Flutter地理数据可视化插件geojson_vi的使用

geojson_vi 是一个开源的Dart和Flutter库，旨在高效处理符合RFC 7946标准的GeoJSON地理空间数据。它为开发者提供了强大的工具来解析、读取、创建、更新、搜索和删除地理空间数据。

功能亮点

• 解析和读取GeoJSON数据：geojson_vi 允许开发者快速解析和读取GeoJSON数据，确保完全符合RFC 7946标准。
• 创建、更新、搜索和删除GeoJSON数据：开发者可以轻松地操作GeoJSON数据，从创建新条目到更新、搜索和删除现有数据。
• 支持所有GeoJSON对象：包括多种几何类型（如 GeoJSONPoint, GeoJSONMultiPoint, GeoJSONLineString, GeoJSONMultiLineString, GeoJSONPolygon, GeoJSONMultiPolygon, GeoJSONGeometryCollection），以及 Feature 和 FeatureCollection，使其成为管理多样化地理空间数据的强大工具。

使用示例

创建GeoJSON对象

import 'package:geojson_vi/geojson_vi.dart';

void main() {
  // 创建点对象
  final point = GeoJSONPoint([105.7743099, 21.0717561]);

  // 创建线对象
  final pos1 = [105.7771289, 21.0715458];
  final pos2 = [105.7745218, 21.0715658];
  final pos3 = [105.7729125, 21.0715358];
  final lineString = GeoJSONLineString([pos1, pos2, pos3]);

  // 创建多边形对象
  final p01 = [105.7739666, 21.0726795]; // The first position
  final p02 = [105.7739719, 21.0721991];
  final p03 = [105.7743394, 21.0721966];
  final p04 = [105.7743310, 21.0725269];
  final p05 = [105.7742564, 21.0726120];
  final p06 = [105.7741865, 21.0726095];
  final p07 = [105.7741785, 21.0726746];
  final p08 = [105.7739666, 21.0726795]; // The last position
  final linerRing = [p01, p02, p03, p04, p05, p06, p07, p08];
  final polygon = GeoJSONPolygon([linerRing]);

  // 创建Feature对象
  final featurePoint = GeoJSONFeature(
    point,
    properties: {
      'marker-color': '#7e7e7e',
      'marker-size': 'medium',
      'marker-symbol': 'college',
      'title': 'Hanoi University of Mining and Geology',
      'department': 'Geoinformation Technology',
      'address':
          'No.18 Vien Street - Duc Thang Ward - Bac Tu Liem District - Ha Noi, Vietnam',
      'url': 'http://humg.edu.vn'
    },
  );

  final featureLine = GeoJSONFeature(
    lineString,
    properties: {
      'stroke': '#7e7e7e',
      'stroke-width': 2,
      'stroke-opacity': 1,
      'title': 'Vien St.'
    },
  );

  final featurePolygon = GeoJSONFeature(
    polygon,
    properties: {
      'stroke': '#555555',
      'stroke-width': 2,
      'stroke-opacity': 1,
      'fill': '#ab7942',
      'fill-opacity': 0.5,
      'title': "HUMG's Office"
    },
  );

  // 创建FeatureCollection对象并添加Feature
  final featureCollection = GeoJSONFeatureCollection([]);
  featureCollection.features.add(featurePoint);
  featureCollection.features.add(featureLine);
  featureCollection.features.add(featurePolygon);

  // 输出GeoJSON格式的数据
  print(featureCollection.toJSON());
}

示例输出

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {
        "marker-color": "#7e7e7e",
        "marker-size": "medium",
        "marker-symbol": "college",
        "title": "Hanoi University of Mining and Geology",
        "department": "Geoinformation Technology",
        "address": "No.18 Vien Street - Duc Thang Ward - Bac Tu Liem District - Ha Noi, Vietnam",
        "url": "http://humg.edu.vn"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [
          105.7743099,
          21.0717561
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "stroke": "#7e7e7e",
        "stroke-width": 2,
        "stroke-opacity": 1,
        "title": "Vien St."
      },
      "geometry": {
        "type": "LineString",
        "coordinates": [
          [
            105.7771289,
            21.0715458
          ],
          [
            105.7745218,
            21.0715658
          ],
          [
            105.7729125,
            21.0715358
          ]
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "stroke": "#555555",
        "stroke-width": 2,
        "stroke-opacity": 1,
        "fill": "#ab7942",
        "fill-opacity": 0.5,
        "title": "HUMG's Office"
      },
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              105.7739666,
              21.0726795
            ],
            [
              105.7739719,
              21.0721991
            ],
            [
              105.7743394,
              21.0721966
            ],
            [
              105.774331,
              21.0725269
            ],
            [
              105.7742564,
              21.072612
            ],
            [
              105.7741865,
              21.0726095
            ],
            [
              105.7741785,
              21.0726746
            ],
            [
              105.7739666,
              21.0726795
            ]
          ]
        ]
      }
    }
  ]
}

参考资料

• RFC 7946: The GeoJSON Format

特性和问题反馈

请在 GitHub Issues 提交功能请求和Bug报告。

通过以上内容，您可以快速上手使用 geojson_vi 插件来处理和可视化GeoJSON地理空间数据。希望这些信息对您有所帮助！