jsbeans

/*!
 * Copyright (c) 2009 Francesco Mele jsbeans@francescomele.com
 *
 * This Software is licenced under the LGPL Licence (GNU Lesser General 
 * Public License).
 * In addition to the LGPL Licence the Software is subject to the 
 * following conditions:
 * 
 * 	i	every modification must be public and comunicated to the Author
 * 	ii	every "jsbean" added to this library must be self consistent 
 * 		except for the dependence from jsbeans-x.x.x.js
 * 	iii	copyright notice and this permission notice shall be included 
 * 		in all copies or substantial portions of the Software
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * Pure javascript implementation of <a href="http://en.wikipedia.org/wiki/Tag_cloud">Tag cloud</a>
 * @namespace jsbeans
 * @class TagCloud
 * @static
 * */
jsbeans.TagCloud = {
	/**
	 * Renders TagCloud
	 * @method render
	 * @param id {String} the id of the DOM container
	 * @param items {Array} an Array in the form "WORD:WEIGHT" (sample: <code>["Internet:11", "Facebook:42", "Twitter:2", "Google:40"]</code>)
	 * @param [func] {Function} an optional callback fired on the "onclick" event on each tag. As each tag is placed in an anchor, the anchor itself will be passed on the callback.
	 * @static
	 * */
	render: function(id, items) {
		var target = document.getElementById(id);
		if (typeof target == "undefined" || typeof target.innerHTML == "undefined") {
			return;
		}
		target.innerHTML = "";
		// items are in the form ["<word_1>:<weight_1>", "<word_2>:<weight_2>"]
		// e.g. ["Internet:11", "Facebook:42", "Twitter:2", "Google:40"]
		if (!items.length) {
			return;
		}
		var _items = new Array();
		var max = 0;
		var min = 0;
		for (var i = 0, item; item = items[i]; i++) {
			var sp = item.split(":");
			_items[sp[0]] = sp[1];
			var candidate = parseInt(sp[1]);
			if (candidate > max) {
				max = candidate;
			}
			if (candidate < min) {
				min = candidate;
			}
		}
		var fn = arguments[2];
		var hasCallback = !!fn && typeof fn != "string" && !fn.nodeName && fn.constructor != Array && /function/i.test( fn + "" );
		for (var word in _items) {
			var weight = Math.floor((((_items[word]-min)*100/(max-min)) + 50));
			var el = document.createElement("a");
			el.setAttribute("weight", weight);
			el.setAttribute("title", weight);
			el.setAttribute("href", "javascript:void(0)");
			el.setAttribute("id", "jsbeans_tagcloud_" + target.id + "_" + word.replace(" ", "_"));
			el.styleClass = "tagcloud";
			el.style.fontSize = weight + "%";
			el.style.padding = "4px";
			el.innerHTML = word;

			if (hasCallback) {
				el.onclick = function() {
					fn(this);
				};
			}
			
			target.appendChild(el);
			el = null;
			
			var blank = document.createTextNode(" ");
			target.appendChild(blank);
			blank = null;
		}
	}
};