Oxygene

A read-only Flutter widget that renders an L-system / turtle-graphics tree from a compact genome string. You hand it one string; it unrolls the string into a branching tree and fits the drawing to its box. The widget is non-interactive by design — no taps, no gestures — so it is safe to drop into cards, previews, lists, or full-screen views.

Live gallery & editor

See it in action at limenhort.com/oxygene. The site has an editor for building your own trees and a gallery of ready-made examples. Each example shows its genome string, so you can copy one and paste it straight into the genome: argument below.

Features

  • Single public widget — Oxygene — with a tiny, stable API.
  • Accepts both the plain genome form and the compact short form (<old> || <buffer> | <count>); the widget expands the short form itself.
  • Fits the tree to the available space; draws nothing of its own around it (border, background, and clipping are the caller's responsibility — wrap it in a Container if you want a frame).
  • Invalid genomes fail soft: a structural error yields a truncated or blank tree, never a thrown exception.

Getting started

Add it to your app's pubspec.yaml:

dependencies:
  oxygene: ^1.0.0

Or run:

flutter pub add oxygene

Usage

import 'package:oxygene/oxygene.dart';

// paste a genome copied from the gallery at limenhort.com/oxygene
Oxygene(genome: '0,1-0*3v9,1-0*a,1-0*a');

Parameters

Parameter Type Default Description
genome String required The genome string (plain or short form).
width double? null Box width; falls back to the parent's constraints.
height double? null Box height; falls back to the parent's constraints.
backgroundColor Color Colors.white Fill behind the tree.
leafScale double 2.0 Size multiplier for leaf (branch-tip) markers.

Genome format

A genome is a comma-separated list of tokens, e.g. 0,2-0*11v0,1-0*a,2-0*a. Each token is tail-?*head:

  • tail (before -) — segment length / distance to the child.
  • head (after *):
    • a single number 0–11 — a node with one child; the number is a direction on a 12-hour clock.
    • LvR (two distinct numbers) — a fork with two children.
    • a — a leaf (branch tip).

Directions are cumulative and relative: a child's angle is added to its ancestor's, modulo 12.

Short form. A genome may also be written compactly as <old> || <buffer> | <count>, meaning "graft buffer into every leaf of old, count times." Oxygene expands this for you, so either form can be passed to genome:.

Additional information

Libraries

oxygene