ExpandableDataModelDecorator.hpp Example File

    /*
     * Copyright (c) 2013 BlackBerry Limited.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     * http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */

    #ifndef EXPANDABLEDATAMODELDECORATOR_HPP_
    #define EXPANDABLEDATAMODELDECORATOR_HPP_

    #include <bb/cascades/datamanager/DataModelDecorator>

    /**
     * This class creates an expandable header type of model. It allows the user to show collapsed
     * headers as an overview, and expand the headers items for more granular detail.
     */
    class ExpandableDataModelDecorator: public bb::cascades::datamanager::DataModelDecorator {
        Q_OBJECT

    public:
        ExpandableDataModelDecorator(QObject* parent = 0);
        virtual ~ExpandableDataModelDecorator();

        /*
         * Inject "expanded" data value to true or false depending
         * if the data index equals the expanded index.
         * Call the method data of the DataModel it wraps.
         *
         * @see DataModel
         */

        Q_INVOKABLE virtual QVariant data(const QVariantList &indexPath);

        /**
         * This method returns none zero children count only when the
         * selected index equals the expand index.
         * Call the method childCount of the DataModel it wraps.
         *
         * @see DataModel
         */
        virtual int childCount(const QVariantList& indexPath);

        /*
         * This method confirms child count only at time when selected
         * index equals that of the expand index.
         * Call the method hasChildren of the DataModel it wraps.
         *
         * @see DataModel
         */
        virtual bool hasChildren(const QVariantList& indexPath);

    public Q_SLOTS:

        // This method toggles expanding or collapsing of header items.
        // It sets the expanded index and emits itemsChanged signal once the
        // index has been set to expand or collapse.
        void expandHeader(const QVariantList& indexPath, bool expand);

    private:
        // Sets the index to collapse or expand.
        int m_expandedIndex;

        // This is a helper method to verify index path correctness, and whether the
        // index is expandable or not(already expanded).
        bool isExpandable(const QVariantList& indexPath) const;
    };
    #endif /* EXPANDABLEDATAMODELDECORATOR_HPP_ */