mauda.undoredo
Class UndoRedo

java.lang.Object
  mauda.undoredo.UndoRedo

All Implemented Interfaces:

ExerciseUpdateListener

Direct Known Subclasses:

AnimatedUndoRedo

public class UndoRedo
extends java.lang.Object
implements ExerciseUpdateListener

Stores copies of the current data-structure (e.g. FibHeap), so that it is possible to quickly undo/redo operations. If a animated redo needed, please use AnimatedUndoRedo.

Author:

Markus Krebs

Constructor Summary

UndoRedo(Exercise exercise)
Creates a UndoRedo-Handler.

Method Summary

boolean	canBack() Check if a step back is possible
boolean	canForward() Check if a step forward is possible
boolean	canRedo() Check if a redo is possible
boolean	canUndo() Check if an undo is possible
void	clear() Clears all entries in the undo-redo-queue
void	exerciseUpdate(ExerciseUpdateEvent e) Invoked when an Event occures
java.lang.Object	getDSObject() Method for retrieving the current data-structure-object,
java.lang.Object	getEntry(int offset) Methode for retrieving a specific data-structure-object
int	getRedoJumpDelta() Returns the new delta-positoin to jump to, when the next action should be a redo.
int	getUndoJumpDelta() Returns the new delta-position to jump to, when the next action should be an undo.
void	initialSnapshot(java.lang.Object o) Creates a snapshot for a given operation.
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

UndoRedo

public UndoRedo(Exercise exercise)

Creates a UndoRedo-Handler.

Parameters:

exercise - The Exercise

Method Detail

exerciseUpdate

public void exerciseUpdate(ExerciseUpdateEvent e)

Description copied from interface: ExerciseUpdateListener

Invoked when an Event occures

Specified by:

exerciseUpdate in interface ExerciseUpdateListener

Parameters:

e - The event

initialSnapshot

public void initialSnapshot(java.lang.Object o)

Creates a snapshot for a given operation.
In this data-structure (UndoRedo) there must be always one entry at the beginning because if the user jumps to the beginning of the exercise a valid data-structure (e.g. an empty one) is necessary. This method generates this initial data-structure.

Parameters:

o - generally deliver null

canBack

public boolean canBack()

Check if a step back is possible

Returns:

Returns true, if possible, false, otherwise

canForward

public boolean canForward()

Check if a step forward is possible

Returns:

Returns true, if possible, false, otherwise

canUndo

public boolean canUndo()

Check if an undo is possible

Returns:

Returns true, if possible, false, otherwise

canRedo

public boolean canRedo()

Check if a redo is possible

Returns:

Returns true, if possible, false, otherwise

getUndoJumpDelta

public int getUndoJumpDelta()

Returns the new delta-position to jump to, when the next action should be an undo.

Returns:

relative jump-delta

getRedoJumpDelta

public int getRedoJumpDelta()

Returns the new delta-positoin to jump to, when the next action should be a redo.

Returns:

relative jump-delta

clear

public void clear()

Clears all entries in the undo-redo-queue

getDSObject

public java.lang.Object getDSObject()

Method for retrieving the current data-structure-object,

Returns:

The data-structure-object, e.g. FibHeap

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

getEntry

public java.lang.Object getEntry(int offset)

Methode for retrieving a specific data-structure-object

Parameters:

offset - The offset inside the undo-redo-queue

Returns:

The data-structure-object, e.g. FibHeap