89 lines
2.5 KiB
JavaScript
89 lines
2.5 KiB
JavaScript
import Map from '../src/ol/Map.js';
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import View from '../src/ol/View.js';
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import TileLayer from '../src/ol/layer/Tile.js';
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import {fromLonLat} from '../src/ol/proj.js';
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import XYZ from '../src/ol/source/XYZ.js';
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import {getRenderPixel} from '../src/ol/render.js';
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const key = 'get_your_own_D6rA4zTHduk6KOKTXzGB';
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const attributions = '<a href="https://www.maptiler.com/copyright/" target="_blank">© MapTiler</a> ' +
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'<a href="https://www.openstreetmap.org/copyright" target="_blank">© OpenStreetMap contributors</a>';
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const roads = new TileLayer({
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source: new XYZ({
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attributions: attributions,
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url: 'https://api.maptiler.com/maps/streets/{z}/{x}/{y}.png?key=' + key,
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tileSize: 512,
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maxZoom: 22
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})
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});
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const imagery = new TileLayer({
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source: new XYZ({
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attributions: attributions,
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url: 'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
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maxZoom: 20
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})
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});
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const container = document.getElementById('map');
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const map = new Map({
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layers: [roads, imagery],
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target: container,
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view: new View({
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center: fromLonLat([-109, 46.5]),
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zoom: 6
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})
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});
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let radius = 75;
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document.addEventListener('keydown', function(evt) {
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if (evt.which === 38) {
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radius = Math.min(radius + 5, 150);
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map.render();
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evt.preventDefault();
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} else if (evt.which === 40) {
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radius = Math.max(radius - 5, 25);
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map.render();
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evt.preventDefault();
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}
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});
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// get the pixel position with every move
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let mousePosition = null;
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container.addEventListener('mousemove', function(event) {
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mousePosition = map.getEventPixel(event);
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map.render();
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});
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container.addEventListener('mouseout', function() {
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mousePosition = null;
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map.render();
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});
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// before rendering the layer, do some clipping
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imagery.on('prerender', function(event) {
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const ctx = event.context;
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ctx.save();
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ctx.beginPath();
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if (mousePosition) {
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// only show a circle around the mouse
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const pixel = getRenderPixel(event, mousePosition);
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const offset = getRenderPixel(event, [mousePosition[0] + radius, mousePosition[1]]);
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const canvasRadius = Math.sqrt(Math.pow(offset[0] - pixel[0], 2) + Math.pow(offset[1] - pixel[1], 2));
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ctx.arc(pixel[0], pixel[1], canvasRadius, 0, 2 * Math.PI);
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ctx.lineWidth = 5 * canvasRadius / radius;
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ctx.strokeStyle = 'rgba(0,0,0,0.5)';
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ctx.stroke();
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}
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ctx.clip();
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});
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// after rendering the layer, restore the canvas context
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imagery.on('postrender', function(event) {
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const ctx = event.context;
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ctx.restore();
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});
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