README.md

## README.md

      
          Raw
        
        
              README.md
            
          
    Only works in full screen http://bl.ocks.org/ZJONSSON/raw/5581551/

  
## example.css
body {
  background: none repeat scroll 0 0 #DADADA;
  color: #333333;
  font-family: Helvetica,Arial,sans-serif;
  font-size: 14px;
  line-height: 1.4;
  margin: 0;
  padding: 0;
}

.top {
  color: #EEEEEE;
  background-color: #3F3F3F;
  border-bottom: 2px solid #E17600;
  padding: 5px;
  height: 32px;
  font-size: 24px;
  text-align: center;
  text-shadow: 2px 2px 1px #666666;
}

h2 {
  margin-top: 0px;
  margin-bottom: 5px;
}

#content {
  background-color: #FFFFFF;
  border: 1px solid #CCCCCC;
  margin-left: auto;
  margin-right: auto;
  margin-top: 10px;
  width: 900px;
  padding: 10px;
}

.demo-container {
  background: linear-gradient(#F6F6F6 0px, #FFFFFF 50px) repeat scroll 0 0 transparent;
  border: 1px solid #DDDDDD;
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.15);
  height: 300px;
  margin: 10px auto 10px;
  padding: 20px 15px 15px;
}

#placeholder {
  height: 100%;
  width: 100%;
}

.bottom {
  color: #888888;
  font-size: 12px;
  text-align: center;
}

.bottom a {
  color: #888888;
}

#threshold {
  border: 0;
  color: #f6931f;
  font-weight: bold;
  width: 60px;
}

hr {
  margin-top: 15px;
  margin-bottom: 5px;
  border: 0;
  height: 1px;
  background: #333;
  background-image: -webkit-linear-gradient(left, #ccc, #333, #ccc);
  background-image: -moz-linear-gradient(left, #ccc, #333, #ccc);
  background-image: -ms-linear-gradient(left, #ccc, #333, #ccc);
  background-image: -o-linear-gradient(left, #ccc, #333, #ccc);
}

a {
  color: #E17600;
}

## index.html
<!DOCTYPE html>
<html>

<head>
  <meta charset='utf-8'>
  <title>Flot - Downsampling Plugin</title>

  <script type="text/javascript" src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
  <script type="text/javascript" src="http://www.flotcharts.org/flot/jquery.flot.js"></script>
  <script type="text/javascript" src="simplify.js"></script>

  <link rel="stylesheet" href="http://code.jquery.com/ui/1.10.2/themes/smoothness/jquery-ui.css" />
  <script src="http://code.jquery.com/ui/1.10.2/jquery-ui.js"></script>

  <script type="text/javascript" src="https://raw.github.com/sveinn-steinarsson/flot-downsample/master/demo_data.js"></script>

  <script type="text/javascript" src="https://raw.github.com/sveinn-steinarsson/flot-downsample/master/example.js"></script>
  <link rel="stylesheet" type="text/css" href="example.css" />

</head>

<body>

<div id="content">
  <h2>Simplification Example</h2>

  <div class="demo-container">
    <div id="placeholder"></div>
  </div>

  <p>
    <label for="data">Data:</label>
    <select id="data">
      <option value="0">Demo 1</option>
      <option value="1">Demo 2</option>
      <option value="2">Demo 3</option>
    </select>

    <label for="threshold">Threshold:</label>
    <input type="text" id="threshold" readonly/> (Total count: <span id="length">0</span>)
  </p>
  <div id="slider-threshold"></div>
  <hr />

  <p>
  This is a fork of <a href="https://github.com/sveinn-steinarsson/flot-downsample">flot-downsample</a> by <a href="https://github.com/sveinn-steinarsson">Sveinn Steinarsson</a>.  I rewrote the simplification procedure to replicate <a href="http://www2.dcs.hull.ac.uk/CISRG/publications/DPs/DP10/DP10.html">Visvalningham's algorithm</a> similar to Mike Bostock's <a href="http://bost.ocks.org/mike/simplify/">simplify</a>.  I decided to <a href="http://bl.ocks.org/ZJONSSON/raw/5581551/"></a>write it from scratch</a> to get better understanding of the dynamics.  Mike's version uses bianry heap, which could be slightly more efficient than the bisect routine I apply in my example.
</div>

</body>
</html>

## simplify.js
(function ($) {
  "use strict";

  // Calculates the area of a triangle formed by current point, last one and next one
  function calcArea(d) {
    if (!d.prev || !d.next) return;
    var x2 = d[0], y2 = d[1],
        x1 = d.prev[0], y1 = d.prev[1],
        x3 = d.next[0], y3 = d.next[1];
    return  1/2 * Math.abs(x1*(y2-y3)+x2*(y3-y1)+x3*(y1-y2));
  }

  function bisect(a,d,f) {
    var lo = 0, hi = a.length;
    while (lo < hi) {
      var mid = lo + hi >>> 1;
      if (f(a[mid]) < f(d)) lo = mid + 1;
      else hi = mid;
    }
    return lo;
  }

  var area = function(d) { return d.area;};

  function simplify(data) {
    // Start by taking a fresh copy just in case
    data = data.map(function(d) { return [d[0],d[1]];});

    var triangles = [],
        results = [],
        first = data[0],
        last = data[data.length-1];

    // We want first and last to be always included in filter
    first.i = last.i = 0;

    data.forEach(function(d,i) {
      if ((d.next = data[i+1]) && (d.prev = data[i-1]))
        relocate(d);
    });

    function relocate(d) {
      // If the area already exists, the element is in triangles and must be removed/replaced
      if (d.area) triangles.splice(bisect(triangles,d,area),1);
      // If we can calculate an area, we need to insert into triangles (sorted by area)
      if (d.area = calcArea(d)) triangles.splice(bisect(triangles,d,area),0,d);
      return d;
    }

    while(triangles.length) {
      // Remove the top triangle (smallest area) and push to results
      var t = triangles.splice(0,1)[0];
      results.push(t);
      // Connect the adjecent points and relocate both
      t.prev.next = relocate(t.next);
      t.next.prev = relocate(t.prev);
    }

    // Finally we reverse the results so largest triangles are at the top
    results = results.reverse()
      .map(function(d,i) { d.i = i+2; return d; })
      .sort(function(a,b) { return a[0]-b[0]; });

    return [first].concat(results).concat([last]);
}

 // Caches defined
 var results = [],
      lastData;

  function processRawData ( plot, series ) {
    // We cache the results,  because we can.
    if (lastData !== series.data[0]) {
      lastData = series.data[0];
      results = simplify(series.data);
    }
    series.data = results.filter(function(d) { return d.i < series.downsample.threshold;})
}


  var options = {
    series: {
      downsample: {
        threshold: 1000 // 0 disables downsampling for this series.
      }
    }
  };

  function init(plot) {
    plot.hooks.processRawData.push(processRawData);
  }

  $.plot.plugins.push({
    init: init,
    options: options,
    name: "downsample",
    version: "0.1"
  });

})(jQuery);