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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              .view
	width: 100vw
	height: 100vh
	background: #1E2D2F
	display: flex
	justify-content: center
	align-items: center

canvas
	position: absolute
	box-sizing: border-box
	&:first-child
		background-color: rgba(#1E2D2F, 1)
		padding: 10px
            
          
!
            
              // citation
// -----------------------
// https://forum.processing.org/two/discussion/10104/drawing-x-number-of-lines-from-the-centre-of-a-circle-out-to-the-circumference
// http://stackoverflow.com/questions/9705123/how-can-i-get-sin-cos-and-tan-to-use-degrees-instead-of-radians
// http://stackoverflow.com/questions/2353211/hsl-to-rgb-color-conversion
// http://stackoverflow.com/questions/21771939/html5-canvas-overlay-transparent-gradients
// https://gist.github.com/conorbuck/2606166
// http://stackoverflow.com/questions/2049582/how-to-determine-if-a-point-is-in-a-2d-triangle

rgbToHsl = (r, g, b) => {
    r /= 255, g /= 255, b /= 255;
    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if(max == min){
        h = s = 0; // achromatic
    } else {
        var d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        switch(max){
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2; break;
            case b: h = (r - g) / d + 4; break;
        }
        h /= 6;
    }
    return [h, s, l];
}

class ColorWheel {
	constructor(size, parent) {
		// canvas setup
		this.width = size;
		this.height = size;
		this.radLarge = (size / 2) - 5;
		this.radSmall = this.radLarge - 40;
		this.parent = document.querySelector(parent);
		this.cx = this.width / 2;
		this.cy = this.height / 2;
		// event variables
		this.active = false;
		this.color = null;
		this.pos = null;
		// segment construction
		this.points = 40;
		this.angle = 360 / this.points;
		this.arc = Math.PI * 2 / this.points;
		// create
		this.init();
	}
	init() {
		// outer canvas
		this.outer = document.createElement('canvas');
		this.outer.width = this.width;
		this.outer.height = this.height;
		this.ctxA = this.outer.getContext('2d');
		// inner canvas
		this.inner = document.createElement('canvas');
		this.inner.width = this.width;
		this.inner.height = this.height;
		this.ctxB = this.inner.getContext('2d');
		this.ctxB.globalCompositeOperation = 'hard-light';
		// dot canvas
		this.dot = document.createElement('canvas');
		this.dot.width = this.width;
		this.dot.height = this.height;
		this.ctxC = this.dot.getContext('2d');
		// build
		this.parent.appendChild(this.outer);
		this.parent.appendChild(this.inner);
		this.parent.appendChild(this.dot);
		// add spectrum
		this.spectrum();
		// add events
		this.setEvents();
	}
	circle(ctx, x, y, r, style, start, end) {
		ctx.beginPath();
		ctx.arc(x, y, r, start || 0, end || Math.PI * 2);
		if (style.fill) {
			ctx.fillStyle = style.fill;
			ctx.fill();
		}
		if (style.stroke) {
			ctx.strokeStyle = style.stroke;
			ctx.stroke();
		}
		if (style.lineWidth) {
			ctx.lineWidth = style.lineWidth;
		}
	}
	triangle(ctx, points, fill) {
		ctx.beginPath();
		ctx.moveTo(points[0].x, points[0].y);
		for (let i = points.length - 2; i >= 0; i--) {
			ctx.lineTo(points[i].x, points[i].y);
		}
		ctx.fillStyle = fill;
		ctx.fill();
	}
	spectrum() {
		for (let i = 1; i <= this.points; i++) {
			// arc points
			let a = i * this.angle;
			let b = (i - 1) * this.angle;
			// gradient vector
			let radius = this.radSmall + (this.radLarge - this.radSmall) / 2;
			let x1 = Math.cos(this.toRadians(a)) * radius + this.cx;
			let y1 = Math.sin(this.toRadians(a)) * radius + this.cy;
			let x2 = Math.cos(this.toRadians(b)) * radius + this.cx;
			let y2 = Math.sin(this.toRadians(b)) * radius + this.cy;
			// gradient
			let g = this.ctxA.createLinearGradient(x1, y1, x2, y2);
			g.addColorStop(0, 'hsl( ' + a + ', 100%, 50%)');
			g.addColorStop(1, 'hsl( ' + b + ', 100%, 50%)');
			// draw arc
			let o = 0.001;
			this.ctxA.beginPath();
			this.ctxA.arc(this.cx, this.cy, this.radLarge, this.toRadians(b) - o, this.toRadians(a) + o, false);
			this.ctxA.arc(this.cx, this.cy, this.radSmall, this.toRadians(a) + o, this.toRadians(b) - o, true);
			this.ctxA.fillStyle = g;
			this.ctxA.fill();
		}
	}
	toRadians(angle) {
		// convert angle to radians
		return angle * (Math.PI / 180);
	}
	inCircle(x0, y0, x1, y1, r) {
		// center of circle (x0,y0), mouse coordinates (x1,y1), radius (r)
		return Math.sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0)) < r;
	}
	inTriangle(p, p0, p1, p2) {
		// point in circle (p), triangle points (p0, p1, p2)
		var A = 1/2 * (-p1.y * p2.x + p0.y * (-p1.x + p2.x) + p0.x * (p1.y - p2.y) + p1.x * p2.y);
		var sign = A < 0 ? -1 : 1;
		var s = (p0.y * p2.x - p0.x * p2.y + (p2.y - p0.y) * p.x + (p0.x - p2.x) * p.y) * sign;
		var t = (p0.x * p1.y - p0.y * p1.x + (p0.y - p1.y) * p.x + (p1.x - p0.x) * p.y) * sign;
		return s > 0 && t > 0 && (s + t) < 2 * A * sign;
	}
	update (e, cw) {
		// get mouse pos
		let x = e.clientX - cw.inner.offsetLeft;
		let y = e.clientY - cw.inner.offsetTop;
		this.pos = {x: x, y: y};
		// check mouse is within bounds
		let outer = cw.inCircle(cw.cx, cw.cy, x, y, cw.radLarge),
			 inner = cw.inCircle(cw.cx, cw.cy, x, y, cw.radSmall),
			 tri;
		// check mouse in triangle
		if (this.tri) {
			tri = this.inTriangle( this.pos, this.tri[0], this.tri[1], this.tri[2] );
		}
		// draw
		if (outer && !inner) {
			cw.draw(x, y, false);
		} else if (tri) {
			cw.draw(x, y, true)
		}
	}
	draw(x, y, tri) {
		console.log(x,y,tri)
		// get pixel data
		let da = this.ctxA.getImageData(x, y, 1, 1).data;
		let db = this.ctxB.getImageData(x, y, 1, 1).data;
		// draw equilateral triangle
		if (!tri) {
			// clear triangle canvas
			this.ctxB.clearRect(0, 0, this.inner.width, this.inner.height);
			this.ang = Math.atan2(y - this.cy, x - this.cx) * (180 / Math.PI);
			this.color = 'rgb(' + da[0] + ',' + da[1] + ',' + da[2] + ')';
			let angs = [0, 120, 240, 180];
			let pts = this.tri = [];
			for (let i = 0; i < angs.length; i++) {
				pts.push({
					x: Math.cos( this.toRadians( this.ang + angs[i] )) * this.radSmall + this.cx,
					y: Math.sin( this.toRadians( this.ang + angs[i] )) * this.radSmall + this.cy
				})
			}
			// gradient 1 = black => white
			let g1 = this.ctxB.createLinearGradient(pts[1].x, pts[1].y, pts[2].x, pts[2].y);
			let hsl = rgbToHsl(da[0], da[1], da[2]);			
			g1.addColorStop(0, 'hsl(' + hsl[0] * 360 + ',0%,100%)');
			g1.addColorStop(1, 'hsl(' + hsl[0] * 360 + ',0%,0%)');
			// gradient 2 = hue => transparent
			let g2 = this.ctxB.createLinearGradient(pts[0].x, pts[0].y, pts[3].x, pts[3].y);
			g2.addColorStop(0, this.color);
			g2.addColorStop(1, 'rgba(' + da[0] + ',' + da[1] + ',' + da[2] + ', 0)');
			// draw
			this.triangle(this.ctxB, pts, g2);
			this.triangle(this.ctxB, pts, g1);
		}
		// clear dot canvas
		this.ctxC.clearRect(0, 0, this.dot.width, this.dot.height);
		let choice = tri ? db : da;
		this.dotCol = 'rgba(' + choice[0] + ',' + choice[1] + ',' + choice[2] + ',' + choice[3] + ')';
		let s = {stroke: '#fff', lineWidth: 2, fill: this.dotCol};
		this.circle(this.ctxC, x, y, 10, s);
		
		// TESTING - update view background
		this.parent.style.background = this.dotCol;
	}
	setEvents() {
		let self = this;
		this.dot.addEventListener('mousedown', e => {
			self.active = true;
			if (self.active) self.update(e, self);
		}, false);
		this.dot.addEventListener('mouseup', e => {
			self.active = false;
		}, false);
		this.dot.addEventListener('mousemove', e => {
			if (self.active) self.update(e, self);
		}, false);
		this.draw( 230, 30, false );
	}
}

let colorWheel = new ColorWheel(350, '.view');
            
          
!
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