Trigger to click on an html element in angular.js

To achieve what you have to do, you can use angular events or you can share an object through isolate scope and add a function to it.

Examples:

1- With Angularjs Events: (PLUNKER)

HTML:

<div click-to-edit></div>
<button type="button" ng-click="item.toggle()">Toggle from Controller</button>

Controller:

app.controller('MainCtrl', function($scope) {
    $scope.toggle = function(){
        //Emit the event
        $scope.$broadcast('app.myEvent');
    };
});

Directive:

app.directive('clickToEdit', function() {
    return {
        restrict: 'A',
        template: `
            <div ng-show="editState">
                <div>
                    <input type="text"/>
                    <button type="button" ng-click="item.toggle()">Cancel</button>
                </div>
            </div>
        `,
        link: function (scope, element, attrs) {
            scope.editState = false;

            scope.toggle = function () {
                scope.editState = !scope.editState;
            }

            //Listen and handler the event
            scope.$on('app.myEvent', function(event){
                scope.toggle();
            });
        }
    }
});

2- Share object through isolate scope: (PLUNKER)

HTML:

<div click-to-edit item="item"></div>
<button type="button" ng-click="item.toggle()">Toggle from Controller</button>

Controller:

app.controller('MainCtrl', function($scope) {
    $scope.item = {};
});

Directive:

app.directive('clickToEdit', function() {
    return {
        restrict: 'A',
        scope: {
            item: '='
        }
        template: `
            <div ng-show="editState">
                <div>
                    <input type="text"/>
                    <button type="button" ng-click="item.toggle()">Cancel</button>
                </div>
            </div>
        `,
        link: function (scope, element, attrs) {
            scope.editState = false;

            //Here you add the function to the isolate scope 'item' variable
            scope.item.toggle = function () {
                scope.editState = !scope.editState;
            }
        }
    }
});