92 lines
2.8 KiB
JavaScript
92 lines
2.8 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 BingMaps from '../src/ol/source/BingMaps.js';
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const key = 'As1HiMj1PvLPlqc_gtM7AqZfBL8ZL3VrjaS3zIb22Uvb9WKhuJObROC-qUpa81U5';
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const imagery = new TileLayer({
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source: new BingMaps({key: key, imagerySet: 'Aerial'})
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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: [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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// after rendering the layer, show an oversampled version around the pointer
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imagery.on('postrender', function(event) {
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if (mousePosition) {
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const context = event.context;
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const pixelRatio = event.frameState.pixelRatio;
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const half = radius * pixelRatio;
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const centerX = mousePosition[0] * pixelRatio;
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const centerY = mousePosition[1] * pixelRatio;
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const originX = centerX - half;
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const originY = centerY - half;
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const size = 2 * half + 1;
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const sourceData = context.getImageData(originX, originY, size, size).data;
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const dest = context.createImageData(size, size);
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const destData = dest.data;
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for (let j = 0; j < size; ++j) {
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for (let i = 0; i < size; ++i) {
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const dI = i - half;
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const dJ = j - half;
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const dist = Math.sqrt(dI * dI + dJ * dJ);
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let sourceI = i;
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let sourceJ = j;
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if (dist < half) {
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sourceI = Math.round(half + dI / 2);
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sourceJ = Math.round(half + dJ / 2);
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}
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const destOffset = (j * size + i) * 4;
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const sourceOffset = (sourceJ * size + sourceI) * 4;
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destData[destOffset] = sourceData[sourceOffset];
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destData[destOffset + 1] = sourceData[sourceOffset + 1];
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destData[destOffset + 2] = sourceData[sourceOffset + 2];
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destData[destOffset + 3] = sourceData[sourceOffset + 3];
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}
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}
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context.beginPath();
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context.arc(centerX, centerY, half, 0, 2 * Math.PI);
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context.lineWidth = 3 * pixelRatio;
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context.strokeStyle = 'rgba(255,255,255,0.5)';
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context.putImageData(dest, originX, originY);
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context.stroke();
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context.restore();
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}
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});
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