DesignerTransaction Class
Important
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Provides a way to group a series of design-time actions to improve performance and enable most types of changes to be undone.
public ref class DesignerTransaction abstract : IDisposable
public abstract class DesignerTransaction : IDisposable
type DesignerTransaction = class
interface IDisposable
Public MustInherit Class DesignerTransaction
Implements IDisposable
- Inheritance
-
DesignerTransaction
- Implements
The following code example program demonstrates how to create a DesignerTransaction from a designer. To run this sample, compile the source code into a class library. You must add a reference to the System.Design assembly. In a new project, add a reference to the compiled DLL and add the component in the library to the Toolbox.
There is extensive support for this feature in Visual Studio.
Also see Walkthrough: Automatically Populating the Toolbox with Custom Components.
The designer can optionally display notifications about designer transaction events. If you add an instance of the DTComponent
to a form while in design mode, a message box appears asking whether you would like to receive designer transaction event notifications. You may toggle these notifications using the shortcut menu that appears when you right-click an instance of the DTComponent
. Transactions are created when you change values using the Properties window. You can also have the designer perform a transaction by clicking Perform Example Transaction on the shortcut menu for the component.
#using <system.dll>
#using <system.design.dll>
#using <system.windows.forms.dll>
using namespace System;
using namespace System::ComponentModel;
using namespace System::ComponentModel::Design;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::Design;
/*
This sample demonstrates how to perform a series of actions in a designer
transaction, how to change values of properties of a component from a
designer, and how to complete transactions without being interrupted
by other activities.
To run this sample, add this code to a class library project and compile.
Create a new Windows Forms project or load a form in the designer. Add a
reference to the class library that was compiled in the first step.
Right-click the Toolbox in design mode and click Customize Toolbox.
Browse to the class library that was compiled in the first step and
select OK until the DTComponent item appears in the Toolbox. Add an
instance of this component to the form.
When the component is created and added to the component tray for your
design project, the Initialize method of the designer is called.
This method displays a message box informing you that designer transaction
event handlers will be registered unless you click Cancel. When you set
properties in the properties window, each change will be encapsulated in
a designer transaction, allowing the change to be undone later.
When you right-click the component, the shortcut menu for the component
is displayed. The designer constructs this menu according to whether
designer transaction notifications are enabled, and offers the option
of enabling or disabling the notifications, depending on the current
mode. The shortcut menu also presents a Perform Example Transaction
item, which will set the values of the component's StringProperty and
CountProperty properties. You can undo the last designer transaction using
the Undo command provided by the Visual Studio development environment.
*/
private ref class DTDesigner: public ComponentDesigner
{
private:
bool notification_mode;
int count;
void LinkDTNotifications( Object^ /*sender*/, EventArgs^ /*e*/ )
{
if ( !notification_mode )
{
IDesignerHost^ host = dynamic_cast<IDesignerHost^>(GetService( IDesignerHost::typeid ));
if ( host != nullptr )
{
notification_mode = true;
host->TransactionOpened += gcnew EventHandler( this, &DTDesigner::OnDesignerTransactionOpened );
host->TransactionClosed += gcnew DesignerTransactionCloseEventHandler( this, &DTDesigner::OnDesignerTransactionClosed );
}
}
}
void UnlinkDTNotifications( Object^ /*sender*/, EventArgs^ /*e*/ )
{
if ( notification_mode )
{
IDesignerHost^ host = dynamic_cast<IDesignerHost^>(GetService( IDesignerHost::typeid ));
if ( host != nullptr )
{
notification_mode = false;
host->TransactionOpened -= gcnew EventHandler( this, &DTDesigner::OnDesignerTransactionOpened );
host->TransactionClosed -= gcnew DesignerTransactionCloseEventHandler( this, &DTDesigner::OnDesignerTransactionClosed );
}
}
}
void OnDesignerTransactionOpened( Object^ /*sender*/, EventArgs^ /*e*/ )
{
MessageBox::Show( "A Designer Transaction was started. (TransactionOpened)" );
}
void OnDesignerTransactionClosed( Object^ /*sender*/, DesignerTransactionCloseEventArgs^ /*e*/ )
{
MessageBox::Show( "A Designer Transaction was completed. (TransactionClosed)" );
}
void DoTransaction( Object^ /*sender*/, EventArgs^ /*e*/ )
{
IDesignerHost^ host = static_cast<IDesignerHost^>(GetService( IDesignerHost::typeid ));
DesignerTransaction^ t = host->CreateTransaction( "Change Text and Size" );
/* The code within the using statement is considered to be a single transaction.
When the user selects Undo, the system will undo everything executed in this code block.
*/
if ( notification_mode )
MessageBox::Show( "Entering a Designer-Initiated Designer Transaction" );
// The .NET Framework automatically associates the TypeDescriptor with the correct component
PropertyDescriptor^ someText = TypeDescriptor::GetProperties( Component )[ "StringProperty" ];
someText->SetValue( Component, "This text was set by the designer for this component." );
PropertyDescriptor^ anInteger = TypeDescriptor::GetProperties( Component )[ "CountProperty" ];
anInteger->SetValue( Component, count );
count++;
// Complete the designer transaction.
t->Commit();
if ( notification_mode )
MessageBox::Show( "Designer-Initiated Designer Transaction Completed" );
}
public:
property DesignerVerbCollection^ Verbs
{
// The Verbs property is overridden from ComponentDesigner
virtual DesignerVerbCollection^ get() override
{
DesignerVerbCollection^ dvc = gcnew DesignerVerbCollection;
dvc->Add( gcnew DesignerVerb( "Perform Example Transaction",gcnew EventHandler( this, &DTDesigner::DoTransaction ) ) );
if ( notification_mode )
dvc->Add( gcnew DesignerVerb( "End Designer Transaction Notifications",
gcnew EventHandler( this, &DTDesigner::UnlinkDTNotifications ) ) );
else
dvc->Add( gcnew DesignerVerb( "Show Designer Transaction Notifications",
gcnew EventHandler( this, &DTDesigner::LinkDTNotifications ) ) );
return dvc;
}
}
virtual void Initialize( IComponent^ component ) override
{
ComponentDesigner::Initialize( component );
notification_mode = false;
count = 10;
IDesignerHost^ host = dynamic_cast<IDesignerHost^>(GetService( IDesignerHost::typeid ));
if ( host == nullptr )
{
MessageBox::Show( "The IDesignerHost service interface could not be obtained." );
return;
}
if ( MessageBox::Show( "Press the Yes button to display notification message boxes for the designer transaction opened and closed notifications.", "Link DesignerTransaction Notifications?", MessageBoxButtons::YesNo, MessageBoxIcon::Question, MessageBoxDefaultButton::Button1, MessageBoxOptions::RightAlign ) == DialogResult::Yes )
{
host->TransactionOpened += gcnew EventHandler( this, &DTDesigner::OnDesignerTransactionOpened );
host->TransactionClosed += gcnew DesignerTransactionCloseEventHandler( this, &DTDesigner::OnDesignerTransactionClosed );
notification_mode = true;
}
}
public:
~DTDesigner()
{
UnlinkDTNotifications( this, gcnew EventArgs );
}
};
// Associate the DTDesigner with this component
[DesignerAttribute(DTDesigner::typeid)]
public ref class DTComponent: public System::ComponentModel::Component
{
private:
String^ m_String;
int m_Count;
void InitializeComponent()
{
m_String = "Initial Value";
m_Count = 0;
}
public:
property String^ StringProperty
{
String^ get()
{
return m_String;
}
void set( String^ value )
{
m_String = value;
}
}
property int CountProperty
{
int get()
{
return m_Count;
}
void set( int value )
{
m_Count = value;
}
}
};
using System;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms;
using System.Windows.Forms.Design;
/*
This sample demonstrates how to perform a series of actions in a designer
transaction, how to change values of properties of a component from a
designer, and how to complete transactions without being interrupted
by other activities.
To run this sample, add this code to a class library project and compile.
Create a new Windows Forms project or load a form in the designer. Add a
reference to the class library that was compiled in the first step.
Right-click the Toolbox in design mode and click Customize Toolbox.
Browse to the class library that was compiled in the first step and
select OK until the DTComponent item appears in the Toolbox. Add an
instance of this component to the form.
When the component is created and added to the component tray for your
design project, the Initialize method of the designer is called.
This method displays a message box informing you that designer transaction
event handlers will be registered unless you click Cancel. When you set
properties in the properties window, each change will be encapsulated in
a designer transaction, allowing the change to be undone later.
When you right-click the component, the shortcut menu for the component
is displayed. The designer constructs this menu according to whether
designer transaction notifications are enabled, and offers the option
of enabling or disabling the notifications, depending on the current
mode. The shortcut menu also presents a Perform Example Transaction
item, which will set the values of the component's StringProperty and
CountProperty properties. You can undo the last designer transaction using
the Undo command provided by the Visual Studio development environment.
*/
namespace DesignerTransactionSample
{
// Associate the DTDesigner with this component
[DesignerAttribute(typeof(DTDesigner))]
public class DTComponent : System.ComponentModel.Component
{
private string m_String;
private int m_Count;
public string StringProperty
{
get
{ return m_String; }
set
{ m_String = value; }
}
public int CountProperty
{
get
{ return m_Count; }
set
{ m_Count = value; }
}
private void InitializeComponent()
{
m_String = "Initial Value";
m_Count = 0;
}
}
internal class DTDesigner : ComponentDesigner
{
private bool notification_mode = false;
private int count = 10;
// The Verbs property is overridden from ComponentDesigner
public override DesignerVerbCollection Verbs
{
get
{
DesignerVerbCollection dvc = new DesignerVerbCollection();
dvc.Add( new DesignerVerb("Perform Example Transaction", new EventHandler(this.DoTransaction)) );
if(notification_mode)
dvc.Add(new DesignerVerb("End Designer Transaction Notifications", new EventHandler(this.UnlinkDTNotifications)));
else
dvc.Add(new DesignerVerb("Show Designer Transaction Notifications", new EventHandler(this.LinkDTNotifications))); return dvc;
}
}
public override void Initialize(System.ComponentModel.IComponent component)
{
base.Initialize(component);
IDesignerHost host = (IDesignerHost)GetService(typeof(IDesignerHost));
if(host == null)
{
MessageBox.Show("The IDesignerHost service interface could not be obtained.");
return;
}
if( MessageBox.Show("Press the Yes button to display notification message boxes for the designer transaction opened and closed notifications.","Link DesignerTransaction Notifications?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1, MessageBoxOptions.RightAlign) == DialogResult.Yes )
{
host.TransactionOpened += new EventHandler(OnDesignerTransactionOpened);
host.TransactionClosed += new DesignerTransactionCloseEventHandler(OnDesignerTransactionClosed);
notification_mode = true;
}
}
private void LinkDTNotifications(object sender, EventArgs e)
{
if(notification_mode == false)
{
IDesignerHost host = (IDesignerHost)GetService(typeof(IDesignerHost));
if(host != null)
{
notification_mode = true;
host.TransactionOpened += new EventHandler(OnDesignerTransactionOpened);
host.TransactionClosed += new DesignerTransactionCloseEventHandler(OnDesignerTransactionClosed);
}
}
}
private void UnlinkDTNotifications(object sender, EventArgs e)
{
if(notification_mode)
{
IDesignerHost host = (IDesignerHost)GetService(typeof(IDesignerHost));
if(host != null)
{
notification_mode = false;
host.TransactionOpened -= new EventHandler(OnDesignerTransactionOpened);
host.TransactionClosed -= new DesignerTransactionCloseEventHandler(OnDesignerTransactionClosed);
}
}
}
private void OnDesignerTransactionOpened(object sender, EventArgs e)
{
System.Windows.Forms.MessageBox.Show("A Designer Transaction was started. (TransactionOpened)");
}
private void OnDesignerTransactionClosed(object sender, DesignerTransactionCloseEventArgs e)
{
System.Windows.Forms.MessageBox.Show("A Designer Transaction was completed. (TransactionClosed)");
}
private void DoTransaction(object sender, EventArgs e)
{
IDesignerHost host = (IDesignerHost)GetService(typeof(IDesignerHost));
DesignerTransaction t = host.CreateTransaction("Change Text and Size");
/* The code within the using statement is considered to be a single transaction.
When the user selects Undo, the system will undo everything executed in this code block. */
using (t)
{
if(notification_mode)
System.Windows.Forms.MessageBox.Show("Entering a Designer-Initiated Designer Transaction");
// The .NET Framework automatically associates the TypeDescriptor with the correct component
PropertyDescriptor someText = TypeDescriptor.GetProperties(Component)["StringProperty"];
someText.SetValue(Component, "This text was set by the designer for this component.");
PropertyDescriptor anInteger = TypeDescriptor.GetProperties(Component)["CountProperty"];
anInteger.SetValue(Component, count);
count++;
// Complete the designer transaction.
t.Commit();
if(notification_mode)
System.Windows.Forms.MessageBox.Show("Designer-Initiated Designer Transaction Completed");
}
}
protected override void Dispose(bool disposing)
{
UnlinkDTNotifications(this, new EventArgs());
base.Dispose(disposing);
}
}
}
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Windows.Forms
Imports System.Windows.Forms.Design
' This sample demonstrates how to perform a series of actions in a designer
' transaction, how to change values of properties of a component from a
' designer, and how to complete transactions without being interrupted
' by other activities.
' To run this sample, add this code to a class library project and compile.
' Create a new Windows Forms project or load a form in the designer. Add a
' reference to the class library that was compiled in the first step.
' Right-click the Toolbox in design mode and click Customize Toolbox.
' Browse to the class library that was compiled in the first step and
' select OK until the DTComponent item appears in the Toolbox. Add an
' instance of this component to the form.
' When the component is created and added to the component tray for your
' design project, the Initialize method of the designer is called.
' This method displays a message box informing you that designer transaction
' event handlers are being registered unless you click Cancel. When you set
' properties in the properties window, each change will be encapsulated in
' a designer transaction, allowing the change to be undone later.
' When you right-click the component, the shortcut menu for the component
' is displayed. The designer constructs this menu according to whether
' designer transaction notifications are enabled, and offers the option
' of enabling or disabling the notifications, depending on the current
' mode. The shortcut menu also presents a Perform Example Transaction
' item which will set the values of the component's StringProperty and
' CountProperty properties. You can undo the last designer transaction using
' the Undo command provided by the Visual Studio development environment.
Namespace DesignerTransactionSample
' Associate the DTDesigner with this component
<DesignerAttribute(GetType(DTDesigner))> _
Public Class DTComponent
Inherits System.ComponentModel.Component
Private m_String As String
Private m_Count As Integer
Public Property StringProperty() As String
Get
Return m_String
End Get
Set(ByVal Value As String)
m_String = Value
End Set
End Property
Public Property CountProperty() As Integer
Get
Return m_Count
End Get
Set(ByVal Value As Integer)
m_Count = Value
End Set
End Property
Private Sub InitializeComponent()
m_String = "Initial Value"
m_Count = 0
End Sub
End Class
Friend Class DTDesigner
Inherits ComponentDesigner
Private notification_mode As Boolean = False
Private count As Integer = 10
' The Verbs property is overridden from ComponentDesigner
Public Overrides ReadOnly Property Verbs() As DesignerVerbCollection
Get
Dim dvc As New DesignerVerbCollection()
dvc.Add(New DesignerVerb("Perform Example Transaction", AddressOf Me.DoTransaction))
If notification_mode Then
dvc.Add(New DesignerVerb("End Designer Transaction Notifications", AddressOf Me.UnlinkDTNotifications))
Else
dvc.Add(New DesignerVerb("Show Designer Transaction Notifications", AddressOf Me.LinkDTNotifications))
End If
Return dvc
End Get
End Property
Public Overrides Sub Initialize(ByVal component As System.ComponentModel.IComponent)
MyBase.Initialize(component)
Dim host As IDesignerHost = CType(GetService(GetType(IDesignerHost)), IDesignerHost)
If host Is Nothing Then
MessageBox.Show("The IDesignerHost service interface could not be obtained.")
Return
End If
If MessageBox.Show("Press the Yes button to display notification message boxes for the designer transaction opened and closed notifications.", "Link DesignerTransaction Notifications?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1, MessageBoxOptions.RightAlign) = DialogResult.Yes Then
AddHandler host.TransactionOpened, AddressOf OnDesignerTransactionOpened
AddHandler host.TransactionClosed, AddressOf OnDesignerTransactionClosed
notification_mode = True
End If
End Sub
Private Sub LinkDTNotifications(ByVal sender As Object, ByVal e As EventArgs)
If notification_mode = False Then
Dim host As IDesignerHost = CType(GetService(GetType(IDesignerHost)), IDesignerHost)
If (host IsNot Nothing) Then
notification_mode = True
AddHandler host.TransactionOpened, AddressOf OnDesignerTransactionOpened
AddHandler host.TransactionClosed, AddressOf OnDesignerTransactionClosed
End If
End If
End Sub
Private Sub UnlinkDTNotifications(ByVal sender As Object, ByVal e As EventArgs)
If notification_mode Then
Dim host As IDesignerHost = CType(GetService(GetType(IDesignerHost)), IDesignerHost)
If (host IsNot Nothing) Then
notification_mode = False
RemoveHandler host.TransactionOpened, AddressOf Me.OnDesignerTransactionOpened
RemoveHandler host.TransactionClosed, AddressOf Me.OnDesignerTransactionClosed
End If
End If
End Sub
Private Sub OnDesignerTransactionOpened(ByVal sender As Object, ByVal e As EventArgs)
System.Windows.Forms.MessageBox.Show("A Designer Transaction was started. (TransactionOpened)")
End Sub
Private Sub OnDesignerTransactionClosed(ByVal sender As Object, ByVal e As DesignerTransactionCloseEventArgs)
System.Windows.Forms.MessageBox.Show("A Designer Transaction was completed. (TransactionClosed)")
End Sub
Private Sub DoTransaction(ByVal sender As Object, ByVal e As EventArgs)
Dim host As IDesignerHost = CType(GetService(GetType(IDesignerHost)), IDesignerHost)
Dim t As DesignerTransaction = host.CreateTransaction("Change Text and Size")
' The code within the using statement is considered to be a single transaction.
' When the user selects Undo, the system will undo everything executed in this code block.
Try
If (notification_mode) Then
System.Windows.Forms.MessageBox.Show("Entering a Designer-Initiated Designer Transaction")
End If
Dim someText As PropertyDescriptor = TypeDescriptor.GetProperties(Component)("StringProperty")
someText.SetValue(Component, "This text was set by the designer for this component.")
Dim anInteger As PropertyDescriptor = TypeDescriptor.GetProperties(Component)("CountProperty")
anInteger.SetValue(Component, count)
count = count + 1
Exit Try
Finally
t.Commit()
End Try
If (notification_mode) Then
System.Windows.Forms.MessageBox.Show("Designer-Initiated Designer Transaction Completed")
End If
End Sub
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
UnlinkDTNotifications(Me, New EventArgs())
MyBase.Dispose(disposing)
End Sub
End Class
End Namespace 'DesignerTransactionSample
Transactions can track actions that can be undone later. Changes made during a transaction can be reversed by canceling a transaction, which automatically attempts to reverse each change by setting each changed property to its pre-change value. Transactions can also improve performance during a series of operations by deferring updates to the display until the completion of the transaction.
When a transaction is in progress, some components defer their processing until the transaction has completed by listening to the TransactionOpening and TransactionClosed events. The Properties window, for example, does not update its display after a transaction has opened until the transaction has closed.
To use transactions for reversible or multiple operations, have your designer create a DesignerTransaction for each operation or series of operations which should be reversible. Be careful not to perform actions outside the transactions that might prevent a sequence of undo events from completing successfully.
You can obtain a new DesignerTransaction by calling the CreateTransaction method of an IDesignerHost. Be sure to obtain each DesignerTransaction from the active IDesignerHost in order to correctly integrate with the designer transaction processing mechanism, rather than creating a new DesignerTransaction directly.
To perform an action within a transaction, you must first create a transaction. Then you must call the OnComponentChanging method before each change or set of changes occurs, and the OnComponentChanged method after each change or set of changes occur. Finally, complete and close the transaction by calling the Commit method.
Note
When making changes to property values, use the SetValue method of a PropertyDescriptor, which calls the component change methods of the IComponentChangeService and creates a DesignerTransaction representing the change automatically.
To perform a transaction, complete the following steps:
Call CreateTransaction to obtain a DesignerTransaction that can be used to control the transaction.
Within a
try
block, for each action that you want to track with a DesignerTransaction, call the OnComponentChanging method, make the change or changes, then call the OnComponentChanged method to signal that the change or changes have been made.To complete the transaction, call Commit from within a
finally
block.
In C#, you can use the using
statement rather than a try/finally
block, such as in the following example.
using (host.CreateTransaction() {
// Insert your code here.
}
To cancel and attempt to roll back a transaction before it has been committed, call the Cancel method. When the Cancel method is invoked, the actions tracked by the DesignerTransaction are reversed to attempt to roll back the changes. To undo actions that occurred as part of earlier transactions, you must use the undo command provided by the development environment.
Designer |
Initializes a new instance of the DesignerTransaction class with no description. |
Designer |
Initializes a new instance of the DesignerTransaction class using the specified transaction description. |
Canceled |
Gets a value indicating whether the transaction was canceled. |
Committed |
Gets a value indicating whether the transaction was committed. |
Description |
Gets a description for the transaction. |
Cancel() |
Cancels the transaction and attempts to roll back the changes made by the events of the transaction. |
Commit() |
Commits this transaction. |
Dispose(Boolean) |
Releases the unmanaged resources used by the DesignerTransaction and optionally releases the managed resources. |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
Finalize() |
Releases the resources associated with this object. This override commits this transaction if it was not already committed. |
Get |
Serves as the default hash function. (Inherited from Object) |
Get |
Gets the Type of the current instance. (Inherited from Object) |
Memberwise |
Creates a shallow copy of the current Object. (Inherited from Object) |
On |
Raises the |
On |
Performs the actual work of committing a transaction. |
To |
Returns a string that represents the current object. (Inherited from Object) |
IDisposable. |
Releases all resources used by the DesignerTransaction. |
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
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