我将使用基于chart.js的ng2-charts。我试图在甜甜圈图表中添加文本，但我无法设置文本或注册插件。有人能帮忙吗？到目前为止，我发现了几个关于如何在javascript中完成此操作的不完整答案，但我在angular 2和typescript实现chart.js方面遇到了困难。
我的模板文件：
<div style="display: block" class="donut">
<canvas #mycanvas baseChart
[data]="doughnutChartData"
[labels]="doughnutChartLabels"
[chartType]="doughnutChartType"
[options]="doughnutChartOptions"
[datasets]="doughnutChartDatasets"
(chartHover)="chartHovered($event)"
(chartClick)="chartClicked($event)"></canvas>
</div>
<script>
Chart.pluginService.register({
afterDraw: function (chart) {
if (chart.config.options.elements.center) {
var helpers = Chart.helpers;
var centerX = (chart.chartArea.left + chart.chartArea.right) / 2;
var centerY = (chart.chartArea.top + chart.chartArea.bottom) / 2;
var ctx = chart.chart.ctx;
ctx.save();
var fontSize = helpers.getValueOrDefault(chart.config.options.elements.center.fontSize, Chart.defaults.global.defaultFontSize);
var fontStyle = helpers.getValueOrDefault(chart.config.options.elements.center.fontStyle, Chart.defaults.global.defaultFontStyle);
var fontFamily = helpers.getValueOrDefault(chart.config.options.elements.center.fontFamily, Chart.defaults.global.defaultFontFamily);
var font = helpers.fontString(fontSize, fontStyle, fontFamily);
ctx.font = font;
ctx.fillStyle = helpers.getValueOrDefault(chart.config.options.elements.center.fontColor, Chart.defaults.global.defaultFontColor);
ctx.textAlign = 'center';
ctx.textBaseline = 'middle';
ctx.fillText(chart.config.options.elements.center.text, centerX, centerY);
ctx.restore();
}
},
})
</script>
还有一个ts文件: app.component.ts
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'app works!';
colors = {
indigo: '#14143e',
pink: '#fd1c49',
orange: '#ff6e00',
yellow: '#f0c800',
mint: '#00efab',
cyan: '#05d1ff',
purple: '#841386',
white: '#fff'
};
// Doughnut
public doughnutChartLabels:string[] = ['Drive Score', ''];
public doughnutChartData:number[] = [85, 15];
public doughnutChartType:string = 'doughnut';
public doughnutChartOptions: any = {
cutoutPercentage: 80,
elements: {
center: {
text: 'Hello',
fontColor: '#000',
fontFamily: "'Helvetica Neue', 'Helvetica', 'Arial', sans-serif",
fontSize: 24,
fontStyle: 'normal'
}
}
};
public doughnutChartDatasets: any[] = [
{
data: [300, 50, 100],
options: this.doughnutChartOptions,
backgroundColor: [
"#FF6384",
"#36A2EB",
"#FFCE56"
],
hoverBackgroundColor: [
"#FF6384",
"#36A2EB",
"#FFCE56"
]
}];
// events
public chartClicked(e:any):void {
console.log(e);
}
public chartHovered(e:any):void {
console.log(e);
}
constructor(){
}
}