UndoCollection Class

The UndoCollection class is used to manage operations that need undo/redo functinality. The collection contains properties to specify the number of allowed operations to undo or redo.

Inheritance Hierarchy

SystemObject
  SystemMarshalByRefObject
    Atalasoft.ImagingMarshalByRefReadOnlyCollectionBase
      Atalasoft.ImagingUndoCollection

Namespace: Atalasoft.Imaging
Assembly: Atalasoft.dotImage (in Atalasoft.dotImage.dll) Version: 11.4.0.9.0.377 (.NET 4.5.2, x86)

Syntax

Copy

public class UndoCollection : MarshalByRefReadOnlyCollectionBase, 
	IDisposable

Public Class UndoCollection
	Inherits MarshalByRefReadOnlyCollectionBase
	Implements IDisposable

The UndoCollection type exposes the following members.

Properties

	Name	Description
	Count	The number of items in the collection. (Inherited from MarshalByRefReadOnlyCollectionBase.)
	InnerList	Gets the ArrayList stored within the collection. (Inherited from MarshalByRefReadOnlyCollectionBase.)
	IsSynchronized	Gets a value indicating whether access to the collection is synchronized (thread-safe). (Inherited from MarshalByRefReadOnlyCollectionBase.)
	Item	Gets the undo item.
	Levels	Gets or set the number of Undo levels in this collection.
	NumRedos	Gets the current number of redos in the collection.
	NumUndos	Gets the current number of undos in the collection.
	SyncRoot	Gets an object that can be used to synchronize access to the collection. (Inherited from MarshalByRefReadOnlyCollectionBase.)

Top

Methods

	Name	Description
	Add	Add a new undo level to the undo collection specifying the description and if the Image is copied.
	Clear	Clears the undo/redo collection items.
	CopyTo(Array, Int32)	Copies the collection items into an array. (Inherited from MarshalByRefReadOnlyCollectionBase.)
	CopyTo(UndoLevel, Int32)	Copies the UndoLevels into an array.
	CreateObjRef	Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
	Dispose	Clean up unmanaged resources by disposing each AtalaImage in the collection.
	Dispose(Boolean)	Releases unmanaged and - optionally - managed resources.
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Finalizes an instance of the UndoCollection class. (Overrides ObjectFinalize.)
	GetEnumerator	Returns a reference to an IEnumerator interface, whose purpose is to grant access to an enumeration's items. (Inherited from MarshalByRefReadOnlyCollectionBase.)
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetLifetimeService	Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	InitializeLifetimeService	Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	MemberwiseClone(Boolean)	Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
	OnGetCurrentImageCollection	Raises the [E:GetCurrentImageCollection] event.
	OnNewImageCollection	Raises the [E:NewImageCollection] event.
	Redo	The Redo method redo's the most recent udno in this UndoCollection.
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Undo	The Undo method undo's the most recently added item to this UndoCollection.

Top

Remarks

NOTE: The UndoCollection class is intended for use in the Workspace class only, and should not be used on its own. The UndoCollection relies on the Workspace'sImageCollection in order to save the current images.

The undo collection may be used to create an Undo/Redo menu in your project. The Add method should be called at the point you want to save as the 'undo point' (for examble, BEFORE an ImageCommand is applied). To undo or redo an operation, simply call the Undo or Redo methods. You can access the Description property to determine what the next undo or redo will accomplish. The following code example shows how this is done.

Examples

Accessing the description of the next operation to undo/redo.

UndoDescriptionCS (C#)

Copy

WorkspaceViewer Viewer;
...
string undoDescription = Viewer.Undos[Viewer.Undos.Count - Viewer.Undos.NumUndos].Description;
string redoDescription = Viewer.Undos[Viewer.Undos.Count - Viewer.Undos.NumUndos - 1].Description;

UndoDescriptionVB (Visual Basic)

Copy

Dim Viewer As WorkspaceViewer
...
Dim undoDescription As String = Viewer.Undos(Viewer.Undos.Count - Viewer.Undos.NumUndos).Description 
Dim redoDescription As String = Viewer.Undos(Viewer.Undos.Count - Viewer.Undos.NumUndos - 1).Description

Reference

Atalasoft.Imaging Namespace