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Forked from letmaik/index.html
Created April 7, 2022 11:32
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Leaflet GridLayer example with Canvas
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<title>GridLayer Test</title>
<meta charset="utf-8" />
<link rel="stylesheet" href="https://unpkg.com/[email protected]/dist/leaflet.css" />
<style>
body {
padding: 0;
margin: 0;
}
html, body, #map {
height: 100%;
width: 100%;
}
</style>
</head>
<body>
<div id="map"></div>
<script src="https://unpkg.com/[email protected]/dist/leaflet.js"></script>
<script>
var map = new L.Map('map', { center: [10, 0], zoom: 2});
var tiles = new L.GridLayer();
tiles.createTile = function(coords) {
var tile = L.DomUtil.create('canvas', 'leaflet-tile');
var ctx = tile.getContext('2d');
var size = this.getTileSize()
tile.width = size.x
tile.height = size.y
// calculate projection coordinates of top left tile pixel
var nwPoint = coords.scaleBy(size)
// calculate geographic coordinates of top left tile pixel
var nw = map.unproject(nwPoint, coords.z)
ctx.fillStyle = 'white';
ctx.fillRect(0, 0, size.x, 50);
ctx.fillStyle = 'black';
ctx.fillText('x: ' + coords.x + ', y: ' + coords.y + ', zoom: ' + coords.z, 20, 20);
ctx.fillText('lat: ' + nw.lat + ', lon: ' + nw.lng, 20, 40);
ctx.strokeStyle = 'red';
ctx.beginPath();
ctx.moveTo(0, 0);
ctx.lineTo(size.x-1, 0);
ctx.lineTo(size.x-1, size.y-1);
ctx.lineTo(0, size.y-1);
ctx.closePath();
ctx.stroke();
return tile;
}
L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
attribution: 'Map data &copy; <a href="http://www.osm.org">OpenStreetMap</a>'
}).addTo(map)
tiles.addTo(map)
</script>
</body>
</html>
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