interactive-vis-course/Week13/animated_lines.html at gh-pages · arnicas/interactive-vis-course · GitHub

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<!-- code from http://big-elephants.com/2014-06/unrolling-line-charts-d3js/ -->
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Animated Lines and Line Sections</title>

<style>

  .chart {
    min-height: 200;
    min-width: 600;
  }

  svg {
    background-color: #eee;
  }

</style>

</head>
<body>

<h2>Animating Lines and Line Sections</h2>

<p>Data shown are Algerian fertility rates over time (1960-2013), from UNICEF/World Bank. Note: I suggest making any highlight or animated segment have a thicker stroke-width than the base line.</p>

<br>

<button id="button2">Click for a smooth animation.</button>
<div class="chart" id="chart2"></div>
<button id="button3">Click to highlight a section.</button>
<div class="chart" id="chart3"></div>
<button id="button4">Click to animate a hightlighted section.</button>
<div class="chart" id="chart4"></div>

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js"></script>


<script>


var width = 700,
  height = 200;

var dateFormat = d3.time.format("%Y").parse;

var x_scale, y_scale;  // making these global so they can be seen in ex3 after def in ex2; could have just set the domain there.

// this is shared by both, so make it global
var lineFunction = d3.svg.line()
    .x(function(d) {return x_scale(dateFormat(d.Year));})
    .y(function(d) {return y_scale(+d.Fertility); });

d3.csv("data/fertility_algeria.csv", doLines);

function doLines(error, data) {
  ex2(data);
  ex3(data);
  ex4(data);
}

// the full animation one
function ex2(data) {

  x_scale = d3.scale.linear().range([0,width]).domain(d3.extent(data, function(d) {return dateFormat(d.Year)}));
  // just adding a little manual padding here
  y_scale = d3.scale.linear().range([height-5,10]).domain(d3.extent(data, function(d) {return +d.Fertility;}));

  var example2 = d3.select("#chart2")
    .append("svg")
    .attr("width", width)
    .attr("height", height)
    .attr("id", "exampleTwo");

  var path = example2
    .append("path")
    .attr("id", "Series2")
    .attr("fill", "none")
    .attr("stroke", "black")
    .attr("stroke-width", 2)
    .attr("d", lineFunction(data))
    .style("display", "none");

    // you need a path to be created before you can get the length.
  var totalLength = path.node().getTotalLength();

  path
    .attr("stroke-dasharray", totalLength + " " + totalLength)
    .attr("stroke-dashoffset", totalLength)
    .style("display", null) // now we can display it
    .transition()
      .duration(2000)
      .ease("linear")
      .attr("stroke-dashoffset", 0);  // we animate the offset down to 0.

    // this is repetitive with the above, but it shows how you would repeat the drawing...

  d3.select("#button2").on("click", function() {
      path
        .attr("stroke-dasharray", totalLength + " " + totalLength)
        .attr("stroke-dashoffset", totalLength)
        .style("display", null)
        .transition()
          .duration(2000)
          .ease("linear")
          .attr("stroke-dashoffset", 0);
    });

}

// the colored highlight section
function ex3(data) {

  var example3 = d3.select("#chart3")
    .append("svg")
    .attr("width", width)
    .attr("height", height)
    .attr("id", "exampleThree");

    example3
      .datum(data)
      .append("path")
      .attr("id", "Series3")
      .attr("d", lineFunction)
      .attr("fill", "none")
      .attr("stroke", "black")
      .attr("stroke-width", 2);

    d3.select("#button3")
      .on("click", function() {
        example3.datum(data.slice(20,44))
        .append("path")
        .attr("d", lineFunction)
        .attr("fill", "none")
        .attr("stroke", "orange")
        .attr("stroke-width", 3); // make it thicker so it totally covers the base line
      });
}

function ex4(data) {

  var example4 = d3.select("#chart4")
    .append("svg")
    .attr("width", width)
    .attr("height", height)
    .attr("id", "exampleFour");

    example4
      .datum(data)
      .append("path")
      .attr("id", "Series3")
      .attr("d", lineFunction)
      .attr("fill", "none")
      .attr("stroke", "black")
      .attr("stroke-width", 2);

    d3.select("#button4")
      .on("click", function() {

        var pathoverlay = example4
            .append("path")
            .attr("id", "Series4")
            .attr("fill", "none")
            .attr("stroke", "black")
            .attr("stroke-width", 2)
            .attr("d", lineFunction(data.slice(20,44)))
            .style("display", "none");

        // you need a path to be created before you can get the length.
      var totalLength = pathoverlay.node().getTotalLength();

      pathoverlay
        .attr("stroke-dasharray", totalLength + " " + totalLength)
        .attr("stroke-dashoffset", totalLength)
        .style("display", null) // now we can display it
        .attr("stroke", "orange")
        .transition()
          .duration(1000)
          .ease("linear")
          .attr("stroke-dashoffset", 0) // we animate the offset down to 0
          .attr("stroke-width", 3); // make it thicker so it totally covers the base line
      });
}

</script>
</body>
</html>