Heatmap

Heatmap JavaScript Library v1.2

Usage:

1. Initialize. You need to create a object with these fields: width, height, sigma, radius, context.Then, execute heatmap(object).For example,

    var config = {
    	width: 1000, //width of the canvas
    	height: 800, //height of the canvas
    	sigma: 8, // sigma of Gauss Kernel
    	radius: 60, // raidus of Gauss kernel
    	quality: 4, //1 is the best quality, 
    		//the quality will decrease with the value increase
    		//lower quality means less time consuming					
    	context: $(canvas).getContext('2d')  //the context of the canvas
    }
    heatmap(config);
   

2. Call heatmap.draw(nodes) to update and render the heatmap,nodes is an array with objects like {x: _x, y: _y}.For example,

    var nodes = [{x:100, y:20}, {x:400, y:30}, {x:70, y:340}];
    heatmap.draw(nodes); 
   

   node can also formed as [{x:100, y:20, count:3}];

3. Each time the size of the canvas is changed, please call heatmap.setSize(newWidth, newHeight).

4. Use heatmap.fixMaxDensity() or heatmap.releaseMaxDensity() to fix or release the max density value. You need to execute fixMaxDensity after drawing and execute releaseMaxDensity before drawing.

AUTHOR: Zeek Wang
Date: 2013/07/22