D3 Examples - Canvas Path Benchmark

Canvas Path Benchmark
This example benchmarks the time taken to draw a line consisting of 10000 separate segments into an HTML5 Canvas.
On Chrome and Safari the SVG in 2012 the Canvas results were about 20x faster than those measured by the equivalent SVG Path Benchmark. On Firefox, Opera, and IE9 the results are similar.
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<!DOCTYPE html>
<html>
<head>
    <title>Canvas Path Benchmark</title>
    <style type="text/css">
      body { margin: 0px 10px; }
      h1 { font-size: 1.3em; line-height: 1.0em; }
      table { font-size: 0.8em; margin: 0px 10px; padding: 2px }
      th { text-align: center; font-weight: bold; padding: 0px  10px 0px 10px; }
      td { text-align: center; font-weight: normal; padding: 0px  10px 0px 10px; }
      ul.hlist { display: inline-block; list-style-type: none; margin: 0px; padding-left: 15px; }
      ul.hlist li { display: inline-table; vertical-align: top; list-style-type: none }
      #canvas { width: 400px; height: 400px; padding:0px;
        background-color: #eeeeee; color:gray; border: solid 1px #cccccc }
    </style>
    <script type="text/javascript">
      window.requestAnimFrame = (function() {
        return window.requestAnimationFrame ||
               window.webkitRequestAnimationFrame ||
               window.mozRequestAnimationFrame ||
               window.oRequestAnimationFrame ||
               window.msRequestAnimationFrame ||
               function(/* function FrameRequestCallback */ callback, /* DOMElement Element */ element) {
                 return window.setTimeout(callback, 1000/60);
               };
      })();
      window.cancelRequestAnimFrame = (function() {
        return window.cancelCancelRequestAnimationFrame ||
               window.webkitCancelRequestAnimationFrame ||
               window.mozCancelRequestAnimationFrame ||
               window.oCancelRequestAnimationFrame ||
               window.msCancelRequestAnimationFrame ||
               window.clearTimeout;
      })();
    </script>
</head>
<body>
  <h1>Canvas Path Benchmark</h1>
  <p id="user-agent"></p>
  <ul class="hlist">
    <li><canvas id="canvas"></canvas></li>
    <li>
      <table>
        <thead>
          <th>Line Segments</td>
          <th>Elapsed Time</td>
          <th>Time of Last Set</td>
        </thead>
        <tbody id="results"></tbody>
      </table>
    </li>
  </ul>
  <script type="text/javascript">
    window.onload=function() {
      
      var user_agent = document.getElementById("user-agent");
      user_agent.innerHTML = navigator.userAgent;
​
      var canvas = document.getElementById("canvas");
      canvas.width = canvas.clientWidth;
      canvas.height = canvas.clientHeight;
​
      var half_width  = canvas.width / 2;
      var half_height = canvas.height / 2;
​
      var xpos = half_width;
      var ypos = half_height;
​
      var ctx = canvas.getContext('2d');
      ctx.globalCompositeOperation = "source-over";
      ctx.lineWidth = 1;
      ctx.strokeStyle = "rgba(255,65,0, 1.0)";
​
      var i, j;
​
      var factor = 15;
      var factor_div_2 = factor / 2;
      var correction = 0.0035;
      
      function addLineSegments(num) {
        for (i=0; i < num; i++) {
          ctx.beginPath();
          ctx.moveTo(xpos, ypos);
          xpos += (factor * Math.random() - factor_div_2) + (half_width  - xpos) * correction;
          ypos += (factor * Math.random() - factor_div_2) + (half_height - ypos) * correction;
          ctx.lineTo(xpos, ypos);
          ctx.closePath();
          ctx.stroke();
        }
      };
​
      var results = document.getElementById("results");
      var table_row, table_data;
      
      function addToResults(samples, elapsed_time, sample_time) {
        table_row = document.createElement('tr');
        table_data = document.createElement('td');
        table_data.innerHTML = samples;
        table_row.appendChild(table_data);
        table_data = document.createElement('td');
        table_data.innerHTML = elapsed_time;
        table_row.appendChild(table_data);
        table_data = document.createElement('td');
        table_data.innerHTML = sample_time;
        table_row.appendChild(table_data);
        results.appendChild(table_row);
      };
​
      var increment = 1000;
      var count = 0;
      var elapsed_time = 0;
      var sample_time, sample_start, sample_end;
​
      function runSet() {
        sample_start = +new Date();
        addLineSegments(increment);
        sample_end = +new Date();
        sample_time = sample_end-sample_start;
        elapsed_time += sample_time;
        count += increment;
        addToResults(count, elapsed_time, sample_time);
      }
        
      function benchmark(){
        if (count < 10000) {
          requestAnimFrame(benchmark, canvas);
          runSet();
        }
      };
      requestAnimFrame(benchmark, canvas);
    };
  </script>
</body>
</html>
    