OSM 矢量瓦片

发布于 2022-11-30 23:36:05 字数 4702 浏览 0 评论 0 收藏 0

加载 OpenStreetMap 矢量瓦片。

地图加载 Mapzen 矢量瓦片。本示例使用 TopoJSON 格式的 layerName 的选项参数来确定样式和图层("water", "roads", "buildings")。注意：对于矢量瓦片来说，[ol/format/MVT] 效率更高。

main.js

import 'ol/ol.css';
import Map from 'ol/Map';
import TopoJSON from 'ol/format/TopoJSON';
import VectorTileLayer from 'ol/layer/VectorTile';
import VectorTileSource from 'ol/source/VectorTile';
import View from 'ol/View';
import {Fill, Stroke, Style} from 'ol/style';
import {fromLonLat} from 'ol/proj';

const key = 'Your Nextzen API key from https://developers.nextzen.org/';

const roadStyleCache = {};
const roadColor = {
  'major_road': '#776',
  'minor_road': '#ccb',
  'highway': '#f39',
};
const buildingStyle = new Style({
  fill: new Fill({
    color: '#666',
    opacity: 0.4,
  }),
  stroke: new Stroke({
    color: '#444',
    width: 1,
  }),
});
const waterStyle = new Style({
  fill: new Fill({
    color: '#9db9e8',
  }),
});
const roadStyle = function (feature) {
  const kind = feature.get('kind');
  const railway = feature.get('railway');
  const sort_key = feature.get('sort_key');
  const styleKey = kind + '/' + railway + '/' + sort_key;
  let style = roadStyleCache[styleKey];
  if (!style) {
    let color, width;
    if (railway) {
      color = '#7de';
      width = 1;
    } else {
      color = roadColor[kind];
      width = kind == 'highway' ? 1.5 : 1;
    }
    style = new Style({
      stroke: new Stroke({
        color: color,
        width: width,
      }),
      zIndex: sort_key,
    });
    roadStyleCache[styleKey] = style;
  }
  return style;
};

const map = new Map({
  layers: [
    new VectorTileLayer({
      source: new VectorTileSource({
        attributions:
          '&copy; OpenStreetMap contributors, Who’s On First, ' +
          'Natural Earth, and openstreetmapdata.com',
        format: new TopoJSON({
          layerName: 'layer',
          layers: ['water', 'roads', 'buildings'],
        }),
        maxZoom: 19,
        url:
          'https://tile.nextzen.org/tilezen/vector/v1/all/{z}/{x}/{y}.topojson?api_key=' +
          key,
      }),
      style: function (feature, resolution) {
        switch (feature.get('layer')) {
          case 'water':
            return waterStyle;
          case 'roads':
            return roadStyle(feature);
          case 'buildings':
            return resolution < 10 ? buildingStyle : null;
          default:
            return null;
        }
      },
    }),
  ],
  target: 'map',
  view: new View({
    center: fromLonLat([-74.0064, 40.7142]),
    maxZoom: 19,
    zoom: 15,
  }),
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>OSM Vector Tiles</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
      .map {
        background: #f8f4f0;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "osm-vector-tiles",
  "dependencies": {
    "ol": "7.1.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}

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