Chart.js Linear 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 Linear 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-getGradient" aria-selected="true">GetGradient</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-getGradient">
        <pre>
let width, height, gradient;
function getGradient(ctx, chartArea) {
  const chartWidth = chartArea.right - chartArea.left;
  const chartHeight = chartArea.bottom - chartArea.top;
  if (!gradient || width !== chartWidth || height !== chartHeight) {
    // Create the gradient because this is either the first render
    // or the size of the chart has changed
    width = chartWidth;
    height = chartHeight;
    gradient = ctx.createLinearGradient(0, chartArea.bottom, 0, chartArea.top);
    gradient.addColorStop(0, Utils.CHART_COLORS.blue);
    gradient.addColorStop(0.5, Utils.CHART_COLORS.yellow);
    gradient.addColorStop(1, Utils.CHART_COLORS.red);
  }

  return gradient;
}
        </pre>
      </div>
      <div class="tab-pane fade show tab-pane-code" id="myChart-config">
        <pre>
const config = {
  type: 'line',
  data: data,
  options: {
    responsive: true,
    plugins: {
      legend: {
        position: 'top',
      },
    }
  },
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-setup">
        <pre>
const DATA_COUNT = 7;
const NUMBER_CFG = {count: DATA_COUNT, min: -100, max: 100};
const labels = Utils.months({count: 7});

const data = {
  labels: labels,
  datasets: [
    {
      label: 'Dataset 1',
      data: Utils.numbers(NUMBER_CFG),
      borderColor: function(context) {
        const chart = context.chart;
        const {ctx, chartArea} = chart;

        if (!chartArea) {
          // This case happens on initial chart load
          return;
        }
        return getGradient(ctx, chartArea);
      },
    },
  ]
};
        </pre>
      </div>
      <div class="tab-pane fade tab-pane-code" id="myChart-actions">
        <pre>
const actions = [
  {
    name: 'Randomize',
    handler(chart) {
      chart.data.datasets.forEach(dataset => {
        dataset.data = Utils.numbers({count: chart.data.labels.length, min: -100, max: 100});
      });
      chart.update();
    }
  },
  {
    name: 'Add Data',
    handler(chart) {
      const data = chart.data;
      if (data.datasets.length > 0) {
        data.labels = Utils.months({count: data.labels.length + 1});

        for (let index = 0; index < data.datasets.length; ++index) {
          data.datasets[index].data.push(Utils.rand(-100, 100));
        }

        chart.update();
      }
    }
  },
  {
    name: 'Remove Data',
    handler(chart) {
      chart.data.labels.splice(-1, 1); // remove the label first

      chart.data.datasets.forEach(dataset => {
        dataset.data.pop();
      });

      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 actions = [
  {
    name: 'Randomize',
    handler(chart) {
      chart.data.datasets.forEach(dataset => {
        dataset.data = Utils.numbers({count: chart.data.labels.length, min: -100, max: 100});
      });
      chart.update();
    }
  },
  {
    name: 'Add Data',
    handler(chart) {
      const data = chart.data;
      if (data.datasets.length > 0) {
        data.labels = Utils.months({count: data.labels.length + 1});

        for (let index = 0; index < data.datasets.length; ++index) {
          data.datasets[index].data.push(Utils.rand(-100, 100));
        }

        chart.update();
      }
    }
  },
  {
    name: 'Remove Data',
    handler(chart) {
      chart.data.labels.splice(-1, 1); // remove the label first

      chart.data.datasets.forEach(dataset => {
        dataset.data.pop();
      });

      chart.update();
    }
  }
];

const DATA_COUNT = 7;
const NUMBER_CFG = {count: DATA_COUNT, min: -100, max: 100};
const labels = Utils.months({count: 7});

const data = {
  labels: labels,
  datasets: [
    {
      label: 'Dataset 1',
      data: Utils.numbers(NUMBER_CFG),
      borderColor: function(context) {
        const chart = context.chart;
        const {ctx, chartArea} = chart;

        if (!chartArea) {
          // This case happens on initial chart load
          return;
        }
        return getGradient(ctx, chartArea);
      },
    },
  ]
};

const config = {
  type: 'line',
  data: data,
  options: {
    responsive: true,
    plugins: {
      legend: {
        position: 'top',
      },
    }
  },
};

let width, height, gradient;
function getGradient(ctx, chartArea) {
  const chartWidth = chartArea.right - chartArea.left;
  const chartHeight = chartArea.bottom - chartArea.top;
  if (!gradient || width !== chartWidth || height !== chartHeight) {
    // Create the gradient because this is either the first render
    // or the size of the chart has changed
    width = chartWidth;
    height = chartHeight;
    gradient = ctx.createLinearGradient(0, chartArea.bottom, 0, chartArea.top);
    gradient.addColorStop(0, Utils.CHART_COLORS.blue);
    gradient.addColorStop(0.5, Utils.CHART_COLORS.yellow);
    gradient.addColorStop(1, Utils.CHART_COLORS.red);
  }

  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);
    });
});