Scenic is an application framework written directly on the Elixir/Erlang/OTP stack. With it you can build client-side applications that operate identically across all supported operating systems, including MacOS, Ubuntu, Nerves/Linux, and more.

Scenic is primarily aimed at fixed screen connected devices (IoT), but can also be used to build portable applications.

Helpful Guides

If you are new to scenic, then you should read the General Overview, Getting Started, and Structure of a Scene guides first.

Configure Scenic

In order to start Scenic, you should first build a configuration for one or more ViewPorts. These configuration maps will be passed in to the main Scenic supervisor. These configurations should live in your app’s config.exs file.

use Mix.Config

# Configure the main viewport for the Scenic application
config :my_application, :viewport, %{
      name: :main_viewport,
      size: {700, 600},
      default_scene: {MyApplication.Scene.Example, nil},
      drivers: [
        %{
          module: Scenic.Driver.Glfw,
          name: :glfw,
          opts: [resizeable: false, title: "Example Application"],
        }
      ]
    }

In the ViewPort configuration you can do things like set a name for the ViewPort process, its size, the default scene and start one or more drivers.

See the documentation for ViewPort Configuration to learn more about how to set the options on a viewport.

Note that all the drivers are in seperate Hex packages as you should choose the correct one for your application. For example, the Scenic.Driver.Glfw driver draws your scenes into a window under MacOS and Ubuntu. It should work on other OS’s as well, such as other flavors of Unix or Windows, but I haven’t worked on or tested those yet.

Supervise Scenic

The Scenic module itself is a supervisor that manages all the machinery that makes the Scenes, ViewPorts, and Drivers run.

In order to run any Scenic application, you will need to start the Scenic supervisor in your supervision tree.

Load a configuration for one or more ViewPorts, then add Scenic to your root supervisor.

defmodule MyApplication do

  def start(_type, _args) do
    import Supervisor.Spec, warn: false

    # load the viewport configuration from config
    main_viewport_config = Application.get_env(:my_application :viewport)

    # start the application with the viewport
    children = [
      supervisor(Scenic, [viewports: [main_viewport_config]]),
    ]
    Supervisor.start_link(children, strategy: :one_for_one)
  end

end

Note that you can start the Scenic supervisor without any ViewPort Configurations. In that case, you are responsible for supervising the ViewPorts yourself. This is not recommended for devices as Scenic should know how to restart the main ViewPort in the event of an error.