Ch. 11, Fig. 10 - D3.js in Action

This is the code for Chapter 11, Figure 10 from D3.js in Action which uses mixed mode rendering to improve network performance via drawing nodes with SVG while drawing edges with HTML5 Canvas. This allows you to maintain mouse events on your nodes while dramatically improving animation performance.

<html>
<head>
  <title>D3 in Action Chapter 11 - Example 6</title>
  <meta charset="utf-8" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
</head>
<style>
body, html {
    margin: 0;
  }
canvas {
  position: absolute;
  width: 500px;
  height: 500px;
}
svg {
  position: absolute;
  width:500px;
  height:500px;
}
path.country {
    fill: gray;
    stroke-width: 1;
    stroke: black;
    opacity: .5;
}
path.sample {
    stroke: black;
    stroke-width: 1px;
    fill: red;
    fill-opacity: .5;
}
line.link {
      stroke-width: 1px;
      stroke: black;
      stroke-opacity: .5;
}
circle.node {
  fill: red;
  stroke: white;
  stroke-width: 1px;
}
circle.xy {
  fill: pink;
  stroke: black;
  stroke-width: 1px;
}
</style>
<body>
<canvas height="500" width="500"></canvas>
<div id="viz">
  <svg></svg>
</div>
</body>
  <footer>
    
<script>
  var linkScale = d3.scale.linear().domain([0,.9,.95,1]).range([0,10,100,1000]);

sampleNodes = d3.range(3000).map(function(d) {
    var datapoint = {};
    datapoint.id = "Sample Node " + d;

return datapoint;
  })
  sampleLinks = [];
    var y = 0;
    while (y < 1000) {
      var randomSource = Math.floor(Math.random() * 1000);
      var randomTarget = Math.floor(linkScale(Math.random()));
      var linkObject = {source: sampleNodes[randomSource], target: sampleNodes[randomTarget]}
      if (randomSource != randomTarget) {
       sampleLinks.push(linkObject);
      }
      y++;
  }
  
      force = d3.layout.force()
      .size([500,500])
      .gravity(.5)
      .nodes(sampleNodes)
      .links(sampleLinks)
      .on("tick", forceTick);

d3.select("svg").selectAll("circle.node")
      .data(sampleNodes)
      .enter()
      .append("circle")
      .attr("r", 3)
      .style("fill", "red")
      .attr("class", "node")
      .style("stroke", "white")
      .style("stroke-width", "1px");
      
      force.start();
      
      function forceTick() {
      	var context = d3.select("canvas").node().getContext("2d");
        context.clearRect(0,0,500,500);
        
        context.lineWidth = 1;
        context.strokeStyle = "rgba(0, 0, 0, 0.5)";

sampleLinks.forEach(function (link) {
        context.beginPath();
        context.moveTo(link.source.x,link.source.y)
        context.lineTo(link.target.x,link.target.y)
        context.stroke();
      })

d3.selectAll("circle.node")
        .attr("cx", function(d) {return d.x})
        .attr("cy", function(d) {return d.y});
      }
      
      
</script>
  </footer>

</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js