Animated Skills Diagram with Raphaël

In this tutorial we will show you how to create a diagram using Raphaël – a small JavaScript library that is great for working with vector graphics. The idea is very simple: we will draw some arcs using mathematical functions and we’ll be displaying a skill percentage in a main circle when we hover over those arcs.
Let’s start with the markup.

The Markup

The HTML structure is going to consist of a main container with the class ‘get’. This container stores all data that we need to draw the arcs. Then we create a new div element with the id ‘diagram’ which will be the container for the arcs:

<div id="diagram"></div>
<div class="get">
	<div class="arc">
		<span class="text">jQuery</span>
		<input type="hidden" class="percent" value="95" />
		<input type="hidden" class="color" value="#97BE0D" />
	</div>
	<div class="arc">

		<span class="text">CSS3</span>
		<input type="hidden" class="percent" value="90" />
		<input type="hidden" class="color" value="#D84F5F" />
	</div>
	<div class="arc">
		<span class="text">HTML5</span>
		<input type="hidden" class="percent" value="80" />
		<input type="hidden" class="color" value="#88B8E6" />

	</div>
	<div class="arc">
		<span class="text">PHP</span>
		<input type="hidden" class="percent" value="53" />
		<input type="hidden" class="color" value="#BEDBE9" />
	</div>
	<div class="arc">
		<span class="text">MySQL</span>
		<input type="hidden" class="percent" value="45" />
		<input type="hidden" class="color" value="#EDEBEE" />
	</div>
</div>

The CSS

In the CSS we will only do two things: hide the elements with the class ‘get’ and set the width and height of the div with the id ‘diagram’:

.get {
	display:none;
}

#diagram {
	float:left;
	width:600px;
	height:600px;
}

The JavaScript

The main idea is to first create a new Raphael object (variable ‘r’) and draw our first circle with a radius that we specify in ‘rad’.
Then we create a new circle in the Raphael object. We center the circle (x: 300px and y: 300px) and we add some text to it.

var o = {
	init: function(){
		this.diagram();	
	},
	random: function(l, u){
		return Math.floor((Math.random()*(u-l+1))+l);
	},
	diagram: function(){
		var r = Raphael('diagram', 600, 600),
			rad = 73;

		r.circle(300, 300, 85).attr({ stroke: 'none', fill: '#193340' });

		var title = r.text(300, 300, 'Skills').attr({
			font: '20px Arial',
			fill: '#fff'
		}).toFront();

	}
}

Now, let’s go one step further.
We’ll extend the Raphael object with some custom attributes:

• alpha – angle of the arc
• random – random number from the specified range
• sx, sy – start drawing from this point
• x, y – end drawing at this point
• path
  • M – move to the starting point. No line is drawn. All path data must begin with a ‘moveto’ command.
  • A – radius-x, radius-y x-axis-rotation, large-arc-flag, sweep-flag, x, y (read more: https://developer.mozilla.org/en/SVG/Tutorial/Paths)

var o = {
	init: function(){
		this.diagram();	
	},
	random: function(l, u){
		return Math.floor((Math.random()*(u-l+1))+l);
	},
	diagram: function(){
		var r = Raphael('diagram', 600, 600),
			rad = 73;

		r.circle(300, 300, 85).attr({ stroke: 'none', fill: '#193340' });

		var title = r.text(300, 300, 'Skills').attr({
			font: '20px Arial',
			fill: '#fff'
		}).toFront();

		r.customAttributes.arc = function(value, color, rad){
			var v = 3.6*value,
				alpha = v == 360 ? 359.99 : v,
				random = o.random(91, 240),
				a = (random-alpha) * Math.PI/180,
				b = random * Math.PI/180,
				sx = 300 + rad * Math.cos(b),
				sy = 300 - rad * Math.sin(b),
				x = 300 + rad * Math.cos(a),
				y = 300 - rad * Math.sin(a),
				path = [['M', sx, sy], ['A', rad, rad, 0, +(alpha > 180), 1, x, y]];
			return { path: path, stroke: color }
		}

		$('.get').find('.arc').each(function(i){
			var t = $(this), 
				color = t.find('.color').val(),
				value = t.find('.percent').val(),
				text = t.find('.text').text();

			rad += 30;	
			var z = r.path().attr({ arc: [value, color, rad], 'stroke-width': 26 });

			z.mouseover(function(){
                this.animate({ 'stroke-width': 50, opacity: .75 }, 1000, 'elastic');
                if(Raphael.type != 'VML') //solves IE problem
					this.toFront();
				title.animate({ opacity: 0 }, 500, '>', function(){
					this.attr({ text: text + 'n' + value + '%' }).animate({ opacity: 1 }, 500, '<');
				});
            }).mouseout(function(){
				this.animate({ 'stroke-width': 26, opacity: 1 }, 1000, 'elastic');
            });
		});
	}
}

Then we’ll retrieve all the data needed, such as the percentage value, the color of the arc and the text. We increase the radius value for each arc and finally create a new arc path.
In the last step we are adding some animations on hover. When the mouse will be over the arc the title (which is placed in the main circle) is changing. Also, we’ll make the arc a little bit bigger.

Conclusion

In today’s tutorial you’ve learned some first steps on how to use Raphaël. It is a powerful library and you can do a lot of great stuff with it. Visit the Raphaël website for more examples.