114 lines
2.8 KiB
JavaScript
114 lines
2.8 KiB
JavaScript
import GeoJSON from '../src/ol/format/GeoJSON.js';
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import Map from '../src/ol/Map.js';
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import OSM from '../src/ol/source/OSM.js';
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import Projection from '../src/ol/proj/Projection.js';
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import VectorTileSource from '../src/ol/source/VectorTile.js';
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import View from '../src/ol/View.js';
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import {
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Tile as TileLayer,
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VectorTile as VectorTileLayer,
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} from '../src/ol/layer.js';
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// Converts geojson-vt data to GeoJSON
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const replacer = function (key, value) {
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if (value.geometry) {
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let type;
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const rawType = value.type;
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let geometry = value.geometry;
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if (rawType === 1) {
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type = 'MultiPoint';
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if (geometry.length == 1) {
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type = 'Point';
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geometry = geometry[0];
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}
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} else if (rawType === 2) {
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type = 'MultiLineString';
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if (geometry.length == 1) {
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type = 'LineString';
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geometry = geometry[0];
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}
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} else if (rawType === 3) {
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type = 'Polygon';
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if (geometry.length > 1) {
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type = 'MultiPolygon';
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geometry = [geometry];
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}
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}
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return {
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'type': 'Feature',
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'geometry': {
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'type': type,
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'coordinates': geometry,
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},
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'properties': value.tags,
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};
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} else {
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return value;
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}
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};
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const map = new Map({
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layers: [
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new TileLayer({
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source: new OSM(),
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}),
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],
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target: 'map',
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view: new View({
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center: [0, 0],
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zoom: 2,
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}),
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});
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const url = 'data/geojson/countries.geojson';
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fetch(url)
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.then(function (response) {
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return response.json();
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})
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.then(function (json) {
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const tileIndex = geojsonvt(json, {
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extent: 4096,
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debug: 1,
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});
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const format = new GeoJSON({
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// Data returned from geojson-vt is in tile pixel units
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dataProjection: new Projection({
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code: 'TILE_PIXELS',
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units: 'tile-pixels',
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extent: [0, 0, 4096, 4096],
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}),
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});
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const vectorSource = new VectorTileSource({
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tileUrlFunction: function (tileCoord) {
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// Use the tile coordinate as a pseudo URL for caching purposes
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return JSON.stringify(tileCoord);
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},
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tileLoadFunction: function (tile, url) {
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const tileCoord = JSON.parse(url);
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const data = tileIndex.getTile(
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tileCoord[0],
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tileCoord[1],
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tileCoord[2]
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);
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const geojson = JSON.stringify(
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{
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type: 'FeatureCollection',
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features: data ? data.features : [],
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},
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replacer
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);
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const features = format.readFeatures(geojson, {
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extent: vectorSource.getTileGrid().getTileCoordExtent(tileCoord),
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featureProjection: map.getView().getProjection(),
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});
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tile.setFeatures(features);
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},
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});
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const vectorLayer = new VectorTileLayer({
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source: vectorSource,
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});
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map.addLayer(vectorLayer);
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});
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