Chart.js - 在折线图中为背景的特定部分着色

本文介绍了Chart.js - 在折线图中为背景的特定部分着色的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

I have a line chart much like this one: http://www.chartjs.org/samples/latest/charts/line/basic.html

I would like to color the areas -100 < y < -40 and 40 < y < 100 a slight tint of red to indicate that point that fall in that area are in a danger zone.

This was a quick sketch using paint. Anything similar to this is welcome. How can I do this? I tried looking into the documentation but found nothing.

I currently have a workaround using a line chart stacked over a horizontal bar chart but it is far from ideal.

Thanks in advance!

解决方案

You can use annotation plugin and in particular Box annotations.

Here below there is an example with Scatter chart:

var randomScalingFactor = function() {
  return (Math.random() > 0.5 ? 1.0 : -1.0) * Math.round(Math.random() * 100);
};
var randomColor = function(opacity) {
  return 'rgba(' + Math.round(Math.random() * 255) + ',' + Math.round(Math.random() * 255) + ',' + Math.round(Math.random() * 255) + ',' + (opacity || '.3') + ')';
};
var data = {
  datasets: [{
    label: "My First dataset",
    data: [{
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }]
  }, {
    label: "My Second dataset",
    data: [{
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }, {
      x: randomScalingFactor(),
      y: randomScalingFactor(),
    }]
  }]
};
data.datasets.forEach(function(dataset) {
  dataset.borderColor = randomColor(0.4);
  dataset.backgroundColor = randomColor(0.1);
  dataset.pointBorderColor = randomColor(0.7);
  dataset.pointBackgroundColor = randomColor(0.5);
  dataset.pointBorderWidth = 1;
});

var ctx = document.getElementById("canvas").getContext("2d");
window.myScatter = new Chart(ctx, {
	type: 'scatter',
  data: data,
  options: {
    scales: {
      xAxes: [{
        position: 'bottom',
        gridLines: {
          zeroLineColor: "rgba(0,255,0,1)"
        },
        scaleLabel: {
          display: true,
          labelString: 'x axis'
        },
      }],
      yAxes: [{
        position: 'left',
        gridLines: {
          zeroLineColor: "rgba(0,255,0,1)"
        },
        scaleLabel: {
          display: true,
          labelString: 'y axis'
        },
        ticks: {
        	min: -100,
          max: 100
        }
      }]
    },
    annotation: {
      drawTime: "afterDraw",
      events: ['dblclick'],
      annotations: [{
      	id: 'low-box',
        type: 'box',
        xScaleID: 'x-axis-1',
        yScaleID: 'y-axis-1',
        xMin: -100,
        xMax: 100,
        yMin: -100,
        yMax: -40,
        backgroundColor: 'rgba(255, 0, 0, 0.3)',
        //borderColor: 'rgb(255, 0, 0)',
        borderWidth: 1
      },{
      	id: 'hi-box',
        type: 'box',
        xScaleID: 'x-axis-1',
        yScaleID: 'y-axis-1',
        xMin: -100,
        xMax: 100,
        yMin: 100,
        yMax: 40,
        backgroundColor: 'rgba(255, 0, 0, 0.3)',
        //borderColor: 'rgb(255, 0, 0)',
        borderWidth: 1
      }]
    }
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.bundle.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/chartjs-plugin-annotation/0.5.7/chartjs-plugin-annotation.min.js"></script>

<canvas id="canvas"></canvas>

这篇关于Chart.js - 在折线图中为背景的特定部分着色的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！

本站部分内容来源互联网,如果有图片或者内容侵犯您的权益请联系我们删除！

Chart.js - 在折线图中为背景的特定部分着色

问题描述

相关文档推荐