54 lines
1.5 KiB
JavaScript
54 lines
1.5 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 OSM from '../src/ol/source/OSM.js';
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const osm = new TileLayer({
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source: new OSM()
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});
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const map = new Map({
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layers: [osm],
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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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osm.on('prerender', function(event) {
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const ctx = event.context;
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// calculate the pixel ratio and rotation of the canvas
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const matrix = event.inversePixelTransform;
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const canvasPixelRatio = Math.sqrt(matrix[0] * matrix[0] + matrix[1] * matrix[1]);
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const canvasRotation = -Math.atan2(matrix[1], matrix[0]);
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ctx.save();
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// center the canvas and remove rotation to position clipping
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ctx.translate(ctx.canvas.width / 2, ctx.canvas.height / 2);
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ctx.rotate(-canvasRotation);
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ctx.scale(3 * canvasPixelRatio, 3 * canvasPixelRatio);
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ctx.translate(-75, -80);
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ctx.beginPath();
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ctx.moveTo(75, 40);
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ctx.bezierCurveTo(75, 37, 70, 25, 50, 25);
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ctx.bezierCurveTo(20, 25, 20, 62.5, 20, 62.5);
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ctx.bezierCurveTo(20, 80, 40, 102, 75, 120);
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ctx.bezierCurveTo(110, 102, 130, 80, 130, 62.5);
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ctx.bezierCurveTo(130, 62.5, 130, 25, 100, 25);
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ctx.bezierCurveTo(85, 25, 75, 37, 75, 40);
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ctx.clip();
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ctx.translate(75, 80);
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ctx.scale(1 / 3 / canvasPixelRatio, 1 / 3 / canvasPixelRatio);
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// reapply canvas rotation and position
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ctx.rotate(canvasRotation);
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ctx.translate(-ctx.canvas.width / 2, -ctx.canvas.height / 2);
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});
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osm.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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