图表区域背景颜色chartjs

Question

I have problem with chart js, i want to coloring chart area like image above

I try to find configuration from charJs Docs , but nothing matched. its possible or not to change chart area background color? if possible anyone can help me?

Html

<canvas id="barChart" width="600" height="300"></canvas>

Javascript

var ctx = document.getElementById("barChart");
var barChart = new Chart(ctx,{
  type: 'bar',
  data: {
    labels:["Label1","Label2","Label3","Label4"],
    borderColor : "#fffff",
    datasets: [
      {
        data: ["2","3","1","4"],
        borderColor : "#fff",
        borderWidth : "3",
        hoverBorderColor : "#000",
        backgroundColor: [
          "#f38b4a",
          "#56d798",
          "#ff8397",
          "#6970d5" 
        ],
        hoverBackgroundColor: [
          "#f38b4a",
          "#56d798",
          "#ff8397",
          "#6970d5"
        ]
      }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks:{
          min : 0,
          stepSize : 1,
          fontColor : "#000",
          fontSize : 14
        },
        gridLines:{
          color: "#000",
          lineWidth:2,
          zeroLineColor :"#000",
          zeroLineWidth : 2
        },
        stacked: true
      }],
      xAxes: [{
        ticks:{
          fontColor : "#000",
          fontSize : 14
        },
        gridLines:{
          color: "#fff",
          lineWidth:2
        }
      }]
    },
    responsive:false
  }
});

Here's my current code jsFiddle

so everyone can try for find solution. thanks for your help.

Answer 1

There is no built-in method to change background color, but you can use CSS. JSFiddle .

ctx.style.backgroundColor = 'rgba(255,0,0,255)';

EDIT

If you want to fill exact area of chart and no whole div, you can write your own chart.js plugin. Try it on JSFiddle .

        Chart.pluginService.register({
            beforeDraw: function (chart, easing) {
                if (chart.config.options.chartArea && chart.config.options.chartArea.backgroundColor) {
                    var ctx = chart.chart.ctx;
                    var chartArea = chart.chartArea;

                    ctx.save();
                    ctx.fillStyle = chart.config.options.chartArea.backgroundColor;
                    ctx.fillRect(chartArea.left, chartArea.top, chartArea.right - chartArea.left, chartArea.bottom - chartArea.top);
                    ctx.restore();
                }
            }
        });

        var config = {
  type: 'bar',
  data: {
    labels:["Label1","Label2","Label3","Label4"],
    borderColor : "#fffff",
    datasets: [
      {
        data: ["2","3","1","4"],
        borderColor : "#fff",
        borderWidth : "3",
        hoverBorderColor : "#000",
        backgroundColor: [
          "#f38b4a",
          "#56d798",
          "#ff8397",
          "#6970d5" 
        ],
        hoverBackgroundColor: [
          "#f38b4a",
          "#56d798",
          "#ff8397",
          "#6970d5"
        ]
      }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks:{
          min : 0,
          stepSize : 1,
          fontColor : "#000",
          fontSize : 14
        },
        gridLines:{
          color: "#000",
          lineWidth:2,
          zeroLineColor :"#000",
          zeroLineWidth : 2
        },
        stacked: true
      }],
      xAxes: [{
        ticks:{
          fontColor : "#000",
          fontSize : 14
        },
        gridLines:{
          color: "#fff",
          lineWidth:2
        }
      }]
    },
    responsive:false,
    chartArea: {
        backgroundColor: 'rgba(251, 85, 85, 0.4)'
    }
  }
};

        var ctx = document.getElementById("barChart").getContext("2d");
        new Chart(ctx, config);

Answer 2

The canvas background is transparent by definition, like any element, so you just need to define the background-color in your canvas, for example, in your case you will need this CSS:

JSFiddle

canvas#barChart {
  background-color: #f00;
}

or HTML inline, to clarify the idea:

<canvas id="barChart" width="600" height="300" style="background-color: #f00;"></canvas>

Answer 3

This works on latest chartjs

    const custom_canvas_background_color = {
      id: 'custom_canvas_background_color',
      beforeDraw: (chart, args, options) => {
        const {
          ctx,
          chartArea: { top, right, bottom, left, width, height },
          scales: { x, y },
        } = chart;
        ctx.save();
        ctx.globalCompositeOperation = 'destination-over';
        ctx.fillStyle = '#E5E5E5';
        ctx.fillRect(left, top, width, height);
        ctx.restore();
      },
    };

Then add as plugin

 plugins: [custom_canvas_background_color]

Answer 4

You can achieve this by implementing this Chartjs plugin plugin / example . The plugin allows you to enhance your chart. For example zoom in or pan on to your chart. But also change the background color. Using setBackgroundColor(color); //updates the background color of the chart setBackgroundColor(color); //updates the background color of the chart .

Answer 5

If you want to set a colour for the whole Canvas (and not just the plotting area), you can do it like this:

Chart.pluginService.register({
  beforeDraw: ({ config: { options }, ctx }) => {
    if (options.chartArea?.backgroundColor) {
      ctx.save();
      ctx.fillStyle = options.chartArea.backgroundColor;
      ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
      ctx.restore();
    }
  }
});

const chart = new Chart(document.getElementById('chart'), {
  options: {
    chartArea: {
      backgroundColor: 'rgba(255, 255, 255, 1)'
    }
  }
});

This will be applied to the PNG when using chart.toBase64Image()