←Select platform

UndoRedoChanged Event

Summary

Occurs when the undo or redo buffer changes.

Syntax

C++

public event EventHandler UndoRedoChanged

  
Public Event UndoRedoChanged As EventHandler

public: 
event EventHandler^ UndoRedoChanged

Remarks

This event will be fired when the undo/redo buffer changes. This gives the application a chance to update the user interface if needed.

The undo/redo buffer changes whenever an object inside the Container changes either by user interaction through the user interface or by code.

You can use the [CanUndo](annautomation-canundo] and [CanRedo](annautomation-canredo] property to determine whether this AnnAutomation can undo or redo an operation.

For more information, refer to Undoing Automation Operations (Deprecated).

Example

This example updates an Undo and Redo menu handler's status.

using Leadtools; 
using Leadtools.Annotations; 
using Leadtools.WinForms; 
using Leadtools.Drawing; 
 
public void AnnAutomation_UndoRedoChanged(AnnAutomationManager manager) 
{ 
   // subscribe to the UndoRedoChanged event of all automations 
   foreach (AnnAutomation automation in manager.Automations) 
      automation.UndoRedoChanged += new EventHandler(automation_UndoRedoChanged); 
} 
 
private void automation_UndoRedoChanged(object sender, EventArgs e) 
{ 
   AnnAutomation automation = sender as AnnAutomation; 
 
   // assume _menuItemUndo is the Undo menu, and _menuItemRedo is the Redo menu 
   _menuItemUndo.Enabled = automation.CanUndo; 
   _menuItemRedo.Enabled = automation.CanRedo; 
}

Imports Leadtools 
Imports Leadtools.Annotations 
Imports Leadtools.WinForms 
Imports Leadtools.Drawing 
 
Public Sub AnnAutomation_UndoRedoChanged(ByVal manager As AnnAutomationManager) 
   ' subscribe to the UndoRedoChanged event of all automations 
   For Each automation As AnnAutomation In manager.Automations 
      AddHandler automation.UndoRedoChanged, AddressOf automation_UndoRedoChanged 
   Next automation 
End Sub 
 
Private Sub automation_UndoRedoChanged(ByVal sender As Object, ByVal e As EventArgs) 
   Dim automation As AnnAutomation = CType(IIf(TypeOf sender Is AnnAutomation, sender, Nothing), AnnAutomation) 
 
   ' assume _menuItemUndo is the Undo menu, and _menuItemRedo is the Redo menu 
   _menuItemUndo.Enabled = automation.CanUndo 
   _menuItemRedo.Enabled = automation.CanRedo 
End Sub