org.vectomatic.client.rep.command
Class CommandHistory

java.lang.Object
  org.vectomatic.client.rep.command.CommandHistory

public class CommandHistory
extends Object

Class to represent an undo/redo stack of commands with a fixed depth. The oldest command is automatically removed when the stack capacity is exhausted.

Author:

Lukas Laag

Constructor Summary

CommandHistory(int capacity)
Constructor

Method Summary

void	addCommand(ICommand command) Adds a new command to the stack
void	addCommandHistoryListener(ICommandHistoryListener listener)
boolean	canRedo() Returns true if the command stack contains a command which can be redone false otherwise.
boolean	canUndo() Returns true if the command stack contains a command which can be undone false otherwise.
void	fireCommandHistoryChange()
int	getCapacity() Returns the stack capacity
ICommand[]	getCommands() Gets all the commands currently in the stack
int	getCurrentCommand() Returns the index of the current command in the array returned by getCommands().
ICommand	getRedoCommand() Returns the command which will be redone if undo is invoked
ICommand	getUndoCommand() Returns the command which will be undone if undo is invoked
boolean	needsSaving()
void	purge() Clears the stack
void	redo() Redoes the previously undone command
void	removeCommandHistoryListener(ICommandHistoryListener listener)
void	setCapacity(int capacity) Specifies a new capacity for the stack If the new capacity is smaller than the previous one, a proportional window of commands around the current command will be kept.
void	setSavePoint()
void	undo() Undoes the current command

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CommandHistory

public CommandHistory(int capacity)

Constructor

Parameters:

capacity - The depth of the undo stack

Method Detail

canUndo

public boolean canUndo()

Returns true if the command stack contains a command which can be undone false otherwise.

Returns:

true if the command stack contains a command which can be undone false otherwise.

canRedo

public boolean canRedo()

Returns true if the command stack contains a command which can be redone false otherwise.

Returns:

true if the command stack contains a command which can be redone false otherwise.

undo

public void undo()

Undoes the current command

redo

public void redo()

Redoes the previously undone command

addCommand

public void addCommand(ICommand command)

Adds a new command to the stack

Parameters:

command - the command to add

getUndoCommand

public ICommand getUndoCommand()

Returns the command which will be undone if undo is invoked

Returns:

getRedoCommand

public ICommand getRedoCommand()

Returns the command which will be redone if undo is invoked

Returns:

getCommands

public ICommand[] getCommands()

Gets all the commands currently in the stack

Returns:

getCurrentCommand

public int getCurrentCommand()

Returns the index of the current command in the array returned by getCommands(). It can vary between 0 and N where N is the number of commands in the stack. 0 means before the least recent command (redo is possible, undo is impossible). N means after the most recent command (redo is impossible, undo is possible)

Returns:

purge

public void purge()

Clears the stack

setCapacity

public void setCapacity(int capacity)

Specifies a new capacity for the stack If the new capacity is smaller than the previous one, a proportional window of commands around the current command will be kept.

Parameters:

capacity -

getCapacity

public int getCapacity()

Returns the stack capacity

Returns:

addCommandHistoryListener

public void addCommandHistoryListener(ICommandHistoryListener listener)

removeCommandHistoryListener

public void removeCommandHistoryListener(ICommandHistoryListener listener)

fireCommandHistoryChange

public void fireCommandHistoryChange()

setSavePoint

public void setSavePoint()

needsSaving

public boolean needsSaving()