Angularjs 如何将指令转换为组件1.5？

这是我的指令如何转换成组件？我正在将我的应用程序转换为angular 1.5。 如何将此指令转换为组件？这是我想转换成组件的文件上传指令

app.directive('ngThumb', ['$window', function($window) {
        var helper = {
            support: !!($window.FileReader && $window.CanvasRenderingContext2D),
            isFile: function(item) {
                return angular.isObject(item) && item instanceof $window.File;
            },
            isImage: function(file) {
                var type =  '|' + file.type.slice(file.type.lastIndexOf('/') + 1) + '|';
                return '|jpg|png|jpeg|bmp|gif|'.indexOf(type) !== -1;
            }
        };

        return {
            restrict: 'A',
            template: '<canvas/>',
            link: function(scope, element, attributes) {
                if (!helper.support) return;

                var params = scope.$eval(attributes.ngThumb);

                if (!helper.isFile(params.file)) return;
                if (!helper.isImage(params.file)) return;

                var canvas = element.find('canvas');
                var reader = new FileReader();

                reader.onload = onLoadFile;
                reader.readAsDataURL(params.file);

                function onLoadFile(event) {
                    var img = new Image();
                    img.onload = onLoadImage;
                    img.src = event.target.result;
                }

                function onLoadImage() {
                    var width = params.width || this.width / this.height * params.height;
                    var height = params.height || this.height / this.width * params.width;
                    canvas.attr({ width: width, height: height });
                    canvas[0].getContext('2d').drawImage(this, 0, 0, width, height);
                }
            }
        };
    }]);

---

需要使用controller而不是link函数，并向controller注入$element

.component("ngThumb", ['$window', function($window) {
    var helper = {
        support: !!($window.FileReader && $window.CanvasRenderingContext2D),
        isFile: function(item) {
            return angular.isObject(item) && item instanceof $window.File;
        },
        isImage: function(file) {
            var type = '|' + file.type.slice(file.type.lastIndexOf('/') + 1) + '|';
            return '|jpg|png|jpeg|bmp|gif|'.indexOf(type) !== -1;
        }
    };
    return {
        //link fn is deprecated now
        controller: function($scope, $element) {
            if (!helper.support) return;
            var params = $scope.$eval($element[0].ngThumb);
            if (!helper.isFile(params.file)) return;
            if (!helper.isImage(params.file)) return;
            var canvas = $element.find('canvas');
            var reader = new FileReader();
            reader.onload = onLoadFile;
            reader.readAsDataURL(params.file);

            function onLoadFile(event) {
                var img = new Image();
                img.onload = onLoadImage;
                img.src = event.target.result;
            }

            function onLoadImage() {
                var width = params.width || this.width / this.height * params.height;
                var height = params.height || this.height / this.width * params.width;
                canvas.attr({
                    width: width,
                    height: height
                });
                canvas[0].getContext('2d').drawImage(this, 0, 0, width, height);
            }
        },
        template: '<canvas/>'
    }
}])

---

需要使用controller而不是link函数，并向controller注入$element

.component("ngThumb", ['$window', function($window) {
    var helper = {
        support: !!($window.FileReader && $window.CanvasRenderingContext2D),
        isFile: function(item) {
            return angular.isObject(item) && item instanceof $window.File;
        },
        isImage: function(file) {
            var type = '|' + file.type.slice(file.type.lastIndexOf('/') + 1) + '|';
            return '|jpg|png|jpeg|bmp|gif|'.indexOf(type) !== -1;
        }
    };
    return {
        //link fn is deprecated now
        controller: function($scope, $element) {
            if (!helper.support) return;
            var params = $scope.$eval($element[0].ngThumb);
            if (!helper.isFile(params.file)) return;
            if (!helper.isImage(params.file)) return;
            var canvas = $element.find('canvas');
            var reader = new FileReader();
            reader.onload = onLoadFile;
            reader.readAsDataURL(params.file);

            function onLoadFile(event) {
                var img = new Image();
                img.onload = onLoadImage;
                img.src = event.target.result;
            }

            function onLoadImage() {
                var width = params.width || this.width / this.height * params.height;
                var height = params.height || this.height / this.width * params.width;
                canvas.attr({
                    width: width,
                    height: height
                });
                canvas[0].getContext('2d').drawImage(this, 0, 0, width, height);
            }
        },
        template: '<canvas/>'
    }
}])