Chart.js

Question

我希望创建这样的折线图：

但是我不知道如何给背景添加渐变。此时我有了正确显示该行的代码。这是我的图表的代码：

     const ctx = document.getElementById("myChart");
      var speedData = {
        labels: [
          "Jan",
          "Feb",
          "Mar",
          "Apr",
          "May",
          "Jun",
          "Jul",
          "Aug",
          "Sep",
          "Oct",
          "Nov",
          "Dec"
        ],
        datasets: [
          {
            label: "Car Speed",
            data: this.car.energyConsumption,
            lineTension: 0,
            pointBackgroundColor: "#131921",
            pointBorderColor: "white",
            pointBorderWidth: 3,
            pointRadius: 6,
            borderColor: "white"
          }
        ]
      };

      var chartOptions = {
        legend: {
          display: false
        }
      };
      new Chart(ctx, {
        type: "line",
        data: speedData,
        options: chartOptions
      });
    }

Answer 1

backgroundColor 与 createLinearGradient should help here. backgroundColor propertly takes in different types of colors。您需要创建一个渐变并指定相同的渐变。

已为您重用代码创建了示例代码段。按照第 4-7 行和第 34 行。

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

// Create gradient here
const ctxForGradient = document.getElementById('myChart').getContext('2d');
const gradientFill = ctxForGradient.createLinearGradient(0, 500, 0, 50);
gradientFill.addColorStop(0, "rgba(255, 0, 0, 0.9)");
gradientFill.addColorStop(1, "rgba(0, 0, 255, 0.9)");

var speedData = {
  labels: [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug",
    "Sep",
    "Oct",
    "Nov",
    "Dec"
  ],

  datasets: [{
    label: "Car Speed",
    data: [7, 9, 5, 8, 9, 7, 6, 10, 4, 5, 7, 8, 9],
    lineTension: 0,
    pointBackgroundColor: "#131921",
    pointBorderColor: "white",
    pointBorderWidth: 3,
    pointRadius: 6,
    borderColor: "white",
    backgroundColor: gradientFill // Fill gradient here
  }]
};

var chartOptions = {
  legend: {
    display: false
  }
};
new Chart(ctx, {
  type: "line",
  data: speedData,
  options: chartOptions
});

<script src="https://cdn.jsdelivr.net/npm/chart.js@2.8.0"></script>
<canvas id="myChart"></canvas>

希望对您有所帮助。恢复任何 doubts/clarification.

Chart.js - 向折线图背景添加渐变

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javascript

gradient