`class State`

Persists and restores presentation controller state to/from a JSON file.

Tracks the current slide index, clock elapsed time, and clock running state. This allows the presentation to survive server restarts without losing position.

Definitions

`DEFAULT_PATH = ".presently.json"`

The default state file path.

`def initialize(path = DEFAULT_PATH)`

Initialize a new state instance.

Signature

parameter　path　String: The file path for the state file.

Implementation

def initialize(path = DEFAULT_PATH)
	@path = path
end

`attr :path`

Signature

attribute　String: The file path for the state file.

`def save(controller)`

Save the controller's current state to disk.

Signature

parameter　controller　PresentationController: The controller to save.

Implementation

def save(controller)
	data = {
		current_index: controller.current_index,
		elapsed: controller.clock.elapsed,
		running: controller.clock.running?,
		started: controller.clock.started?,
	}
	
	File.write(@path, JSON.pretty_generate(data))
rescue => error
	Console.warn(self, "Failed to save state", exception: error)
end

`def restore(controller)`

Restore persisted state into the given controller.

Signature

parameter　controller　PresentationController: The controller to restore into.

Implementation

def restore(controller)
	return unless File.exist?(@path)
	
	data = JSON.parse(File.read(@path), symbolize_names: true)
	
	# Restore slide position:
	if index = data[:current_index]
		controller.go_to(index.to_i)
	end
	
	# Restore clock state:
	if data[:started]
		controller.clock.restore!(data[:elapsed].to_f, running: data[:running])
	end
rescue => error
	Console.warn(self, "Failed to restore state", exception: error)
end