How to: Adjust the Attributes, Events, and Properties of a Component in Design Mode
Caution
This content was written for .NET Framework. If you're using .NET 6 or a later version, use this content with caution. The designer system has changed for Windows Forms and it's important that you review the Designer changes since .NET Framework article.
You can use your custom designer to modify the attributes, events, and properties of your component in design mode.
Example
The following code example demonstrates how to create a custom designer that adjusts a component's attributes, events, and properties. A designer class called DemoControlDesigner is attached to a DemoControl class and performs the following operations:
Adds a property to the DemoControl class.
Removes a property from the DemoControl class.
Shadows a property of the DemoControl class.
Changes attributes of a DemoControl class property
Creates a component on the design surface and attaches an event handler.
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Diagnostics
Imports System.Drawing
Imports System.Drawing.Design
Imports System.Data
Imports System.Reflection
Imports System.Runtime.Serialization
Imports System.Text
Imports System.Windows.Forms
Imports System.Windows.Forms.Design
Imports System.Windows.Forms.Design.Behavior
Public Class Form1
Inherits Form
Private demoControl1 As DemoControl
Private components As System.ComponentModel.IContainer = Nothing
Public Sub New()
InitializeComponent()
End Sub
Protected Overrides Sub Dispose(disposing As Boolean)
If disposing AndAlso (components IsNot Nothing) Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
#Region "Windows Form Designer generated code"
Private Sub InitializeComponent()
Me.demoControl1 = New DemoControl
Me.SuspendLayout()
'
'demoControl1
'
Me.demoControl1.Location = New System.Drawing.Point(53, 54)
Me.demoControl1.Name = "demoControl1"
Me.demoControl1.TabIndex = 0
'
'Form1
'
Me.ClientSize = New System.Drawing.Size(492, 482)
Me.Controls.Add(Me.demoControl1)
Me.Name = "Form1"
Me.Text = "r"
Me.ResumeLayout(False)
End Sub
#End Region
End Class
' This control is derived from UserContro, with no additional logic.
' The design-related code is implemented in DemoControlDesigner.
<DesignerAttribute(GetType(DemoControlDesigner)), _
ToolboxItem(GetType(DemoControl.DemoToolboxItem))> _
Public Class DemoControl
Inherits Label
Private components As System.ComponentModel.IContainer = Nothing
Public Sub New()
InitializeComponent()
MessageBox.Show("DemoControl", "Constructor")
End Sub
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing AndAlso (components IsNot Nothing) Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
Private Sub InitializeComponent()
End Sub
' Toolbox items must be serializable.
<Serializable(), _
System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.InheritanceDemand, Name:="FullTrust"), _
System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.LinkDemand, Name:="FullTrust")> _
Class DemoToolboxItem
Inherits ToolboxItem
' The add components dialog in VS looks for a public
' ctor that takes a type.
Public Sub New(ByVal toolType As Type)
MyBase.New(toolType)
End Sub 'New
' And you must provide this special constructor for serialization.
' If you add additional data to MyToolboxItem that you
' want to serialize, you may override Deserialize and
' Serialize methods to add that data.
Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext)
Deserialize(info, context)
End Sub 'New
' This implementation sets the new control's Text and
' AutoSize properties.
Protected Overrides Function CreateComponentsCore(ByVal host As IDesignerHost, ByVal defaultValues As IDictionary) As IComponent()
Dim comps As IComponent() = MyBase.CreateComponentsCore(host, defaultValues)
' The returned IComponent array contains a single
' component, which is an instance of DemoControl.
CType(comps(0), DemoControl).Text = "This text was set by CreateComponentsCore."
CType(comps(0), DemoControl).AutoSize = True
Return comps
End Function
End Class
End Class
' This class demonstrates a designer that attaches to various
' services and changes the properties exposed by the control
' being designed.
<System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
Public Class DemoControlDesigner
Inherits ControlDesigner
' This member backs the Locked property.
Private lockedValue As Boolean = False
' This is the collection of DesignerActionLists that
' defines the smart tags offered on the control.
Private actionListsValue As DesignerActionListCollection = Nothing
' This Timer is created when you select the Create Timer
' smart tag item.
Private createdTimer As Timer = Nothing
' These are the services which DemoControlDesigner will use.
Private actionService As DesignerActionService = Nothing
Private actionUiService As DesignerActionUIService = Nothing
Private changeService As IComponentChangeService = Nothing
Private eventService As IDesignerEventService = Nothing
Private host As IDesignerHost = Nothing
Private optionService As IDesignerOptionService = Nothing
Private eventBindingService As IEventBindingService = Nothing
Private listService As IExtenderListService = Nothing
Private referenceService As IReferenceService = Nothing
Private selectionService As ISelectionService = Nothing
Private typeResService As ITypeResolutionService = Nothing
Private componentDiscoveryService As IComponentDiscoveryService = Nothing
Private toolboxService As IToolboxService = Nothing
Private undoEng As UndoEngine = Nothing
Public Sub New()
MessageBox.Show("DemoControlDesigner", "Constructor")
End Sub
' The Dispose method override is implemented so event handlers
' can be removed. This prevents objects from lingering in
' memory beyond the desired lifespan.
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If (Me.changeService IsNot Nothing) Then
' Unhook event handlers.
RemoveHandler Me.changeService.ComponentChanged, AddressOf ChangeService_ComponentChanged
RemoveHandler Me.changeService.ComponentAdded, AddressOf ChangeService_ComponentAdded
RemoveHandler Me.changeService.ComponentRemoved, AddressOf changeService_ComponentRemoved
End If
If (Me.eventService IsNot Nothing) Then
RemoveHandler Me.eventService.ActiveDesignerChanged, AddressOf eventService_ActiveDesignerChanged
End If
If (Me.selectionService IsNot Nothing) Then
RemoveHandler Me.selectionService.SelectionChanged, AddressOf selectionService_SelectionChanged
End If
End If
MyBase.Dispose(disposing)
End Sub
' This method initializes the designer.
Public Overrides Sub Initialize(ByVal component As IComponent)
MyBase.Initialize(component)
' Connect to various designer services.
InitializeServices()
' Set up the BackColor value that will be serialized.
' This is the shadowed property on the designer.
Me.BackColor = Color.Chartreuse
' Set up the BackColor value that will be displayed.
Me.Control.BackColor = Color.AliceBlue
End Sub 'Initialize
' This method creates the DesignerActionList on demand, causing
' smart tags to appear on the control being designed.
Public Overrides ReadOnly Property ActionLists() As DesignerActionListCollection
Get
If actionListsValue Is Nothing Then
actionListsValue = New DesignerActionListCollection()
actionListsValue.Add(New DemoActionList(Me.Component))
End If
Return actionListsValue
End Get
End Property
' This utility method connects the designer to various
' services it will use.
Private Sub InitializeServices()
' Acquire a reference to DesignerActionService.
Me.actionService = GetService(GetType(DesignerActionService))
' Acquire a reference to DesignerActionUIService.
Me.actionUiService = GetService(GetType(DesignerActionUIService))
' Acquire a reference to IComponentChangeService.
Me.changeService = GetService(GetType(IComponentChangeService))
' Hook the IComponentChangeService events.
If (Me.changeService IsNot Nothing) Then
AddHandler Me.changeService.ComponentChanged, AddressOf ChangeService_ComponentChanged
AddHandler Me.changeService.ComponentAdded, AddressOf ChangeService_ComponentAdded
AddHandler Me.changeService.ComponentRemoved, AddressOf changeService_ComponentRemoved
End If
' Acquire a reference to ISelectionService.
Me.selectionService = GetService(GetType(ISelectionService))
' Hook the SelectionChanged event.
If (Me.selectionService IsNot Nothing) Then
AddHandler Me.selectionService.SelectionChanged, AddressOf selectionService_SelectionChanged
End If
' Acquire a reference to IDesignerEventService.
Me.eventService = GetService(GetType(IDesignerEventService))
If (Me.eventService IsNot Nothing) Then
AddHandler Me.eventService.ActiveDesignerChanged, AddressOf eventService_ActiveDesignerChanged
End If
' Acquire a reference to IDesignerHost.
Me.host = GetService(GetType(IDesignerHost))
' Acquire a reference to IDesignerOptionService.
Me.optionService = GetService(GetType(IDesignerOptionService))
' Acquire a reference to IEventBindingService.
Me.eventBindingService = GetService(GetType(IEventBindingService))
' Acquire a reference to IExtenderListService.
Me.listService = GetService(GetType(IExtenderListService))
' Acquire a reference to IReferenceService.
Me.referenceService = GetService(GetType(IReferenceService))
' Acquire a reference to ITypeResolutionService.
Me.typeResService = GetService(GetType(ITypeResolutionService))
' Acquire a reference to IComponentDiscoveryService.
Me.componentDiscoveryService = GetService(GetType(IComponentDiscoveryService))
' Acquire a reference to IToolboxService.
Me.toolboxService = GetService(GetType(IToolboxService))
' Acquire a reference to UndoEngine.
Me.undoEng = GetService(GetType(UndoEngine))
If (Me.undoEng IsNot Nothing) Then
MessageBox.Show("UndoEngine")
End If
End Sub
' This is the shadowed property on the designer.
' This value will be serialized instead of the
' value of the control's property.
Public Property BackColor() As Color
Get
Return CType(ShadowProperties("BackColor"), Color)
End Get
Set(ByVal value As Color)
If (Me.changeService IsNot Nothing) Then
Dim backColorDesc As PropertyDescriptor = TypeDescriptor.GetProperties(Me.Control)("BackColor")
Me.changeService.OnComponentChanging(Me.Control, backColorDesc)
Me.ShadowProperties("BackColor") = value
Me.changeService.OnComponentChanged(Me.Control, backColorDesc, Nothing, Nothing)
End If
End Set
End Property
' This is the property added by the designer in the
' PreFilterProperties method.
Private Property Locked() As Boolean
Get
Return lockedValue
End Get
Set(ByVal value As Boolean)
lockedValue = value
End Set
End Property
' The PreFilterProperties method is where you can add or remove
' properties from the component being designed.
'
' In this implementation, the Visible property is removed,
' the BackColor property is shadowed by the designer, and
' the a new property, called Locked, is added.
Protected Overrides Sub PreFilterProperties(ByVal properties As IDictionary)
' Always call the base PreFilterProperties implementation
' before you modify the properties collection.
MyBase.PreFilterProperties(properties)
' Remove the visible property.
properties.Remove("Visible")
' Shadow the BackColor property.
Dim propertyDesc As PropertyDescriptor = TypeDescriptor.CreateProperty(GetType(DemoControlDesigner), CType(properties("BackColor"), PropertyDescriptor), New Attribute(-1) {})
properties("BackColor") = propertyDesc
' Create the Locked property.
properties("Locked") = TypeDescriptor.CreateProperty(GetType(DemoControlDesigner), "Locked", GetType(Boolean), CategoryAttribute.Design, DesignOnlyAttribute.Yes)
End Sub
' The PostFilterProperties method is where you modify existing
' properties. You must only use this method to modify existing
' items. Do not add or remove items here. Also, be sure to
' call base.PostFilterProperties(properties) after your filtering
' logic.
'
' In this implementation, the Enabled property is hidden from
' any PropertyGrid or Properties window. This is done by
' creating a copy of the existing PropertyDescriptor and
' attaching two new Attributes: Browsable and EditorBrowsable.
Protected Overrides Sub PostFilterProperties(ByVal properties As IDictionary)
Dim pd As PropertyDescriptor = properties("Enabled")
pd = TypeDescriptor.CreateProperty(pd.ComponentType, pd, New Attribute(1) {New BrowsableAttribute(False), New EditorBrowsableAttribute(EditorBrowsableState.Never)})
properties(pd.Name) = pd
' Always call the base PostFilterProperties implementation
' after you modify the properties collection.
MyBase.PostFilterProperties(properties)
End Sub
#Region "Event Handlers"
Private Sub eventService_ActiveDesignerChanged(ByVal sender As Object, ByVal e As ActiveDesignerEventArgs)
If (e.NewDesigner IsNot Nothing) Then
Dim o As Object = e.NewDesigner
MessageBox.Show(o.ToString(), "ActiveDesignerChanged")
End If
End Sub
Private Sub ChangeService_ComponentChanged(ByVal sender As Object, ByVal e As ComponentChangedEventArgs)
Dim msg As String = String.Format("{0}, {1}", e.Component, e.Member)
MessageBox.Show(msg, "ComponentChanged")
End Sub
Private Sub ChangeService_ComponentAdded(ByVal sender As Object, ByVal e As ComponentEventArgs)
MessageBox.Show(e.ToString(), "ComponentAdded")
End Sub
Private Sub changeService_ComponentRemoved(ByVal sender As Object, ByVal e As ComponentEventArgs)
Dim o As Object = e.Component
MessageBox.Show(o.ToString(), "ComponentRemoved")
End Sub
Private Sub selectionService_SelectionChanged(ByVal sender As Object, ByVal e As EventArgs)
If (Me.selectionService IsNot Nothing) Then
If Me.selectionService.PrimarySelection Is Me.Control Then
MessageBox.Show(Me.Control.ToString(), "SelectionChanged")
End If
End If
End Sub
#End Region
' 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
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.Data;
using System.Reflection;
using System.Runtime.Serialization;
using System.Text;
using System.Windows.Forms;
using System.Windows.Forms.Design;
using System.Windows.Forms.Design.Behavior;
public class Form1 : Form
{
private DemoControl demoControl1;
private System.ComponentModel.IContainer components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.demoControl1 = new DemoControl();
this.SuspendLayout();
//
// demoControl1
//
this.demoControl1.AutoSize = true;
this.demoControl1.BackColor = System.Drawing.Color.Chartreuse;
this.demoControl1.Location = new System.Drawing.Point(0, 0);
this.demoControl1.Name = "demoControl1";
this.demoControl1.Size = new System.Drawing.Size(232, 14);
this.demoControl1.TabIndex = 0;
this.demoControl1.Text = "This text was set by CreateComponentsCore.";
//
// Form1
//
this.ClientSize = new System.Drawing.Size(492, 482);
this.Controls.Add(this.demoControl1);
this.Name = "Form1";
this.Text = "r";
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
}
// This control is derived from UserControl, with only a little
// added logic for the Toolbox interaction.
//
// All of the custom designer code is implemented in the
// DemoControlDesigner class.
[DesignerAttribute(typeof(DemoControlDesigner))]
[ToolboxItem(typeof(DemoToolboxItem))]
public class DemoControl : Label
{
private System.ComponentModel.IContainer components = null;
public DemoControl()
{
InitializeComponent();
MessageBox.Show("DemoControl", "Constructor");
}
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
private void InitializeComponent()
{
//
// DemoControl
//
this.Name = "DemoControl";
}
// Toolbox items must be serializable.
[Serializable]
[System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.InheritanceDemand, Name="FullTrust")]
[System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.LinkDemand, Name="FullTrust")]
class DemoToolboxItem : ToolboxItem
{
// The add components dialog in VS looks for a public
// ctor that takes a type.
public DemoToolboxItem(Type toolType)
: base(toolType)
{
}
// And you must provide this special constructor for serialization.
// If you add additional data to MyToolboxItem that you
// want to serialize, you may override Deserialize and
// Serialize methods to add that data.
DemoToolboxItem(SerializationInfo info, StreamingContext context)
{
Deserialize(info, context);
}
// This implementation sets the new control's Text and
// AutoSize properties.
protected override IComponent[] CreateComponentsCore(
IDesignerHost host,
IDictionary defaultValues)
{
IComponent[] comps = base.CreateComponentsCore(host, defaultValues);
// The returned IComponent array contains a single
// component, which is an instance of DemoControl.
((DemoControl)comps[0]).Text = "This text was set by CreateComponentsCore.";
((DemoControl)comps[0]).AutoSize = true;
return comps;
}
}
}
// This class demonstrates a designer that attaches to various
// services and changes the properties exposed by the control
// being designed.
[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
public class DemoControlDesigner : ControlDesigner
{
// This member backs the Locked property.
private bool lockedValue = false;
// This is the collection of DesignerActionLists that
// defines the smart tags offered on the control.
private DesignerActionListCollection actionLists = null;
// This Timer is created when you select the Create Timer
// smart tag item.
private Timer createdTimer = null;
// These are the services which DemoControlDesigner will use.
private DesignerActionService actionService = null;
private DesignerActionUIService actionUiService = null;
private IComponentChangeService changeService = null;
private IDesignerEventService eventService = null;
private IDesignerHost host = null;
private IDesignerOptionService optionService = null;
private IEventBindingService eventBindingService = null;
private IExtenderListService listService = null;
private IReferenceService referenceService = null;
private ISelectionService selectionService = null;
private ITypeResolutionService typeResService = null;
private IComponentDiscoveryService componentDiscoveryService = null;
private IToolboxService toolboxService = null;
private UndoEngine undoEng = null;
public DemoControlDesigner()
{
MessageBox.Show("DemoControlDesigner", "Constructor");
}
// The Dispose method override is implemented so event handlers
// can be removed. This prevents objects from lingering in
// memory beyond the desired lifespan.
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (this.changeService != null)
{
// Unhook event handlers.
this.changeService.ComponentChanged -=
new ComponentChangedEventHandler(
ChangeService_ComponentChanged);
this.changeService.ComponentAdded -=
new ComponentEventHandler(
ChangeService_ComponentAdded);
this.changeService.ComponentRemoved -=
new ComponentEventHandler(
changeService_ComponentRemoved);
}
if (this.eventService != null)
{
this.eventService.ActiveDesignerChanged -=
new ActiveDesignerEventHandler(
eventService_ActiveDesignerChanged);
}
if (this.selectionService != null)
{
this.selectionService.SelectionChanged -=
new EventHandler(
selectionService_SelectionChanged);
}
}
base.Dispose(disposing);
}
// This method initializes the designer.
public override void Initialize(IComponent component)
{
base.Initialize(component);
// Connect to various designer services.
InitializeServices();
// Set up the BackColor value that will be serialized.
// This is the shadowed property on the designer.
this.BackColor = Color.Chartreuse;
// Set up the BackColor value that will be displayed.
this.Control.BackColor = Color.AliceBlue;
}
// This method creates the DesignerActionList on demand, causing
// smart tags to appear on the control being designed.
public override DesignerActionListCollection ActionLists
{
get
{
if (null == actionLists)
{
actionLists = new DesignerActionListCollection();
actionLists.Add(
new DemoActionList(this.Component));
}
return actionLists;
}
}
// This utility method connects the designer to various
// services it will use.
private void InitializeServices()
{
// Acquire a reference to DesignerActionService.
this.actionService =
GetService(typeof(DesignerActionService))
as DesignerActionService;
// Acquire a reference to DesignerActionUIService.
this.actionUiService =
GetService(typeof(DesignerActionUIService))
as DesignerActionUIService;
// Acquire a reference to IComponentChangeService.
this.changeService =
GetService(typeof(IComponentChangeService))
as IComponentChangeService;
// Hook the IComponentChangeService events.
if (this.changeService != null)
{
this.changeService.ComponentChanged +=
new ComponentChangedEventHandler(
ChangeService_ComponentChanged);
this.changeService.ComponentAdded +=
new ComponentEventHandler(
ChangeService_ComponentAdded);
this.changeService.ComponentRemoved +=
new ComponentEventHandler(
changeService_ComponentRemoved);
}
// Acquire a reference to ISelectionService.
this.selectionService =
GetService(typeof(ISelectionService))
as ISelectionService;
// Hook the SelectionChanged event.
if (this.selectionService != null)
{
this.selectionService.SelectionChanged +=
new EventHandler(selectionService_SelectionChanged);
}
// Acquire a reference to IDesignerEventService.
this.eventService =
GetService(typeof(IDesignerEventService))
as IDesignerEventService;
if (this.eventService != null)
{
this.eventService.ActiveDesignerChanged +=
new ActiveDesignerEventHandler(
eventService_ActiveDesignerChanged);
}
// Acquire a reference to IDesignerHost.
this.host =
GetService(typeof(IDesignerHost))
as IDesignerHost;
// Acquire a reference to IDesignerOptionService.
this.optionService =
GetService(typeof(IDesignerOptionService))
as IDesignerOptionService;
// Acquire a reference to IEventBindingService.
this.eventBindingService =
GetService(typeof(IEventBindingService))
as IEventBindingService;
// Acquire a reference to IExtenderListService.
this.listService =
GetService(typeof(IExtenderListService))
as IExtenderListService;
// Acquire a reference to IReferenceService.
this.referenceService =
GetService(typeof(IReferenceService))
as IReferenceService;
// Acquire a reference to ITypeResolutionService.
this.typeResService =
GetService(typeof(ITypeResolutionService))
as ITypeResolutionService;
// Acquire a reference to IComponentDiscoveryService.
this.componentDiscoveryService =
GetService(typeof(IComponentDiscoveryService))
as IComponentDiscoveryService;
// Acquire a reference to IToolboxService.
this.toolboxService =
GetService(typeof(IToolboxService))
as IToolboxService;
// Acquire a reference to UndoEngine.
this.undoEng =
GetService(typeof(UndoEngine))
as UndoEngine;
if (this.undoEng != null)
{
MessageBox.Show("UndoEngine");
}
}
// This is the shadowed property on the designer.
// This value will be serialized instead of the
// value of the control's property.
public Color BackColor
{
get
{
return (Color)ShadowProperties["BackColor"];
}
set
{
if (this.changeService != null)
{
PropertyDescriptor backColorDesc =
TypeDescriptor.GetProperties(this.Control)["BackColor"];
this.changeService.OnComponentChanging(
this.Control,
backColorDesc);
this.ShadowProperties["BackColor"] = value;
this.changeService.OnComponentChanged(
this.Control,
backColorDesc,
null,
null);
}
}
}
// This is the property added by the designer in the
// PreFilterProperties method.
private bool Locked
{
get
{
return lockedValue;
}
set
{
lockedValue = value;
}
}
// The PreFilterProperties method is where you can add or remove
// properties from the component being designed.
//
// In this implementation, the Visible property is removed,
// the BackColor property is shadowed by the designer, and
// the a new property, called Locked, is added.
protected override void PreFilterProperties(IDictionary properties)
{
// Always call the base PreFilterProperties implementation
// before you modify the properties collection.
base.PreFilterProperties(properties);
// Remove the visible property.
properties.Remove("Visible");
// Shadow the BackColor property.
PropertyDescriptor propertyDesc = TypeDescriptor.CreateProperty(
typeof(DemoControlDesigner),
(PropertyDescriptor)properties["BackColor"],
new Attribute[0]);
properties["BackColor"] = propertyDesc;
// Create the Locked property.
properties["Locked"] = TypeDescriptor.CreateProperty(
typeof(DemoControlDesigner),
"Locked",
typeof(bool),
CategoryAttribute.Design,
DesignOnlyAttribute.Yes);
}
// The PostFilterProperties method is where you modify existing
// properties. You must only use this method to modify existing
// items. Do not add or remove items here. Also, be sure to
// call base.PostFilterProperties(properties) after your filtering
// logic.
//
// In this implementation, the Enabled property is hidden from
// any PropertyGrid or Properties window. This is done by
// creating a copy of the existing PropertyDescriptor and
// attaching two new Attributes: Browsable and EditorBrowsable.
protected override void PostFilterProperties(IDictionary properties)
{
PropertyDescriptor pd =
properties["Enabled"] as PropertyDescriptor;
pd = TypeDescriptor.CreateProperty(
pd.ComponentType,
pd,
new Attribute[2] {
new BrowsableAttribute(false),
new EditorBrowsableAttribute(EditorBrowsableState.Never)});
properties[pd.Name] = pd;
// Always call the base PostFilterProperties implementation
// after you modify the properties collection.
base.PostFilterProperties(properties);
}
#region Event Handlers
void eventService_ActiveDesignerChanged(
object sender,
ActiveDesignerEventArgs e)
{
if (e.NewDesigner != null)
{
MessageBox.Show(
e.NewDesigner.ToString(),
"ActiveDesignerChanged");
}
}
void ChangeService_ComponentChanged(
object sender,
ComponentChangedEventArgs e)
{
string msg = String.Format(
"{0}, {1}", e.Component, e.Member);
MessageBox.Show(msg, "ComponentChanged");
}
void ChangeService_ComponentAdded(
object sender,
ComponentEventArgs e)
{
MessageBox.Show(
e.Component.ToString(),
"ComponentAdded");
}
void changeService_ComponentRemoved(
object sender,
ComponentEventArgs e)
{
MessageBox.Show(
e.Component.ToString(),
"ComponentRemoved");
}
void selectionService_SelectionChanged(
object sender,
EventArgs e)
{
if (this.selectionService != null)
{
if (this.selectionService.PrimarySelection == this.Control)
{
MessageBox.Show(
this.Control.ToString(),
"SelectionChanged");
}
}
}
#endregion
// This class defines the smart tags that appear on the control
// that is being designed.
internal class DemoActionList :
System.ComponentModel.Design.DesignerActionList
{
// Cache a reference to the designer host.
private IDesignerHost host = null;
// Cache a reference to the control.
private DemoControl relatedControl = null;
// Cache a reference to the designer.
private DemoControlDesigner relatedDesigner = null;
//The constructor associates the control
//with the smart tag list.
public DemoActionList(IComponent component)
: base(component)
{
this.relatedControl = component as DemoControl;
this.host =
this.Component.Site.GetService(typeof(IDesignerHost))
as IDesignerHost;
IDesigner dcd = host.GetDesigner(this.Component);
this.relatedDesigner = dcd as DemoControlDesigner;
}
// This method creates and populates the
// DesignerActionItemCollection which is used to
// display smart tag items.
public override DesignerActionItemCollection GetSortedActionItems()
{
DesignerActionItemCollection items =
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 (this.relatedDesigner.createdTimer == null)
{
items.Add(new DesignerActionMethodItem(
this,
"CreateTimer",
"Create Timer",
true));
}
else
{
items.Add(new DesignerActionMethodItem(
this,
"ShowEventHandlerCode",
"Show Event Handler Code",
true));
items.Add(new DesignerActionMethodItem(
this,
"RemoveTimer",
"Remove Timer",
true));
}
items.Add(new DesignerActionMethodItem(
this,
"GetExtenderProviders",
"Get Extender Providers",
true));
items.Add(new DesignerActionMethodItem(
this,
"GetDemoControlReferences",
"Get DemoControl References",
true));
items.Add(new DesignerActionMethodItem(
this,
"GetPathOfAssembly",
"Get Path of Executing Assembly",
true));
items.Add(new DesignerActionMethodItem(
this,
"GetComponentTypes",
"Get ScrollableControl Types",
true));
items.Add(new DesignerActionMethodItem(
this,
"GetToolboxCategories",
"Get Toolbox Categories",
true));
items.Add(new DesignerActionMethodItem(
this,
"SetBackColor",
"Set Back Color",
true));
return items;
}
// 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 void CreateTimer()
{
if (this.host != null)
{
if (this.relatedDesigner.createdTimer == null)
{
// Create and configure the Timer object.
this.relatedDesigner.createdTimer =
this.host.CreateComponent(typeof(Timer)) as Timer;
Timer t = this.relatedDesigner.createdTimer;
t.Interval = 1000;
t.Enabled = true;
EventDescriptorCollection eventColl =
TypeDescriptor.GetEvents(t, new Attribute[0]);
if (eventColl != null)
{
EventDescriptor ed =
eventColl["Tick"] as EventDescriptor;
if (ed != null)
{
PropertyDescriptor epd =
this.relatedDesigner.eventBindingService.GetEventProperty(ed);
epd.SetValue(t, "timer_Tick");
}
}
this.relatedDesigner.actionUiService.Refresh(this.relatedControl);
}
}
}
// 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 void ShowEventHandlerCode()
{
Timer t = this.relatedDesigner.createdTimer;
if (t != null)
{
EventDescriptorCollection eventColl =
TypeDescriptor.GetEvents(t, new Attribute[0]);
if (eventColl != null)
{
EventDescriptor ed =
eventColl["Tick"] as EventDescriptor;
if (ed != null)
{
this.relatedDesigner.eventBindingService.ShowCode(t, ed);
}
}
}
}
// This method uses the IDesignerHost.DestroyComponent method
// to remove the Timer component from the design environment.
private void RemoveTimer()
{
if (this.host != null)
{
if (this.relatedDesigner.createdTimer != null)
{
this.host.DestroyComponent(
this.relatedDesigner.createdTimer);
this.relatedDesigner.createdTimer = null;
this.relatedDesigner.actionUiService.Refresh(
this.relatedControl);
}
}
}
// This method uses IExtenderListService.GetExtenderProviders
// to enumerate all the extender providers and display them
// in a MessageBox.
private void GetExtenderProviders()
{
if (this.relatedDesigner.listService != null)
{
StringBuilder sb = new StringBuilder();
IExtenderProvider[] providers =
this.relatedDesigner.listService.GetExtenderProviders();
for (int i = 0; i < providers.Length; i++)
{
sb.Append(providers[i].ToString());
sb.Append("\r\n");
}
MessageBox.Show(
sb.ToString(),
"Extender Providers");
}
}
// This method uses the IReferenceService.GetReferences method
// to enumerate all the instances of DemoControl on the
// design surface.
private void GetDemoControlReferences()
{
if (this.relatedDesigner.referenceService != null)
{
StringBuilder sb = new StringBuilder();
object[] refs = this.relatedDesigner.referenceService.GetReferences(typeof(DemoControl));
for (int i = 0; i < refs.Length; i++)
{
sb.Append(refs[i].ToString());
sb.Append("\r\n");
}
MessageBox.Show(
sb.ToString(),
"DemoControl References");
}
}
// This method uses the ITypeResolutionService.GetPathOfAssembly
// method to display the path of the executing assembly.
private void GetPathOfAssembly()
{
if (this.relatedDesigner.typeResService != null)
{
System.Reflection.AssemblyName name =
System.Reflection.Assembly.GetExecutingAssembly().GetName();
MessageBox.Show(
this.relatedDesigner.typeResService.GetPathOfAssembly(name),
"Path of executing assembly");
}
}
// This method uses the IComponentDiscoveryService.GetComponentTypes
// method to find all the types that derive from
// ScrollableControl.
private void GetComponentTypes()
{
if (this.relatedDesigner.componentDiscoveryService != null)
{
ICollection components = this.relatedDesigner.componentDiscoveryService.GetComponentTypes(host, typeof(ScrollableControl));
if (components != null)
{
if (components.Count > 0)
{
StringBuilder sb = new StringBuilder();
IEnumerator e = components.GetEnumerator();
while (e.MoveNext())
{
sb.Append(e.Current.ToString());
sb.Append("\r\n");
}
MessageBox.Show(
sb.ToString(),
"Controls derived from ScrollableControl");
}
}
}
}
// This method uses the IToolboxService.CategoryNames
// method to enumerate all the categories that appear
// in the Toolbox.
private void GetToolboxCategories()
{
if (this.relatedDesigner.toolboxService != null)
{
StringBuilder sb = new StringBuilder();
CategoryNameCollection names = this.relatedDesigner.toolboxService.CategoryNames;
foreach (string name in names)
{
sb.Append(name.ToString());
sb.Append("\r\n");
}
MessageBox.Show(sb.ToString(), "Toolbox Categories");
}
}
// This method sets the shadowed BackColor property on the
// designer. This is the value that is serialized by the
// design environment.
private void SetBackColor()
{
ColorDialog d = new ColorDialog();
if (d.ShowDialog() == DialogResult.OK)
{
this.relatedDesigner.BackColor = d.Color;
}
}
}
}
You can change the attributes, events, and properties of your component in design mode by overriding the following methods on your designer:
The following code example demonstrates how to override the PreFilterProperties and
PostFilterProperties methods to change the properties and attributes of the DemoControl class.
' The PreFilterProperties method is where you can add or remove
' properties from the component being designed.
'
' In this implementation, the Visible property is removed,
' the BackColor property is shadowed by the designer, and
' the a new property, called Locked, is added.
Protected Overrides Sub PreFilterProperties(ByVal properties As IDictionary)
' Always call the base PreFilterProperties implementation
' before you modify the properties collection.
MyBase.PreFilterProperties(properties)
' Remove the visible property.
properties.Remove("Visible")
' Shadow the BackColor property.
Dim propertyDesc As PropertyDescriptor = TypeDescriptor.CreateProperty(GetType(DemoControlDesigner), CType(properties("BackColor"), PropertyDescriptor), New Attribute(-1) {})
properties("BackColor") = propertyDesc
' Create the Locked property.
properties("Locked") = TypeDescriptor.CreateProperty(GetType(DemoControlDesigner), "Locked", GetType(Boolean), CategoryAttribute.Design, DesignOnlyAttribute.Yes)
End Sub
// The PreFilterProperties method is where you can add or remove
// properties from the component being designed.
//
// In this implementation, the Visible property is removed,
// the BackColor property is shadowed by the designer, and
// the a new property, called Locked, is added.
protected override void PreFilterProperties(IDictionary properties)
{
// Always call the base PreFilterProperties implementation
// before you modify the properties collection.
base.PreFilterProperties(properties);
// Remove the visible property.
properties.Remove("Visible");
// Shadow the BackColor property.
PropertyDescriptor propertyDesc = TypeDescriptor.CreateProperty(
typeof(DemoControlDesigner),
(PropertyDescriptor)properties["BackColor"],
new Attribute[0]);
properties["BackColor"] = propertyDesc;
// Create the Locked property.
properties["Locked"] = TypeDescriptor.CreateProperty(
typeof(DemoControlDesigner),
"Locked",
typeof(bool),
CategoryAttribute.Design,
DesignOnlyAttribute.Yes);
}
' The PostFilterProperties method is where you modify existing
' properties. You must only use this method to modify existing
' items. Do not add or remove items here. Also, be sure to
' call base.PostFilterProperties(properties) after your filtering
' logic.
'
' In this implementation, the Enabled property is hidden from
' any PropertyGrid or Properties window. This is done by
' creating a copy of the existing PropertyDescriptor and
' attaching two new Attributes: Browsable and EditorBrowsable.
Protected Overrides Sub PostFilterProperties(ByVal properties As IDictionary)
Dim pd As PropertyDescriptor = properties("Enabled")
pd = TypeDescriptor.CreateProperty(pd.ComponentType, pd, New Attribute(1) {New BrowsableAttribute(False), New EditorBrowsableAttribute(EditorBrowsableState.Never)})
properties(pd.Name) = pd
' Always call the base PostFilterProperties implementation
' after you modify the properties collection.
MyBase.PostFilterProperties(properties)
End Sub
// The PostFilterProperties method is where you modify existing
// properties. You must only use this method to modify existing
// items. Do not add or remove items here. Also, be sure to
// call base.PostFilterProperties(properties) after your filtering
// logic.
//
// In this implementation, the Enabled property is hidden from
// any PropertyGrid or Properties window. This is done by
// creating a copy of the existing PropertyDescriptor and
// attaching two new Attributes: Browsable and EditorBrowsable.
protected override void PostFilterProperties(IDictionary properties)
{
PropertyDescriptor pd =
properties["Enabled"] as PropertyDescriptor;
pd = TypeDescriptor.CreateProperty(
pd.ComponentType,
pd,
new Attribute[2] {
new BrowsableAttribute(false),
new EditorBrowsableAttribute(EditorBrowsableState.Never)});
properties[pd.Name] = pd;
// Always call the base PostFilterProperties implementation
// after you modify the properties collection.
base.PostFilterProperties(properties);
}
Compiling the Code
When you make changes to the design-time aspects of a component, you need to rebuild the control project. In addition, if there is another Windows Forms project that is currently open and uses this component, you will probably need to refresh the project to see the changes. Typically, you need to close and reopen the design window containing the component.
Note
You must add a reference to the design-time assembly, System.Design.dll. This assembly is not included in the .NET Framework 4 Client Profile. To add a reference to System.Design.dll, you must change the project's Target Framework to .NET Framework 4.
See Also
Tasks
How to: Access Design-Time Support in Windows Forms
How to: Extend the Appearance and Behavior of Controls in Design Mode
How to: Perform Custom Initialization for Controls in Design Mode