Put sum of values in center of doughnut chart?

问题

I'm drawing this pie chart:

using this code:

dxPieChart: {
    dataSource: dsAlarmsBySeverity,
    size: {
        width: 275,
        height: 150
    },
    palette: ['#FFFF00', '#FF9900', '#CC3300', '#33CC33', '#0066FF'],
    legend: {
        backgroundColor: '#FCFCFC',
        border: {
                color: 'black',
                width: .5,
                visible: true,
                cornerRadius: 10
        },
        verticalAlign: 'middle'
    },
    series: [{
        type: 'doughnut',
        argumentField: 'severity',
        valueField: 'count',
        label: {
            visible: false,
            font: {
                size: 16
            },
            connector: {
                visible: true,
                width: 0.5
            },
            position: 'columns',
            customizeText: function(arg) {
                return arg.argumentText
            }
        },
        border: {
            color: 'black',
            width: .5,
            visible: true
        },
        hoverStyle: {
            border: {
                color: 'black',
                width: .5,
                visible: true
            }
        }
    }]
}

Is there a way to add the sum of all values to the center of the donut? Like so:

回答1:

There is a plugin for what you want to do: https://github.com/ciprianciurea/chartjs-plugin-doughnutlabel

回答2:

As a workaround until the open issue is complete, you could just draw your own total on the canvas element itself.

You will have to manually calculate the x/y position on the canvas (like [150,100] in this example).

var canvas=document.getElementById("myChart");
var ctx=canvas.getContext("2d");
ctx.font="36px verdana";
ctx.fillText("76",150,100);

回答3:

I actually ended up doing this:

<div style="position: relative;" data-bind="dxPieChart: {
  //chart initialization code from above...
}">
    <div style="position: absolute; top: 50%; margin-top: -15px; left: 50%; font-size: 30px; line-height: 30px; margin-left: -50px; width: 100px; text-align: center;" data-bind="text: alarmIDs().length"></div>
    <div style="position: absolute; top: 50%; margin-top: 15px; left: 50%; font-size: 15px; line-height: 15px; margin-left: -50px; width: 100px; text-align: center;">alarms</div>
</div>

When it binds the chart it doesn't overwrite any internal HTML, so this works brilliantly.

来源：https://stackoverflow.com/questions/20911919/put-sum-of-values-in-center-of-doughnut-chart

标签

javascript

html5-canvas

chart.js