如何在ChartJS中将xAxis属性与具有日期值的条形对齐？

Question

使用horizontalbar和stacked: true使用ChartJS构建甘特图。我将日期转换为纪元时间，然后转换为天数以在条形图中使用，然后将其转换回日期以在xAxis中显示，但是条形图和xAxis没有正确对齐，因为xAxis的定制Ticks生成的值最小为0，最大为300。

export class AppComponent implements OnInit {

  data = [
    {task: 'Task 1', startDate: '2018-04-08 00:00:00.000', endDate: '2018-06-08 00:00:00.000'},
    {task: 'Task 2', startDate: '2018-05-08 00:00:00.000', endDate: '2018-07-19 00:00:00.000'},
    {task: 'Task 3', startDate: '2018-07-08 00:00:00.000', endDate: '2018-09-08 00:00:00.000'},
  ];
  chartData;
  options;
  plantingDays = this.getDays('2018-04-01 00:00:00.000');

  constructor() {
  }

  createChart() {
    const that = this;
    this.chartData = {
      labels: this.data.map(t => t.task),
      datasets: [
        {
          data: this.data.map(t => {
            return this.getDays(t.startDate) - this.plantingDays;
          }),
          backgroundColor: 'rgba(63,103,126,0)',
          hoverBackgroundColor: 'rgba(50,90,100,0)',
        },
        {
          data: this.data.map(t => this.getDays(t.endDate) - this.plantingDays),
        },
      ],
    };

    this.options = {
      maintainAspectRatio: false,
      title: {
        display: true,
        text: 'Title of Chart',
      },
      legend: {display: false},
      tooltips: {
        mode: 'index',
        callbacks: {
          label: function (tooltipItem, d) {
            let label = d.datasets[tooltipItem.datasetIndex].label || '';
            const data = d.datasets[tooltipItem.datasetIndex].data;
            const date = new Date((data[tooltipItem.index] + that.plantingDays) * 86400000);
            if (tooltipItem.datasetIndex === 0) {
              label += 'Start Date: ' + that.getDate(date);
            } else if (tooltipItem.datasetIndex === 1) {
              label += 'End Date: ' + that.getDate(date);
            }
            return label;
          },
        },
      },
      scales: {
        xAxes: [{
          stacked: true,
          ticks: {
            callback: function (value, index, values) {
              const v = (value + that.plantingDays) * 86400000;
              console.log(value)
              const d = new Date(v);
              return that.getDate(d);
            },
          },
        }],
        yAxes: [{
          stacked: true,
        }],
      },
    };
  }

  getDate(date) {
    return date.getFullYear() + '-' + ('0' + (date.getMonth() + 1)).substr(-2)
      + '-' + ('0' + (date.getDay() + 1)).substr(-2);
  }

  getDays(date) {
    return new Date(date).getTime() / 86400000;
  }

  ngOnInit() {
    this.createChart();
  }

}

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