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这个例子是我在谷歌上找到的，它工作正常。当我们分别传递 x 和 y 值时，会在索引上创建垂直线。

example() {
    var originalLineDraw = Chart.controllers.line.prototype.draw;
    Chart.helpers.extend(Chart.controllers.line.prototype, {
      draw: function () {
        originalLineDraw.apply(this, arguments);

        var chart = this.chart;
        var ctx = chart.chart.ctx;

        var index = chart.config.data.lineAtIndex;
        if (index) {
          var xaxis = chart.scales['x-axis-0'];
          var yaxis = chart.scales['y-axis-0'];

          ctx.save();
          ctx.beginPath();
          ctx.moveTo(xaxis.getPixelForValue(undefined, index), yaxis.top);
          ctx.strokeStyle = 'red';
          ctx.lineTo(xaxis.getPixelForValue(undefined, index), yaxis.bottom);
          ctx.stroke();
          ctx.restore();
        }
      }
    }); 
 
    var config = {
      type: 'line',
      data: {
        labels: ["January", "February", "March", "April", "May", "June", "July"],
        datasets: [{
          label: "My First dataset",
          data: [12, 3, 2, 1, 8, 8, 2],
          fill: false,
          backgroundColor: 'blue',
          borderColor: 'blue',
        }],
        lineAtIndex: [2,5]
      },
    };
    new Chart('canvas', config);
  }

这是我的代码，我正在尝试在图表上创建垂直线。这是显示股票市场代码表现的财务图表。我必须通过时间和价值观。

demochart() {
   var originalLineDraw = Chart.controllers.line.prototype.draw;
   Chart.helpers.extend(Chart.controllers.line.prototype, {
      draw: function () {
        originalLineDraw.apply(this, arguments);
        var chart = this.chart;
        var ctx = chart.chart.ctx;
        var index = chart.config.data.lineAtIndex;
        if (index) {
            var xaxis = chart.scales['x-axis-0'];
            var yaxis = chart.scales['y-axis-0'];
            ctx.save();
            ctx.beginPath();
            ctx.moveTo(xaxis.getPixelForValue(undefined, index), yaxis.top);
            ctx.strokeStyle = 'red';
            ctx.lineTo(xaxis.getPixelForValue(undefined, index), yaxis.bottom);
            ctx.stroke();
            ctx.restore();
        }
      }
  });
  var config = {
    type: 'line',
    data: {
        datasets: [{
            label: "My First dataset",
            data: [{ x: 1591900200000, y: 1936.88 }, { x: 1592159400000, y: 379.38 }, 
                   { x: 1592245800000, y: 2495.94 }, { x: 1592332200000, y: -938.44 }, 
                   { x: 1592418600000, y: -1697.19 }, { x: 1592505000000, y: -1058.44 },
                   { x: 1592764200000, y: 439.38 }, { x: 1592850600000, y: 758.75 }],
            fill: false,
            backgroundColor: 'blue',
            borderColor: 'blue',
        }],
        lineAtIndex: 2
     }
  };
   new Chart('canvas', config);
}
4

1 回答 1

0

如果您将其更改为此代码，则获取正确像素的代码不正确：xaxis.getPixelForValue(chart.config.data.datasets[0].data[index].x)

现场示例：

var originalLineDraw = Chart.controllers.line.prototype.draw;
Chart.helpers.extend(Chart.controllers.line.prototype, {
  draw: function() {
    originalLineDraw.apply(this, arguments);
    var chart = this.chart;
    var ctx = chart.chart.ctx;
    var index = chart.config.data.lineAtIndex;
    if (index) {
      var xaxis = chart.scales['x-axis-0'];
      var yaxis = chart.scales['y-axis-0'];


      ctx.save();
      ctx.beginPath();
      ctx.moveTo(xaxis.getPixelForValue(chart.config.data.datasets[0].data[index].x), yaxis.top);
      ctx.strokeStyle = 'red';
      ctx.lineTo(xaxis.getPixelForValue(chart.config.data.datasets[0].data[index].x), yaxis.bottom);
      ctx.stroke();
      ctx.restore();
    }
  }
});
var config = {
  type: 'line',
  data: {
    datasets: [{
      label: "My First dataset",
      data: [{
          x: moment(1591900200000),
          y: 1936.88
        }, {
          x: moment(1592159400000),
          y: 379.38
        },
        {
          x: moment(1592245800000),
          y: 2495.94
        }, {
          x: moment(1592332200000),
          y: -938.44
        },
        {
          x: moment(1592418600000),
          y: -1697.19
        }, {
          x: moment(1592505000000),
          y: -1058.44
        },
        {
          x: moment(1592764200000),
          y: 439.38
        }, {
          x: moment(1592850600000),
          y: 758.75
        }
      ],
      fill: false,
      backgroundColor: 'blue',
      borderColor: 'blue',
    }],
    lineAtIndex: 2
  },
  options: {
    scales: {
      xAxes: [{
        type: 'time'
      }]
    }
  }
};
new Chart('chartJSContainer', config);
<body>
  <canvas id="chartJSContainer" width="600" height="400"></canvas>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/chartjs-adapter-moment/1.0.0/chartjs-adapter-moment.min.js"></script>
</body>

于 2021-06-15T22:16:30.130 回答