heatmap.js
Version:
Dynamic JavaScript Heatmaps for the Web
125 lines (112 loc) • 4.75 kB
HTML
<html lang="en">
<head>
<meta charset="utf-8">
<title>Legend Example (DOM Legends) | heatmap.js</title>
<style>
body, html, h2 { margin:0; padding:0; height:100%;}
body { font-family:sans-serif; }
body * { font-weight:200;}
#heatmapContainerWrapper { width:100%; height:100%; position:absolute; background:rgba(0,0,0,.1); }
#heatmapContainer { width:100%; height:100%;}
#heatmapLegend { background:white; position:absolute; bottom:0; right:0; padding:10px; }
#min { float:left; }
#max { float:right; }
h1 { position:absolute; background:black; color:white; padding:10px; font-weight:200;}
#all-examples-info { position:absolute; background:white; font-size:16px; padding:20px; top:100px; width:350px; line-height:150%; border:1px solid rgba(0,0,0,.2);}
</style>
</head>
<body>
<div id="heatmapContainerWrapper">
<div id="heatmapContainer">
</div>
<div id="heatmapLegend">
<h2>Descriptive Legend Title</h2>
<span id="min"></span>
<span id="max"></span>
<img id="gradient" src="" style="width:100%" />
</div>
</div>
<h1>Adding a custom legend to heatmap.js</h1>
<div id="all-examples-info">
<strong style="font-weight:bold;line-height:200%;font-size:18px;">Looking for more examples?</strong> <br />Check out the full <a href="http://www.patrick-wied.at/static/heatmapjs/examples.html?utm_source=gh_local" target="_blank">list of all heatmap.js examples</a> with more pointers & inline documentation.
</div>
<script src="/build/heatmap.js"></script>
<script>
window.onload = function() {
// helper function
function $(id) {
return document.getElementById(id);
};
/* legend code */
// we want to display the gradient, so we have to draw it
var legendCanvas = document.createElement('canvas');
legendCanvas.width = 100;
legendCanvas.height = 10;
var legendCtx = legendCanvas.getContext('2d');
var gradientCfg = {};
function updateLegend(data) {
// the onExtremaChange callback gives us min, max, and the gradientConfig
// so we can update the legend
$('min').innerHTML = data.min;
$('max').innerHTML = data.max;
// regenerate gradient image
if (data.gradient != gradientCfg) {
gradientCfg = data.gradient;
var gradient = legendCtx.createLinearGradient(0, 0, 100, 1);
for (var key in gradientCfg) {
gradient.addColorStop(key, gradientCfg[key]);
}
legendCtx.fillStyle = gradient;
legendCtx.fillRect(0, 0, 100, 10);
$('gradient').src = legendCanvas.toDataURL();
}
};
/* legend code end */
// create a heatmap instance
var heatmap = h337.create({
container: document.getElementById('heatmapContainer'),
maxOpacity: .5,
radius: 10,
blur: .75,
// update the legend whenever there's an extrema change
onExtremaChange: function onExtremaChange(data) {
updateLegend(data);
}
});
// boundaries for data generation
var width = (+window.getComputedStyle(document.body).width.replace(/px/,''));
var height = (+window.getComputedStyle(document.body).height.replace(/px/,''));
// generate 1000 datapoints
var generate = function() {
// randomly generate extremas
var extremas = [(Math.random() * 1000) >> 0,(Math.random() * 1000) >> 0];
var max = Math.max.apply(Math, extremas);
var min = Math.min.apply(Math,extremas);
var t = [];
for (var i = 0; i < 1000; i++) {
var x = (Math.random()* width) >> 0;
var y = (Math.random()* height) >> 0;
var c = ((Math.random()* max-min) >> 0) + min;
// btw, we can set a radius on a point basis
var r = (Math.random()* 80) >> 0;
// add to dataset
t.push({ x: x, y:y, value: c, radius: r });
}
var init = +new Date;
// set the generated dataset
heatmap.setData({
min: min,
max: max,
data: t
});
console.log('took ', (+new Date) - init, 'ms');
};
// initial generate
generate();
// whenever a user clicks on the ContainerWrapper the data will be regenerated -> new max & min
document.getElementById('heatmapContainerWrapper').onclick = function() { generate(); };
};
</script>
</body>
</html>