godot/doc/classes/UndoRedo.xml

<?xml version="1.0" encoding="UTF-8" ?>
<class name="UndoRedo" inherits="Object" version="4.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
	<brief_description>
		Provides a high-level interface for implementing undo and redo operations.
	</brief_description>
	<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 [code]do_*[/code] methods will run. If the [method undo] method is used, the [code]undo_*[/code] methods will run. If the [method redo] method is used, once again, all of the [code]do_*[/code] methods will run.
		Here's an example on how to add an action:
		[codeblocks]
		[gdscript]
		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()
		[/gdscript]
		[csharp]
		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&lt;Node2D&gt;("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();
		}
		[/csharp]
		[/codeblocks]
		[method create_action], [method add_do_method], [method add_undo_method], [method add_do_property], [method add_undo_property], and [method commit_action] should be called one after the other, like in the example. Not doing so could lead to crashes.
		If you don't need to register a method, you can leave [method add_do_method] and [method add_undo_method] out; the same goes for properties. You can also register more than one method/property in the order they should run.
		If you are making an [EditorPlugin] and want to integrate into the editor's undo history, use [EditorUndoRedoManager] instead.
	</description>
	<tutorials>
	</tutorials>
	<methods>
		<method name="add_do_method">
			<return type="void" />
			<param index="0" name="callable" type="Callable" />
			<description>
				Register a [Callable] that will be called when the action is committed.
			</description>
		</method>
		<method name="add_do_property">
			<return type="void" />
			<param index="0" name="object" type="Object" />
			<param index="1" name="property" type="StringName" />
			<param index="2" name="value" type="Variant" />
			<description>
				Register a [param property] that would change its value to [param value] when the action is committed.
			</description>
		</method>
		<method name="add_do_reference">
			<return type="void" />
			<param index="0" name="object" type="Object" />
			<description>
				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.
				[codeblock]
				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()
				[/codeblock]
			</description>
		</method>
		<method name="add_undo_method">
			<return type="void" />
			<param index="0" name="callable" type="Callable" />
			<description>
				Register a [Callable] that will be called when the action is undone.
			</description>
		</method>
		<method name="add_undo_property">
			<return type="void" />
			<param index="0" name="object" type="Object" />
			<param index="1" name="property" type="StringName" />
			<param index="2" name="value" type="Variant" />
			<description>
				Register a [param property] that would change its value to [param value] when the action is undone.
			</description>
		</method>
		<method name="add_undo_reference">
			<return type="void" />
			<param index="0" name="object" type="Object" />
			<description>
				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!).
				[codeblock]
				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()
				[/codeblock]
			</description>
		</method>
		<method name="clear_history">
			<return type="void" />
			<param index="0" name="increase_version" type="bool" default="true" />
			<description>
				Clear the undo/redo history and associated references.
				Passing [code]false[/code] to [param increase_version] will prevent the version number from increasing when the history is cleared.
			</description>
		</method>
		<method name="commit_action">
			<return type="void" />
			<param index="0" name="execute" type="bool" default="true" />
			<description>
				Commit the action. If [param execute] is [code]true[/code] (which it is by default), all "do" methods/properties are called/set when this function is called.
			</description>
		</method>
		<method name="create_action">
			<return type="void" />
			<param index="0" name="name" type="String" />
			<param index="1" name="merge_mode" type="int" enum="UndoRedo.MergeMode" default="0" />
			<description>
				Create a new action. After this is called, do all your calls to [method add_do_method], [method add_undo_method], [method add_do_property], and [method add_undo_property], then commit the action with [method commit_action].
				The way actions are merged is dictated by [param merge_mode]. See [enum MergeMode] for details.
			</description>
		</method>
		<method name="end_force_keep_in_merge_ends">
			<return type="void" />
			<description>
				Stops marking operations as to be processed even if the action gets merged with another in the [constant MERGE_ENDS] mode. See [method start_force_keep_in_merge_ends].
			</description>
		</method>
		<method name="get_action_name">
			<return type="String" />
			<param index="0" name="id" type="int" />
			<description>
				Gets the action name from its index.
			</description>
		</method>
		<method name="get_current_action">
			<return type="int" />
			<description>
				Gets the index of the current action.
			</description>
		</method>
		<method name="get_current_action_name" qualifiers="const">
			<return type="String" />
			<description>
				Gets the name of the current action, equivalent to [code]get_action_name(get_current_action())[/code].
			</description>
		</method>
		<method name="get_history_count">
			<return type="int" />
			<description>
				Returns how many elements are in the history.
			</description>
		</method>
		<method name="get_version" qualifiers="const">
			<return type="int" />
			<description>
				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.
			</description>
		</method>
		<method name="has_redo" qualifiers="const">
			<return type="bool" />
			<description>
				Returns [code]true[/code] if a "redo" action is available.
			</description>
		</method>
		<method name="has_undo" qualifiers="const">
			<return type="bool" />
			<description>
				Returns [code]true[/code] if an "undo" action is available.
			</description>
		</method>
		<method name="is_committing_action" qualifiers="const">
			<return type="bool" />
			<description>
				Returns [code]true[/code] if the [UndoRedo] is currently committing the action, i.e. running its "do" method or property change (see [method commit_action]).
			</description>
		</method>
		<method name="redo">
			<return type="bool" />
			<description>
				Redo the last action.
			</description>
		</method>
		<method name="start_force_keep_in_merge_ends">
			<return type="void" />
			<description>
				Marks the next "do" and "undo" operations to be processed even if the action gets merged with another in the [constant MERGE_ENDS] mode. Return to normal operation using [method end_force_keep_in_merge_ends].
			</description>
		</method>
		<method name="undo">
			<return type="bool" />
			<description>
				Undo the last action.
			</description>
		</method>
	</methods>
	<signals>
		<signal name="version_changed">
			<description>
				Called when [method undo] or [method redo] was called.
			</description>
		</signal>
	</signals>
	<constants>
		<constant name="MERGE_DISABLE" value="0" enum="MergeMode">
			Makes "do"/"undo" operations stay in separate actions.
		</constant>
		<constant name="MERGE_ENDS" value="1" enum="MergeMode">
			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.
		</constant>
		<constant name="MERGE_ALL" value="2" enum="MergeMode">
			Makes subsequent actions with the same name be merged into one.
		</constant>
	</constants>
</class>