Chartjs / ng2-charts line on hover does not work

问题

I'm trying to optimize my chart using ng2-charts on Angular cli app. In general, everything works just fine, the only thing does not is the line on hover to track the data point. This is the ideal chart model I try to make and I also tried to follow its code:

https://stackblitz.com/edit/line-chart?file=app%2Fapp.component.ts

However, when I hover on my chart, only the tooltip is shown.

Here are my codes:

plugin-hoverline.ts: (copy & paste from the link below, credit by @GRUNT)

https://istack.000webhostapp.com/chartjs-plugin-hoverline.js

banner.component.ts: (chart component)

import { Component, OnInit } from '@angular/core';
import { HistoricalBpiService } from '../../services/historical-bpi.service';
import './plugin-hoverline';

@Component({
  selector: 'app-banner',
  templateUrl: './banner.component.html',
  styleUrls: ['./banner.component.scss']
})
export class BannerComponent implements OnInit {

  currentDate:string = new Date().toJSON().slice(0,10).replace(/-/g,'-');

  private dataUrl: string = 'historical/close.json?start=2013-09-01&end=' + this.currentDate;

  constructor(    
    private historicalBpiService:HistoricalBpiService
  ) {}

  // lineChart

  public lineChartData:any = [
    { data:[], label: 'BTC' }
  ];

  public lineChartLabels:Array<any> = [];

  public lineChartOptions:any = {
    responsive: true,
    maintainAspectRatio: false,
    layout: {
      padding: 0
    },
    lineOnHover: {
     enabled: true,
     lineColor: '#bbb',
     lineWidth: 1
   },
    scales: {
      yAxes: [{
        display: false,
        scaleLabel: {
          display: false,
          labelString: 'USD'
        },
        ticks: {
          //min: 0,
          //max: 5000,
          stepSize: 500,
          display: false,
          mirror: true,
          labelOffset: 7,
          padding: -10,
          callback: function(value, index, values) {
            return '$' + value;
          }
        },
        gridLines: {
          display: true,
          tickMarkLength: 0
        }
      }],
      xAxes: [{
        ticks: {
          display: false,
          mirror: true
        },
        gridLines: {
          display: false,
          tickMarkLength: 0
        }
      }]
    },
    elements: {
      point: {
        radius: 0
      },
      line: {
        tension: 0, // 0 disables bezier curves
      }
    },
    hover: {
      mode: 'nearest',
      intersect: false
    },
    tooltips: {
      mode: 'nearest',
      intersect: false,
      backgroundColor: 'rgb(95,22,21)',
      callbacks: {
        title: function (tooltipItems, data) {
          return (tooltipItems[0] || {})['xLabel'];
        },
        label: function (tooltipItem, data) {
          return '$ ' + tooltipItem.yLabel.toLocaleString();
        },
        labelColor: function(tooltipItem, chart) {
          let dataset = chart.config.data.datasets[tooltipItem.datasetIndex];
          return {
            backgroundColor : dataset.backgroundColor
          }
        }
      }
    }
  };
  public lineChartColors:Array<any> = [
    {
      backgroundColor: 'rgba(199,32,48,0.9',
      borderColor: 'rgb(95,22,21);',
      pointBackgroundColor: 'rgba(218,208,163,0.9)',
      pointHoverBackgroundColor: 'rgba(218,208,163,0.9)',
      pointHoverBorderColor: 'rgb(218,208,163)',
      pointHoverRadius: 5,
      steppedLine: false

    }
  ];
  public lineChartLegend:boolean = false;
  public lineChartType:string = 'line';


  // events
  public chartClicked(e:any):void {
    console.log(e);
  }

  public chartHovered(e:any):void {
    console.log(e);
  }

  ngOnInit(){
    this.historicalBpiService.getBpiData(this.dataUrl)
      .subscribe(
        res => {
          //this.lineChartData = Object.keys(res.bpi).map(function (key) { return res.bpi[key];});
          this.lineChartData[0].data = Object.values(res.bpi);
          this.lineChartLabels = Object.keys(res.bpi);
          //console.log(this.lineChartData,this.lineChartLabels);
        }
      )
  }
}

Template:

<div class="chart">
      <canvas baseChart height="360px"
        [datasets]="lineChartData"
        [labels]="lineChartLabels"
        [options]="lineChartOptions"
        [colors]="lineChartColors"
        [legend]="lineChartLegend"
        [chartType]="lineChartType"
        (chartHover)="chartHovered($event)"
        (chartClick)="chartClicked($event)"></canvas>
    </div>

回答1:

TRY using the following code :

chart component

import { Component, OnInit } from '@angular/core';
import { HistoricalBpiService } from '../../services/historical-bpi.service';
import './plugin-hoverline';

@Component({
   selector: 'app-banner',
   templateUrl: './banner.component.html',
   styleUrls: ['./banner.component.scss']
})
export class BannerComponent implements OnInit {

   currentDate: string = new Date().toJSON().slice(0, 10).replace(/-/g, '-');

   private dataUrl: string = 'historical/close.json?start=2013-09-01&end=' + this.currentDate;

   constructor(
      private historicalBpiService: HistoricalBpiService
   ) { }

   // lineChart

   public lineChartData: any = [
      { data: [], label: 'BTC', pointHoverRadius: 5, steppedLine: false }
   ];

   public lineChartLabels: Array<any> = [];

   public lineChartOptions: any = {
      responsive: true,
      maintainAspectRatio: false,
      layout: {
         padding: 0
      },
      lineOnHover: {
         enabled: true,
         lineColor: '#bbb',
         lineWidth: 1
      },
      scales: {
         yAxes: [{
            display: false,
            scaleLabel: {
               display: false,
               labelString: 'USD'
            },
            ticks: {
               //min: 0,
               //max: 5000,
               stepSize: 500,
               display: false,
               mirror: true,
               labelOffset: 7,
               padding: -10,
               callback: function (value, index, values) {
                  return '$' + value;
               }
            },
            gridLines: {
               display: true,
               tickMarkLength: 0
            }
         }],
         xAxes: [{
            ticks: {
               display: false,
               mirror: true
            },
            gridLines: {
               display: false,
               tickMarkLength: 0
            }
         }]
      },
      elements: {
         point: {
            radius: 0
         },
         line: {
            tension: 0, // 0 disables bezier curves
         }
      },
      hover: {
         mode: 'nearest',
         intersect: true
      },
      tooltips: {
         mode: 'nearest',
         intersect: true,
         backgroundColor: 'rgb(95,22,21)',
         callbacks: {
            title: function (tooltipItems, data) {
               return (tooltipItems[0] || {})['xLabel'];
            },
            label: function (tooltipItem, data) {
               return '$ ' + tooltipItem.yLabel.toLocaleString();
            },
            labelColor: function (tooltipItem, chart) {
               let dataset = chart.config.data.datasets[tooltipItem.datasetIndex];
               return {
                  backgroundColor: dataset.backgroundColor
               }
            }
         }
      }
   };
   public lineChartColors: Array<any> = [
      {
         backgroundColor: 'rgba(199,32,48,0.9',
         borderColor: 'rgb(95,22,21);',
         pointBackgroundColor: 'rgba(218,208,163,0.9)',
         pointHoverBackgroundColor: 'rgba(218,208,163,0.9)',
         pointHoverBorderColor: 'rgb(218,208,163)'

      }
   ];
   public lineChartLegend: boolean = false;
   public lineChartType: string = 'line';


   // events
   public chartClicked(e: any): void {
      console.log(e);
   }

   public chartHovered(e: any): void {
      console.log(e);
   }

   ngOnInit() {
      this.historicalBpiService.getBpiData(this.dataUrl)
         .subscribe(
         res => {
            //this.lineChartData = Object.keys(res.bpi).map(function (key) { return res.bpi[key];});
            this.lineChartData[0].data = Object.values(res.bpi);
            this.lineChartLabels = Object.keys(res.bpi);
            //console.log(this.lineChartData,this.lineChartLabels);
         }
         )
   }
}

You should set the pointHoverRadius property inside lineChartData array instead of lineChartColors, also set the intersect property to true for both hover and tooltips

来源：https://stackoverflow.com/questions/46239507/chartjs-ng2-charts-line-on-hover-does-not-work