Generic rendering code. This will start a process that will render a frame at a regular rate in a window of the indicated size. Rendering the frame is done by calling a callback with the current window size and height and the current mouse pointer position.

GenRenderer is using GenServer internally and is thus OTP compatible.

Usually, if you want to use Uderzo, this is the module you want to build around. See also the examples and demos in the repository.

The basic usage of GenRenderer is the same as GenServer: you use the module, supply a render_frame/5 callback and an optional init_renderer/1 callback. There are just more arguments than with GenServer ;-). Short skeleton:

defmodule MyRenderer do
  use Uderzo.GenRenderer

def start_link(...) do
  Uderzo.GenRenderer.start_link(__MODULE__, "My Demo", 800, 600, 60, [], name: __MODULE__)
end

def init_renderer([]) do
  {:ok, %{some: :state}}
end

def render_frame(window_width, window_height, mouse_x, mouse_y, state) do
  ... Paint your frame here ...
  {:ok, state}
end

One important difference with GenServer is that the init_renderer/1 callback isn't called during start time but rather as soon as Uderzo is initialized. This means that you can call functions to load fonts, etcetera, at initialization time.

Note that once called, GenRenderer just goes off and does rendering. There's no requirement to interact with it further, although you can set the user state directly, forcing a redraw if desired.