Angular controller is not defined

I want to create some event handler in my directive`s controller. Here is directive code:

module.exports = function() {
    return {
        restrict: 'EA',
        bindToController: true,
        scope: {
           myarticle: '=article'
        },
        controllerAs: 'ctrl',
        templateUrl: '../../views/draggableArticle.html',
        link: function(scope, element, attr) {
        },
        controller: function() {
            this.clicked = function() {
                alert('clicked');
            };
            this.dragstartHandler = function() {
                alert('draged');
           };
        }
    };
 };

And my view:

<div draggable="true" ondragstart="ctrl.dragstartHandler($event);" ng-click="ctrl.clicked()">
    <h2></h2>
    <p></p>
</div>

When I click on the block it works and alert "clicked", but when i drag a block it gives me an error

Uncaught ReferenceError: ctrl is not defined