Boxart

Terminal graph rendering with Unicode box-drawing characters.

Takes a Graph.t() from libgraph and renders it as ASCII/Unicode art in the terminal, with multiline labels inside nodes, edge labels, and automatic layout.

Usage

graph =
  Graph.new()
  |> Graph.add_vertex("A", label: "Start")
  |> Graph.add_vertex("B", label: "Process")
  |> Graph.add_vertex("C", label: "End")
  |> Graph.add_edge("A", "B")
  |> Graph.add_edge("B", "C")

IO.puts(Boxart.render(graph, direction: :lr))

┌─────────┐    ┌───────────┐    ┌───────┐
│         │    │           │    │       │
│  Start  ├───►│  Process  ├───►│  End  │
│         │    │           │    │       │
└─────────┘    └───────────┘    └───────┘

Branching with edge labels and node shapes:

graph =
  Graph.new()
  |> Graph.add_vertex("A", label: "Start")
  |> Graph.add_vertex("B", label: "Decision", shape: :diamond)
  |> Graph.add_vertex("C", label: "Process")
  |> Graph.add_vertex("D", label: "End")
  |> Graph.add_edge("A", "B")
  |> Graph.add_edge("B", "C", label: "yes")
  |> Graph.add_edge("B", "D", label: "no")

IO.puts(Boxart.render(graph, direction: :td))

┌────────────┐
│            │
│   Start    │
│            │
└──────┬─────┘
       │
       │
       ▼
┌──────◇─────┐
│            │
│  Decision  │
│            │
└──────◇─────┘
       │
       │
       ├─────────────────╮no
    yes│                 │
       ▼                 ▼
┌────────────┐    ┌────────────┐
│            │    │            │
│  Process   │    │    End     │
│            │    │            │
└────────────┘    └────────────┘

Code nodes

Render source code with line numbers inside nodes — useful for control flow graphs, program dependence graphs, and code analysis tools:

graph =
  Graph.new()
  |> Graph.add_vertex("entry",
    source: "def fetch(url) do\n  case HTTP.get(url) do",
    start_line: 1,
    language: :elixir
  )
  |> Graph.add_vertex("ok",
    source: "{:ok, body} ->\n  body",
    start_line: 3
  )
  |> Graph.add_vertex("err",
    source: "{:error, reason} ->\n  raise reason",
    start_line: 5
  )
  |> Graph.add_edge("entry", "ok", label: ":ok")
  |> Graph.add_edge("entry", "err", label: ":error")

IO.puts(Boxart.render(graph, direction: :td))

┌───┬─────────────────────────────┐
│ 1 │ def fetch(url) do           │
│ 2 │   case HTTP.get(url) do     │
└───┴────────────┬────────────────┘
                 │
                 │
                 ├─────────────────────────────────────╮:ok
           :error│                                     │
                 ▼                                     ▼
┌───┬─────────────────────────────┐       ┌───┬─────────────────────┐
│ 5 │ {:error, reason} ->         │       │ 3 │ {:ok, body} ->      │
│ 6 │   raise reason              │       │ 4 │   body              │
└───┴─────────────────────────────┘       └───┴─────────────────────┘

When makeup and makeup_elixir are installed, code is syntax-highlighted with ANSI colors in the terminal.

Vertex labels

Vertex labels are keyword lists (libgraph convention). Boxart recognizes:

• :label — display text inside the node (defaults to inspect(vertex))
• :shape — node shape atom (:rectangle, :diamond, :rounded, :hexagon, :stadium, :circle, :cylinder, etc.)
• :source — source code string (renders as code node with line numbers)
• :start_line — first line number for code display (default: 1)
• :language — language atom for syntax highlighting (e.g. :elixir)

Edge labels

Simple string labels:

Graph.add_edge(g, "A", "B", label: "yes")

Keyword list labels for advanced edge styling:

Graph.add_edge(g, "A", "B", label: [
  label: "yes",         # display text
  style: :dotted,       # :solid (default), :dotted, :thick
  bidirectional: true,  # arrows on both ends
  arrow: false          # no arrow (T-junction instead)
])

Specialized renderers

Beyond directed graphs, Boxart includes standalone renderers for:

• Boxart.Render.StateDiagram — state machine diagrams with start/end markers
• Boxart.Render.Sequence — sequence diagrams with lifelines, messages, activation boxes, notes, and interaction blocks
• Boxart.Render.GitGraph — git branch/commit visualization
• Boxart.Render.Gantt — Gantt charts with task bars and time axis
• Boxart.Render.Mindmap — tree layout with left/right branching (accepts Graph.t())
• Boxart.Render.PieChart — horizontal bar charts

All renderers implement the Boxart.Diagram behaviour.

Color themes

Pass :theme to render with ANSI colors in the terminal:

Boxart.render(graph, theme: :dracula)

Built-in themes: :default, :mono, :neon, :dracula, :nord, :amber, :phosphor.

Custom themes via struct:

theme = %Boxart.Theme{
  node: ~w[blue]a,
  edge: ~w[faint]a,
  arrow: ~w[red bright]a,
  label: ~w[bright]a,
  edge_label: ~w[italic faint]a
}

Boxart.render(graph, theme: theme)

Options

Boxart.render(graph,
  direction: :td,       # :td, :lr, :bt, :rl
  charset: :unicode,    # :unicode (default) or :ascii
  padding_x: 4,         # horizontal padding inside nodes
  padding_y: 2,         # vertical padding inside nodes
  gap: 4,               # gap between nodes
  theme: :default,      # color theme (:mono, :neon, :dracula, :nord, :amber, :phosphor)
  rounded_edges: true   # rounded (╭╮╰╯) or sharp (┌┐└┘) edge corners
)

Installation

def deps do
  [
    {:boxart, "~> 0.1.0"},

    # optional, for syntax highlighting in code nodes
    {:makeup, "~> 1.0"},
    {:makeup_elixir, "~> 1.0"}
  ]
end

Prior art

Boxart's layout engine is an Elixir port of termaid by Fabio Souto, which itself was inspired by mermaid-ascii by Alexander Grooff. We also evaluated beautiful-mermaid by Craft and chose termaid for its cleaner layout pipeline (Sugiyama-style with barycenter crossing minimization, A* routing with soft obstacles, and direction-aware canvas junction merging).

License

MIT