drawcanvas.js

class DrawCanvas {
    constructor(size){
        this.canvas = document.createElement('canvas');
        this.canvas.width = this.canvas.height = size;
        this.ctx = this.canvas.getContext('2d');
    }
    drawGradationShadow(colorRGB){
        let center = [this.canvas.width / 2, this.canvas.height / 2];
        let radius = Math.min(center[0], center[1]) * 0.9;
        let colorFill = 'rgba(' + colorRGB.join(',') + ', 0.0)';
        let colorShadow = 'rgba(' + colorRGB.join(',') + ', 1.0)';
        let gradient = this.ctx.createRadialGradient(
            center[0], center[1], radius,
            center[0], center[1], 0,
        );
        gradient.addColorStop(0, colorFill);
        gradient.addColorStop(1, colorShadow);
        this.ctx.fillStyle = gradient;
        this.ctx.fillRect(0, 0, this.canvas.width, this.canvas.height);
    }
    getElement(){
        return this.canvas;
    }
}