Chart.js - Increase spacing between legend and chart

Question

I have a bar chart where I have drawn 3 vertical lines, each with it's own label at the top. I would like those labels to be above the top of the y-axis (above the 30% line in the example) but below the legend. I can't figure out how to increase the space between the top legend and the chart such that I can have my vertical line labels (15, 24 & 33) be off of the chart itself but below the legend. Any ideas?

Answer 1

Unfortunately, since there is no config option to handle this the only way you can achieve the desired result is to extend Chart.Legend and implement the afterFit() callback.

Here is a quick codepen showing how to do just that. To change the spacing, just change the value in line 9 (currently set to 50). Also, this of course only works with the legend at the top. Hopefully, the example is clear enough for you to modify in case you want to move your legend elsewhere.

Answer 2

If you want do increase spacing in all charts you can put this code before creating :

Chart.Legend.prototype.afterFit = function() {
    this.height = this.height + 50;
};

Of course, I don't try but i think you can change it (or copy the original Chart object before, to keep the original padding).

Bye,

Answer 3

If you want to apply padding below legend for some charts only in your app:

ChartJS >= 2.1.0

Chart.plugins.register({
  id: 'paddingBelowLegends',
  beforeInit: function(chart, options) {
    chart.legend.afterFit = function() {
      this.height = this.height + 50;
    };
  }
});

// ----------------------------------
// disable the plugin only for charts
// where you DO NOT WANT the padding
// ----------------------------------

// for raw ChartJS use:
var chart = new Chart(ctx, {
  config: {
    plugins: {
      paddingBelowLegends: false
    }
  }
});

// for angular-chartjs:
$scope.myChart.options.plugins = { paddingBelowLegends: false }
// then in template:
// <canvas class="chart ..." chart-options="myChart.options" ... />

ChartJS >= 2.5.0

Specific plugins for each chart are supported, it should be possible to do:

var chart = new Chart(ctx, {
  plugins: [{
    beforeInit: function(chart, options) {
      chart.legend.afterFit = function() {
        this.height = this.height + 50;
      };
    }
  }]
});

See ChartJS documentation + inspired by this other answer

Answer 4

If anyone is wondering why the afterFit solution is not working in Chart.js 3.3.0 it is because afterFit function was removed from the legend plugin.

If you want to make this work anyway by taking advantage over the fit function, you can try this hacky solution / workaround:

const plugin = {
  beforeInit(chart) {
    // Get reference to the original fit function
    const originalFit = chart.legend.fit;

    // Override the fit function
    chart.legend.fit = function fit() {
      // Call original function and bind scope in order to use `this` correctly inside it
      originalFit.bind(chart.legend)();
      // Change the height as suggested in another answers
      this.height += 15;
    }
  };
}

I know that this is not an ideal solution, but until we have native support for this legend padding, I'm afraid this is as good we can do right now.

Answer 5

This helped me after 2 days of research.

Chart.Legend.prototype.afterFit = function() {
    this.height = this.height + 50;
};

update this in module.ts file

Answer 6

I'm using react-chartjs-2 (but this is just a port and uses the same configurations object) and I was able to achieve that by changing the labels configuration nested on legend configuration:

chartOptions = {
  legend: {
    labels: {
      padding: 50 -> this one.
    }
  },

You can check the property description here: https://www.chartjs.org/docs/latest/configuration/legend.html

Hope it helps.

Answer 7

I have tried the above approaches on my react(react-chartjs-2) project but no luck. Here I have one different approach like creating custom legends outside the chart. so you can get more control over it

1. Hide default legend
2. Get legend object using any ref method.
3. Loop and make a custom legend using html and css.
4. Sample codesanbox

I am aware that OP is not about reactjs component, but as it is a common issue it will help someone.

Orginal reference

.

Answer 8

After searching the chart.js file I found out that the height of the labels bar is defined there in

height = this._fitRows(titleHeight, fontSize, boxWidth, itemHeight)

OR

this.height = Math.min(height, options.maxHeight || this.maxHeight)

in the fit() function

fit() {
const {options, ctx} = this;
if (!options.display) {
  this.width = this.height = 0;
  return;
}
const labelOpts = options.labels;
const labelFont = toFont(labelOpts.font);
const fontSize = labelFont.size;
const titleHeight = this._computeTitleHeight();
const {boxWidth, itemHeight} = getBoxSize(labelOpts, fontSize);
let width, height;
ctx.font = labelFont.string;
if (this.isHorizontal()) {
  width = this.maxWidth;
  height = this._fitRows(titleHeight, fontSize, boxWidth, itemHeight);
} else {
  height = this.maxHeight;
  width = this._fitCols(titleHeight, fontSize, boxWidth, itemHeight);
}
this.width = Math.min(width, options.maxWidth || this.maxWidth);
this.height = Math.min(height, options.maxHeight || this.maxHeight) + 40;}

And I changed it to +40 as shown above. and it worked fine for me so I wanted to share.