// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
/*!
    \page android-platform-notes.html
    \title Android Platform Notes
    \ingroup androidplatform
    \previouspage Supporting Google Emoji Font Policy
    \nextpage android_runtime_licensing_notes.html
    \brief Information particular to building and running Qt applications on Android.

    This page contains information particular to building and running Qt
    applications on Android. See \l{android_support}{Supported Android Versions}
    for what Android versions and API levels are supported.

    \section1 Android Development in Qt Creator

    The easiest way to develop with Qt for Android is to use
    \l{Qt Creator: Connecting Android Devices}{Qt Creator}. When you use an
    \b{Android Kit} with a Qt Creator project, it builds your code in addition
    to some Android specific files that are required for enabling Qt on Android
    and generating your application bundle. Qt Creator adds these files in a
    subdirectory of your project called \b android. For more information, see
    \l{Android Package Templates}.

    \section1 Application Package

    On Android, apps are distributed to devices as \b{APK} packages. For
    distributing apps in Google Play, a different format called \b{AAB} is used
    instead. For more information, see \l{Publishing to Google Play}.

    Use Qt Creator to build both \b{APK} and \b{AAB} package formats, or build
    them manually. For more information, see \l{Deploying an Application on Android}.

    \section1 Plugins and Imports Special Considerations

    If an application uses plugins that depend on other modules, these modules
    must be listed in the application's dependencies. For more information, see
    \l{Dependencies Detection}.

    \section1 Text Special Considerations

    Because of a bug in some OpenGL drivers, the mechanism used by Qt to cache
    text glyphs does not work as expected on all Android devices, causing text
    to appear scrambled. To remedy this, a workaround is in place, but it can
    increase memory consumption and can also affect text rendering performance.
    The workaround is now used by default on all devices.

    You can disable the workaround by setting the
    \c QT_ANDROID_DISABLE_GLYPH_CACHE_WORKAROUND environment variable to \e 1 or
    \e true. However, you should do so only after verifying that text appears
    correctly on all targeted devices.

    \section1 OpenGL Special Considerations

    Modern devices often support OpenGL ES 3.0 or 3.1 in addition to 2.0. To get
    a suitable OpenGL context, set the requested version via
    \l{QSurfaceFormat::setVersion()}.

    \note The header files, such as \e{gl31.h}, are only available in recent API
    levels, and therefore you need to target API level 21. Keep in mind also that
    using OpenGL ES 3.x features will result in the application breaking on older
    devices that only support 2.0.

    \section1 Assets File System

    Qt for Android provides a special, virtual file system which is based on
    the \l{Android: Accessing original files}{Android Assets mechanism}.
    Files that are put under the directory (\l{ANDROID_PACKAGE_SOURCE_DIR}/assets/)
    are packaged as part of your application package. These can be accessed in
    Qt by prefixing the paths with \c{assets:/}. For more information, see
    \l{Porting to Android}{Porting Qt applications to Android}.

    \section1 Android Supported Architectures

    Qt for Android currently has binaries for \e{armv7a}, \e{arm64-v8a}, \e{x86}
    and \e{x86-64}.

    If you want to support several different ABIs in your application in Google
    Play, the recommendation is to build an Application App Bundle (AAB)
    containing binaries for each of the ABIs. Based on your AAB, Google Play
    generates optimized Application Packages (APK) for each device requesting a
    download.

    For more information, see \l{Building the Android Application}.

    \section1 Known Issues

    Due to a bug on some devices, when you turn off predictive text with
    \c{ImhNoPredictiveText}, this property is ignored and predictive text is
    still enabled. To work around this, set the
    \c{QT_ANDROID_ENABLE_WORKAROUND_TO_DISABLE_PREDICTIVE_TEXT} environment
    variable to \c 1. However, one side effect is that this environment variable
    can cause a problem with other keyboards such as Gboard. If you use a
    language like Japanese, with Gboard, only a QWERTY keyboard is displayed.
    This environment variable is queried each time the keyboard is displayed,
    so it's possible to toggle the workaround on and off, as necessary.

    \section1 Limitations

    Some of the Qt modules might have features that are not supported on Android
    or have limitations. For more information, see \l{QTBUG-72086}.

    \section1 Frequently Asked Questions

    \list
        \li Should I use \c QtActivity or \l{Android: Activity}{Android Activity}
            to create a custom Activity?

        \c QtActivity extends \c Activity and implements the logic needed to load
        the Qt libraries or handle events and native calls between Android and Qt.
        In general, extending \c QtActivity is needed if you are using any native
        calls. Otherwise, extending \c Activity should work.

        \li Should I use \c QtService or \l{Android: Service}{Android Service}?

        The same reasoning as \c QtActivity applies here. Unless you are using
        features that require the Qt libraries to be loaded, like native calls.

        \li Can \l{Android: Fragments}{Android Fragments} be used with Qt? What is
            the equivalent for Fragment in Qt?

        Android Fragments cannot be used with Qt. However, Qt offers it's own modular
        components and views with QML. You can combine multiple components in one
        QML view. For more information, see \l{Qt QML}.
    \endlist
*/
