ng2-charts access chartjs object to apply chartjs functions

问题

I am using ng2-charts and require more control.

The xAxis value range should change dynamically. To achieve this I need to get access to the Chart-Object used by ng2-charts. Then I can do this

Which basically boils down to two steps:

//Chart-Object
var barChartDemo = new Chart(ctx).Bar(barChartData, {
  responsive: true,
  barValueSpacing: 2
});
setInterval(function() {
//removing the first dataentry
  barChartDemo.removeData();
//adding new data
  barChartDemo.addData([dData()], "dD " + index);
  index++;
}, 3000);

I tried this solution but it seems that getComponent() is deprecated. To circumvent this I tried to use @ViewChild (with and without ElementRef) which would result in property "chart" being undefined on the received object.

Looking into the chartjs implementation in ng2-charts I can see that the BaseChartDirective controls the generation of charts and stores the generated chart as a class property (this.chart). However I am not certain how to get access to this property in my component.

ng2-charts is a module and therefore part of my @NgModule imports.

回答1:

The solution was using @ViewChild on the directive directly and forcing a redraw with each new data. Dataadding and removing itself was done on the @Input object lineChartData which is defined in the html like this: [datasets]="lineChartData"

Code:

import { BaseChartDirective } from 'ng2-charts/charts/charts';
export class Example{
    @ViewChild(BaseChartDirective) baseChartDir: BaseChartDirective;
    public lineChartData: Array<any>;

    //call this function whenever you want an updated version of your chart
    this.baseChartDir.ngOnChanges({});

来源：https://stackoverflow.com/questions/42211288/ng2-charts-access-chartjs-object-to-apply-chartjs-functions

标签

angular

chart.js

ng2-charts