Improve interface accessibility and UI reliability

ui/interface_font_controller.gd

@@ -0,0 +1,55 @@
+class_name InterfaceFontController
+extends Node
+
+signal font_mode_changed(use_readable_font: bool)
+
+const READABLE_FONT_PATH: String = "res://ui/fonts/Tuffy_Bold.otf"
+
+var _game_theme: Theme = preload("res://ui/game_theme.tres")
+var _game_font: Font = preload("res://ui/fonts/seattle_avenue.otf")
+var _readable_font: Font
+var _utility_theme: Theme
+var _use_readable_font: bool = false
+
+
+func _ready() -> void:
+	if ResourceLoader.exists(READABLE_FONT_PATH):
+		_readable_font = load(READABLE_FONT_PATH) as Font
+	if _readable_font == null:
+		push_error("Readable interface font resource is unavailable.")
+	else:
+		_readable_font.fallbacks = [_game_font]
+	_utility_theme = _game_theme.duplicate(true)
+	_utility_theme.default_font = readable_font()
+
+
+func set_readable_font_enabled(enabled: bool) -> void:
+	_use_readable_font = enabled
+	_game_theme.default_font = (
+		_readable_font
+		if enabled and _readable_font != null
+		else _game_font
+	)
+	font_mode_changed.emit(_use_readable_font)
+
+
+func is_readable_font_enabled() -> bool:
+	return _use_readable_font
+
+
+func apply_utility_theme(themed_node: Node) -> void:
+	if themed_node == null:
+		return
+	if _utility_theme == null:
+		_utility_theme = _game_theme.duplicate(true)
+		_utility_theme.default_font = (
+			_readable_font if _readable_font != null else _game_font
+		)
+	if themed_node is Control:
+		(themed_node as Control).theme = _utility_theme
+	elif themed_node is Window:
+		(themed_node as Window).theme = _utility_theme
+
+
+func readable_font() -> Font:
+	return _readable_font if _readable_font != null else _game_font