Add input mapping GUI demo

demos/gui/input_mapping/controls.gd

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+# Note for the reader:
+#
+# This demo conveniently uses the same names for actions and for the container nodes
+# that hold each remapping button. This allow to get back to the button based simply
+# on the name of the corresponding action, but it might not be so simple in your project.
+#
+# A better approach for large-scale input remapping might be to do the connections between
+# buttons and wait_for_input through the code, passing as arguments both the name of the
+# action and the node, e.g.:
+# button.connect("pressed", self, "wait_for_input", [ button, action ])
+
+extends Control
+
+var player_actions = [ "move_up", "move_down", "move_left", "move_right", "jump" ]
+var action # To register the action the UI is currently handling
+var button # Button node corresponding to the above action
+
+func wait_for_input(action_bind):
+	action = action_bind
+	# See note at the beginning of the script
+	button = get_node("bindings").get_node(action).get_node("Button")
+	get_node("contextual_help").set_text("Press a key to assign to the '" + action + "' action.")
+	set_process_input(true)
+
+func _input(event):
+	# Handle the first pressed key
+	if (event.type == InputEvent.KEY):
+		# Register the event as handled and stop polling
+		get_tree().set_input_as_handled()
+		set_process_input(false)
+		# Reinitialise the contextual help label
+		get_node("contextual_help").set_text("Click a key binding to reassign it, or press the Cancel action.")
+		if (not event.is_action("ui_cancel")):
+			# Display the string corresponding to the pressed key
+			button.set_text(OS.get_scancode_string(event.scancode))
+			# Start by removing previously key binding(s)
+			for old_event in InputMap.get_action_list(action):
+				InputMap.action_erase_event(action, old_event)
+			# Add the new key binding
+			InputMap.action_add_event(action, event)
+
+func _ready():
+	# Initialise each button with the default key binding from InputMap
+	var input_event
+	for action in player_actions:
+		# We assume that the key binding that we want is the first one (0), if there are several
+		input_event = InputMap.get_action_list(action)[0]
+		# See note at the beginning of the script
+		get_node("bindings").get_node(action).get_node("Button").set_text(OS.get_scancode_string(input_event.scancode))

demos/gui/input_mapping/engine.cfg

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+[application]
+
+name="Input Mapping GUI"
+main_scene="res://controls.scn"
+icon="icon.png"
+
+[display]
+
+width=640
+height=480
+
+[input]
+
+move_up=[key(Up)]
+move_down=[key(Down)]
+move_left=[key(Left)]
+move_right=[key(Right)]
+jump=[key(Space)]