nvd3/src/models/pie.js

nv.models.pie = function() {
  var margin = {top: 20, right: 20, bottom: 20, left: 20},
      width = 500,
      height = 500,
      getLabel = function(d) { return d.label },
      getY = function(d) { return d.y },
      id = Math.floor(Math.random() * 10000), //Create semi-unique ID in case user doesn't select one
      color = d3.scale.category20(),
      showLabels = true,
      donut = false;

  var  dispatch = d3.dispatch('chartClick', 'elementClick', 'elementDblClick', 'tooltipShow', 'tooltipHide');

  function chart(selection) {
    selection.each(function(data) {
      var availableWidth = width - margin.left - margin.right,
          availableHeight = height - margin.top - margin.bottom,
          radius = Math.min(availableWidth, availableHeight) / 2;

      var container = d3.select(this)
          .on('click', function(d,i) {
              dispatch.chartClick({
                  data: d,
                  index: i,
                  pos: d3.event,
                  id: id
              });
          });



      var wrap = container.selectAll('.wrap.pie').data([data]);
      var wrapEnter = wrap.enter().append('g').attr('class','wrap nvd3 pie chart-' + id);
      var gEnter = wrapEnter.append('g');
      var g = wrap.select('g')

      gEnter.append('g').attr('class', 'pie');

      wrap.attr('transform', 'translate(' + margin.left + ',' + margin.top + ')');

      g.select('.pie').attr('transform', 'translate(' + radius + ',' + radius + ')');



      var arc = d3.svg.arc()
                  .outerRadius((radius-(radius / 5)));

      if (donut) arc.innerRadius(radius / 2);


      // Setup the Pie chart and choose the data element
      var pie = d3.layout.pie()
          .value(getY);

      var slices = wrap.select('.pie').selectAll('.slice')
          .data(pie);

      slices.exit().remove();

      var ae = slices.enter().append('svg:g')
              .attr('class', 'slice')
              .on('mouseover', function(d,i){
                d3.select(this).classed('hover', true);
                dispatch.tooltipShow({
                    label: getLabel(d.data),
                    value: getY(d.data),
                    data: d.data,
                    index: i,
                    pos: [d3.event.pageX, d3.event.pageY],
                    id: id
                });
              })
              .on('mouseout', function(d,i){
                d3.select(this).classed('hover', false);
                dispatch.tooltipHide({
                    label: getLabel(d.data),
                    value: getY(d.data),
                    data: d.data,
                    index: i,
                    id: id
                });
              })
              .on('click', function(d,i) {
                console.log(d);
                dispatch.elementClick({
                    label: getLabel(d.data),
                    value: getY(d.data),
                    data: d.data,
                    index: i,
                    pos: d3.event,
                    id: id
                });
                d3.event.stopPropagation();
              })
              .on('dblclick', function(d,i) {
                dispatch.elementDblClick({
                    label: getLabel(d.data),
                    value: getY(d.data),
                    data: d.data,
                    index: i,
                    pos: d3.event,
                    id: id
                });
                d3.event.stopPropagation();
              });

        var paths = ae.append('svg:path')
            .attr('class','path')
            .attr('fill', function(d, i) { return color(i); });
            //.attr('d', arc);

        d3.transition(slices.select('.path'))
            .attr('d', arc)
            //.ease('bounce')
            .attrTween('d', tweenPie);

        if (showLabels) {
          // This does the normal label
          ae.append('text');

          d3.transition(slices.select('text'))
              //.ease('bounce')
              .attr('transform', function(d) {
                 d.outerRadius = radius + 10; // Set Outer Coordinate
                 d.innerRadius = radius + 15; // Set Inner Coordinate
                 return 'translate(' + arc.centroid(d) + ')';
              })
              .attr('text-anchor', 'middle') //center the text on it's origin
              //.style('font', 'bold 12px Arial') // font style's should be set in css!
              .text(function(d, i) {  return getLabel(d.data); });
        }


        // Computes the angle of an arc, converting from radians to degrees.
        function angle(d) {
          var a = (d.startAngle + d.endAngle) * 90 / Math.PI - 90;
          return a > 90 ? a - 180 : a;
        }


        function tweenPie(b) {
          b.innerRadius = 0;
          var i = d3.interpolate({startAngle: 0, endAngle: 0}, b);
          return function(t) {
              return arc(i(t));
          };
        }

    });

    return chart;
  }


  chart.dispatch = dispatch;

  chart.margin = function(_) {
    if (!arguments.length) return margin;
    margin = _;
    return chart;
  };

  chart.width = function(_) {
    if (!arguments.length) return width;
    width = _;
    return chart;
  };

  chart.height = function(_) {
    if (!arguments.length) return height;
    height = _;
    return chart;
  };

  chart.y = function(_) {
    if (!arguments.length) return getY;
    getY = d3.functor(_);
    return chart;
  };

  chart.label = function(_) {
    if (!arguments.length) return getLabel;
    getLabel = _;
    return chart;
  };

  chart.showLabels = function(_) {
    if (!arguments.length) return showLabels;
    showLabels = _;
    return chart;
  };

  chart.donut = function(_) {
    if (!arguments.length) return donut;
    donut = _;
    return chart;
  };

  chart.id = function(_) {
    if (!arguments.length) return id;
    id = _;
    return chart;
  };


  return chart;
}