UndoRedo¶

Inherits: Object

Provides a high-level interface for implementing undo and redo operations.

Description¶

UndoRedo works by registering methods and property changes inside "actions". You can create an action, then provide ways to do and undo this action using function calls and property changes, then commit the action.

When an action is committed, all of the do_* methods will run. If the undo method is used, the undo_* methods will run. If the redo method is used, once again, all of the do_* methods will run.

Here's an example on how to add an action:

var undo_redo = UndoRedo.new()

func do_something():
    pass # Put your code here.

func undo_something():
    pass # Put here the code that reverts what's done by "do_something()".

func _on_my_button_pressed():
    var node = get_node("MyNode2D")
    undo_redo.create_action("Move the node")
    undo_redo.add_do_method(do_something)
    undo_redo.add_undo_method(undo_something)
    undo_redo.add_do_property(node, "position", Vector2(100,100))
    undo_redo.add_undo_property(node, "position", node.position)
    undo_redo.commit_action()

private UndoRedo _undoRedo;

public override void _Ready()
{
    _undoRedo = new UndoRedo();
}

public void DoSomething()
{
    // Put your code here.
}

public void UndoSomething()
{
    // Put here the code that reverts what's done by "DoSomething()".
}

private void OnMyButtonPressed()
{
    var node = GetNode<Node2D>("MyNode2D");
    _undoRedo.CreateAction("Move the node");
    _undoRedo.AddDoMethod(new Callable(this, MethodName.DoSomething));
    _undoRedo.AddUndoMethod(new Callable(this, MethodName.UndoSomething));
    _undoRedo.AddDoProperty(node, "position", new Vector2(100, 100));
    _undoRedo.AddUndoProperty(node, "position", node.Position);
    _undoRedo.CommitAction();
}

Before calling any of the add_(un)do_* methods, you need to first call create_action. Afterwards you need to call commit_action.

If you don't need to register a method, you can leave add_do_method and add_undo_method out; the same goes for properties. You can also register more than one method/property.

If you are making an EditorPlugin and want to integrate into the editor's undo history, use EditorUndoRedoManager instead.

If you are registering multiple properties/method which depend on one another, be aware that by default undo operation are called in the same order they have been added. Therefore instead of grouping do operation with their undo operations it is better to group do on one side and undo on the other as shown below.

undo_redo.create_action("Add object")

# DO
undo_redo.add_do_method(_create_object)
undo_redo.add_do_method(_add_object_to_singleton)

# UNDO
undo_redo.add_undo_method(_remove_object_from_singleton)
undo_redo.add_undo_method(_destroy_that_object)

undo_redo.commit_action()

_undo_redo.CreateAction("Add object");

// DO
_undo_redo.AddDoMethod(new Callable(this, MethodName.CreateObject));
_undo_redo.AddDoMethod(new Callable(this, MethodName.AddObjectToSingleton));

// UNDO
_undo_redo.AddUndoMethod(new Callable(this, MethodName.RemoveObjectFromSingleton));
_undo_redo.AddUndoMethod(new Callable(this, MethodName.DestroyThatObject));

_undo_redo.CommitAction();

Methods¶

void	add_do_method ( Callable callable )
void	add_do_property ( Object object, StringName property, Variant value )
void	add_do_reference ( Object object )
void	add_undo_method ( Callable callable )
void	add_undo_property ( Object object, StringName property, Variant value )
void	add_undo_reference ( Object object )
void	clear_history ( bool increase_version=true )
void	commit_action ( bool execute=true )
void	create_action ( String name, MergeMode merge_mode=0, bool backward_undo_ops=false )
void	end_force_keep_in_merge_ends ( )
String	get_action_name ( int id )
int	get_current_action ( )
String	get_current_action_name ( ) const
int	get_history_count ( )
int	get_version ( ) const
bool	has_redo ( ) const
bool	has_undo ( ) const
bool	is_committing_action ( ) const
bool	redo ( )
void	start_force_keep_in_merge_ends ( )
bool	undo ( )

Signals¶

version_changed ( )

Called when undo or redo was called.

Enumerations¶

enum MergeMode:

MergeMode MERGE_DISABLE = 0

Makes "do"/"undo" operations stay in separate actions.

MergeMode MERGE_ENDS = 1

Makes so that the action's "undo" operations are from the first action created and the "do" operations are from the last subsequent action with the same name.

MergeMode MERGE_ALL = 2

Makes subsequent actions with the same name be merged into one.

Method Descriptions¶

void add_do_method ( Callable callable )

Register a Callable that will be called when the action is committed.

void add_do_property ( Object object, StringName property, Variant value )

Register a property that would change its value to value when the action is committed.

void add_do_reference ( Object object )

Register a reference for "do" that will be erased if the "do" history is lost. This is useful mostly for new nodes created for the "do" call. Do not use for resources.

var node = Node2D.new()
undo_redo.create_action("Add node")
undo_redo.add_do_method(add_child.bind(node))
undo_redo.add_do_reference(node)
undo_redo.add_undo_method(remove_child.bind(node))
undo_redo.commit_action()

void add_undo_method ( Callable callable )

Register a Callable that will be called when the action is undone.

void add_undo_property ( Object object, StringName property, Variant value )

Register a property that would change its value to value when the action is undone.

void add_undo_reference ( Object object )

Register a reference for "undo" that will be erased if the "undo" history is lost. This is useful mostly for nodes removed with the "do" call (not the "undo" call!).

var node = $Node2D
undo_redo.create_action("Remove node")
undo_redo.add_do_method(remove_child.bind(node))
undo_redo.add_undo_method(add_child.bind(node))
undo_redo.add_undo_reference(node)
undo_redo.commit_action()

void clear_history ( bool increase_version=true )

Clear the undo/redo history and associated references.

Passing false to increase_version will prevent the version number from increasing when the history is cleared.

void commit_action ( bool execute=true )

Commit the action. If execute is true (which it is by default), all "do" methods/properties are called/set when this function is called.

void create_action ( String name, MergeMode merge_mode=0, bool backward_undo_ops=false )

Create a new action. After this is called, do all your calls to add_do_method, add_undo_method, add_do_property, and add_undo_property, then commit the action with commit_action.

The way actions are merged is dictated by merge_mode. See MergeMode for details.

The way undo operation are ordered in actions is dictated by backward_undo_ops. When backward_undo_ops is false undo option are ordered in the same order they were added. Which means the first operation to be added will be the first to be undone.

void end_force_keep_in_merge_ends ( )

Stops marking operations as to be processed even if the action gets merged with another in the MERGE_ENDS mode. See start_force_keep_in_merge_ends.

String get_action_name ( int id )

Gets the action name from its index.

int get_current_action ( )

Gets the index of the current action.

String get_current_action_name ( ) const

Gets the name of the current action, equivalent to get_action_name(get_current_action()).

int get_history_count ( )

Returns how many elements are in the history.

int get_version ( ) const

Gets the version. Every time a new action is committed, the UndoRedo's version number is increased automatically.

This is useful mostly to check if something changed from a saved version.

bool has_redo ( ) const

Returns true if a "redo" action is available.

bool has_undo ( ) const

Returns true if an "undo" action is available.

bool is_committing_action ( ) const

Returns true if the UndoRedo is currently committing the action, i.e. running its "do" method or property change (see commit_action).

bool redo ( )

Redo the last action.

void start_force_keep_in_merge_ends ( )

Marks the next "do" and "undo" operations to be processed even if the action gets merged with another in the MERGE_ENDS mode. Return to normal operation using end_force_keep_in_merge_ends.

bool undo ( )

Undo the last action.