Force Layout Semantic Zoom

...with panning as well.

by Nivaldo

HTML

<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js?2.4.6"></script>
<link href='http://mbostock.github.com/d3/ex/force.css' rel='stylesheet' type='text/css' /><script src='http://mbostock.github.com/d3/d3.layout.js?2.4.6' type='text/javascript'> </script><script src='http://mbostock.github.com/d3/d3.geom.js?2.4.6' type='text/javascript'></script>

<div id="chart"></div>

JavaScript

var w = 500,
    h = 500,
    fill = d3.scale.category20();

var vis = d3.select("#chart")
  .append("svg:svg")
    .attr("width", w)
    .attr("height", h)
    .attr("pointer-events", "all")
  .append('svg:g')
    .call(d3.behavior.zoom().on("zoom", redraw))
  .append('svg:g');

vis.append('svg:rect')
    .attr('width', w)
    .attr('height', h)
    .attr('fill', 'white');

function redraw() {
  console.log("here", d3.event.translate, d3.event.scale);
  vis.attr("transform",
      "translate(" + d3.event.translate + ")"
      + " scale(" + d3.event.scale + ")");
}

var draw = function(json) {
  var force = d3.layout.force()
      .charge(-120)
      .linkDistance(30)
      .nodes(json.nodes)
      .links(json.links)
      .size([w, h])
      .start();

  var link = vis.selectAll("line.link")
      .data(json.links)
    .enter().append("svg:line")
      .attr("class", "link")
      .style("stroke-width", function(d) { return Math.sqrt(d.value); })
      .attr("x1", function(d) { return d.source.x; })
      .attr("y1", function(d) { return d.source.y; })
      .attr("x2", function(d) { return d.target.x; })
      .attr("y2", function(d) { return d.target.y; });

  var node = vis.selectAll("circle.node")
      .data(json.nodes)
    .enter().append("svg:circle")
      .attr("class", "node")
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; })
      .attr("r", 5)
      .style("fill", function(d) { return fill(d.group); })
      .call(force.drag);

  node.append("svg:title")
      .text(function(d) { return d.name; });

  vis.style("opacity", 1e-6)
    .transition()
      .duration(1000)
      .style("opacity", 1);

  force.on("tick", function() {
    link.attr("x1", function(d) { return d.source.x; })
        .attr("y1", function(d) { return d.source.y; })
        .attr("x2", function(d) { return d.target.x; })
        .attr("y2", function(d) { return d.target.y; });

    node.attr("cx", function(d) { return d.x; })
       ...