OleUndoEngine.UndoUnit Class

Article
07/12/2014

Extends support for encapsulating a unit of work that a user can undo.

Inheritance Hierarchy

System.Object
System.ComponentModel.Design.UndoEngine.UndoUnit
Microsoft.VisualStudio.Shell.Design.OleUndoEngine.UndoUnit

Namespace: Microsoft.VisualStudio.Shell.Design
Assembly: Microsoft.VisualStudio.Shell.Design (in Microsoft.VisualStudio.Shell.Design.dll)

Syntax

'Declaration
Protected Class UndoUnit _
    Inherits UndoEngine.UndoUnit _
    Implements IOleParentUndoUnit, IOleUndoUnit

protected class UndoUnit : UndoEngine.UndoUnit, 
    IOleParentUndoUnit, IOleUndoUnit

protected ref class UndoUnit : public UndoEngine::UndoUnit, 
    IOleParentUndoUnit, IOleUndoUnit

type UndoUnit =  
    class 
        inherit UndoEngine.UndoUnit 
        interface IOleParentUndoUnit 
        interface IOleUndoUnit 
    end

protected class UndoUnit extends UndoEngine.UndoUnit implements IOleParentUndoUnit, IOleUndoUnit

The OleUndoEngine.UndoUnit type exposes the following members.

Constructors

	Name	Description
	OleUndoEngine.UndoUnit	Initializes a new instance of the OleUndoEngine.UndoUnit class.

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Properties

	Name	Description
	IsEmpty	Gets a value indicating whether the UndoEngine.UndoUnit contains no events. (Inherited from UndoEngine.UndoUnit.)
	Name	Gets the name of the UndoEngine.UndoUnit. (Inherited from UndoEngine.UndoUnit.)
	UndoEngine	Gets the parent UndoEngine. (Inherited from UndoEngine.UndoUnit.)

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Methods

	Name	Description
	Close	Receives a call from the undo engine to close this unit. (Inherited from UndoEngine.UndoUnit.)
	ComponentAdded	Receives a call from the UndoEngine in response to a ComponentAdded event. (Inherited from UndoEngine.UndoUnit.)
	ComponentAdding	Receives a call from the UndoEngine in response to a ComponentAdding event. (Inherited from UndoEngine.UndoUnit.)
	ComponentChanged	Receives a call from the UndoEngine in response to a ComponentChanged event. (Inherited from UndoEngine.UndoUnit.)
	ComponentChanging	Receives a call from the UndoEngine in response to a ComponentChanging event. (Inherited from UndoEngine.UndoUnit.)
	ComponentRemoved	Receives a call from the UndoEngine in response to a ComponentRemoved event. (Inherited from UndoEngine.UndoUnit.)
	ComponentRemoving	Receives a call from the UndoEngine in response to a ComponentRemoving event. (Inherited from UndoEngine.UndoUnit.)
	ComponentRename	Receives a call from the UndoEngine in response to a ComponentRename event. (Inherited from UndoEngine.UndoUnit.)
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetService	Gets an instance of the requested service. (Inherited from UndoEngine.UndoUnit.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Returns a String that represents the current name of the unit. (Inherited from UndoEngine.UndoUnit.)
	Undo	Performs an undo or redo action. (Inherited from UndoEngine.UndoUnit.)
	UndoCore	Called by Undo to perform an undo action. (Inherited from UndoEngine.UndoUnit.)

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Explicit Interface Implementations

	Name	Description
	IOleParentUndoUnit.Add	Adds an undo unit to the parent collection.
	IOleParentUndoUnit.Close	Closes the specified parent undo unit.
	IOleParentUndoUnit.Do	Performs the undo operation.
	IOleParentUndoUnit.FindUnit	Searches for the specified unit in the child undo unit hierarchy.
	IOleParentUndoUnit.GetDescription	Gets the description of the undo unit.
	IOleParentUndoUnit.GetParentState	Gets the state of the top-level parent undo unit.
	IOleParentUndoUnit.GetUnitType	Gets the type of the undo unit.
	IOleParentUndoUnit.OnNextAdd	Notifies the last undo unit in the collection that a new unit has been added.
	IOleParentUndoUnit.Open	Opens an undo unit.
	IOleUndoUnit.Do	Performs the undo operation.
	IOleUndoUnit.GetDescription	Gets the description of the undo unit.
	IOleUndoUnit.GetUnitType	Gets the type of the undo unit.
	IOleUndoUnit.OnNextAdd	Notifies the last undo unit in the collection that a new unit has been added.

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Remarks

The OleUndoEngine.UndoUnit class is a nested class within OleUndoEngine that encapsulates an action that a user can undo by monitoring change notifications and builds up a list of events for each change.

It saves these events using IDesignerSerializationService. An OleUndoEngine.UndoUnit receives event notifications for changes through several methods derived from UndoEngine.UndoUnit, IOleParentUndoUnit and

IOleUndoUnit

By implementing UndoEngine.UndoUnit, IOleParentUndoUnit, and IOleUndoUnit, OleUndoEngine.UndoUnit is able to better support linked undo by providing explicit connection between parent and child undo units.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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