Manages a list of undo/redo commands. More...

Inheritance diagram for UndoManager:

Public Member Functions
	UndoManager (int maxNumberOfUnitsToKeep=30000, int minimumTransactionsToKeep=30)
	Creates an UndoManager. More...

	~UndoManager ()
	Destructor. More...

void	clearUndoHistory ()
	Deletes all stored actions in the list. More...

int	getNumberOfUnitsTakenUpByStoredCommands () const
	Returns the current amount of space to use for storing UndoableAction objects. More...

void	setMaxNumberOfStoredUnits (int maxNumberOfUnitsToKeep, int minimumTransactionsToKeep)
	Sets the amount of space that can be used for storing UndoableAction objects. More...

bool	perform (UndoableAction *action)
	Performs an action and adds it to the undo history list. More...

bool	perform (UndoableAction *action, const String &actionName)
	Performs an action and also gives it a name. More...

void	beginNewTransaction () noexcept
	Starts a new group of actions that together will be treated as a single transaction. More...

void	beginNewTransaction (const String &actionName) noexcept
	Starts a new group of actions that together will be treated as a single transaction. More...

void	setCurrentTransactionName (const String &newName) noexcept
	Changes the name stored for the current transaction. More...

String	getCurrentTransactionName () const noexcept
	Returns the name of the current transaction. More...

bool	canUndo () const noexcept
	Returns true if there's at least one action in the list to undo. More...

String	getUndoDescription () const
	Returns the name of the transaction that will be rolled-back when undo() is called. More...

bool	undo ()
	Tries to roll-back the last transaction. More...

bool	undoCurrentTransactionOnly ()
	Tries to roll-back any actions that were added to the current transaction. More...

void	getActionsInCurrentTransaction (Array< const UndoableAction * > &actionsFound) const
	Returns a list of the UndoableAction objects that have been performed during the transaction that is currently open. More...

int	getNumActionsInCurrentTransaction () const
	Returns the number of UndoableAction objects that have been performed during the transaction that is currently open. More...

Time	getTimeOfUndoTransaction () const
	Returns the time to which the state would be restored if undo() was to be called. More...

Time	getTimeOfRedoTransaction () const
	Returns the time to which the state would be restored if redo() was to be called. More...

bool	canRedo () const noexcept
	Returns true if there's at least one action in the list to redo. More...

String	getRedoDescription () const
	Returns the name of the transaction that will be redone when redo() is called. More...

bool	redo ()
	Tries to redo the last transaction that was undone. More...

Public Member Functions inherited from ChangeBroadcaster
	ChangeBroadcaster () noexcept
	Creates an ChangeBroadcaster. More...

virtual	~ChangeBroadcaster ()
	Destructor. More...

void	addChangeListener (ChangeListener *listener)
	Registers a listener to receive change callbacks from this broadcaster. More...

void	removeChangeListener (ChangeListener *listener)
	Unregisters a listener from the list. More...

void	removeAllChangeListeners ()
	Removes all listeners from the list. More...

void	sendChangeMessage ()
	Causes an asynchronous change message to be sent to all the registered listeners. More...

void	sendSynchronousChangeMessage ()
	Sends a synchronous change message to all the registered listeners. More...

void	dispatchPendingMessages ()
	If a change message has been sent but not yet dispatched, this will call sendSynchronousChangeMessage() to make the callback immediately. More...

Detailed Description

Manages a list of undo/redo commands.

An UndoManager object keeps a list of past actions and can use these actions to move backwards and forwards through an undo history.

To use it, create subclasses of UndoableAction which perform all the actions you need, then when you need to actually perform an action, create one and pass it to the UndoManager's perform() method.

The manager also uses the concept of 'transactions' to group the actions together - all actions performed between calls to beginNewTransaction() are grouped together and are all undone/redone as a group.

The UndoManager is a ChangeBroadcaster, so listeners can register to be told when actions are performed or undone.

See also: UndoableAction

Constructor & Destructor Documentation

UndoManager::UndoManager	(	int	maxNumberOfUnitsToKeep = `30000`,
		int	minimumTransactionsToKeep = `30`
	)

Creates an UndoManager.

Parameters

maxNumberOfUnitsToKeep	each UndoableAction object returns a value to indicate how much storage it takes up (UndoableAction::getSizeInUnits()), so this lets you specify the maximum total number of units that the undomanager is allowed to keep in memory before letting the older actions drop off the end of the list.
minimumTransactionsToKeep	this specifies the minimum number of transactions that will be kept, even if this involves exceeding the amount of space specified in maxNumberOfUnitsToKeep

UndoManager::~UndoManager ( )

Destructor.

Member Function Documentation

void UndoManager::clearUndoHistory ( )

Deletes all stored actions in the list.

int UndoManager::getNumberOfUnitsTakenUpByStoredCommands ( ) const

Returns the current amount of space to use for storing UndoableAction objects.

See also: setMaxNumberOfStoredUnits

void UndoManager::setMaxNumberOfStoredUnits	(	int	maxNumberOfUnitsToKeep,
		int	minimumTransactionsToKeep
	)

Sets the amount of space that can be used for storing UndoableAction objects.

Parameters

maxNumberOfUnitsToKeep	each UndoableAction object returns a value to indicate how much storage it takes up (UndoableAction::getSizeInUnits()), so this lets you specify the maximum total number of units that the undomanager is allowed to keep in memory before letting the older actions drop off the end of the list.
minimumTransactionsToKeep	this specifies the minimum number of transactions that will be kept, even if this involves exceeding the amount of space specified in maxNumberOfUnitsToKeep

See also: getNumberOfUnitsTakenUpByStoredCommands

bool UndoManager::perform ( UndoableAction * action )

Performs an action and adds it to the undo history list.

Parameters

action the action to perform - this object will be deleted by the UndoManager when no longer needed

Returns: true if the command succeeds - see UndoableAction::perform

See also: beginNewTransaction

bool UndoManager::perform	(	UndoableAction *	action,
		const String &	actionName
	)

Performs an action and also gives it a name.

Parameters

action	the action to perform - this object will be deleted by the UndoManager when no longer needed
actionName	if this string is non-empty, the current transaction will be given this name; if it's empty, the current transaction name will be left unchanged. See setCurrentTransactionName()

Returns: true if the command succeeds - see UndoableAction::perform

See also: beginNewTransaction

void UndoManager::beginNewTransaction ( )

noexcept

Starts a new group of actions that together will be treated as a single transaction.

All actions that are passed to the perform() method between calls to this method are grouped together and undone/redone together by a single call to undo() or redo().

void UndoManager::beginNewTransaction ( const String & actionName )

noexcept

Starts a new group of actions that together will be treated as a single transaction.

All actions that are passed to the perform() method between calls to this method are grouped together and undone/redone together by a single call to undo() or redo().

Parameters

actionName a description of the transaction that is about to be performed

void UndoManager::setCurrentTransactionName ( const String & newName )

noexcept

Changes the name stored for the current transaction.

Each transaction is given a name when the beginNewTransaction() method is called, but this can be used to change that name without starting a new transaction.

String UndoManager::getCurrentTransactionName ( ) const

noexcept

Returns the name of the current transaction.

See also: setCurrentTransactionName

bool UndoManager::canUndo ( ) const

noexcept

Returns true if there's at least one action in the list to undo.

See also: getUndoDescription, undo, canRedo

String UndoManager::getUndoDescription ( ) const

Returns the name of the transaction that will be rolled-back when undo() is called.

See also: undo

bool UndoManager::undo ( )

Tries to roll-back the last transaction.

Returns: true if the transaction can be undone, and false if it fails, or if there aren't any transactions to undo

bool UndoManager::undoCurrentTransactionOnly ( )

Tries to roll-back any actions that were added to the current transaction.

This will perform an undo() only if there are some actions in the undo list that were added after the last call to beginNewTransaction().

This is useful because it lets you call beginNewTransaction(), then perform an operation which may or may not actually perform some actions, and then call this method to get rid of any actions that might have been done without it rolling back the previous transaction if nothing was actually done.

Returns: true if any actions were undone.

void UndoManager::getActionsInCurrentTransaction ( Array< const UndoableAction * > & actionsFound ) const

Returns a list of the UndoableAction objects that have been performed during the transaction that is currently open.

Effectively, this is the list of actions that would be undone if undoCurrentTransactionOnly() were to be called now.

The first item in the list is the earliest action performed.

int UndoManager::getNumActionsInCurrentTransaction ( ) const

Returns the number of UndoableAction objects that have been performed during the transaction that is currently open.

See also: getActionsInCurrentTransaction

Time UndoManager::getTimeOfUndoTransaction ( ) const

Returns the time to which the state would be restored if undo() was to be called.

If an undo isn't currently possible, it'll return Time().

Time UndoManager::getTimeOfRedoTransaction ( ) const

Returns the time to which the state would be restored if redo() was to be called.

If a redo isn't currently possible, it'll return Time::getCurrentTime().

bool UndoManager::canRedo ( ) const

noexcept

Returns true if there's at least one action in the list to redo.

See also: getRedoDescription, redo, canUndo

String UndoManager::getRedoDescription ( ) const

Returns the name of the transaction that will be redone when redo() is called.

See also: redo

bool UndoManager::redo ( )

Tries to redo the last transaction that was undone.

Returns: true if the transaction can be redone, and false if it fails, or if there aren't any transactions to redo

The documentation for this class was generated from the following file:

juce_UndoManager.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation