Chart.js Doughnut Empty State 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 Doughnut Empty State</title>
<meta name="keywords" content="LightYear,光年,后台模板,后台管理系统,光年HTML模板">
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</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-config" aria-selected="true">Config</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" data-toggle="tab" href="#myChart-plugin" aria-selected="false">Plugin</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" data-toggle="tab" href="#myChart-data" aria-selected="false">Data</a>
      </li>
    </ul>
    <div class="tab-content">
      <div class="tab-pane fade show active tab-pane-code" id="myChart-config">
        <pre>
const config = {
  type: 'doughnut',
  data: data,
  options: {
    plugins: {
      emptyDoughnut: {
        color: 'rgba(255, 128, 0, 0.5)',
        width: 2,
        radiusDecrease: 20
      }
    }
  },
  plugins: [plugin]
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-plugin">
        <pre>
const plugin = {
  id: 'emptyDoughnut',
  afterDraw(chart, args, options) {
    const {datasets} = chart.data;
    const {color, width, radiusDecrease} = options;
    let hasData = false;

    for (let i = 0; i < datasets.length; i += 1) {
      const dataset = datasets[i];
      hasData |= dataset.data.length > 0;
    }

    if (!hasData) {
      const {chartArea: {left, top, right, bottom}, ctx} = chart;
      const centerX = (left + right) / 2;
      const centerY = (top + bottom) / 2;
      const r = Math.min(right - left, bottom - top) / 2;

      ctx.beginPath();
      ctx.lineWidth = width || 2;
      ctx.strokeStyle = color || 'rgba(255, 128, 0, 0.5)';
      ctx.arc(centerX, centerY, (r - radiusDecrease || 0), 0, 2 * Math.PI);
      ctx.stroke();
    }
  }
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-data">
        <pre>
const data = {
  labels: [],
  datasets: [
    {
      label: 'Dataset 1',
      data: []
    }
  ]
};
        </pre>
      </div>
    </div>
  </div>
</div>

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</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 = {
  labels: [],
  datasets: [
    {
      label: 'Dataset 1',
      data: []
    }
  ]
};

const plugin = {
  id: 'emptyDoughnut',
  afterDraw(chart, args, options) {
    const {datasets} = chart.data;
    const {color, width, radiusDecrease} = options;
    let hasData = false;

    for (let i = 0; i < datasets.length; i += 1) {
      const dataset = datasets[i];
      hasData |= dataset.data.length > 0;
    }

    if (!hasData) {
      const {chartArea: {left, top, right, bottom}, ctx} = chart;
      const centerX = (left + right) / 2;
      const centerY = (top + bottom) / 2;
      const r = Math.min(right - left, bottom - top) / 2;

      ctx.beginPath();
      ctx.lineWidth = width || 2;
      ctx.strokeStyle = color || 'rgba(255, 128, 0, 0.5)';
      ctx.arc(centerX, centerY, (r - radiusDecrease || 0), 0, 2 * Math.PI);
      ctx.stroke();
    }
  }
};

const config = {
  type: 'doughnut',
  data: data,
  options: {
    plugins: {
      emptyDoughnut: {
        color: 'rgba(255, 128, 0, 0.5)',
        width: 2,
        radiusDecrease: 20
      }
    }
  },
  plugins: [plugin]
};

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

const chart = new Chart(ctx, config);