Chart.js Radial Gradient 示例

HTML

CSS

JavaScript

HTML

<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no" />
<title>Chart.js Radial Gradient</title>
<meta name="keywords" content="LightYear,光年,后台模板,后台管理系统,光年HTML模板">
<meta name="description" content="LightYear是一个基于Bootstrap的后台管理系统的HTML模板。">
<meta name="author" content="yinqi">
<link rel="stylesheet" type="text/css" href="http://lyear.itshubao.com/v4/css/bootstrap.min.css">
<link rel="stylesheet" type="text/css" href="http://lyear.itshubao.com/v4/css/style.min.css">
</head>
  
<body>
<div class="chart-example">
  <div class="tab-content">
    <div class="chart-view"><canvas id="myChart"></canvas></div>
    <div class="chart-actions mt-3"></div>
    <ul class="nav nav-tabs mt-3">
      <li class="nav-item">
        <a class="nav-link active" data-toggle="tab" href="#myChart-createRadialGradient3" aria-selected="true">CreateRadialGradient3</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" data-toggle="tab" href="#myChart-config" aria-selected="true">Config</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" data-toggle="tab" href="#myChart-setup" aria-selected="false">Setup</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" data-toggle="tab" href="#myChart-actions" aria-selected="false">Actions</a>
      </li>
    </ul>
    <div class="tab-content">
      <div class="tab-pane fade show active tab-pane-code" id="myChart-createRadialGradient3">
        <pre>
function createRadialGradient3(context, c1, c2, c3) {
  const chartArea = context.chart.chartArea;
  if (!chartArea) {
    // This case happens on initial chart load
    return;
  }

  const chartWidth = chartArea.right - chartArea.left;
  const chartHeight = chartArea.bottom - chartArea.top;
  if (width !== chartWidth || height !== chartHeight) {
    cache.clear();
  }
  let gradient = cache.get(c1 + c2 + c3);
  if (!gradient) {
    // Create the gradient because this is either the first render
    // or the size of the chart has changed
    width = chartWidth;
    height = chartHeight;
    const centerX = (chartArea.left + chartArea.right) / 2;
    const centerY = (chartArea.top + chartArea.bottom) / 2;
    const r = Math.min(
      (chartArea.right - chartArea.left) / 2,
      (chartArea.bottom - chartArea.top) / 2
    );
    const ctx = context.chart.ctx;
    gradient = ctx.createRadialGradient(centerX, centerY, 0, centerX, centerY, r);
    gradient.addColorStop(0, c1);
    gradient.addColorStop(0.5, c2);
    gradient.addColorStop(1, c3);
    cache.set(c1 + c2 + c3, gradient);
  }

  return gradient;
}
        </pre>
      </div>
      <div class="tab-pane fade show tab-pane-code" id="myChart-config">
        <pre>
const config = {
  type: 'polarArea',
  data: data,
  options: {
    plugins: {
      legend: false,
      tooltip: false,
    },
    elements: {
      arc: {
        backgroundColor: function(context) {
          let c = colors[context.dataIndex];
          if (!c) {
            return;
          }
          if (context.active) {
            c = helpers.getHoverColor(c);
          }
          const mid = helpers.color(c).desaturate(0.2).darken(0.2).rgbString();
          const start = helpers.color(c).lighten(0.2).rotate(270).rgbString();
          const end = helpers.color(c).lighten(0.1).rgbString();
          return createRadialGradient3(context, start, mid, end);
        },
      }
    }
  }
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-setup">
        <pre>
function generateData() {
  return Utils.numbers({
    count: DATA_COUNT,
    min: 0,
    max: 100
  });
}

const data = {
  labels: Utils.months({count: DATA_COUNT}),
  datasets: [{
    data: generateData()
  }]
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-actions">
        <pre>
const DATA_COUNT = 5;
Utils.srand(110);

const chartColors = Utils.CHART_COLORS;
const colors = [chartColors.red, chartColors.orange, chartColors.yellow, chartColors.green, chartColors.blue];

const cache = new Map();
let width = null;
let height = null;

const actions = [
  {
    name: 'Randomize',
    handler(chart) {
      chart.data.datasets.forEach(dataset => {
        dataset.data = generateData();
      });
      chart.update();
    }
  },
];
        </pre>
      </div>
    </div>
  </div>
</div>

<script type="text/javascript" src="http://lyear.itshubao.com/v4/js/jquery.min.js"></script>
<script type="text/javascript" src="http://lyear.itshubao.com/v4/js/popper.min.js"></script>
<script type="text/javascript" src="http://lyear.itshubao.com/v4/js/bootstrap.min.js"></script>
<script type="text/javascript" src="https://cdn.bootcdn.net/ajax/libs/Chart.js/4.1.1/chart.umd.min.js"></script>
<script type="text/javascript" src="https://cdn.bootcdn.net/ajax/libs/luxon/3.2.0/luxon.min.js"></script>
<script type="text/javascript" src="http://libs.itshubao.com/chartjs/utils.js"></script>
</body>
</html>

CSS

body{
  background: #fff;
}
.tab-content .chart-view {
  max-width: 800px;
}
.tab-content .tab-pane-code {
  height: 360px;
  overflow: auto;
}
.tab-content .tab-pane-code pre {
  height: 100%;
  margin: 0px;
}
.chart-example {
  width: calc(100% - 2px);
  border: 1px solid #ececec;
  padding: 10px;
}

JavaScript

const DATA_COUNT = 5;
Utils.srand(110);

const chartColors = Utils.CHART_COLORS;
const colors = [chartColors.red, chartColors.orange, chartColors.yellow, chartColors.green, chartColors.blue];

const cache = new Map();
let width = null;
let height = null;

const actions = [
  {
    name: 'Randomize',
    handler(chart) {
      chart.data.datasets.forEach(dataset => {
        dataset.data = generateData();
      });
      chart.update();
    }
  },
];

function generateData() {
  return Utils.numbers({
    count: DATA_COUNT,
    min: 0,
    max: 100
  });
}

const data = {
  labels: Utils.months({count: DATA_COUNT}),
  datasets: [{
    data: generateData()
  }]
};

const config = {
  type: 'polarArea',
  data: data,
  options: {
    plugins: {
      legend: false,
      tooltip: false,
    },
    elements: {
      arc: {
        backgroundColor: function(context) {
          let c = colors[context.dataIndex];
          if (!c) {
            return;
          }
          if (context.active) {
            c = Chart.helpers.getHoverColor(c);
          }
          const mid = Chart.helpers.color(c).desaturate(0.2).darken(0.2).rgbString();
          const start = Chart.helpers.color(c).lighten(0.2).rotate(270).rgbString();
          const end = Chart.helpers.color(c).lighten(0.1).rgbString();
          return createRadialGradient3(context, start, mid, end);
        },
      }
    }
  }
};

function createRadialGradient3(context, c1, c2, c3) {
  const chartArea = context.chart.chartArea;
  if (!chartArea) {
    // This case happens on initial chart load
    return;
  }

  const chartWidth = chartArea.right - chartArea.left;
  const chartHeight = chartArea.bottom - chartArea.top;
  if (width !== chartWidth || height !== chartHeight) {
    cache.clear();
  }
  let gradient = cache.get(c1 + c2 + c3);
  if (!gradient) {
    // Create the gradient because this is either the first render
    // or the size of the chart has changed
    width = chartWidth;
    height = chartHeight;
    const centerX = (chartArea.left + chartArea.right) / 2;
    const centerY = (chartArea.top + chartArea.bottom) / 2;
    const r = Math.min(
      (chartArea.right - chartArea.left) / 2,
      (chartArea.bottom - chartArea.top) / 2
    );
    const ctx = context.chart.ctx;
    gradient = ctx.createRadialGradient(centerX, centerY, 0, centerX, centerY, r);
    gradient.addColorStop(0, c1);
    gradient.addColorStop(0.5, c2);
    gradient.addColorStop(1, c3);
    cache.set(c1 + c2 + c3, gradient);
  }

  return gradient;
}

const ctx = document.getElementById('myChart');

const chart = new Chart(ctx, config);

$.each(actions, function(index, value) {
    let aHtml = $('<a></a>').addClass('btn btn-default m-r-5').html(value.name);
    $('.chart-actions').append(aHtml);
    aHtml.on('click', function () {
        value.handler(chart);
    });
});