com.yworks.support.UndoEngine

	Property	Defined By
		autoAddTimeSpan : int The timespan in milliseconds during which two events will be merged.	UndoEngine
		currentCompoundEdit : ICompoundEdit [read-only] Gets a possibly open current compound edit.	UndoEngine
		mergeUnits : Boolean Whether or not this instance should try to merge newly added units.	UndoEngine
		performingRedo : Boolean [read-only] Indicates whether this instance is currently performing a redo operation.	UndoEngine
		performingUndo : Boolean [read-only] Indicates whether this instance is currently performing an undo operation.	UndoEngine
		redoName : String Returns the name of the redo unit.	UndoEngine
		redoText : String [read-only] The IUndoUnit.redoName of the next redo operation.	UndoEngine
		size : uint The maximum size of the undo queue this instance is managing.	UndoEngine
		undoName : String The name of the undo unit.	UndoEngine
		undoText : String [read-only] The IUndoUnit.undoName of the next undo operation.	UndoEngine

	Method	Defined By
		addToQueue(unit:IUndoUnit):void Adds a new IUndoUnit to the queue.	UndoEngine
		addUnit(unit:IUndoUnit):Boolean This implementation always returns false Allows for collapsing multiple units into one.	UndoEngine
		beginCompoundEdit(undoName:String, redoName:String):ICompoundEdit Begins a compound edit that will use the provided name.	UndoEngine
		canRedo():Boolean Determines whether this instance can currently redo its work.	UndoEngine
		canUndo():Boolean Determines whether this instance can currently undo its work.	UndoEngine
		clear():void Clears the internal queue.	UndoEngine
		dispose():void Frees all used resources and calls end.	UndoEngine
		getToken():Object Returns a token that can be used to store and compare the state of the undo queue.	UndoEngine
		redo():void Redoes the change that is represented by this unit.	UndoEngine
		redoNext():void Redoes the next IUndoUnit	UndoEngine
		replaceUnit(unit:IUndoUnit):Boolean This implementation always returns false Allows for collapsing multiple units into one.	UndoEngine
		toString():String [override]	UndoEngine
		undo():void Undoes all units in this queue.	UndoEngine
		undoNext():void Undoes the next IUndoUnit.	UndoEngine

	Method	Defined By
		onPropertyChanged(name:String, oldValue:Object, newValue:Object):void This will trigger the corresponding PropertyChangedEvent.	UndoEngine

	Event	Summary	Defined By
		propertyChange	Dispatched when the value of the performingUndo or performingRedo property changes.	UndoEngine

Property Detail

autoAddTimeSpan

property

autoAddTimeSpan:int

The timespan in milliseconds during which two events will be merged.

Setting this to 0 will effectively disable automatic merging.

The default value is 100.

This property can be used as the source for data binding.

Implementation
public function get autoAddTimeSpan():int
public function set autoAddTimeSpan(value:int):void

currentCompoundEdit

property

currentCompoundEdit:ICompoundEdit [read-only]

Gets a possibly open current compound edit.

Indicates and possibly returns the currently active ICompoundEdit that has been started using beginCompoundEdit.

Implementation
public function get currentCompoundEdit():ICompoundEdit

See also

beginCompoundEdit()

mergeUnits

property

mergeUnits:Boolean

Whether or not this instance should try to merge newly added units.

If true this instance will try to merge using IUndoUnit.addUnit or replace using IUndoUnit.replaceUnit units in the queue.

This property can be used as the source for data binding.

Implementation
public function get mergeUnits():Boolean
public function set mergeUnits(value:Boolean):void

performingRedo

property

performingRedo:Boolean [read-only]

Indicates whether this instance is currently performing a redo operation.

This property can be used as the source for data binding.

Implementation
public function get performingRedo():Boolean

performingUndo

property

performingUndo:Boolean [read-only]

Indicates whether this instance is currently performing an undo operation.

This property can be used as the source for data binding.

Implementation
public function get performingUndo():Boolean

redoName

property

redoName:String

Returns the name of the redo unit.

Depending on the implementation and context this might be a human readable representation of the redo action or a symbolic name that needs localization.

This property can be used as the source for data binding.

Implementation
public function get redoName():String
public function set redoName(value:String):void

redoText

property

redoText:String [read-only]

The IUndoUnit.redoName of the next redo operation.

This property is not bindable. Use redoName if data binding is needed.

Implementation
public function get redoText():String

size

property

size:uint

The maximum size of the undo queue this instance is managing.

A size of 0 effectively disables this implementation.

This property can be used as the source for data binding.

Implementation
public function get size():uint
public function set size(value:uint):void

undoName

property

undoName:String

The name of the undo unit.

Depending on the implementation and context this might be a human readable representation of the undo action or a symbolic name that needs localization.

This property can be used as the source for data binding.

Implementation
public function get undoName():String
public function set undoName(value:String):void

undoText

property

undoText:String [read-only]

The IUndoUnit.undoName of the next undo operation.

This property is not bindable. Use undoName if data binding is needed.

Implementation
public function get undoText():String

Method Detail

addToQueue

()

method

public function addToQueue(unit:IUndoUnit):void

Adds a new IUndoUnit to the queue.

This implementation will automatically group multiple units into a single unit if the time since the last add is less than autoAddTimeSpan.

Parameters

unit:IUndoUnit — The unit of work to add.

addUnit

()

method

public function addUnit(unit:IUndoUnit):Boolean

This implementation always returns false Allows for collapsing multiple units into one.

Implementation should try to incorporate the change of unit into this and if successful return true. This method will be called by the UndoEngine to collapse multiple events into single events. Typically this unit has been placed onto an undo stack and unit should be placed on top of it. Both units have been done and might be undone in an upcoming action. If this method yields true, the provided unit will not be placed onto the stack but will be IDisposable.disposed.

Parameters

unit:IUndoUnit — The unit to incorporate that happened after this unit.

Returns

Boolean — Whether the state change of unit has been incorporated into this unit and unit can be disposed of.

beginCompoundEdit

()

method

public function beginCompoundEdit(undoName:String, redoName:String):ICompoundEdit

Begins a compound edit that will use the provided name.

This will create a new edit that can independently be canceled or ended. Note that only if the outer-most instance is ended, the corresponding IUndoUnit units will be enqueued into this instance.

Parameters

	`undoName:String` — The undo name to use for the edit.

	`redoName:String` — The redo name to use for the edit.

Returns

ICompoundEdit — A compound edit implemenation that needs to be canceled or ended later.

canRedo

()

method

public function canRedo():Boolean

Determines whether this instance can currently redo its work.

Returns

Boolean — Whether a call to redo will succeed.

canUndo

()

method

public function canUndo():Boolean

Determines whether this instance can currently undo its work.

Returns

Boolean — Whether a call to undo will succeed.

clear

()

method

public function clear():void

Clears the internal queue.

dispose

()

method

public function dispose():void

Frees all used resources and calls end.

getToken

()

method

public function getToken():Object

Returns a token that can be used to store and compare the state of the undo queue.

E.g. an application can retrieve the token once the user has saved his document. Comparing the token returned by this instance with another one retrieved at a later point in time enables the application to determine whether the document is in the same state.

Returns

Object — An object that can be checked against other tokens via the Object.equals(Object) method.

onPropertyChanged

()

method

protected function onPropertyChanged(name:String, oldValue:Object, newValue:Object):void

This will trigger the corresponding PropertyChangedEvent.

Parameters

	`name:String` — The name of the property that changed.

	`oldValue:Object`

	`newValue:Object`

redo

()

method

public function redo():void

Redoes the change that is represented by this unit.

This method will only succeed if canRedo yields true.

redoNext

()

method

public function redoNext():void

Redoes the next IUndoUnit

replaceUnit

()

method

public function replaceUnit(unit:IUndoUnit):Boolean

This implementation always returns false Allows for collapsing multiple units into one.

Implementation should try to incorporate the change of unit into this and if successful return true. This method will be called by the UndoEngine to collapse multiple events into single events. Typically unit has already been placed onto an undo stack and this should be placed on top of it. Both units have been done and might be undone in an upcoming action. If this method yields true, this unit will replace the unit on the top of the stack and unit will be IDisposable.Disposed.

Parameters

unit:IUndoUnit — The unit to incorporate that happened before this unit.

Returns

Boolean — Whether the state change of unit has been incorporated into this unit and unit can be disposed of.

toString

()

method

override public function toString():String

Returns

String

undo

()

method

public function undo():void

Undoes all units in this queue. Undoes the change that is represented by this unit.

This method will only succeed if canUndo yields true.

undoNext

()

method

public function undoNext():void

Undoes the next IUndoUnit.

Event Detail

propertyChange

Event

Event Object Type: mx.event.PropertyChangeEvent
PropertyChangeEvent.type property = mx.event.PropertyChangeEvent.PROPERTY_CHANGE

Dispatched when the value of the performingUndo or performingRedo property changes.

Wed Oct 7 2015, 04:52 PM +02:00

yFiles FLEX 1.9 API Documentation	All Packages \| All Classes \| Index \| Frames No Frames
UndoEngine	Properties \| Methods \| Events

Package	com.yworks.support
Class	public class UndoEngine
Inheritance	UndoEngine flash.events.EventDispatcher
Implements	IUndoUnit