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Base on the code sample from Konstantin S., you could register a plugin globally inside the componentDidMount()
method and implement an afterDraw
function as follows:
componentDidMount() {
Chart.pluginService.register({
afterDraw: chart => {
var needleValue = chart.chart.config.data.datasets[0].needleValue;
var dataTotal = chart.chart.config.data.datasets[0].data.reduce((a, b) => a + b, 0);
var angle = Math.PI + (1 / dataTotal * needleValue * Math.PI);
var ctx = chart.chart.ctx;
var cw = chart.chart.canvas.offsetWidth;
var ch = chart.chart.canvas.offsetHeight;
var cx = cw / 2;
var cy = ch - 6;
ctx.translate(cx, cy);
ctx.rotate(angle);
ctx.beginPath();
ctx.moveTo(0, -3);
ctx.lineTo(ch - 10, 0);
ctx.lineTo(0, 3);
ctx.fillStyle = 'rgb(0, 0, 0)';
ctx.fill();
ctx.rotate(-angle);
ctx.translate(-cx, -cy);
ctx.beginPath();
ctx.arc(cx, cy, 5, 0, Math.PI * 2);
ctx.fill();
}
});
}
This expects the property needleValue
to be defined inside the dataset.
datasets: [{
data: [500, 500, 500],
needleValue: 580,
...
}],
Please have a look at your amended CodeSandbox
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Source:stackexchange.com