Add text inside doughnut chart from chart js-2 in react

问题

i want to add a text message inside my doughnut pie chart. To be more specific i want something like this:

I came across the same issue here in stack overflow by they use chart js in jquery and since i'm new to javascript i got confused. This is how i define my pie chart:

<Doughnut
            data={sectorsData}
            width={250}
            height={250}
            options={{
              legend: {
                display: false
              },
              maintainAspectRatio: false,
              responsive: true,
              cutoutPercentage: 60
            }}
          />

回答1:

My example uses the property text on the data to specify the inner text:

const data = {
  labels: [...],
  datasets: [...],
  text: '23%'
};

import React from 'react';
import ReactDOM from 'react-dom';
import {Doughnut} from 'react-chartjs-2';

// some of this code is a variation on https://jsfiddle.net/cmyker/u6rr5moq/
var originalDoughnutDraw = Chart.controllers.doughnut.prototype.draw;
Chart.helpers.extend(Chart.controllers.doughnut.prototype, {
  draw: function() {
    originalDoughnutDraw.apply(this, arguments);
    
    var chart = this.chart.chart;
    var ctx = chart.ctx;
    var width = chart.width;
    var height = chart.height;

    var fontSize = (height / 114).toFixed(2);
    ctx.font = fontSize + "em Verdana";
    ctx.textBaseline = "middle";

    var text = chart.config.data.text,
        textX = Math.round((width - ctx.measureText(text).width) / 2),
        textY = height / 2;

    ctx.fillText(text, textX, textY);
  }
});

const data = {
	labels: [
		'Red',
		'Green',
		'Yellow'
	],
	datasets: [{
		data: [300, 50, 100],
		backgroundColor: [
		'#FF6384',
		'#36A2EB',
		'#FFCE56'
		],
		hoverBackgroundColor: [
		'#FF6384',
		'#36A2EB',
		'#FFCE56'
		]
	}],
  text: '23%'
};

class DonutWithText extends React.Component {

  render() {
    return (
      <div>
        <h2>React Doughnut with Text Example</h2>
        <Doughnut data={data} />
      </div>
    );
  }
};

ReactDOM.render(
  <DonutWithText />,
  document.getElementById('root')
);

<script src="https://gor181.github.io/react-chartjs-2/common.js"></script>
<script src="https://gor181.github.io/react-chartjs-2/bundle.js"></script>

<div id="root">
</div>

You'll have to scroll down a bit to see in when running the CodeSnippet due to some weird console error.

It works properly in CodePen though, where I wrote it: http://codepen.io/anon/pen/OpdBOq?editors=1010

来源：https://stackoverflow.com/questions/42759306/add-text-inside-doughnut-chart-from-chart-js-2-in-react

标签

javascript

reactjs

pie-chart

react-chartjs