Chart.js - add gradient instead of solid color - implementing solution

Question

I am using Chart.js and everything is ok, but I want to replace current color background (fillColor : \"rgba(250,174,50,0.5)\") with a gradient. I have solution for replaci

Answer 1

For using in react I did the following way you need to pass an id to your component and then fetch the element using that id

import React, { Component } from 'react'
import { Line } from 'react-chartjs-2'

export default class GraphComponent extends Component{
  constructor(props){
    super(props)
    this.state = {
      chartData: {}
    }
  }

  componentDidMount(){
    //your code
    var ctx = document.getElementById('canvas').getContext("2d")
    var gradient = ctx.createLinearGradient(0, 0, 0, 400)
    gradient.addColorStop(0, 'rgba(229, 239, 255, 1)')
    gradient.addColorStop(1, '#FFFFFF')
    const newData = {
      labels: [1, 1],
      datasets: [
        {
          label: 'usd',
          data: [1,1],
          backgroundColor: gradient,
          borderColor: this.props.border_color,
          pointRadius: 0
        }
      ]

    }
    this.setState({chartData: newData})
  }

  //more of your code

  render(){
    return(
          <Line
            id='canvas'//you need to give any id you want
            data={this.state.chartData}
            width={100}
            height={30}
            options={{
              legend: {
                display: false
              }
            }}
          />

    )
  }
}

this is only my second answer so please forgive me if I have made any mistakes in writing

Answer 2

NOTE: Copied From CODEPEN

This solution creates a nice vertical gradient graph with a red theme

    // ============================================
// As of Chart.js v2.5.0
// http://www.chartjs.org/docs
// ============================================

var chart    = document.getElementById('chart').getContext('2d'),
    gradient = chart.createLinearGradient(0, 0, 0, 400);

gradient.addColorStop(0, 'rgba(255, 0,0, 0.5)');
gradient.addColorStop(0.5, 'rgba(255, 0, 0, 0.25)');
gradient.addColorStop(1, 'rgba(255, 0, 0, 0)');


var data  = {
    labels: [ 'January', 'February', 'March', 'April', 'May', 'June' ],
    datasets: [{
            label: 'Custom Label Name',
            backgroundColor: gradient,
            pointBackgroundColor: 'white',
            borderWidth: 1,
            borderColor: '#911215',
            data: [50, 55, 80, 81, 54, 50]
    }]
};


var options = {
    responsive: true,
    maintainAspectRatio: true,
    animation: {
        easing: 'easeInOutQuad',
        duration: 520
    },
    scales: {
        xAxes: [{
            gridLines: {
                color: 'rgba(200, 200, 200, 0.05)',
                lineWidth: 1
            }
        }],
        yAxes: [{
            gridLines: {
                color: 'rgba(200, 200, 200, 0.08)',
                lineWidth: 1
            }
        }]
    },
    elements: {
        line: {
            tension: 0.4
        }
    },
    legend: {
        display: false
    },
    point: {
        backgroundColor: 'white'
    },
    tooltips: {
        titleFontFamily: 'Open Sans',
        backgroundColor: 'rgba(0,0,0,0.3)',
        titleFontColor: 'red',
        caretSize: 5,
        cornerRadius: 2,
        xPadding: 10,
        yPadding: 10
    }
};


var chartInstance = new Chart(chart, {
    type: 'line',
    data: data,
        options: options
});

check out this pen https://codepen.io/grayghostvisuals/pen/gpROOz

Answer 3

The link you provided was pretty clear, you have to put in the field fillColor in datasets a linearGradient object instead of a plain color. You can do complex gradients, but here is the code of a simple one (changing the opacity of the same orange) :

var gradient = ctx.createLinearGradient(0, 0, 0, 400);
gradient.addColorStop(0, 'rgba(250,174,50,1)');   
gradient.addColorStop(1, 'rgba(250,174,50,0)');

And your complete datasets :

datasets: [
            {
                fillColor : gradient, // Put the gradient here as a fill color
                strokeColor : "#ff6c23",
                pointColor : "#fff",
                pointStrokeColor : "#ff6c23",
                pointHighlightFill: "#fff",
                pointHighlightStroke: "#ff6c23",
                data : [25.0,32.4,22.2,39.4,34.2,22.0,23.2,24.1,20.0,18.4,19.1,17.4]
            }
        ]

See it in action in this JSFiddle

Answer 4

Note: For those people who is using newer version (v2.7.0) of Chart.js, find out that is not working while you're copy-paste @bviale's answer back to your code base; Some property names has changed:

fillColor -> backgroundColor
strokeColor -> borderColor
pointColor -> pointBackgroundColor
pointStrokeColor -> pointBorderColor

You will need to update those property names to make it work.

Reference: https://github.com/chartjs/Chart.js/blob/master/docs/charts/line.md#dataset-properties