com.bbn.openmap.event
Class UndoStack

java.lang.Object
  com.bbn.openmap.MapHandlerChild
      com.bbn.openmap.OMComponent
          com.bbn.openmap.event.UndoStack

All Implemented Interfaces:

LightMapHandlerChild, PropertyConsumer, java.awt.event.ActionListener, java.beans.beancontext.BeanContextChild, java.beans.beancontext.BeanContextMembershipListener, java.util.EventListener

public class UndoStack
extends OMComponent
implements java.awt.event.ActionListener

Provides a stack of actions that can be undone/redone. The UndoEvent objects contain the information needed to implement the actions. The UndoStack is told to push UndoEvents on their source objects by UndoStackTriggers using a regular ActionListener/ActionEvent mechanism. The UndoStack is an ActionListener to the triggers (GUI buttons/menu items that say Undo or Redo).

Field Summary

static java.lang.String	ClearCmd
static java.lang.String	ClearRedoCmd
static java.lang.String	ClearUndoCmd
protected UndoEvent	currentState The notion of the current state is important.
static int	DEFAULT_MAX_SIZE
static java.lang.String	RedoCmd
protected java.util.Stack<UndoEvent>	redoStack
static int	REMEMBER_ALL
protected int	stackSize
protected UndoStackSupport	triggers
static java.lang.String	UndoCmd
protected java.util.Stack<UndoEvent>	undoStack

Fields inherited from class com.bbn.openmap.OMComponent

i18n, propertyPrefix

Fields inherited from class com.bbn.openmap.MapHandlerChild

beanContextChildSupport, isolated

Fields inherited from interface com.bbn.openmap.PropertyConsumer

EditorProperty, initPropertiesProperty, LabelEditorProperty, ScopedEditorProperty

Constructor Summary

UndoStack()

Method Summary

void	actionPerformed(java.awt.event.ActionEvent ae)
void	addUndoStackTrigger(UndoStackTrigger trigger) UndoStackTriggers should call this method to add themselves for stack notifications, and all will be well.
void	clearStacks(boolean clearUndoStack, boolean clearRedoStack) Clear out the chosen undo stacks and fire an event to update the triggers on stack status.
void	fireStackStatus()
protected UndoEvent	getWhatWillHappenNextFromStack(java.util.Stack<UndoEvent> stack)
protected void	redo() Take a UndoEvent off the forwardStack, and push it on the backStack.
protected void	rememberLastThing(UndoEvent event) Put a new UndoEvent on the backStack, to remember for later in case we need to back up.
void	removeUndoStackTrigger(UndoStackTrigger trigger) UndoStackTriggers should call this method to remove themselves from stack notifications, and all will be well.
void	setTheWayThingsAre(UndoEvent event) Sets the current state of some object on the stack.
protected void	undo() Take a UndoEvent off the backStack, and push it on the forward stack, and invoke the new currentState so the source component gets modified.

Methods inherited from class com.bbn.openmap.OMComponent

getProperties, getPropertyInfo, getPropertyPrefix, setProperties, setProperties, setPropertyPrefix

Methods inherited from class com.bbn.openmap.MapHandlerChild

addPropertyChangeListener, addVetoableChangeListener, childrenAdded, childrenRemoved, findAndInit, findAndInit, findAndUndo, firePropertyChange, fireVetoableChange, getBeanContext, isIsolated, removePropertyChangeListener, removeVetoableChangeListener, setBeanContext, setIsolated

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAX_SIZE

public static final int DEFAULT_MAX_SIZE

See Also:

Constant Field Values

REMEMBER_ALL

public static final int REMEMBER_ALL

See Also:

Constant Field Values

currentState

protected transient UndoEvent currentState

The notion of the current state is important. When the user does something, a component that is interested in undo/redo should push a current state to this stack. This current state reflects the state of some object at the current time. If another state gets set, then the old state is now put on the undo stack. If the undo command is given to this stack, then an event is popped off the undo stack, set to be the current state. The old state gets pushed to the redo stack.

stackSize

protected int stackSize

UndoCmd

public static final transient java.lang.String UndoCmd

See Also:

Constant Field Values

RedoCmd

public static final transient java.lang.String RedoCmd

See Also:

Constant Field Values

ClearUndoCmd

public static final transient java.lang.String ClearUndoCmd

See Also:

Constant Field Values

ClearRedoCmd

public static final transient java.lang.String ClearRedoCmd

See Also:

Constant Field Values

ClearCmd

public static final transient java.lang.String ClearCmd

See Also:

Constant Field Values

undoStack

protected final java.util.Stack<UndoEvent> undoStack

redoStack

protected final java.util.Stack<UndoEvent> redoStack

triggers

protected final UndoStackSupport triggers

Constructor Detail

UndoStack

public UndoStack()

Method Detail

setTheWayThingsAre

public void setTheWayThingsAre(UndoEvent event)

Sets the current state of some object on the stack. The stack doesn't care what that event/state represents, since it has all the info needed to tell components how to get back to this state later. Anyway, this current state kinda hangs out in limbo. If another event/state comes in, the current state gets pushed on the undo stack. The redo stack gets cleared, since a new state path forward has been established.

Parameters:

event -

actionPerformed

public void actionPerformed(java.awt.event.ActionEvent ae)

Specified by:

actionPerformed in interface java.awt.event.ActionListener

rememberLastThing

protected void rememberLastThing(UndoEvent event)

Put a new UndoEvent on the backStack, to remember for later in case we need to back up.

Parameters:

event - UndoEvent.

undo

protected void undo()

Take a UndoEvent off the backStack, and push it on the forward stack, and invoke the new currentState so the source component gets modified.

redo

protected void redo()

Take a UndoEvent off the forwardStack, and push it on the backStack.

clearStacks

public void clearStacks(boolean clearUndoStack,
                        boolean clearRedoStack)

Clear out the chosen undo stacks and fire an event to update the triggers on stack status. Also sets the current state, which isn't held by either stack, to null.

Parameters:

clearUndoStack - clear out the undo stack.

clearRedoStack - clear out the redo stack.

fireStackStatus

public void fireStackStatus()

getWhatWillHappenNextFromStack

protected UndoEvent getWhatWillHappenNextFromStack(java.util.Stack<UndoEvent> stack)

addUndoStackTrigger

public void addUndoStackTrigger(UndoStackTrigger trigger)

UndoStackTriggers should call this method to add themselves for stack notifications, and all will be well.

removeUndoStackTrigger

public void removeUndoStackTrigger(UndoStackTrigger trigger)

UndoStackTriggers should call this method to remove themselves from stack notifications, and all will be well.