AngularJs service for caching images

img.directive.js

(function(){

angular
	.module('app')
	.directive('img', img);

img.$inject = [];
function img() {
	return ({
		restrict: 	'E',
		controller: imgController,
		link: 		imgLink
	});
}

function imgLink(scope, element, attrs) {
	var img 	= element[0];
	var load 	= scope.load(attrs['src'], 'blob', 100);

	load.then(function(src) {
		img['src'] = src;
	});
}

imgController.$inject = ['$scope', 'my_img'];
function imgController($scope, my_img) {
	var self 	= $scope;
	self.load 	= my_img.load;
}

})();

img.service.js

(function(){

angular
	.module('app')
	.factory('my_img', my_img);

my_img.$inject = ['$q', '$http'];
function my_img($q, $http) {
	var self 	= this;
	var _imgs 	= {};

	var _getDataType = function(src) {
		var ext 	= src.replace(/^[a-z\/\\]*\./i, '');
		var hash 	= {'jpg': 'image/jpeg', 'png': 'image/png', 'jpeg': 'image/jpeg'};

		return (hash[ext]);
	};

	var _getBase64Url = function(src, quality) {
		var deferred 	= $q.defer();
		var img 		= new Image();
		img['src'] 		= src;

		img.onload = function() {
	        var canvas 		= document.createElement('CANVAS');
	        canvas.height 	= this.height;
	        canvas.width 	= this.width;

	        canvas.getContext('2d').drawImage(this, 0, 0);
			deferred.resolve(canvas.toDataURL(_getDataType(src), quality));
    	};

    	return (deferred.promise);
	};

	var _getBlobUrl = function(src, quality) {
		var deferred 	= $q.defer();

    	$http.get(src, { 'responseType': 'arraybuffer' }).then(function(result) {
    		var blob 		= new Blob([ result['data'] ], { 'type': _getDataType(src) });
    		blob 			= blob.slice(0, blob.size * quality, _getDataType(src));
			var urlCreator 	= window.URL || window.webkitURL;
    		var imageUrl 	= urlCreator.createObjectURL( blob );

  	        deferred.resolve(imageUrl);
    	});

    	return (deferred.promise);
	};

	/*
	** src : 		source image
	** [encoding] : 	encoding type, b64 (base64) or blob -- Default blob
	** [quality] : 	quality from 0 to 100 -- Default 100
	*/
	self.load = function(src, encoding, quality) {
		if (!_getDataType(src)) {
			return ($q.resolve(src));
		}
		var hash 		= {'b64': _getBase64Url, 'blob': _getBlobUrl};
		var encodingFn 	= encoding && hash[encoding] || hash['blob'];
		quality 		= quality && (quality / 100) || 1;

		_imgs[src] = (!_imgs[src]) ? encodingFn.apply(null, [src, quality]) : _imgs[src];

		return (_imgs[src]);
	};

	return (self);
}

})();