Allow exporting variables of type Variant

[KoBeWi]

Inspired by godotengine/godot-proposals#9269
Closes godotengine/godot-proposals#9368

This PR allows for exporting variables of type Variant. They show a property editor similar to what Array and Dictionary are using:

JRnkfXjKv5.mp4

This allows for nice flexibility, where you can change not only the variable, but also its value and allows for better customization.

example plugin for "tri-state bool"

@tool
extends EditorPlugin

var state3 := TriStateBoolInspectorPlugin.new()

func _enter_tree() -> void:
	add_inspector_plugin(state3)


func _exit_tree() -> void:
	remove_inspector_plugin(state3)

class TriStateBoolInspectorPlugin extends EditorInspectorPlugin:
	func _can_handle(object: Object) -> bool:
		return true
	
	func _parse_property(object: Object, type: Variant.Type, name: String, hint_type: PropertyHint, hint_string: String, usage_flags: int, wide: bool) -> bool:
		if type == TYPE_NIL and hint_string == "3bool":
			add_property_editor(name, TriStateBoolEditor.new())
			return true
		return false

class TriStateBoolEditor extends EditorProperty:
	var button: TriStateCheckbox
	
	func _init() -> void:
		button = TriStateCheckbox.new()
		add_child(button)
		button.pressed.connect(func(): get_edited_object().set(get_edited_property(), button.state))
	
	func _update_property() -> void:
		button.state = get_edited_object().get(get_edited_property())

class TriStateCheckbox extends Button:
	const STATES = [null, false, true]
	
	var textures: Array[Texture2D]
	var state: Variant:
		set(s):
			state = s
			icon = textures[STATES.find(state)]
	
	func _init() -> void:
		size_flags_horizontal = SIZE_SHRINK_BEGIN
		
		for color in [Color.RED, Color.GREEN, Color.BLUE]:
			var gradient := Gradient.new()
			gradient.remove_point(1)
			gradient.colors = [color]
			
			var texture := GradientTexture2D.new()
			texture.gradient = gradient
			texture.width = 16
			texture.height = 16
			textures.append(texture)
	
	func _pressed() -> void:
		for i in STATES.size():
			if STATES[i] == state:
				state = STATES[(i + 1) % STATES.size()]
				break

Example usage:

@export_custom(0, "3bool") var boolean_hat_trick

godot.windows.editor.dev.x86_64_RzAIgcf3TZ.mp4

(the text is updated with _process().

[dalexeev]

• See also Added support for generic type exported properties in gdscript #33080.

I wanted to salvage/re-implement it. I think this should work like Dictionary key/value editor, the user could select the type first, then the value.

[KoBeWi]

I thought about that too, but opted for a simpler solution (as the goal was customizability itself).
I can rework this into the type dropdown widget if that's better.

[KoBeWi]

Ok reworked

JRnkfXjKv5.mp4

[Jan-PieterInghels]

Just checking in to see if this can be approved and merged?

[AThousandShips]

We're currently in feature freeze so this won't be considered until 4.4, and it's not been decided on yet

[Calinou]

Code looks good to me at a glance. Could you look into rebasing this on top of master?

PS: Is there much use in exposing Object in the list of types in the dropdown? As far as I know, you can't give it any useful value directly in the inspector.

[KoBeWi]

PS: Is there much use in exposing Object in the list of types in the dropdown? As far as I know, you can't give it any useful value directly in the inspector.

You can assign it a Resource.

[KoBeWi]

Sus change after rebase.

[KoBeWi]

For some reason this crashes without null check. I did not bother investigating why, it just makes no sense. No other plugin has this problem.

[Mickeon]

Interest in this PR came up again in godotengine/godot-proposals#7016 (comment) . Just for transparency and linking.

[Gnumaru]

Since 4.4 beta 1 came out, we are feature freezed and this probably won't get to be merged in 4.4.

But is there anything preventing this to be merged? That is, besides the collosal work of maintainers in evaluating the enormous ammount of pull request the godot project receives every day and deciding, for non bugfix PRs, wheter it is worth or not incorporating into the engine, and if so, deciding when doing it?

[Calinou]

Tested locally (rebased on top of master a7146ef), there's a build error:

Generating core/version_generated.gen.h ...
Generating core/version_hash.gen.cpp ...
Compiling core/version_hash.gen.cpp ...
Compiling editor/scu/scu_editor_4.gen.cpp ...
Linking Static Library core/libcore.linuxbsd.editor.x86_64.a ...
Ranlib Library core/libcore.linuxbsd.editor.x86_64.a ...
In file included from editor/scu/scu_editor_4.gen.cpp:4:
./editor/editor_properties.cpp: In member function 'void EditorPropertyVariant::_notification(int)':
./editor/editor_properties.cpp:91:30: error: 'class MenuButton' has no member named 'set_icon'
   91 |                 change_type->set_icon(get_editor_theme_icon("Edit"));
      |                              ^~~~~~~~
scons: *** [editor/scu/scu_editor_4.gen.linuxbsd.editor.x86_64.o] Error 1
scons: building terminated because of errors.

[Calinou]

It works now 🙂

(The full line of d is @export var d: Variant = null, it's cut off on the screenshot.)

Note that the Variant type hint must be specified explicitly, and you must not set a default value of null for it to work as a proper Variant export where you can change the type. I think this makes sense, as this is an uncommon use case and it's better to be explicit about it.