Using Gradient Effect in Chart.js with Angular

I am trying to enhance the appearance of my chart by adding a Gradient effect, but I am struggling with properly implementing it in my Angular project. Despite finding similar solutions online, I keep encountering the error message 

ERROR TypeError: this.canvas is undefined
regardless of how I initialize the DOM element. Can anyone offer assistance with this issue? PS: I am using the ng2-charts package.

Here is my ViewChild and initialization code:

@ViewChild("canvas") canvas: ElementRef;
lineChartColors;

ngAfterContentInit() {
    const domCanvasAccess = this.canvas.nativeElement as HTMLCanvasElement;
    const gradientColor = domCanvasAccess.getContext('2d').createLinearGradient(0, 0, 0, 200);
    gradientColor.addColorStop(0, 'green');
    gradientColor.addColorStop(1, 'white');
    this.lineChartColors = [
        {
            backgroundColor: gradientColor,
            borderColor: "black",
        }
    ];
}

For further details, here is a helpful StackBlitz link: https://stackblitz.com/edit/angular-ivy-uop8dm?file=src/app/app.component.ts

angulartypescriptchart.jsng2-charts

Answer №1

Important: Here is my method for achieving this without utilizing ng2-charts,

To begin, I follow the instructions provided in the charts.js documentation to create the Chart:

 const myChart = new Chart(
        "canvas",
        {...
        }

Subsequently, I proceed to incorporate the gradient into the chart:

const context = myChart.ctx;
const height = myChart.height;
const gradient = context.createLinearGradient(0, 0, 0, height);
gradient.addColorStop(1, "rgba(128, 182, 244, 0.6)");
gradient.addColorStop(0, "rgba(255, 255, 255, 0.6)");
myChart.data.datasets[0].backgroundColor = gradient;

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