如何使用 Chart.js

问题描述

我正在尝试在 React 中使用 Chart.js 制作折线图。 我没有使用 DOM 来创建和访问画布。 我可以安排背景颜色，但我只想将其设为渐变。我该怎么做？

我的代码如下：

import React from "react";
import { Line } from "@reactchartjs/react-chart.js";

const data = {
  labels: ["day1","day2","day3","day4","day5","day6"],datasets: [
    {
      label: "Your BMI",data: [28.3,28,27,27.6,25,25.6],fill: true,backgroundColor: "rgba(10,10,.2)",borderColor: "rgba(152,222,217,0.2)"
    }
  ]
};




const options = {
  scales: {
    yAxes: [
      {
        ticks: {
          beginAtZero: true
        }
      }
    ]
  }
};

const LineChart = () => (
  <>
    <Line data={data} options={options} />
  </>
);

export default LineChart;

输出如下： https://i.stack.imgur.com/D5lwg.png

解决方法

您可以使用画布“createLinearGradient”方法。

文档： https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/createLinearGradient， https://developer.mozilla.org/en-US/docs/Web/API/CanvasGradient/addColorStop

示例：https://codepen.io/alexgill/pen/MWbjXOP

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var gradient = ctx.createLinearGradient(0,400);
gradient.addColorStop(0,'rgba(10,10,.2)');   
gradient.addColorStop(1,'rgba(255,255,1)');


const data = {
  labels: ["day1","day2","day3","day4","day5","day6"],datasets: [
    {
      label: "Your BMI",data: [28.3,28,27,27.6,25,25.6],backgroundColor : gradient,borderColor: "rgba(152,222,217,0.2)"
    }
  ]
};