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拖拽加载数据

发布于 2022-11-30 23:36:02 字数 7028 浏览 0 评论 0 收藏 0

本示例演示使用拖拽交互

本示例演示使用拖拽交互。拖拽 GPX, GeoJSON, IGC, KML, or TopoJSON 文件添加到地图上。此方法不支持投影坐标系转换，因此仅支持渲染 EPSG:4326 和 EPSG:3857 投影坐标系数据。

main.js

import 'ol/ol.css';
import DragAndDrop from 'ol/interaction/DragAndDrop';
import Map from 'ol/Map';
import View from 'ol/View';
import {GPX, GeoJSON, IGC, KML, TopoJSON} from 'ol/format';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {Vector as VectorSource, XYZ} from 'ol/source';

const key = 'Get your own API key at https://www.maptiler.com/cloud/';
const attributions =
  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

const map = new Map({
  layers: [
    new TileLayer({
      source: new XYZ({
        attributions: attributions,
        url:
          'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
        maxZoom: 20,
      }),
    }),
  ],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2,
  }),
});

const extractStyles = document.getElementById('extractstyles');
let dragAndDropInteraction;

function setInteraction() {
  if (dragAndDropInteraction) {
    map.removeInteraction(dragAndDropInteraction);
  }
  dragAndDropInteraction = new DragAndDrop({
    formatConstructors: [
      GPX,
      GeoJSON,
      IGC,
      // use constructed format to set options
      new KML({extractStyles: extractStyles.checked}),
      TopoJSON,
    ],
  });
  dragAndDropInteraction.on('addfeatures', function (event) {
    const vectorSource = new VectorSource({
      features: event.features,
    });
    map.addLayer(
      new VectorLayer({
        source: vectorSource,
      })
    );
    map.getView().fit(vectorSource.getExtent());
  });
  map.addInteraction(dragAndDropInteraction);
}
setInteraction();

extractStyles.addEventListener('change', setInteraction);

const displayFeatureInfo = function (pixel) {
  const features = [];
  map.forEachFeatureAtPixel(pixel, function (feature) {
    features.push(feature);
  });
  if (features.length > 0) {
    const info = [];
    let i, ii;
    for (i = 0, ii = features.length; i < ii; ++i) {
      info.push(features[i].get('name'));
    }
    document.getElementById('info').innerHTML = info.join(', ') || '&nbsp';
  } else {
    document.getElementById('info').innerHTML = '&nbsp;';
  }
};

map.on('pointermove', function (evt) {
  if (evt.dragging) {
    return;
  }
  const pixel = map.getEventPixel(evt.originalEvent);
  displayFeatureInfo(pixel);
});

map.on('click', function (evt) {
  displayFeatureInfo(evt.pixel);
});

// Sample data downloads

const link = document.getElementById('download');

function download(fullpath, filename) {
  fetch(fullpath)
    .then(function (response) {
      return response.blob();
    })
    .then(function (blob) {
      if (navigator.msSaveBlob) {
        // link download attribute does not work on MS browsers
        navigator.msSaveBlob(blob, filename);
      } else {
        link.href = URL.createObjectURL(blob);
        link.download = filename;
        link.click();
      }
    });
}

document.getElementById('download-gpx').addEventListener('click', function () {
  download('data/gpx/fells_loop.gpx', 'fells_loop.gpx');
});

document
  .getElementById('download-geojson')
  .addEventListener('click', function () {
    download('data/geojson/roads-seoul.geojson', 'roads-seoul.geojson');
  });

document.getElementById('download-igc').addEventListener('click', function () {
  download('data/igc/Ulrich-Prinz.igc', 'Ulrich-Prinz.igc');
});

document.getElementById('download-kml').addEventListener('click', function () {
  download('data/kml/states.kml', 'states.kml');
});

document
  .getElementById('download-topojson')
  .addEventListener('click', function () {
    download('data/topojson/fr-departments.json', 'fr-departments.json');
  });

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Drag-and-Drop</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;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div><label><input type="checkbox" id="extractstyles" checked /> Extract styles from KML</label></div>
    <br />
    <div>
      <a id="download" download></a>
      Download samples:&nbsp;&nbsp;
      <button id="download-gpx">GPX</button>
      &nbsp;
      <button id="download-geojson">GeoJSON</button>
      &nbsp;
      <button id="download-igc">IGC</button>
      &nbsp;
      <button id="download-kml">KML</button>
      &nbsp;
      <button id="download-topojson">TopoJSON</button>
    </div>
    <br />
    <div id="info">&nbsp;</div>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "drag-and-drop",
  "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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