mi-flatland 3.0.1

Model text file + layout text file -> beautiful diagram

Flatland Model Diagram (non) Editor

NEW Status January 13, 2025

I have recently rebuilt the entire application based on a series of modules available on GitHub and PyPI. Will be deploying in ernest in the coming days.

Am de-commisioning the old version on GitHub and PyPI named 'flatland-model-diagram-editor' Now it is just 'flatland' here on GitHub and 'mi-flatland' on PyPI

Ah yes, yet another tool for generating diagrams from text. But this one is different (otherwise I wouldn't have wasted all this time building it!)

I built Flatland because the following benefits are critical for productive model development:

1. Complete separation of the model semantics from the diagram layout
2. Complete separation of model semantics from model notation
3. Consistent layout of model diagrams without forcing the user to accept or hack awkard, non-sensical placements of nodes and connectors (yeah, I'm lookin at YOU PlantUML)
4. Maximum layout power with minimal specification: No more carpal tunnel pixel pushing!
5. Beautiful, readable diagram output in many output formats (pdf, svg, etc)
6. Support for industrial strength modeling (many hundreds and thousands of model elements)
7. Use your favorite text editor and all the advanced facilities of it and whatever IDE you like without having to learn yet another draw tool that makes you and your team's life difficult.
8. And since we're here on GitHub, wouldn't it be nice if all of your models were under proper configuration management where you and your team can diff and merge to your heart's content? Wouldn't it be nice to update a diagram layout without touching the underlying model (and vice versa)?

Basically, I have wasted way too many hours of my career pushing pixels around and I just couldn't take it anymore!

Flatland is a model diagram non-editor written by me Leon Starr that generates beautiful PDFs (and other output formats) based on two very human-readable input text files. The model file specifies model semantics (state transitions, generalizations, classes etc) while the layout file specifies (node placement and alignment, connector anchors) and lightly refers to some elements in the model file. You can think of the layout file as a "style sheet" for your models. Some benefits:

Follow me on BlueSky and LinkedIn for updates.

Models to Code

In the meantime, if you are curious about the whole MBSE thing that this tool supports, take a look at our book. Also, various resources at the Model Integration website.

Installation

Flatland is a command-line program published on PyPI as mi-flatland. You install it once into an isolated Python virtual environment and then run it with the flatland command. The steps below assume no prior Python experience — if you're already comfortable with Python, just run the commands in the code blocks and skip the explanations.

What you'll need

• Python 3.11 or 3.12. (Python 3.13 and newer are not yet supported.)
• macOS, Linux, or Windows.

1. Install Python

If you don't already have a supported version, download Python 3.12 from python.org and run the installer for your platform. Any install method is fine (the official installer, Homebrew, etc.) as long as the version is 3.11 or 3.12. Having other Python versions already on your machine is not a problem.

Confirm it's available:

python3 --version

You should see something like Python 3.12.7. (On Windows the command is usually py --version.)

2. Create a virtual environment

A virtual environment is just a folder that holds a private copy of Python and the packages flatland needs, kept separate from the rest of your system so nothing conflicts. Python has this built in — no extra tools required. Create one (here named flatland-env, but you can call it anything):

macOS / Linux

python3 -m venv ~/flatland-env

Windows (PowerShell)

py -m venv $HOME\flatland-env

3. Activate the environment

Activating tells your terminal to use the environment you just created.

macOS / Linux

source ~/flatland-env/bin/activate

Windows (PowerShell)

& $HOME\flatland-env\Scripts\Activate.ps1

Your prompt now starts with (flatland-env), which means it's active. You'll need to run this activate command again each time you open a new terminal before using flatland.

4. Install flatland

pip install --upgrade pip
pip install mi-flatland

5. Check the version

flatland -V

This prints something like Flatland version: 3.0.0, confirming the install worked.

6. Generate your first diagram

Flatland ships with example models. Copy them into your current folder:

flatland -E

This creates an examples/ directory. Move into the elevator example and generate a class diagram:

cd examples/elevator
flatland -m elevator.xcm -l elevator_xUML.mls -d elevator.pdf

That command supplies three things:

• -m elevator.xcm — the model file (.xcm = class model, .xsm = state-machine model)
• -l elevator_xUML.mls — the layout file (.mls), which positions everything
• -d elevator.pdf — the output file to generate

The extension you give to -d selects the output format. Use .pdf for PDF or .svg for SVG — so the same model and layout produce an SVG just by changing the name:

flatland -m elevator.xcm -l elevator_xUML.mls -d elevator.svg

A layout file refers to specific model content, so each .mls only works with its matching model. A single model can have several layouts (e.g. elevator_xUML.mls and elevator_Starr.mls here), grouped together so you can tell which files belong with which.

Run flatland -h to see every option (grid overlay, rulers, no-color, and more).

Where your settings live

The first time you run flatland it creates two folders of YAML configuration files under your home directory at ~/.config:

• flatland — layout, title-block, and positional parameters.
• mi_tablet — graphics and text styles, plus any logos or other media.

You can browse and edit these (each file has explanatory comments), but edit carefully. If anything breaks, just delete the folder and flatland will recreate the defaults on its next run.

Coming back later

Whenever you open a new terminal, re-activate the environment (step 3) before running flatland. Prefer not to activate every time? Installing with pipx (pipx install mi-flatland) puts the flatland command on your PATH globally while keeping it isolated.