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new leaflet sample [work in progress] #4

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merged 6 commits into from
Jan 22, 2016
Merged

new leaflet sample [work in progress] #4

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4fd6987
new leaflet sample, work in progress
jgravois Jan 22, 2016
306623d
dig elevation data out of canvas correctly
jgravois Jan 22, 2016
634fc68
static min/max
jgravois Jan 22, 2016
c60ab56
hack to get rid of white line
jgravois Jan 22, 2016
334aa8c
add configurable elevation range
jgravois Jan 22, 2016
003bbe8
custom tile size in object constructor
jgravois Jan 22, 2016
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154 changes: 154 additions & 0 deletions js/leaflet.html
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Original file line number Diff line number Diff line change
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<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Lerc in Leaflet</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />

<!-- Load Leaflet from CDN-->
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.css" />
<script src="http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.js"></script>
<!--script src="../node_modules/leaflet/dist/leaflet-src.js"></script-->

<script src="./LercCodec.js"></script>

<style>
body {
margin:0;
padding:0;
}

#map {
position: absolute;
top:0;
bottom:0;
right:0;left:0;
}

#info-pane {
position: absolute;
top: 10px;
right: 10px;
z-index: 10;
padding: 1em;
background: white;
}
</style>
</head>
<body>

<div id="map"></div>
<div id="info-pane" class="leaflet-bar">
<label>
pixel range (m)
</label>
<input id="pixelRangeMin" type="text" value="0" onchange="lerc.redraw()">
<input id="pixelRangeMax" type="text" value="8000" onchange="lerc.redraw()">
</div>

<script>
var url;

var map = L.map('map', {
noWrap: true
}).setView([40, -100], 3);

var lerc = L.tileLayer.canvas({
noWrap: true,
tileSize: 257,
attribution: 'USGS, Esri <a href="https://github.com/Esri/lerc">LERC</a>'
});

lerc.drawTile = function(canvas, tilePoint, zoom) {
var ctx = canvas.getContext('2d');
// ctx.fillStyle = '#00FFFF';
// ctx.fillRect(0, 0, 257, 257);
var canvasPos = canvas.getBoundingClientRect();
var url = 'http://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer/tile/' +
zoom +
'/' +
tilePoint.y +
'/' +
tilePoint.x;

var lerc = LERC();
var xhr = new XMLHttpRequest();
xhr.responseType = "arraybuffer";
xhr.open("Get", url, true);
xhr.send();
var pixels, mask, min, max, height, width;
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
var decodedPixelBlock = lerc.decode(xhr.response, { returnMask: true });
width = decodedPixelBlock.width;
height = decodedPixelBlock.height;
// range suitable for the whole world
min = document.getElementById('pixelRangeMin').value;
max = document.getElementById('pixelRangeMax').value;
pixels = decodedPixelBlock.pixelData;
mask = decodedPixelBlock.maskData;
// imageCanvas.width = width;
// imageCanvas.height = height;

var imageData = ctx.createImageData(width, height);
var data = imageData.data;
var f = 255 / (max - min);
var pv = 0;
var index = 0;
var nPixels = width * height;
// optimization for no mask case (mid of most rasters)
if (mask) {
for (var i = 0; i < nPixels; i++) {
if (mask[i]) {
pv = (pixels[i] - min) * f;
data[i * 4] = pv;
data[i * 4 + 1] = pv;
data[i * 4 + 2] = pv;
// the 4th position controls transparency (rgb, a)
data[i * 4 + 3] = 255;
}
else {
// not sure why, but 100% transparent doesn't show underlying canvas paint...
data[i * 4 + 3] = 255;
}
}
}
else {
for (var i = 0; i < nPixels; i++) {
pv = (pixels[i] - min) * f;
data[i * 4] = pv;
data[i * 4 + 1] = pv;
data[i * 4 + 2] = pv;
data[i * 4 + 3] = 255;
}
}
ctx.putImageData(imageData, 0, 0);
}

// map.on('mousemove', function (evt) {
// var info = document.getElementById('info-pane');
// var x = evt.layerPoint.x;
// var y = evt.layerPoint.y;
// var pixel = ctx.getImageData(x, y, 1, 1);
// var data = pixel.data;
// info.innerHTML = "elevation: " + data[0] + " meters";
// })

// canvas.onmousemove = function (evt) {
// // this isn't robust enough to survive a pan
// var info = document.getElementById('info-pane');
// var x = evt.layerX;
// var y = evt.layerY;
// var pixel = ctx.getImageData(x, y, 1, 1);
// var data = pixel.data;
// info.innerHTML = "elevation: " + data[0] + " meters";
// }
}


}

lerc.addTo(map);
</script>
</body>
</html>