CODEWITHSUNDEEP
javascriptchartschart.js
lapadets
lapadets

Reputation: 1095

Chart JS attempt to stacked bar chart tooltip for only one dataset

I want to create a chart using Chart JS. By default there is no stacked bar chart, but in the official documentation they list this extension: https://github.com/Regaddi/Chart.StackedBar.js

What I want to achieve though, is not necessarily a stacked bar chart. Here is an example: stacked-bar chart example

So my data is the red, and I would like to fill in the rest with up to max value with black.

My problem is that I cannot format the tooltip when I hoover over a bar. Ideally I would like to format it such that only the red dataset is shown.

Here is my code:

var barChartData = {
        labels : [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31],
        datasets : [
        {
            fillColor : "rgba(0,12,4,1)",
            strokeColor : "rgba(220,220,220,0.8)",
            highlightFill: "rgba(0,0,0,0.75)",
            highlightStroke: "rgba(220,220,220,1)",
            data : [8, 5, 15, 23, 20, 0, 11, 20, 25, 15, 10, 0,
                    0, 0, 10, 12, 25, 20, 15, 25, 0, 5,
                    5, 3, 0, 0, 0, 7, 15, 12, 0,]
        },
        {
            fillColor : "rgba(192,12,4,1)",
            strokeColor : "rgba(220,220,220,0.8)",
            highlightFill: "rgba(192,12,4,0.5)",
            highlightStroke: "rgba(220,220,220,1)",
            data : [17, 20, 10, 2, 5, 0, 14, 5, 0, 10, 15, 25,
                    0, 0, 15, 13, 0, 5, 10, 0, 25, 20,
                    20, 22, 25, 0, 0, 18, 10, 13, 25,]
        },
    ]
};
window.onload = function(){
    var ctx = document.getElementById("canvas").getContext("2d");
    window.myBar = new Chart(ctx).StackedBar(barChartData, {
        responsive : true,
        tooltipFillColor: "rgba(0,0,0,0.8)",
        multiTooltipTemplate: "<%= 'Used MB' %> : <%= value %>",
        scaleOverride : true,
        scaleSteps : 5,
        scaleStepWidth : 5,
        scaleStartValue : 0,
        barValueSpacing : 3,
        barShowStroke: false
    });
};

Any ideas how this is possible? Or is it possible to create this with only a simple bar chart?

I cannot figure out how the multiTooltipTemplate: "<%= 'Used MB' %> : <%= value %>", formatting works.

Please don't suggest other libraries, I am interested in Chart JS.

Upvotes: 0

Views: 1658

Answers (1)

potatopeelings
potatopeelings

Reputation: 41075

You can extend your chart to do this.

Preview

enter image description here

Script

Chart.types.Bar.extend({
    name: "BarAlt",
    draw: function () {
        Chart.types.Bar.prototype.draw.apply(this, arguments);

        var ctx = this.chart.ctx;
        var scale = this.scale;

        ctx.save();
        ctx.fillStyle = 'black';
        this.datasets[0].bars.forEach(function (bar, i) {
            if (bar.value != 0) {
                ctx.beginPath();
                ctx.moveTo(bar.x - bar.width / 2, bar.y);
                ctx.lineTo(bar.x + bar.width / 2, bar.y);
                ctx.lineTo(bar.x + bar.width / 2, scale.startPoint);
                ctx.lineTo(bar.x - bar.width / 2, scale.startPoint);
                ctx.closePath();
                ctx.fill();
            }
        })
        ctx.restore();
    }
});

and then

window.myBar = new Chart(ctx).BarAlt(barChartData, {
    ...

You can change the tooltipFillColor if you feel that the tooltip doesn't stand out from the black background.

Fiddle - http://jsfiddle.net/o0geemtp/

Upvotes: 1

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