Angular image parent cover directive

mediasUtils.directive.js

angular.module('MediasUtils',[])
/**
 * @description An angular directive that resize media to cover his parent size.
 */
.directive('mediaCover',function (){

		var  linkFn
			,layoutFn
			;
		/**
		 * Angular link function
		 * @param scope
		 * @param elm
		 * @param attrs
		 * @return void
		 */
		linkFn = function (scope,elm,attrs){

			var  $elm;
			$elm = angular.element(elm);

			if ($elm[0].tagName == 'IMG'){
				$elm.on('load',function (){
					layoutFn(angular.element(this));
				})
			}else {
				layoutFn(elm);
			}

		};

		/**
		 * Layout and resize the elm based on his parent width and height.
		 * @param elm
		 * @return void
		 */
		layoutFn = function (elm){

			var  parentW = elm.parent()[0].offsetWidth
				,parentH = elm.parent()[0].offsetHeight
				,mediaW= elm[0].offsetWidth
				,mediaH = elm[0].offsetHeight
				,sw = (parentW/mediaW)
				,sh = (parentH/mediaH)
				,s = Math.max (sw,sh)
 				,offsetW = (parentW - (mediaW*s))/2
 				,offsetH = (parentH -(mediaH*s))/2
 				;

			elm.css({

				 marginLeft:offsetW+'px'
				,marginTop:offsetH+'px'
				,width:mediaW*s+'px'
 				,height:mediaH*s+'px'

			})
		};

		return {
			 restrict:'A'
			,link:linkFn
		}

	});