UndoCaretaker (ICEpdf :: Viewer : Swing/AWT Viewer RI 7.3.1 API)

java.lang.Object
- org.icepdf.ri.common.UndoCaretaker

```
public class UndoCaretaker
extends Object
```
Undo caretaker implementation for the Viewer RI. Currently only annotation can be manipulate but this class can easily handle any class that implements the Memento interfce.

Since:

4.0

Constructor Summary

Constructors
Constructor Description

UndoCaretaker()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`addState(Memento previousState, Memento newState)`	Adds the give states to the history list.
`boolean`	`isRedo()`	Gets the status of the redo command.
`boolean`	`isUndo()`	Gets the status of the undo command.
`Memento`	`redo()`	Redo the last state change.
`Memento`	`undo()`	Undo the last state change.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - UndoCaretaker
```
public UndoCaretaker()
```
- Method Detail
  - undo
```
public Memento undo()
```
    Undo the last state change. Only possible if there are items in the undo history list.
  - isUndo
```
public boolean isUndo()
```
    Gets the status of the undo command.
    
    Returns:
    
    true if an undo command is possible, false if undo can not be done.
  - redo
```
public Memento redo()
```
    Redo the last state change. ONly possible if there have been previous undo call.
  - isRedo
```
public boolean isRedo()
```
    Gets the status of the redo command.
    
    Returns:
    
    true if an redo command is possible, false if the redo can not be done.
  - addState
```
public void addState(Memento previousState,
                     Memento newState)
```
    Adds the give states to the history list.
    
    Parameters:
    
    previousState - previous state
    
    newState - new state.