Disable undo/redo buttons when there is nothing to undo/redo

lorien/Main.gd

@@ -238,13 +238,17 @@ func _on_files_dropped(files: PackedStringArray) -> void:
 
 # -------------------------------------------------------------------------------------------------
 func _make_project_active(project: Project) -> void:
+	var previous_project: Project = ProjectManager.get_active_project()
+
 	ProjectManager.make_project_active(project)
 	_canvas.use_project(project)
 
 	if !_menubar.has_tab(project):
 		_menubar.make_tab(project)
 	_menubar.set_tab_active(project)
 
+	_toolbar._on_active_project_changed(previous_project, project)
+
 # -------------------------------------------------------------------------------------------------
 func _is_mouse_on_ui() -> bool:
 	var on_ui := Utils.is_mouse_in_control(_menubar)

lorien/ProjectManager/Project.gd

@@ -1,9 +1,17 @@
 class_name Project
 
+# Emitted whenever something marks the project as dirty, even if it's already dirty.
+signal dirtied
+
 var id: int # this is used at runtime only and will not be persisted; project ids are not garanteed to be the same between restarts
 var undo_redo: UndoRedo
 
-var dirty := false
+var dirty := false:
+	set(value):
+		dirty = value
+		if value == true:
+			dirtied.emit()
+
 var loaded := false
 
 var filepath: String

lorien/UI/Components/FlatTextureButton.gd

@@ -4,46 +4,51 @@ extends TextureButton
 # -------------------------------------------------------------------------------------------------
 @export var hover_tint := Color.WHITE
 @export var pressed_tint := Color.WHITE
+@export var disabled_tint := Color(0.4, 0.4, 0.4)
 var _normal_tint: Color
 
 # -------------------------------------------------------------------------------------------------
 func _ready() -> void:
 	_normal_tint = self_modulate
 	mouse_entered.connect(_on_mouse_entered)
 	mouse_exited.connect(_on_mouse_exited)
-	pressed.connect(_on_pressed)
-
-	if toggle_mode && button_pressed:
-		self_modulate = pressed_tint
+	toggled.connect(_on_toggled)
+	_update_tint()
 
 # -------------------------------------------------------------------------------------------------
 func _exit_tree() -> void:
 	mouse_entered.disconnect(_on_mouse_entered)
 	mouse_exited.disconnect(_on_mouse_exited)
-	pressed.disconnect(_on_pressed)
+	toggled.disconnect(_on_toggled)
 
 # -------------------------------------------------------------------------------------------------
 func _on_mouse_entered() -> void:
-	if !button_pressed:
-		self_modulate = hover_tint
+	call_deferred("_update_tint")
 
 # -------------------------------------------------------------------------------------------------
 func _on_mouse_exited() -> void:
-	if !button_pressed:
-		self_modulate = _normal_tint
+	call_deferred("_update_tint")
 
 # -------------------------------------------------------------------------------------------------
 func toggle() -> void:
-	if button_pressed:
-		self_modulate = _normal_tint
-	else:
-		self_modulate = pressed_tint
 	button_pressed = !button_pressed
 
 # -------------------------------------------------------------------------------------------------
-func _on_pressed() -> void:
-	if toggle_mode:
-		if button_pressed:
-			self_modulate = pressed_tint
-		else:
-			self_modulate = _normal_tint
+func _on_toggled(_toggled_on: bool) -> void:
+	_update_tint()
+
+# -------------------------------------------------------------------------------------------------
+func set_is_disabled(value: bool) -> void:
+	disabled = value
+	_update_tint()
+
+# -------------------------------------------------------------------------------------------------
+func _update_tint() -> void:
+	if disabled:
+		self_modulate = disabled_tint
+	elif button_pressed:
+		self_modulate = pressed_tint
+	elif is_hovered():
+		self_modulate = hover_tint
+	else:
+		self_modulate = _normal_tint

lorien/UI/Toolbar.gd

@@ -165,3 +165,34 @@ func _change_active_tool_button(btn: TextureButton) -> void:
 # -------------------------------------------------------------------------------------------------
 func get_brush_color_button() -> Control:
 	return _color_button
+
+# -------------------------------------------------------------------------------------------------
+func _on_active_project_changed(previous_project: Project, current_project: Project) -> void:
+	_update_undo_redo_buttons()
+
+	if previous_project != null:
+		previous_project.dirtied.disconnect(_on_project_dirtied)
+		previous_project.undo_redo.version_changed.disconnect(_on_undo_or_redo_occured)
+
+	if current_project != null:
+		current_project.dirtied.connect(_on_project_dirtied)
+		current_project.undo_redo.version_changed.connect(_on_undo_or_redo_occured)
+
+# -------------------------------------------------------------------------------------------------
+func _on_project_dirtied() -> void:
+	_update_undo_redo_buttons()
+
+# -------------------------------------------------------------------------------------------------
+func _on_undo_or_redo_occured() -> void:
+	_update_undo_redo_buttons()
+
+# -------------------------------------------------------------------------------------------------
+func _update_undo_redo_buttons() -> void:
+	var active_project: Project = ProjectManager.get_active_project()
+	if active_project == null:
+		_undo_button.set_is_disabled(true)
+		_redo_button.set_is_disabled(true)
+		return
+
+	_undo_button.set_is_disabled(!active_project.undo_redo.has_undo())
+	_redo_button.set_is_disabled(!active_project.undo_redo.has_redo())