adds image generator

lib/image_generator.ex

@@ -0,0 +1,96 @@
+defmodule ImageGenerator do
+  @doc """
+  Generates an image of the maze using the erlang egd library.
+  """
+
+  defstruct [:maze, :image, :wall_color]
+
+  @cell_size 20
+
+  @doc """
+  Generates an image of the maze.
+  """
+  @spec run(Maze.t()) :: :ok
+  def run(maze) do
+    %__MODULE__{maze: maze, wall_color: :egd.color(:black)}
+    |> initialize_image()
+    |> draw_walls()
+    |> save_image()
+    |> destroy_image()
+  end
+
+  defp initialize_image(%{maze: %{width: width, height: height}} = ctx) do
+    image = :egd.create(width * @cell_size + 1, height * @cell_size + 1)
+
+    %{ctx | image: image}
+  end
+
+  defp draw_walls(%{maze: %{width: width, height: height}} = ctx) do
+    for x <- 0..(width - 1), y <- 0..(height - 1), reduce: ctx do
+      acc -> draw_cell_walls(_cell_position = {x, y}, acc)
+    end
+  end
+
+  defp draw_cell_walls(cell_position, %{maze: maze} = ctx) do
+    cell = Maze.get(maze, cell_position)
+
+    Enum.reduce(cell.walls, ctx, fn
+      {direction, true}, acc -> draw_wall(acc, cell_position, direction)
+      {_direction, false}, acc -> acc
+    end)
+  end
+
+  defp draw_wall(ctx, _cell_position = {x, y}, :north) do
+    :egd.line(
+      ctx.image,
+      {x * @cell_size, y * @cell_size,},
+      {x * @cell_size, (y + 1) * @cell_size,},
+      ctx.wall_color
+    )
+
+    ctx
+  end
+
+  defp draw_wall(ctx, _cell_position = {x, y}, :south) do
+    :egd.line(
+      ctx.image,
+      {(x + 1) * @cell_size, y * @cell_size,},
+      {(x + 1) * @cell_size, (y + 1) * @cell_size},
+      ctx.wall_color
+    )
+
+    ctx
+  end
+
+  defp draw_wall(ctx, _cell_position = {x, y}, :west) do
+    :egd.line(
+      ctx.image,
+      {x * @cell_size, y * @cell_size},
+      {(x + 1) * @cell_size, y * @cell_size},
+      ctx.wall_color
+    )
+
+    ctx
+  end
+
+  defp draw_wall(ctx, _cell_position = {x, y}, :east) do
+    :egd.line(
+      ctx.image,
+      {x * @cell_size, (y + 1) * @cell_size},
+      {(x + 1) * @cell_size, (y + 1) * @cell_size},
+      ctx.wall_color
+    )
+
+    ctx
+  end
+
+  defp save_image(ctx) do
+    ctx.image
+    |> :egd.render()
+    |> :egd.save("output.png")
+
+    ctx
+  end
+
+  defp destroy_image(ctx), do: :egd.destroy(ctx.image)
+end