文章来源于网络收集而来，版权归原创者所有，如有侵权请及时联系！

UTFGrid

发布于 2022-11-30 23:36:06 字数 4886 浏览 0 评论 0 收藏 0

This example shows how to read data from a UTFGrid source.

Point to a country to see its name and flag.

Tiles made with TileMill. Hosting on mapbox.com or with open-source TileServer.

main.js

import 'ol/ol.css';
import Map from 'ol/Map';
import Overlay from 'ol/Overlay';
import TileJSON from 'ol/source/TileJSON';
import TileLayer from 'ol/layer/Tile';
import UTFGrid from 'ol/source/UTFGrid';
import View from 'ol/View';

const key =
  'Your Mapbox access token from https://mapbox.com/ here';

const mapLayer = new TileLayer({
  source: new TileJSON({
    url:
      'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' +
      key,
  }),
});

const gridSource = new UTFGrid({
  url:
    'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' +
    key,
});

const gridLayer = new TileLayer({source: gridSource});

const view = new View({
  center: [0, 0],
  zoom: 1,
});

const mapElement = document.getElementById('map');
const map = new Map({
  layers: [mapLayer, gridLayer],
  target: mapElement,
  view: view,
});

const infoElement = document.getElementById('country-info');
const flagElement = document.getElementById('country-flag');
const nameElement = document.getElementById('country-name');

const infoOverlay = new Overlay({
  element: infoElement,
  offset: [15, 15],
  stopEvent: false,
});
map.addOverlay(infoOverlay);

const displayCountryInfo = function (coordinate) {
  const viewResolution = /** @type {number} */ (view.getResolution());
  gridSource.forDataAtCoordinateAndResolution(
    coordinate,
    viewResolution,
    function (data) {
      // If you want to use the template from the TileJSON,
      //  load the mustache.js library separately and call
      //  info.innerHTML = Mustache.render(gridSource.getTemplate(), data);
      mapElement.style.cursor = data ? 'pointer' : '';
      if (data) {
        flagElement.src = 'data:image/png;base64,' + data['flag_png'];
        nameElement.innerHTML = data['admin'];
      }
      infoOverlay.setPosition(data ? coordinate : undefined);
    }
  );
};

map.on('pointermove', function (evt) {
  if (evt.dragging) {
    return;
  }
  const coordinate = map.getEventCoordinate(evt.originalEvent);
  displayCountryInfo(coordinate);
});

map.on('click', function (evt) {
  displayCountryInfo(evt.coordinate);
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>UTFGrid</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;
      }
      #country-name {
        color: black;
        font-size: 12pt;
        font-weight: bold;
        text-shadow: white 0.1em 0.1em 0.2em;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div style="display: none;">
      <!-- Overlay with the country info -->
      <div id="country-info">
        <div id="country-name">&nbsp;</div>
        <img id="country-flag" src="" />
      </div>
    </div>
    <script src="main.js"></script>
  </body>
</html>

package.json

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

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

列表为空，暂无数据