This example will manually add a new rectangle object to an automation object and then start editing it.

Visual Basic

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Public Sub AnnAutomation_BeginUndo(ByVal automation As AnnAutomation)    ' first create a new undo node    automation.BeginUndo()    Try       ' add a new rectangle object       Dim rectObj As AnnRectangleObject = New AnnRectangleObject()       rectObj.Bounds = New AnnRectangle(100, 100, 200, 200, AnnUnit.Pixel)       rectObj.Pen = New AnnPen(Color.Blue, New AnnLength(1, AnnUnit.Pixel))       rectObj.Brush = New AnnSolidBrush(Color.Yellow)       automation.Container.Objects.Add(rectObj)       ' "select" this object       automation.StartEditing(rectObj, False)       ' commit the undo node       automation.EndUndo()    Catch ex As Exception       ' in case of errors, cancel the undo node       automation.CancelUndo()       Throw ex    End Try    MessageBox.Show("Object has been added as is now selected. Next will call //Undo// to undo the operation")    automation.Undo()    MessageBox.Show("Operation has been undone. Next will call //Redo// to redo the operation")    automation.Redo()    MessageBox.Show("Object should be back and selected") End Sub

C#

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public void AnnAutomation_BeginUndo(AnnAutomation automation)  {     // first create a new undo node     automation.BeginUndo();     try     {        // add a new rectangle object        AnnRectangleObject rectObj = new AnnRectangleObject();        rectObj.Bounds = new AnnRectangle(100, 100, 200, 200, AnnUnit.Pixel);        rectObj.Pen = new AnnPen(Color.Blue, new AnnLength(1, AnnUnit.Pixel));        rectObj.Brush = new AnnSolidBrush(Color.Yellow);        automation.Container.Objects.Add(rectObj);          // "select" this object        automation.StartEditing(rectObj, false);          // commit the undo node        automation.EndUndo();     }     catch(Exception ex)     {        // in case of errors, cancel the undo node        automation.CancelUndo();        throw ex;     }       MessageBox.Show("Object has been added as is now selected.  Next will call //Undo// to undo the operation");     automation.Undo();     MessageBox.Show("Operation has been undone.  Next will call //Redo// to redo the operation");     automation.Redo();     MessageBox.Show("Object should be back and selected");  }

Use this method along with the EndUndo and CancelUndo methods to programmatically add a node to the undo stack maintained by this AnnAutomation. Typically, you add an undo node as follows:

1. Call the BeginUndo method before you make any changes to create a new node.
2. Perform any changes to the AnnAutomation object.
3. Call the EndUndo method to commit this undo node into the undo stack of the AnnAutomation object.
4. In case of errors (typically in a catch statement), call the CancelUndo method to remove the node and cancel the operation.

You do not need to manually call the BeginUndo, EndUndo or CancelUndo methods when calling methods from this AnnAutomation object directly. The AnnAutomation object will internally do this for you. For example, when you call the AnnAutomation.Delete method to delete the object(s) currently being edited, the AnnAutomation object will perform the above sequence internally to add the undo node.

Use the UndoCapacity property to get or set the number of user actions that can be reversed using the Undo method, or re-applied using the Redo method. The default for the UndoCapacity property is 10 actions.

For more information, refer to Undoing Automation Operations.

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

Reference