trinhnguyenvn / node-heatmap

canvas heatmaps in node.js and the browser

heatmap

Heatmaps for node.js and the browser, groovy!

example

blob.js

var heatmap = require('heatmap');

var heat = heatmap(500, 500, { radius : 30 });
for (var i = 0; i < 5000; i++) {
    var rho = Math.random() * 2 * Math.PI;
    var z = Math.pow(Math.random(), 2) * 200;
    
    var x = 250 + Math.cos(rho) * z;
    var y = 250 + Math.sin(rho) * z;
    
    heat.addPoint(x, y);
}
heat.draw();

var fs = require('fs');
fs.writeFileSync('blob.png', heat.canvas.toBuffer());

methods

var heatmap = require('heatmap');

var heat = heatmap(...)

Create a new heatmap from an existing canvas element, a numeric width and height, or an option object with canvas or width and height fields.

Optionally, you can set the opts.radius and opts.threshold to control the rendering a little.

heat.addPoint(x, y, params)

Add a point to the heatmap with a radius.

params can have:

• radius, defaults to heat.radius || 20
• weight, defaults to 0.1

heat.scale(x, y)

Scale the canvas by the coefficients x and y.

If y is undefined, scale both x and y by the first parameter, x.

heat.draw()

Render all the points onto the canvas element.

heat.canvas

The HTML Canvas element.

Protip: with the canvas module for node you can heat.canvas.buffer() to get a Buffer with a PNG file all up in it.

install

With npm, just do:

npm install heatmap