maplibre-legend

A Rust crate to generate SVG legends from a MapLibre GL style JSON.

Given a MapLibre style (e.g. style.json), this library parses all layers and produces standalone SVG symbols or a combined legend, complete with optional labels and raster entries.

This project is a work in progress. It doesn't yet support all layer types, but it does cover the most common cases. By using each layer's metadata attribute, you can flexibly customize how the legend is generated—especially the labels.

Features

• Parse MapLibre GL style (v8) JSON into a structured Style model.
• Render individual layer legends (fill, line, circle) as SVG snippets.
• Optionally include raster layers.
• Render labels and customizable dimensions (default_width/default_height).
• Stack all layers into one combined SVG with separators.
• For finer details, the metadata attribute of the layer is used.

Installation

Add this crate to your Cargo.toml:

[dependencies]
maplibre-legend = "0.1.0"  # replace with the latest version

Then in your code:

use maplibre_legend::MapLibreLegend;

Usage

use maplibre_legend::MapLibreLegend;
use std::fs;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let style_json = fs::read_to_string("style.json")?;

    let legend = MapLibreLegend::new(&style_json, 250,40, true, true)?;

    /// Render a single layer
    if let Some(svg) = legend.render_layer("vs2023", Some(true)) {
        fs::write("vs2023.svg", svg)?;
    }

    /// Render all layers
    let combined = legend.render_all(true);
    fs::write("combined.svg", combined)?;

    Ok(())
}

Examples

Given the included style.json (which defines various raster, fill, line and circle layers with metadata.legend.label), calling:

let svg = legend.render_all(true);

produces a full-page legend similar to:

style.json	style2.json	style3.json

Crate Modules

• circle: renders circle layers
• line: renders line layers
• fill: renders polygon (fill) layers
• raster: renders raster (tile) layers
• default: renders a gray polygon
• common: shared types (Style, Layer, etc.)

Contributing

1. Fork the repo and create a feature branch.
2. Run cargo fmt and cargo clippy to keep code clean.
3. Submit a pull request—feedback is welcome!

License

This project is licensed under the MIT License. See the LICENSE file for details.