jimm.datavision.gui.cmd
Class CommandHistory

java.lang.Object
  jimm.datavision.gui.cmd.CommandHistory

public class CommandHistory
extends java.lang.Object

A command history holds comands and manages undo and redo behavior. To use a new command for the first time, pass it to perform. You can then call undo and redo to walk the command history chain.

Author:

Jim Menard, jimm@io.com

Field Summary

protected int	baselineIndex If the command index is different than the baseline index then something has changed, and isChanged will return true.
protected int	commandIndex
protected java.util.ArrayList	commands
protected javax.swing.JMenuItem	redoMenuItem
protected javax.swing.JMenuItem	undoMenuItem

Constructor Summary

CommandHistory()

CommandHistory(javax.swing.JMenuItem undoMenuItem, javax.swing.JMenuItem redoMenuItem)

Method Summary

void	add(Command command) Add a command to the history list without performing it.
boolean	canRedo() Answers the question, "Is there anything to redo?"
boolean	canUndo() Answers the question, "Is there anything to undo?"
java.lang.String	getCommandName(int index) Return the name of the command at index.
java.lang.String	getRedoName() Return the name of the command that would be redone were one to call redo().
java.lang.String	getUndoName() Return the name of the command that would be undone were one to call undo().
boolean	isChanged() Answers the question, "Has anything changed?"
void	perform(Command command) Perform a command and add it to the history list.
void	redo() Redo the command under the the history cursor.
void	setBaseline() Resets the baseline index.
void	setMenuItems(javax.swing.JMenuItem undoMenuItem, javax.swing.JMenuItem redoMenuItem)
void	undo() Undo the command at the history cursor.
protected void	updateMenu()
protected void	updateMenuItem(javax.swing.JMenuItem item, java.lang.String verb, java.lang.String cmdName, boolean canDo)

Methods inherited from class java.lang.Object

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

Field Detail

commands

protected java.util.ArrayList commands

commandIndex

protected int commandIndex

baselineIndex

protected int baselineIndex

If the command index is different than the baseline index then something has changed, and isChanged will return true.

undoMenuItem

protected javax.swing.JMenuItem undoMenuItem

redoMenuItem

protected javax.swing.JMenuItem redoMenuItem

Constructor Detail

CommandHistory

public CommandHistory()

CommandHistory

public CommandHistory(javax.swing.JMenuItem undoMenuItem,
                      javax.swing.JMenuItem redoMenuItem)

Method Detail

setMenuItems

public void setMenuItems(javax.swing.JMenuItem undoMenuItem,
                         javax.swing.JMenuItem redoMenuItem)

canUndo

public boolean canUndo()

Answers the question, "Is there anything to undo?"

canRedo

public boolean canRedo()

Answers the question, "Is there anything to redo?"

setBaseline

public void setBaseline()

Resets the baseline index. The method isChanged returns false only when the baseline index is equal to the current command index.

isChanged

public boolean isChanged()

Answers the question, "Has anything changed?"

add

public void add(Command command)

Add a command to the history list without performing it. If the history cursor is not at the top of the stack, first erase all of the commands after the cursor.

Parameters:

command - the command to add

perform

public void perform(Command command)

Perform a command and add it to the history list. If the history cursor is not at the top of the stack, first erase all of the commands after the cursor.

Parameters:

command - the command to perform

undo

public void undo()

Undo the command at the history cursor.

redo

public void redo()

Redo the command under the the history cursor.

getUndoName

public java.lang.String getUndoName()

Return the name of the command that would be undone were one to call undo(). Returns null if there is no such command.

getRedoName

public java.lang.String getRedoName()

Return the name of the command that would be redone were one to call redo(). Returns null if there is no such command.

getCommandName

public java.lang.String getCommandName(int index)

Return the name of the command at index. Returns null if there is no such command.

updateMenu

protected void updateMenu()

updateMenuItem

protected void updateMenuItem(javax.swing.JMenuItem item,
                              java.lang.String verb,
                              java.lang.String cmdName,
                              boolean canDo)