[Chartjs]-Chartjs v2 stroke shadow

by

16👍

✅

Yes!

You could accomplish the same stroke shadow effect for line chart with ChartJS v2 in the following way …

let draw = Chart.controllers.line.prototype.draw;
Chart.controllers.line = Chart.controllers.line.extend({
    draw: function() {
        draw.apply(this, arguments);
        let ctx = this.chart.chart.ctx;
        let _stroke = ctx.stroke;
        ctx.stroke = function() {
            ctx.save();
            ctx.shadowColor = '#E56590';
            ctx.shadowBlur = 10;
            ctx.shadowOffsetX = 0;
            ctx.shadowOffsetY = 4;
            _stroke.apply(this, arguments)
            ctx.restore();
        }
    }
});

let ctx = document.getElementById("canvas").getContext('2d');
let myChart = new Chart(ctx, {
    type: 'line',
    data: {
        labels: ["January", "February", "March", "April", "May", "June", "July"],
        datasets: [{
            label: "My First dataset",
            data: [65, 59, 80, 81, 56, 55, 40],
            borderColor: '#ffb88c',
            pointBackgroundColor: "#fff",
            pointBorderColor: "#ffb88c",
            pointHoverBackgroundColor: "#ffb88c",
            pointHoverBorderColor: "#fff",
            pointRadius: 4,
            pointHoverRadius: 4,
            fill: false
        }]
    }
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>
<canvas id="canvas" width="600" height="300" style="background-color:#fff"></canvas>

1👍

The proper answer is given on this issue at the github page for Chart.js by etimberg and Ashot-KR.

See this fiddle for the work in action, the red line is the shadow.

Adopted from the fiddle, giving a proper shadow, include this code:

(function()
{
    var ShadowLineElement = Chart.elements.Line.extend({
        draw: function()
        {
            var ctx = this._chart.ctx;
            var originalStroke = ctx.stroke;
            ctx.stroke = function()
            {
                ctx.save();
                ctx.shadowColor = 'rgba(0,0,0,0.4)';
                ctx.shadowBlur = 2;
                ctx.shadowOffsetX = 0.5;
                ctx.shadowOffsetY = 0.5;
                originalStroke.apply(this, arguments);
                ctx.restore();
            };
            Chart.elements.Line.prototype.draw.apply(this, arguments);
            ctx.stroke = originalStroke;
        }
    });
    Chart.defaults.ShadowLine = Chart.defaults.line;
    Chart.controllers.ShadowLine = Chart.controllers.line.extend({
        datasetElementType: ShadowLineElement
    });
})();

And then change the dataset type from type: 'line' to type: 'ShadowLine'.

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