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Description
The HeatmapRenderer creates a surface using a standard Gaussian blur algorithm used in data visualization for illustrating areas of concentration within datasets. (Added at version 3.11 of the JS API)Code
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no">
<title>FeatureLayer using Weighted HeatmapRenderer</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.46/dijit/themes/claro/claro.css">
<link rel="stylesheet" href="https://js.arcgis.com/3.46/esri/css/esri.css">
<style>
html, body, #map {
width: 100%;
height: 100%;
margin: 0;
padding: 0;
}
.blurInfo {
position: absolute;
top: 10px;
right: 5px;
font-size: 1.25em;
font-family: monospace;
color: #4C4C4C;
width: 240px;
background-color: #FFFFFF;
padding: 10px;
border: 2px solid #57585A;
border-radius: 20px;
}
.blurInfo p span {
background-color: #FFFFFF;
padding: 0 5px;
border-radius: 5px;
}
.blurInfo input[type=range] {
width: 100%;
display: block;
}
</style>
<script src="https://js.arcgis.com/3.46/"></script>
<script>
var map;
require([
"dojo/number",
"esri/InfoTemplate",
"esri/layers/FeatureLayer",
"esri/map",
"esri/renderers/HeatmapRenderer",
"dojo/domReady!"
], function (number, InfoTemplate, FeatureLayer, Map, HeatmapRenderer){
map = new Map("map", {
basemap: "gray-vector",
zoom: 3,
center: [-103, 18],
minZoom: 3,
maxZoom: 5
});
// --------------------------------------------------------------------
// Format the magnitude value in the pop up to show one decimal place.
// Uses the dojo/number module to perform formatting.
// --------------------------------------------------------------------
formatMagnitude = function (value, key, data){
return number.format(value, {places: 1, locale: "en-us"});
};
var infoTemplate = new InfoTemplate("Attributes",
"Name: ${Name}<br>Magnitude: ${Magnitude:formatMagnitude}");
var serviceURL = "//services.arcgis.com/V6ZHFr6zdgNZuVG0/arcgis/rest/services/Earthquakes_Since_1970/FeatureServer/0";
var heatmapFeatureLayerOptions = {
mode: FeatureLayer.MODE_SNAPSHOT,
outFields: ["Name", "Magnitude"],
infoTemplate: infoTemplate
};
var heatmapFeatureLayer = new FeatureLayer(serviceURL, heatmapFeatureLayerOptions);
var blurCtrl = document.getElementById("blurControl");
var maxCtrl = document.getElementById("maxControl");
var minCtrl = document.getElementById("minControl");
var valCtrl = document.getElementById("valueControl");
var heatmapRenderer = new HeatmapRenderer({
field: "Magnitude",
blurRadius: blurCtrl.value,
maxPixelIntensity: maxCtrl.value,
minPixelIntensity: minCtrl.value
});
heatmapFeatureLayer.setRenderer(heatmapRenderer);
map.addLayer(heatmapFeatureLayer);
/** Add event handlers for interactivity **/
var sliders = document.querySelectorAll(".blurInfo p~input[type=range]");
var addLiveValue = function (ctrl){
var val = ctrl.previousElementSibling.querySelector("span");
ctrl.addEventListener("input", function (evt){
val.innerHTML = evt.target.value;
});
};
for (var i = 0; i < sliders.length; i++) {
addLiveValue(sliders.item(i));
}
blurCtrl.addEventListener("change", function (evt){
var r = +evt.target.value;
if (r !== heatmapRenderer.blurRadius) {
heatmapRenderer.blurRadius = r;
heatmapFeatureLayer.redraw();
}
});
maxCtrl.addEventListener("change", function (evt){
var r = +evt.target.value;
if (r !== heatmapRenderer.maxPixelIntensity) {
heatmapRenderer.maxPixelIntensity = r;
heatmapFeatureLayer.redraw();
}
});
minCtrl.addEventListener("change", function (evt){
var r = +evt.target.value;
if (r !== heatmapRenderer.minPixelIntensity) {
heatmapRenderer.minPixelIntensity = r;
heatmapFeatureLayer.redraw();
}
});
// --------------------------------------------------------------------
// When check / uncheck the control for the HeatmapRenderer field,
// we will leave the blurRadius and the minPixelIntensity values the
// same. However we will adjust the maxPixelIntensity value so it
// spreads the colors across the range of magnitude values. For your
// own dataset, you will need to experiment to find what looks good
// based upon the level of geography when you display the heatmap
// and the values in your dataset.
// --------------------------------------------------------------------
valCtrl.addEventListener("change", function (evt){
var chk = evt.target.checked;
if (!chk) {
document.getElementById("maxValue").innerHTML = 21;
maxCtrl.value = 21;
heatmapRenderer.maxPixelIntensity = 21;
}
else {
document.getElementById("maxValue").innerHTML = 250;
maxCtrl.value = 250;
heatmapRenderer.maxPixelIntensity = 250;
}
heatmapRenderer.field = (chk) ? "Magnitude" : null;
heatmapFeatureLayer.redraw();
});
});
</script>
</head>
<body>
<div id="map"></div>
<div class="blurInfo">
<p>
<label for="valueControl">Weight by magnitude</label>
<input id="valueControl" type="checkbox" checked>
</p>
<p>Blur Radius : <span id="blurValue">10</span></p>
<input id="blurControl" type="range" max=30 min=0 value=10 step=1/>
<p>Max Value : <span id="maxValue">100</span></p>
<input id="maxControl" type="range" max=500 min=0 value=100 step=1/>
<p>Min Value : <span id="minValue">0</span></p>
<input id="minControl" type="range" max=500 min=0 value=0 step=1/>
</div>
</body>
</html>