponent)
        MyBase.New(component)
        Me.relatedControl = component '

        Me.host = Me.Component.Site.GetService(GetType(IDesignerHost))

        Dim dcd As IDesigner = host.GetDesigner(Me.Component)
        Me.relatedDesigner = dcd

    End Sub

    ' This method creates and populates the 
    ' DesignerActionItemCollection which is used to 
    ' display smart tag items.
    Public Overrides Function GetSortedActionItems() As DesignerActionItemCollection
        Dim items As New DesignerActionItemCollection()

        ' If the Timer component has not been created, show the
        ' "Create Timer" DesignerAction item.
        '
        ' If the Timer component exists, show the timer-related
        ' options.
        If Me.relatedDesigner.createdTimer Is Nothing Then
            items.Add(New DesignerActionMethodItem(Me, "CreateTimer", "Create Timer", True))
        Else
            items.Add(New DesignerActionMethodItem(Me, "ShowEventHandlerCode", "Show Event Handler Code", True))

            items.Add(New DesignerActionMethodItem(Me, "RemoveTimer", "Remove Timer", True))
        End If

        items.Add(New DesignerActionMethodItem(Me, "GetExtenderProviders", "Get Extender Providers", True))

        items.Add(New DesignerActionMethodItem(Me, "GetDemoControlReferences", "Get DemoControl References", True))

        items.Add(New DesignerActionMethodItem(Me, "GetPathOfAssembly", "Get Path of Executing Assembly", True))

        items.Add(New DesignerActionMethodItem(Me, "GetComponentTypes", "Get ScrollableControl Types", True))

        items.Add(New DesignerActionMethodItem(Me, "GetToolboxCategories", "Get Toolbox Categories", True))

        items.Add(New DesignerActionMethodItem(Me, "SetBackColor", "Set Back Color", True))

        Return items
    End Function

    ' This method creates a Timer component using the 
    ' IDesignerHost.CreateComponent method. It also 
    ' creates an event handler for the Timer component's
    ' tick event.
    Private Sub CreateTimer()
        If (Me.host IsNot Nothing) Then
            If Me.relatedDesigner.createdTimer Is Nothing Then
                ' Create and configure the Timer object.
                Me.relatedDesigner.createdTimer = Me.host.CreateComponent(GetType(Timer))

                Dim t As Timer = Me.relatedDesigner.createdTimer
                t.Interval = 1000
                t.Enabled = True

                Dim eventColl As EventDescriptorCollection = TypeDescriptor.GetEvents(t, New Attribute(-1) {})

                If (eventColl IsNot Nothing) Then
                    Dim ed As EventDescriptor = eventColl("Tick")

                    If (ed IsNot Nothing) Then
                        Dim epd As PropertyDescriptor = Me.relatedDesigner.eventBindingService.GetEventProperty(ed)

                        epd.SetValue(t, "timer_Tick")
                    End If
                End If

                Me.relatedDesigner.actionUiService.Refresh(Me.relatedControl)
            End If
        End If
    End Sub

    ' This method uses the IEventBindingService.ShowCode
    ' method to start the Code Editor. It places the caret
    ' in the timer_tick method created by the CreateTimer method.
    Private Sub ShowEventHandlerCode()
        Dim t As Timer = Me.relatedDesigner.createdTimer

        If (t IsNot Nothing) Then
            Dim eventColl As EventDescriptorCollection = TypeDescriptor.GetEvents(t, New Attribute(-1) {})
            If (eventColl IsNot Nothing) Then
                Dim ed As EventDescriptor = eventColl("Tick")

                If (ed IsNot Nothing) Then
                    Me.relatedDesigner.eventBindingService.ShowCode(t, ed)
                End If
            End If
        End If
    End Sub

    ' This method uses the IDesignerHost.DestroyComponent method
    ' to remove the Timer component from the design environment.
    Private Sub RemoveTimer()
        If (Me.host IsNot Nothing) Then
            If (Me.relatedDesigner.createdTimer IsNot Nothing) Then
                Me.host.DestroyComponent(Me.relatedDesigner.createdTimer)

                Me.relatedDesigner.createdTimer = Nothing

                Me.relatedDesigner.actionUiService.Refresh(Me.relatedControl)
            End If
        End If
    End Sub

    ' This method uses IExtenderListService.GetExtenderProviders
    ' to enumerate all the extender providers and display them 
    ' in a MessageBox.
    Private Sub GetExtenderProviders()
        If (Me.relatedDesigner.listService IsNot Nothing) Then
            Dim sb As New StringBuilder()

            Dim providers As IExtenderProvider() = Me.relatedDesigner.listService.GetExtenderProviders()

            Dim i As Integer
            For i = 0 To providers.Length - 1
                Dim o As Object = providers(i)
                sb.Append(o.ToString())
                sb.Append(ControlChars.Cr + ControlChars.Lf)
            Next i

            MessageBox.Show(sb.ToString(), "Extender Providers")
        End If
    End Sub

    ' This method uses the IReferenceService.GetReferences method
    ' to enumerate all the instances of DemoControl on the 
    ' design surface.
    Private Sub GetDemoControlReferences()
        If (Me.relatedDesigner.referenceService IsNot Nothing) Then
            Dim sb As New StringBuilder()

            Dim refs As Object() = Me.relatedDesigner.referenceService.GetReferences(GetType(DemoControl))

            Dim i As Integer
            For i = 0 To refs.Length - 1
                sb.Append(refs(i).ToString())
                sb.Append(ControlChars.Cr + ControlChars.Lf)
            Next i

            MessageBox.Show(sb.ToString(), "DemoControl References")
        End If
    End Sub

    ' This method uses the ITypeResolutionService.GetPathOfAssembly
    ' method to display the path of the executing assembly.
    Private Sub GetPathOfAssembly()
        If (Me.relatedDesigner.typeResService IsNot Nothing) Then
            Dim name As System.Reflection.AssemblyName = System.Reflection.Assembly.GetExecutingAssembly().GetName()

            MessageBox.Show(Me.relatedDesigner.typeResService.GetPathOfAssembly(name), "Path of executing assembly")
        End If
    End Sub


    ' This method uses the IComponentDiscoveryService.GetComponentTypes 
    ' method to find all the types that derive from 
    ' ScrollableControl.
    Private Sub GetComponentTypes()
        If (Me.relatedDesigner.componentDiscoveryService IsNot Nothing) Then
            Dim components As ICollection = Me.relatedDesigner.componentDiscoveryService.GetComponentTypes(host, GetType(ScrollableControl))

            If (components IsNot Nothing) Then
                If components.Count > 0 Then
                    Dim sb As New StringBuilder()

                    Dim e As IEnumerator = components.GetEnumerator()

                    While e.MoveNext()
                        sb.Append(e.Current.ToString())
                        sb.Append(ControlChars.Cr + ControlChars.Lf)
                    End While

                    MessageBox.Show(sb.ToString(), "Controls derived from ScrollableControl")
                End If
            End If
        End If
    End Sub


    ' This method uses the IToolboxService.CategoryNames
    ' method to enumerate all the categories that appear
    ' in the Toolbox.
    Private Sub GetToolboxCategories()
        If (Me.relatedDesigner.toolboxService IsNot Nothing) Then
            Dim sb As New StringBuilder()

            Dim names As CategoryNameCollection = Me.relatedDesigner.toolboxService.CategoryNames

            Dim name As String
            For Each name In names
                sb.Append(name.ToString())
                sb.Append(ControlChars.Cr + ControlChars.Lf)
            Next name

            MessageBox.Show(sb.ToString(), "Toolbox Categories")
        End If
    End Sub


    ' This method sets the shadowed BackColor property on the 
    ' designer. This is the value that is serialized by the 
    ' design environment.
    Private Sub SetBackColor()
        Dim d As New ColorDialog()
        If d.ShowDialog() = DialogResult.OK Then
            Me.relatedDesigner.BackColor = d.Color
        End If
    End Sub
End Class

Windows 98, Windows Server 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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0
Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback

Community Additions

ADD
Show:
© 2014 Microsoft. All rights reserved.