IDocumentUndoManager

All Known Implementing Classes:

DocumentUndoManager
```
public interface IDocumentUndoManager
```
Interface for a document undo manager. Tracks changes in a document and builds a history of text commands that describe the undoable changes to the document.
Clients must explicitly connect to the undo manager to express their interest in the undo history. Clients should disconnect from the undo manager when they are no longer interested in tracking the undo history. If there are no clients connected to the undo manager, it will not track the document's changes and will dispose of any history that was previously kept.

Clients may also listen to the undo manager for notifications before and after undo or redo events are performed. Clients must connect to the undo manager in addition to registering listeners.

Clients may implement this interface.

Since:

3.2

See Also:

DocumentUndoManagerRegistry, IDocumentUndoListener, IDocument

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`addDocumentUndoListener(IDocumentUndoListener listener)` Adds the specified listener to the list of document undo listeners that are notified before and after changes are undone or redone in the document.
`void`	`beginCompoundChange()` Signals the undo manager that all subsequent changes until `endCompoundChange` is called are to be undone in one piece.
`void`	`commit()` Closes the currently open text edit and open a new one.
`void`	`connect(java.lang.Object client)` Connects to the undo manager.
`void`	`disconnect(java.lang.Object client)` Disconnects from the undo manager.
`void`	`endCompoundChange()` Signals the undo manager that the sequence of changes which started with `beginCompoundChange` has been finished.
`IUndoContext`	`getUndoContext()` Returns the undo context registered for this document
`void`	`redo()` Repeats the most recently rolled back text change.
`boolean`	`redoable()` Returns whether at least one text change can be repeated.
`void`	`removeDocumentUndoListener(IDocumentUndoListener listener)` Removes the specified listener from the list of document undo listeners.
`void`	`reset()` Resets the history of the undo manager.
`void`	`setMaximalUndoLevel(int undoLimit)` Sets the limit of the undo history to the specified value.
`void`	`transferUndoHistory(IDocumentUndoManager manager)` Transfers the undo history from the specified document undo manager to this undo manager.
`void`	`undo()` Rolls back the most recently executed text change.
`boolean`	`undoable()` Returns whether at least one text change can be rolled back.

- Method Detail
  - addDocumentUndoListener
```
void addDocumentUndoListener(IDocumentUndoListener listener)
```
    Adds the specified listener to the list of document undo listeners that are notified before and after changes are undone or redone in the document. This method has no effect if the instance being added is already in the list.
    Notifications will not be received if there are no clients connected to the receiver. Registering a document undo listener does not implicitly connect the listener to the receiver.
    
    Document undo listeners must be prepared to receive notifications from a background thread. Any UI access occurring inside the implementation must be properly synchronized using the techniques specified by the client's widget library.
    
    Parameters:
    
    listener - the document undo listener to be added as a listener
  - removeDocumentUndoListener
```
void removeDocumentUndoListener(IDocumentUndoListener listener)
```
    Removes the specified listener from the list of document undo listeners.
    Removing a listener which is not registered has no effect
    
    Parameters:
    
    listener - the document undo listener to be removed
  - getUndoContext
```
IUndoContext getUndoContext()
```
    Returns the undo context registered for this document
    
    Returns:
    
    the undo context registered for this document
  - commit
```
void commit()
```
    Closes the currently open text edit and open a new one.
  - connect
```
void connect(java.lang.Object client)
```
    Connects to the undo manager. Used to signify that a client is monitoring the history kept by the undo manager. This message has no effect if the client is already connected.
    
    Parameters:
    
    client - the object connecting to the undo manager
  - disconnect
```
void disconnect(java.lang.Object client)
```
    Disconnects from the undo manager. Used to signify that a client is no longer monitoring the history kept by the undo manager. If all clients have disconnected from the undo manager, the undo history will be deleted.
    
    Parameters:
    
    client - the object disconnecting from the undo manager
  - beginCompoundChange
```
void beginCompoundChange()
```
    Signals the undo manager that all subsequent changes until endCompoundChange is called are to be undone in one piece.
  - endCompoundChange
```
void endCompoundChange()
```
    Signals the undo manager that the sequence of changes which started with beginCompoundChange has been finished. All subsequent changes are considered to be individually undo-able.
  - setMaximalUndoLevel
```
void setMaximalUndoLevel(int undoLimit)
```
    Sets the limit of the undo history to the specified value. The provided limit will supersede any previously set limit.
    
    Parameters:
    
    undoLimit - the length of this undo manager's history
  - reset
```
void reset()
```
    Resets the history of the undo manager. After that call, there aren't any undo-able or redo-able text changes.
  - undoable
```
boolean undoable()
```
    Returns whether at least one text change can be rolled back.
    
    Returns:
    
    true if at least one text change can be rolled back
  - redoable
```
boolean redoable()
```
    Returns whether at least one text change can be repeated. A text change can be repeated only if it was executed and rolled back.
    
    Returns:
    
    true if at least on text change can be repeated
  - undo
```
void undo()
   throws ExecutionException
```
    Rolls back the most recently executed text change.
    
    Throws:
    
    ExecutionException - if an exception occurred during undo
  - redo
```
void redo()
   throws ExecutionException
```
    Repeats the most recently rolled back text change.
    
    Throws:
    
    ExecutionException - if an exception occurred during redo
  - transferUndoHistory
```
void transferUndoHistory(IDocumentUndoManager manager)
```
    Transfers the undo history from the specified document undo manager to this undo manager. This message should only be used when it is known that the content of the document of the original undo manager when the last undo operation was recorded is the same as this undo manager's current document content, since the undo history is based on document indexes. It is the responsibility of the caller to ensure that this call is used correctly.
    
    Parameters:
    
    manager - the document undo manger whose history is to be transferred to the receiver

Interface IDocumentUndoManager

Method Summary

Method Detail

addDocumentUndoListener

removeDocumentUndoListener

getUndoContext

commit

connect

disconnect

beginCompoundChange

endCompoundChange

setMaximalUndoLevel

reset

undoable

redoable

undo

redo

transferUndoHistory