I am currently working on a project where I am drawing a sin wave on a canvas and adding movement to it.
export class CanvasComponent implements OnInit {
@ViewChild('canvas', { static: true })
canvas: ElementRef<HTMLCanvasElement>;
ctx: CanvasRenderingContext2D;
winddrawvalue = 0;
windvalue = 0;
constructor() { }
@Input() set speeddata(speed: number){
this.windvalue = speed;
this.drawWind();
}
ngOnInit(): void {
this.ctx = this.canvas.nativeElement.getContext('2d');
}
drawWind() {
requestAnimationFrame(this.drawWind.bind(this));
const canvas = this.canvas.nativeElement;
this.ctx.lineWidth = 2;
this.ctx.clearRect(0, 0, canvas.width, canvas.height);
this.ctx.beginPath();
this.ctx.moveTo(-10, canvas.height / 2 - 12);
for (let i = 0; i < canvas.width; i++) {
this.ctx.lineTo(i, canvas.height / 2 - 12 + Math.sin(i * 0.04 + this.winddrawvalue) * 15);
}
this.ctx.moveTo(-10, canvas.height / 2);
for (let i = 0; i < canvas.width; i++) {
this.ctx.lineTo(i, canvas.height / 2 + Math.sin(i * 0.04 + this.winddrawvalue) * 15);
}
this.ctx.moveTo(-10, canvas.height / 2 + 12);
for (let i = 0; i < canvas.width; i++) {
this.ctx.lineTo(i, canvas.height / 2 + 12 + Math.sin(i * 0.04 + this.winddrawvalue) * 15);
}
this.ctx.stroke();
this.winddrawvalue += this.windvalue;
}
}
Every time I press the button to redraw the canvas, it moves at double the speed of before. In an attempt to fix this issue, I tried:
request = requestAnimationFrame(this.drawWind.bind(this));
@Input() set speeddata(speed: number){
this.windvalue = speed;
this.stopAnimation(this.request);
this.drawWind();
}
stopAnimation(req) {
cancelAnimationFrame(req);
}
I used cancelAnimationFrame() with hopes that it would retrieve the requestID to stop the ongoing animation, but unfortunately, it did not work as expected.