Chartjs 3 doughnut chart rounded corners

Question

I am using chart js version 3 and I want to draw doughnut with rounded edges I find the solution with the version 2 of chart js however due to breaking changes in chart js 3 I couldn't make the solution compatible with version 3.
Here is the working solution in version 2

Chart.defaults.RoundedDoughnut    = Chart.helpers.clone(Chart.defaults.doughnut);
Chart.controllers.RoundedDoughnut = Chart.controllers.doughnut.extend({
    draw: function(ease) {
        var ctx           = this.chart.ctx;
        var easingDecimal = ease || 1;
        var arcs          = this.getMeta().data;
        Chart.helpers.each(arcs, function(arc, i) {
            arc.transition(easingDecimal).draw();

            var pArc   = arcs[i === 0 ? arcs.length - 1 : i - 1];
            var pColor = pArc._view.backgroundColor;

            var vm         = arc._view;
            var radius     = (vm.outerRadius + vm.innerRadius) / 2;
            var thickness  = (vm.outerRadius - vm.innerRadius) / 2;
            var startAngle = Math.PI - vm.startAngle - Math.PI / 2;
            var angle      = Math.PI - vm.endAngle - Math.PI / 2;

            ctx.save();
            ctx.translate(vm.x, vm.y);

            ctx.fillStyle = i === 0 ? vm.backgroundColor : pColor;
            ctx.beginPath();
            ctx.arc(radius * Math.sin(startAngle), radius * Math.cos(startAngle), thickness, 0, 2 * Math.PI);
            ctx.fill();

            ctx.fillStyle = vm.backgroundColor;
            ctx.beginPath();
            ctx.arc(radius * Math.sin(angle), radius * Math.cos(angle), thickness, 0, 2 * Math.PI);
            ctx.fill();

            ctx.restore();
        });
    }
});

window.onload = function() {
    new Chart(document.getElementById('usersChart'), {
        type   : 'RoundedDoughnut',
        data   : {
            datasets: [
                {
                    data           : [40, 20, 20, 20],
                    backgroundColor: [
                        '#e77099',
                        '#5da4e7',
                        '#8f75e7',
                        '#8fe768'
                    ],
                    borderWidth    : 0
                }]
        },
        options: {
            cutoutPercentage: 70
        }
    });
};

here is the result chart:

LeeLenalee · Accepted Answer · 2022-06-28T10:42:11.753

In v3 you can get rounded corners natively by using the borderRadius option:

const options = {
  type: 'doughnut',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
      label: '# of Votes',
      data: [12, 19, 3, 5, 2, 3],
      backgroundColor: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
      borderRadius: 1000
    }]
  },
  options: {}
}

const ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.8.0/chart.js"></script>
</body>

EDIT:
Based on answer from wahab memon but edited so it applies to all elements:

Chart.defaults.elements.arc.borderWidth = 0;
Chart.defaults.datasets.doughnut.cutout = '85%';

var chartInstance = new Chart(document.getElementById("chartJSContainer"), {
  type: 'doughnut',
  data: {
    labels: [
      'Label 1',
      'Label 2',
      'Label 3',
      'Label 4'
    ],
    datasets: [{
      label: 'My First Dataset',
      data: [22, 31, 26, 19],
      backgroundColor: [
        '#000000',
        '#ffff00',
        '#aaaaaa',
        '#ff0000'
      ]
    }]
  },

  plugins: [{
    afterUpdate: function(chart) {
      const arcs = chart.getDatasetMeta(0).data;

      arcs.forEach(function(arc) {
        arc.round = {
          x: (chart.chartArea.left + chart.chartArea.right) / 2,
          y: (chart.chartArea.top + chart.chartArea.bottom) / 2,
          radius: (arc.outerRadius + arc.innerRadius) / 2,
          thickness: (arc.outerRadius - arc.innerRadius) / 2,
          backgroundColor: arc.options.backgroundColor
        }
      });
    },
    afterDraw: (chart) => {
      const {
        ctx,
        canvas
      } = chart;

      chart.getDatasetMeta(0).data.forEach(arc => {
        const startAngle = Math.PI / 2 - arc.startAngle;
        const endAngle = Math.PI / 2 - arc.endAngle;

        ctx.save();
        ctx.translate(arc.round.x, arc.round.y);
        ctx.fillStyle = arc.options.backgroundColor;
        ctx.beginPath();
        ctx.arc(arc.round.radius * Math.sin(endAngle), arc.round.radius * Math.cos(endAngle), arc.round.thickness, 0, 2 * Math.PI);
        ctx.closePath();
        ctx.fill();
        ctx.restore();
      });
    }
  }]
});

<script src="https://cdn.jsdelivr.net/npm/chart.js@3.8.0/dist/chart.js"></script>

<body>
  <canvas id="chartJSContainer" width="200" height="200"></canvas>
</body>

But the result is different form what I looking for I add the chart image in the question — Daniel.V, Jun 28 '22 at 10:27

Chartjs 3 doughnut chart rounded corners

1 Answers1