libgd-gis

Map Styles and GeoJSON Rendering

Styling maps with GD::GIS::Style

libgd-gis uses YAML-based style definitions to control how maps and layers are rendered.

map.style = GD::GIS::Style.load("solarized")

This loads a style definition from a YAML file and applies it globally to the map.

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Style files (.yml)

Styles are defined using YAML files, usually located in:

examples/styles/

A style file describes how each layer should be drawn.

roads:
  motorway:
    stroke: [88, 110, 117]
    stroke_width: 10
  primary:
    stroke: [147, 161, 161]
    stroke_width: 6
  minor:
    stroke: [203, 75, 22]
    stroke_width: 1

water:
  stroke: [38, 139, 210]
  fill: [7, 54, 66]

parks:
  fill: [42, 161, 152]

Key concepts

• Top-level keys define layer categories
• Nested keys define sub-types
• Colors are RGB arrays
• Stroke and fill depend on geometry type

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Adding GeoJSON data

GEOJSON = "data/home_store.geojson"
map.add_geojson(GEOJSON)

This parses the GeoJSON file, classifies its features, and renders them using the active style.

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Style-driven rendering

The same GeoJSON can be rendered with different styles without changing the data.

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Summary

• Styles are YAML-based
• Styles control all visual output
• GeoJSON rendering depends entirely on the active style

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