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Many Polygons with geojson-vt on Leaflet

Sample of using geojson-vt generated tiles inside leaflet 0.7. It uses custom (generic) TiledCanvas L.CanvasTiles.js .

info also here

<!doctype html>
<html>
<head>
<title>Many polygons with geojson-vt on Leaflet</title>
<meta charset="utf-8">
<style>
html, body {
height: 100%;
padding: 0;
margin: 0;
background: rgb(14, 21, 30);
height: 100%;
font-family: Tahoma, Geneva, Verdana, sans-serif;
font-size:12px;
color:#808080;
}
#map {
position: absolute;
height: 100%;
width: 100%;
background-color: #333;
}
</style>
</head>
<body>
<div id="map"></div>
<div id="drop" style="position:absolute; right:0px; top:0px; width: 200px; height:50%;background-color: white;
border-style:dashed; border-color: blue; border-width:1px; border-radius:4px;padding:5px; opacity:0.9">
<b>Drop WGS84 GeoJSON here</b>
</div>
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.css" />
<script src="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.js"></script>
<script src="http://www.sumbera.com/gist/js/vt/geojson-vt-dev.js"></script>
<script src="http://www.sumbera.com/gist/js/leaflet/canvas/L.CanvasTiles.js"></script>
<script src="http://www.sumbera.com/gist/data/CZDistricts.js"></script>
<script>
var leafletMap = L.map('map').setView([50.00, 14.44], 9);
L.tileLayer("http://{s}.sm.mapstack.stamen.com/(toner-background,$fff[difference],$fff[@23],$fff[hsl-saturation@20],toner-lines[destination-in])/{z}/{x}/{y}.png")
.addTo(leafletMap);
var tileOptions = {
maxZoom: 20, // max zoom to preserve detail on
tolerance: 5, // simplification tolerance (higher means simpler)
extent: 4096, // tile extent (both width and height)
buffer: 64, // tile buffer on each side
debug: 0, // logging level (0 to disable, 1 or 2)
indexMaxZoom: 0, // max zoom in the initial tile index
indexMaxPoints: 100000, // max number of points per tile in the index
};
//-------------------------------------------------
function colorizeFeatures(data) {
var counter = 0;
for (var i = 0; i < data.features.length; i++) {
data.features[i].properties.color = 'hsl(' + 360 * Math.random() + ', 50%, 50%)';
if (data.features[i].geometry.coordinates[0])
counter += data.features[i].geometry.coordinates[0].length;
else{
console.log("empty coordinates at " + i + " patching with 0.0...");
data.features[i].geometry.coordinates[0] = 0.0
data.features[i].geometry.coordinates[1] = 0.0
}
}
return counter;
}
var tileIndex = geojsonvt(data, tileOptions);
var dropArea = document.getElementById('drop');
dropArea.ondragover = function () {
return false;
};
dropArea.ondragend = function () {
return false;
};
dropArea.ondrop = function (e) {
// -- helper from viz.js test of geojson-vt
function humanFileSize(size) {
var i = Math.floor(Math.log(size) / Math.log(1024));
return Math.round(100 * (size / Math.pow(1024, i))) / 100 + ' ' + ['B', 'kB', 'MB', 'GB'][i];
}
var reader = new FileReader();
reader.readAsText(e.dataTransfer.files[0]);
dropArea.innerHTML += "<br/>";
dropArea.innerHTML += "<br/>Loading... " + e.dataTransfer.files[0].name.toString();
var start = new Date().getTime();
reader.onload = function (event) {
var elapsed = new Date().setTime(new Date().getTime() - start);
dropArea.innerHTML += " " + elapsed + "ms";
try {
dropArea.innerHTML += "<br/>&nbsp;Parsing... " + humanFileSize(event.target.result.length);
start = new Date().getTime();
var data;
data = JSON.parse(event.target.result);
elapsed = new Date().setTime(new Date().getTime() - start);
dropArea.innerHTML += " " + elapsed + "ms";
var vertCount = colorizeFeatures(data);
start = new Date().getTime();
dropArea.innerHTML += "<br/>&nbsp;Indexing... " + data.features.length + " features";
dropArea.innerHTML += "<br/>&nbsp;with " + vertCount + " vertexes";
tileIndex = geojsonvt(data, tileOptions); //eslint-disable-line
elapsed = new Date().setTime(new Date().getTime() - start);
dropArea.innerHTML += " " + elapsed + "ms";
tileLayer.redraw();
} catch (err) {
dropArea.innerHTML += "<br/>&nbsp;Error: " + err;
}
};
e.preventDefault();
return false;
};
colorizeFeatures(data);
var tileLayer = L.canvasTiles()
.params({ debug: false, padding: 5 })
.drawing(drawingOnCanvas)
var pad = 0;
tileLayer.addTo(leafletMap);
function drawingOnCanvas(canvasOverlay, params) {
var bounds = params.bounds;
params.tilePoint.z = params.zoom;
var ctx = params.canvas.getContext('2d');
ctx.globalCompositeOperation = 'source-over';
console.log('getting tile z' + params.tilePoint.z + '-' + params.tilePoint.x + '-' + params.tilePoint.y);
var tile = tileIndex.getTile(params.tilePoint.z, params.tilePoint.x, params.tilePoint.y);
if (!tile) {
console.log('tile empty');
return;
}
ctx.clearRect(0, 0, params.canvas.width, params.canvas.height);
var features = tile.features;
ctx.strokeStyle = 'grey';
for (var i = 0; i < features.length; i++) {
var feature = features[i],
type = feature.type;
ctx.fillStyle = feature.tags.color ? feature.tags.color : 'rgba(255,0,0,0.05)';
ctx.beginPath();
for (var j = 0; j < feature.geometry.length; j++) {
var geom = feature.geometry[j];
if (type === 1) {
ctx.arc(geom[0] * ratio + pad, geom[1] * ratio + pad, 2, 0, 2 * Math.PI, false);
continue;
}
for (var k = 0; k < geom.length; k++) {
var p = geom[k];
var extent = 4096;
var x = p[0] / extent * 256;
var y = p[1] / extent * 256;
if (k) ctx.lineTo(x + pad, y + pad);
else ctx.moveTo(x + pad, y + pad);
}
}
if (type === 3 || type === 1) ctx.fill('evenodd');
ctx.stroke();
}
};
</script>
</body>
</html>
Licensed under MIT
Copyright (c) 2015 Stanislav Sumbera,
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
(the "Software"), to deal in the Software without restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
@Sumbera
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Sumbera commented Dec 7, 2015

MIT

@hjrobinson
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How can I add two separate layers using this? This is so I can toggle them on and off in the layer control. This code still seems to render better than gridlayer.

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