I have found similar questions in Stack Overflow, but all of them were addressed one and two years ago. Now Chart.js has come up in version 2, and lots of the documentation changes. Can someone please help me showing an example of pie chart with labels - or pie chart with all of its segment's tooltips are visible?

UPDATE

Thanks to @potatopeelings, his answer works perfectly for Chart.js v2.1.

Although I initially asked how to permanently show tooltips on pie chart here, I found a better solution: showing values as labels in percentages! It is now enabled for pie chart in Chart.js v2.1. In the chart options:

animation: {

  duration: 0,

  onComplete: function () {

    var self = this,

        chartInstance = this.chart,

        ctx = chartInstance.ctx;



    ctx.font = '18px Arial';

    ctx.textAlign = center;

    ctx.fillStyle = #ffffff;



    Chart.helpers.each(self.data.datasets.forEach(function (dataset, datasetIndex) {

        var meta = self.getDatasetMeta(datasetIndex),

            total = 0, //total values to compute fraction

            labelxy = [],

            offset = Math.PI / 2, //start sector from top

            radius,

            centerx,

            centery, 

            lastend = 0; //prev arc's end line: starting with 0



        for (var val of dataset.data) { total += val; } 



        Chart.helpers.each(meta.data.forEach( function (element, index) {

            radius = 0.9 * element._model.outerRadius - element._model.innerRadius;

            centerx = element._model.x;

            centery = element._model.y;

            var thispart = dataset.data[index],

                arcsector = Math.PI * (2 * thispart / total);

            if (element.hasValue() && dataset.data[index] > 0) {

              labelxy.push(lastend + arcsector / 2 + Math.PI + offset);

            }

            else {

              labelxy.push(-1);

            }

            lastend += arcsector;

        }), self)



        var lradius = radius * 3 / 4;

        for (var idx in labelxy) {

          if (labelxy[idx] === -1) continue;

          var langle = labelxy[idx],

              dx = centerx + lradius * Math.cos(langle),

              dy = centery + lradius * Math.sin(langle),

              val = Math.round(dataset.data[idx] / total * 100);

          ctx.fillText(val + '%', dx, dy);

        }



    }), self);

  }

},