create () {
        this.el = document.createElement('div');
        this.el.className = this.CSS_PREFIX + 'modal ge_picker_modal';
        this.el.style.backgroundColor = this.bgColor;

        this.canvas = document.createElement('canvas');
        this.canvas.className = this.CSS_PREFIX + 'canvas ge_picker_canvas';
        this.canvas.style.backgroundColor = this.bgColor;

        this.el.appendChild(this.canvas);
        this.ctx = this.canvas.getContext('2d');

        let ratio = getDevicePixelRatio(this.ctx);
        this.canvas.width = this.width * ratio;
        this.canvas.height = this.height * ratio;
        this.ctx.scale(ratio, ratio);
    }
This initializes the renderer. It uses requestAnimationFrame() to
 smoothly render changes in the color picker as user interacts with it.