OleUndoEngine.UndoUnit Class

Article
04/29/2015

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

Inheritance Hierarchy

Object
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 UndoUnit _
    Implements IOleUndoUnit, IOleParentUndoUnit

protected class UndoUnit : UndoUnit, 
    IOleUndoUnit, IOleParentUndoUnit

protected ref class UndoUnit : public UndoUnit, 
    IOleUndoUnit, IOleParentUndoUnit

type UndoUnit =  
    class 
        inherit UndoUnit 
        interface IOleUndoUnit 
        interface IOleParentUndoUnit 
    end

protected class UndoUnit extends UndoUnit implements IOleUndoUnit, IOleParentUndoUnit

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 UndoUnit contains no events. (Inherited from UndoUnit.)
	Name	Gets the name of the UndoUnit. (Inherited from UndoUnit.)
	UndoEngine	Gets the parent UndoEngine. (Inherited from UndoUnit.)

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Methods

	Name	Description
	Close	Receives a call from the undo engine to close this unit. (Inherited from UndoUnit.)
	ComponentAdded	Receives a call from the UndoEngine in response to a ComponentAdded event. (Inherited from UndoUnit.)
	ComponentAdding	Receives a call from the UndoEngine in response to a ComponentAdding event. (Inherited from UndoUnit.)
	ComponentChanged	Receives a call from the UndoEngine in response to a ComponentChanged event. (Inherited from UndoUnit.)
	ComponentChanging	Receives a call from the UndoEngine in response to a ComponentChanging event. (Inherited from UndoUnit.)
	ComponentRemoved	Receives a call from the UndoEngine in response to a ComponentRemoved event. (Inherited from UndoUnit.)
	ComponentRemoving	Receives a call from the UndoEngine in response to a ComponentRemoving event. (Inherited from UndoUnit.)
	ComponentRename	Receives a call from the UndoEngine in response to a ComponentRename event. (Inherited from 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 the default hash function. (Inherited from Object.)
	GetService	Gets an instance of the requested service. (Inherited from 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 UndoUnit.)
	Undo	Performs an undo or redo action. (Inherited from UndoUnit.)
	UndoCore	Called by Undo to perform an undo action. (Inherited from 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 UndoUnit, IOleParentUndoUnit and

IOleUndoUnit

By implementing 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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