// Copyright (C) 2024 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page qtabstractlistmoder-kotlin-example.html
    \title Exposing QtAbstractListModel to QML
    \brief Uses a \l QtAbstractListModel to share data between Android code and
    a QML view.
    \ingroup qtquickexamples

    \section1 Overview

    \image qtabstractlistmodel_portrait.png

    This example consists of two separate projects: A QML project and a Kotlin-based Android
    project which will host and display the QML content. It shows how to use \l QtAbstractListModel
    to share data from the Android side to the QML view which displays the data using a
    \l ListView.

    \section1 Running the example

    To run this example, you need Android Studio and a \l {Qt for Android} installation.

    The \l {Qt Gradle Plugin} will be used to build the QML project during the Android project
    build process. For this, the example has some plugin configuration in the app-level
    build.gradle file which may need to be modified if the plugin cannot, for example, find the Qt
    kit directory.

    \snippet android/models/qtabstractlistmodel_kotlin/app/build.gradle build.gradle QtBuild config

    For further configuration of the plugin, please refer to the
    \l [Qt Gradle Plugin]{Configure the plugin}{Qt Gradle Plugin documentation}.

    \section1 QML project

    The QML project is quite simple, it defines a data model as a property of the root object
    and some UI elements to display the data from that model.

    \snippet android/models/qtabstractlistmodel/Main.qml QML root item and dataModel definition

    To display the data from the model, a ListView is created. The \c model property is then set
    to the data model declared earlier.

    \snippet android/models/qtabstractlistmodel/Main.qml ListView definition

    In order to display the data model, the ListView needs a delegate which will be instantiated
    for each item in the data model. In this case, the delegate will be a \l Rectangle that holds
    two \l Text elements in a \l Column, displaying the data from each element in the data model.

    \snippet android/models/qtabstractlistmodel/Main.qml ListView delegate definition

    \section1 Kotlin project

    The Android side consists of a single \l {Android: Activity} {Activity} and the definition for the data model used
    earlier in the QML view.

    \section2 Data model

    The data model \c MyListModel is a child class of QtAbstractListModel, with
    \c ArrayList<String> as the internal storage system for data. In the initializer block of
    \c MyListModel, it generates some random data for the list.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel definition

    Each item in the model has a set of data elements associated with it, each with its own role.
    Custom implementations of QtAbstractItemModel must define a custom role for each data
    element. Each role has an associated \l {Kotlin: Int} {Int} value, which is used when
    retrieving the data, and a \l {Kotlin: String} {String} value, which specifies the name of the
    data element when used from QML.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel::roleNames

    While the \c Int values in the \c "roleNames()" method may be hard-coded, this example
    specifies a custom enum class \c DataRole within \c MyListModel, which is used when referring
    to these values. In this example, we define two roles: UUID and Row.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel::DataRole enum

    When it comes to returning data from the data model, the class must override the
    \c "QtAbstractListModel::data()" method. This method takes two parameters: \l QtModelIndex and
    \c Int, which refer to the index and role of the data element, respectively.

    In \c "MyDataModel::data()", the \c UUID role returns the data from the given index in the
    internal data, while the \c Row role returns the row of the requested element.

    \note This method, along with some others, is annotated with a
    \l {Kotlin: Synchronized} {@Synchronized} tag. This is due to calls to these methods
    originating from the Qt thread and accessing the underlying data possibly at the same time as
    requests from the Android thread via the \c "addRow()" and \c "removeRow()" methods.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel::data

    To allow outside actors to manipulate the QtAbstractItemModel, the example adds two additional
    methods to \c MyDataModel. To add data to the row, it has the \c "addRow()" method; to remove
    data, there is the \c "removeRow()" method. These are used from the main activity.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel::addRow

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MyListModel.kt MyListModel::removeRow

    \section2 Main activity

    The \c MainActivity class is a simple Kotlin-based Activity but also implements the
    interface \c QtQmlStatusChangeListener to listen to QML loading status events. It also
    stores the \c QtQuickViewContent object for the main view of the QML application and an instance
    of the data model detailed above.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MainActivity.kt MainActivity definition

    When creating the main Activity of the application, the example first creates a \l QtQuickView
    and places it into the view hierarchy.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MainActivity.kt Adding QtQuickView

    After adding the QtQuickView into the UI, the example finds the buttons that are used to
    manipulate the data model and sets some click listeners to call \c addRow() and \c removeRow()
    on the member data model.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MainActivity.kt Adding control buttons

    Once the UI setup and listeners are done, the QML component can be prepared and loaded. The
    example sets the \c MainActivity as a listener for the status change signal of the QML
    component and tells \c QtQuickView to load the QML component.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MainActivity.kt Loading the QML component

    Finally, once the QML component is successfully loaded, the example assigns the value of the
    MyDataModel instance into the \c dataModel property in the QML component.

    \snippet android/models/qtabstractlistmodel_kotlin/app/src/main/java/com/example/qtlm_in_kotlin_based_android_project/MainActivity.kt Linking the data model
 */
