How can I assign a distinct background color to individual sections in Chart.js?

Question

How can I assign a distinct background color to individual sections in Chart.js?

Wanting to Customize Grid Background Colors in Line Chart using react-chartjs-2

I am looking to have different background colors for each grid in my Line chart. Is this functionality possible with the react-chartjs-2 library?

This is the desired appearance of the LineChart: https://i.sstatic.net/ZayIy.png

Below is my current code/configuration:

const options = {
        responsive: true,
        scales: {
            y: {
                grid: {
                    backgroundColor: [
                        'rgba(36, 206, 0, 0.8)',
                        'rgba(255, 255, 0, .8)',
                        'rgba(255, 162, 0, 0.8)',
                        'rgba(36, 206, 0, 0.8)',
                    ],
                },
    };

Thank you for taking the time to review.

javascript css reactjs canvas chart.js

Answer 1

Answer №1

If you want to add a gradient background to your ChartJS chart, you can utilize an inline plugin for that purpose:

var GradientBgPlugin = {
  beforeDraw: function(chart, args, options) {
    const ctx = chart.ctx;
    const canvas = chart.canvas;
    const chartArea = chart.chartArea;

    // Creating a linear gradient for the chart background
    var gradientBack = canvas.getContext("2d").createLinearGradient(0, 250, 0, 0);
    gradientBack.addColorStop(0, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.16, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.17, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.25, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.26, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.5, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.51, "rgba(251,221,221,1)");
    gradientBack.addColorStop(1, "rgba(251,221,221,1)");

    ctx.fillStyle = gradientBack;
    ctx.fillRect(chartArea.left, chartArea.bottom,
      chartArea.right - chartArea.left, chartArea.top - chartArea.bottom);
  }
};

To apply this plugin to your chart, simply include it in your Chart options like this:

plugins: [GradientBgPlugin]

Your chart should now display with the gradient background as shown in this JSFiddle example.

UPDATE

If you are using React Charts JS 2, you'll need to make slight adjustments to the setup. Define the plugin in the following way:

const plugins = [{
  beforeDraw: function(chart) {
    const ctx = chart.ctx;
    const canvas = chart.canvas;
    const chartArea = chart.chartArea;

    // Creating a linear gradient for the chart background
    var gradientBack = canvas.getContext("2d").createLinearGradient(0, 250, 0, 0);
    gradientBack.addColorStop(0, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.16, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.17, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.25, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.26, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.5, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.51, "rgba(251,221,221,1)");
    gradientBack.addColorStop(1, "rgba(251,221,221,1)");

    ctx.fillStyle = gradientBack;
    ctx.fillRect(chartArea.left, chartArea.bottom,
      chartArea.right - chartArea.left, chartArea.top - chartArea.bottom);
  }
}];

To integrate this plugin, use the following method:

<Line data={data} plugins={plugins} />

You can view the functioning gradient background on your chart at CodeSandbox here.

Answer 2

If you want to add a gradient background to your ChartJS chart, you can utilize an inline plugin for that purpose:

var GradientBgPlugin = {
  beforeDraw: function(chart, args, options) {
    const ctx = chart.ctx;
    const canvas = chart.canvas;
    const chartArea = chart.chartArea;

    // Creating a linear gradient for the chart background
    var gradientBack = canvas.getContext("2d").createLinearGradient(0, 250, 0, 0);
    gradientBack.addColorStop(0, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.16, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.17, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.25, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.26, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.5, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.51, "rgba(251,221,221,1)");
    gradientBack.addColorStop(1, "rgba(251,221,221,1)");

    ctx.fillStyle = gradientBack;
    ctx.fillRect(chartArea.left, chartArea.bottom,
      chartArea.right - chartArea.left, chartArea.top - chartArea.bottom);
  }
};

To apply this plugin to your chart, simply include it in your Chart options like this:

plugins: [GradientBgPlugin]

Your chart should now display with the gradient background as shown in this JSFiddle example.

UPDATE

If you are using React Charts JS 2, you'll need to make slight adjustments to the setup. Define the plugin in the following way:

const plugins = [{
  beforeDraw: function(chart) {
    const ctx = chart.ctx;
    const canvas = chart.canvas;
    const chartArea = chart.chartArea;

    // Creating a linear gradient for the chart background
    var gradientBack = canvas.getContext("2d").createLinearGradient(0, 250, 0, 0);
    gradientBack.addColorStop(0, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.16, "rgba(213,235,248,1)");
    gradientBack.addColorStop(0.17, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.25, "rgba(226,245,234,1)");
    gradientBack.addColorStop(0.26, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.5, "rgba(252,244,219,1)");
    gradientBack.addColorStop(0.51, "rgba(251,221,221,1)");
    gradientBack.addColorStop(1, "rgba(251,221,221,1)");

    ctx.fillStyle = gradientBack;
    ctx.fillRect(chartArea.left, chartArea.bottom,
      chartArea.right - chartArea.left, chartArea.top - chartArea.bottom);
  }
}];

To integrate this plugin, use the following method:

<Line data={data} plugins={plugins} />

You can view the functioning gradient background on your chart at CodeSandbox here.

Answer 3

Answer №2

If you want to add custom colors to the chart area, you can create a personalized inline plugin for that purpose. Within the options section, include an object detailing the sections you wish to highlight and the colors you want them to be.

For example:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: '# of Votes',
        data: [100, 19, 3, 5, 2, 3],
        borderWidth: 1
      },
      {
        label: '# of Points',
        data: [7, 11, 5, 8, 3, 7],
        borderWidth: 1
      }
    ]
  },
  options: {
    plugins: {
      backgrounds: {
        hbars: [{
            from: 28,
            to: 100,
            color: "rgb(195, 230, 195)"
          },
          {
            from: 20,
            to: 28,
            color: "rgb(230, 220, 195)"
          },
          {
            from: 0,
            to: 20,
            color: "rgb(230, 195, 195)"
          }
        ]
      }
    }
  },
  plugins: [{
    id: 'backgrounds',
    beforeDraw: (chart, args, options) => {
      const {
        ctx,
        chartArea,
        scales: {
          y
        }
      } = chart;

      options.hbars.forEach((hBar) => {
        ctx.save();
        ctx.fillStyle = hBar.color;
        ctx.fillRect(chartArea.left, y.getPixelForValue(hBar.from), chartArea.right - chartArea.left, y.getPixelForValue(hBar.to) - y.getPixelForValue(hBar.from));
        ctx.restore();
      })
    }
  }]
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.2.0/chart.js"></script>
</body>

Answer 4

If you want to add custom colors to the chart area, you can create a personalized inline plugin for that purpose. Within the options section, include an object detailing the sections you wish to highlight and the colors you want them to be.

For example:

var options = {
  type: 'line',
  data: {
    labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
    datasets: [{
        label: '# of Votes',
        data: [100, 19, 3, 5, 2, 3],
        borderWidth: 1
      },
      {
        label: '# of Points',
        data: [7, 11, 5, 8, 3, 7],
        borderWidth: 1
      }
    ]
  },
  options: {
    plugins: {
      backgrounds: {
        hbars: [{
            from: 28,
            to: 100,
            color: "rgb(195, 230, 195)"
          },
          {
            from: 20,
            to: 28,
            color: "rgb(230, 220, 195)"
          },
          {
            from: 0,
            to: 20,
            color: "rgb(230, 195, 195)"
          }
        ]
      }
    }
  },
  plugins: [{
    id: 'backgrounds',
    beforeDraw: (chart, args, options) => {
      const {
        ctx,
        chartArea,
        scales: {
          y
        }
      } = chart;

      options.hbars.forEach((hBar) => {
        ctx.save();
        ctx.fillStyle = hBar.color;
        ctx.fillRect(chartArea.left, y.getPixelForValue(hBar.from), chartArea.right - chartArea.left, y.getPixelForValue(hBar.to) - y.getPixelForValue(hBar.from));
        ctx.restore();
      })
    }
  }]
}

var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);

<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.2.0/chart.js"></script>
</body>

Answer 5

Answer №3

If you need more detailed information, check out this resource: https://medium.com/@omi10859/alternative-background-lines-in-chartjs-a626ce4d3bcb

The annotation plugin in chartjs allows for the creation of custom elements within a chart.

import annotationPlugin from "chartjs-plugin-annotation";
import {Chart} from 'chart.js';
Chart.register(annotationPlugin);

This code snippet demonstrates how to add a box element to our chart.

{
  type: 'box', #Selecting the drawing type
  drawTime: 'beforeDraw', #Determines whether the box will be in the foreground or background
  yMin: 5, #Minimum value on the y-axis
  yMax: 10, #Maximum value on the y-axis
  borderColor: 'rgb(242, 244, 248, 0.9)', #Color of the box's border
  borderWidth: 1, #Width of the box's border
  backgroundColor: '#F2F4F8', #Background color of the box
}
# Include options when rendering the chart
const options = {
  plugins: {annotation: {annotations: background_annotation}
}

This code example will produce the following result: https://i.sstatic.net/JYGTD.png

Answer 6

If you need more detailed information, check out this resource: https://medium.com/@omi10859/alternative-background-lines-in-chartjs-a626ce4d3bcb

The annotation plugin in chartjs allows for the creation of custom elements within a chart.

import annotationPlugin from "chartjs-plugin-annotation";
import {Chart} from 'chart.js';
Chart.register(annotationPlugin);

This code snippet demonstrates how to add a box element to our chart.

{
  type: 'box', #Selecting the drawing type
  drawTime: 'beforeDraw', #Determines whether the box will be in the foreground or background
  yMin: 5, #Minimum value on the y-axis
  yMax: 10, #Maximum value on the y-axis
  borderColor: 'rgb(242, 244, 248, 0.9)', #Color of the box's border
  borderWidth: 1, #Width of the box's border
  backgroundColor: '#F2F4F8', #Background color of the box
}
# Include options when rendering the chart
const options = {
  plugins: {annotation: {annotations: background_annotation}
}

This code example will produce the following result: https://i.sstatic.net/JYGTD.png

How can I assign a distinct background color to individual sections in Chart.js?

Answer №1

Answer №2

Answer №3

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