dv_map 1.1.0

Prebuilt Natural Earth GeoJSON maps for Flutter geographic visualizations.

dv_map

Prebuilt Natural Earth Admin 0 GeoJSON maps packaged for Flutter with tree shaking support.

Features

• ✅ Flutter widgets - Ready-to-use widgets for rendering maps
• ✅ Tree shaking - Only imports the maps you use
• ✅ No asset bundling - Maps are embedded as Dart constants
• ✅ Type safe - Each map is a named getter
• ✅ 450+ maps - World maps and individual countries at 2 resolutions (110m, 50m)
• ✅ Interactive - Tap detection and event handling
• ✅ Customizable - Full control over styling and projections

Data source

These GeoJSON files are derived from the Natural Earth Admin 0 – Countries datasets:

• https://naciscdn.org/naturalearth/110m/cultural/ne_110m_admin_0_countries.zip
• https://naciscdn.org/naturalearth/50m/cultural/ne_50m_admin_0_countries.zip
• https://naciscdn.org/naturalearth/10m/cultural/ne_10m_admin_0_countries.zip

The maps are Natural Earth country boundaries converted to GeoJSON at scales 110m (low), 50m (medium), and 10m (high resolution).

Usage

Map Widgets (Recommended)

Each map file exports both the GeoJSON data AND a ready-to-use widget:

import 'package:flutter/material.dart';
import 'package:dv_geo_core/dv_geo_core.dart';

// Import specific maps - each exports both data and widget
import 'package:dv_map/maps/world/110m.dart';
import 'package:dv_map/maps/asia/china/110m.dart';
import 'package:dv_map/maps/africa/nigeria/50m.dart';

class MyMapApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          // Use the generated World110mWidget
          Expanded(
            child: World110mWidget(
              projection: MercatorProjection(),
              fillColor: Colors.grey.shade300,
              strokeColor: Colors.grey.shade700,
              onFeatureTap: (feature, position) {
                print('Tapped: ${feature.properties!['name']}');
              },
            ),
          ),
          // Use the generated China110mWidget (no continent prefix!)
          Expanded(
            child: China110mWidget(
              projection: MercatorProjection(),
              fillColor: Colors.red.shade200,
              strokeColor: Colors.red.shade700,
            ),
          ),
          // Use the generated Nigeria50mWidget
          Expanded(
            child: Nigeria50mWidget(
              projection: MercatorProjection(),
              fillColor: Colors.green.shade300,
            ),
          ),
        ],
      ),
    );
  }
}

Generated widgets: Each map file (e.g., world/110m.dart, asia/china/110m.dart) exports:

• Data getter: world110m, asiaChina110m, etc.
• Widget class: World110mWidget, AsiaChina110mWidget, etc.

All generated widgets support:

• Custom projections (Mercator, Orthographic, Albers, etc.)
• Custom fill and stroke colors
• Interactive tap detection
• Full customization via parameters

Base widget (for advanced custom use):

• MapWidget - Base widget for rendering any GeoJSON data with full control

Accessing Raw GeoJSON Data

Each map file exports the raw GeoJSON data as a getter:

import 'package:dv_map/maps/world/110m.dart';
import 'package:dv_map/maps/africa/nigeria/50m.dart';

void main() {
  // Access the raw GeoJSON data (no async loading needed)
  final world = world110m;             // GeoJsonFeatureCollection
  final nigeria = africaNigeria50m;    // GeoJsonFeatureCollection

  print('World has ${world.features.length} countries');
  print('Nigeria has ${nigeria.features.length} features');

  // Access feature properties
  for (final feature in world.features) {
    print(feature.properties!['name']);
  }
}

Tree-shakeable: Your app only bundles the maps you import.

Available maps

Directory structure:

lib/maps/
├── world/
│   ├── 110m.dart           # World map (low resolution)
│   ├── 50m.dart            # World map (medium resolution)
│   ├── 10m.dart            # World map (high resolution)
│   └── world.dart          # Exports all world scales
├── africa/
│   ├── africa.dart         # Exports all African countries
│   ├── nigeria/
│   │   ├── 110m.dart
│   │   ├── 50m.dart
│   │   ├── 10m.dart
│   │   └── nigeria.dart    # Exports all Nigeria scales
│   └── ... (other countries)
├── asia/
│   ├── asia.dart           # Exports all Asian countries
│   └── {country}/{scale}.dart
├── europe/
│   ├── europe.dart         # Exports all European countries
│   └── {country}/{scale}.dart
├── north-america/
│   ├── north-america.dart  # Exports all North American countries
│   └── {country}/{scale}.dart
├── south-america/
│   ├── south-america.dart  # Exports all South American countries
│   └── {country}/{scale}.dart
└── oceania/
    ├── oceania.dart        # Exports all Oceanian countries
    └── {country}/{scale}.dart

Naming conventions:

• Directory structure: {continent}/{country}/{scale}.dart
• Data getters: {continent}{Country}{Scale} (camelCase, includes continent)
• Widget classes: {Country}{Scale}Widget (PascalCase + Widget, NO continent prefix)

World maps:

File	Data Getter	Widget Class	Size
maps/world/110m.dart	world110m	World110mWidget	~171 KB
maps/world/50m.dart	world50m	World50mWidget	~1.3 MB

Country maps examples:

File	Data Getter	Widget Class
maps/africa/nigeria/110m.dart	africaNigeria110m	Nigeria110mWidget
maps/asia/japan/50m.dart	asiaJapan50m	Japan50mWidget
maps/asia/china/110m.dart	asiaChina110m	China110mWidget
maps/asia/afghanistan/110m.dart	asiaAfghanistan110m	Afghanistan110mWidget
maps/africa/south-sudan/50m.dart	africaSouthSudan50m	SouthSudan50mWidget

Note:

• Data getters include continent prefix for namespacing (e.g., asiaChina110m)
• Widget classes omit continent prefix for cleaner usage (e.g., China110mWidget)
• Hyphens in country names are converted to underscores in data getters and PascalCase in widget names

Tree Shaking & Bundle Size

Bundle size - Only imported maps are included:

• world.110m only: ~171 KB
• world.50m only: ~1.3 MB
• world.110m + 5 countries (110m): ~350 KB
• Import what you need!

Size comparison:

Map	Raw JSON	Gzipped in Dart	Savings
world.110m	921 KB	171 KB	81%
world.50m	8.4 MB	1.3 MB	84%
Country (avg)	~100 KB	~15 KB	85%

Maps are stored as gzipped binary (base64 encoded) for maximum compression.

How It Works

1. GeoJSON files are gzip compressed during code generation
2. Binary data is base64-encoded and embedded as Dart strings
3. First access: Data is decoded, decompressed, and parsed
4. Subsequent accesses: Cached GeoJsonFeatureCollection is returned
5. Tree shaking: Flutter's build system only bundles imported maps

Generating maps

To regenerate the map files from assets:

cd packages/dv_map
dart scripts/generate_map_widgets.dart

This script:

• Reads all .json files from assets/
• Gzip compresses each file
• Base64 encodes the compressed data
• Generates Dart files with getter functions
• Creates continent-level index files