/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \page android-building.html
    \title Qt for Android - Building from Source
    \brief How to configure and build Qt for Android directly from source.
    \previouspage android-getting-started.html
    \nextpage porting-to-android.html

    Qt for Android has some requirements that you are recommended to know before
    going through this guide. Accomplish the tasks in
    \l{Getting Started with Qt for Android} first.

    You can download the Qt sources from the \l {Qt Downloads} page, or follow
    the wiki guide for \l {Getting the source code}.

    \section1 Building on Linux

    \section2 Prepare the Build Environment

    First, install the Android SDK in one of two ways:

    \list
        \li \l{Using Manual Installation}
        \li \l{Using Qt Creator}
        \li \l{Using Android Studio}
    \endlist

    Then, you need the following tools:

    \list
        \li A JDK package such as \l{AdoptOpenJDK}, \l{Java SE Development Kit}{JDK},
            or \l{OpenJDK}.
        \li \c CMake
        \li \c Ninja
    \endlist

    \section3 Using Manual Installation

    For more information, see \l{Getting Started with Qt for Android}.

    \section3 Using Qt Creator

    For more information, see \l{Qt Creator: Connecting Android Devices}{Connecting Android Devices}.

    \section3 Using Android Studio

    You can use \l {Android: Android Studio}{Android Studio} to download and installl
    the Android SDK packages required for developing applications for Android. For
    more information, see \l{Android: Update your tools with the SDK Manager}
    {Android Studio documentation}.


    \section1 Building Qt for Android

    Qt 6 allows building Qt for Android from source code using \c CMake. Qt 6 keeps
    the same configure script from Qt 5. The main difference is that Qt for Android
    is dependent on a host Qt build, which means to build Qt for Android, you
    need to build Qt for the desktop platform used as a host (for example Linux,
    macOS, or Windows).

    With the configure script, the same arguments can be used as before. For more
    information, see \l {Building Qt Sources}.

    Qt for Android supports the following ABIs \e{armeabi-v7a}, \e{arm64-v8a},
    \e{x86}, and \e{x86_64}.

    \note Qt 6.0 does not support multi-abi feature, for that reason setting the
    \e {-android-abis} is mandatory.

    \section1 Building on Linux

    To build Qt for Android under a Linux environment, follow the steps below:

    \section2 Unpacking the Archive

    If you have downloaded the source code archive from \l {Qt Downloads}, then
    unpack the archive if you have not done so already. For example, if you have
    the \c{qt-everywhere-src-%VERSION%.tar.xz} package, type the following commands
    at a command line prompt:

    \snippet snippets/code/doc_src_installation.qdoc 0

    This creates the directory \c{/tmp/qt-everywhere-src-%VERSION%}
    containing the files from the archive. We only support the GNU version of
    the tar archiving utility. Note that on some systems it is called gtar.

    Otherwise if you cloned the source code from Git, the source will be under
    \e qt5 folder.

    \section2 Configuring and Building on Linux

    Set the following environment variables, and add them to your \c{PATH};
    preferably at the end of \c{~/.profile}:

    \badcode
    export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
    export CMAKE_ROOT=~/Qt/Tools/CMake/bin
    export NINJA_ROOT=~/Qt/Tools/Ninja
    export PATH=$JAVA_HOME/bin:$CMAKE_ROOT:$NINJA_ROOT:$PATH
    \endcode

    \note JDK 11 or earlier must be used to properly build Qt for Android.

    \note We use \l{OpenJDK} here, but you can also use other JDK alternatives
    such as \l{AdoptOpenJDK}.

    To configure Qt for Android, create a shadow build directory to keep the source
    directory clean:

    \badcode
    mkdir <path_to_build_dir>/build-qt
    cd <path_to_build_dir>/build-qt

    <path_to_qt_source>/configure -platform android-clang -prefix </path/to/install> -android-ndk <path/to/sdk>/ndk/<ndk_version> -android-sdk <path/to/sdk> -qt-host-path <path_to_host_qt_installation> -android-abis arm64-v8a
    \endcode

    \l{Qt Configure Options} contains more information about the configure options.

    You can customize your build configuration in a more advanced manner. For
    more information, see \l {Advanced Build Arguments}.

    \note For more information about building Qt 6 with CMake, see \l {Building with CMake}.

    To build the configured Qt code, run the following command:

    \badcode
    cmake --build . --parallel
    \endcode

    Also, the following is possible instead:

    \badcode
    ninja -j$(nproc)
    \endcode

    \note \e{nproc} is optional. It represents the number of parallel jobs your
    system can do.

    Now, to install Qt, run the following command:

    \badcode
    cmake --install .
    \endcode

    If you haven't provided the \c{--prefix <install-dir>} configure option, the
    installation is placed under \c{/usr/local/Qt-<version>}. In Debian/Ubuntu,
    you should prefix the \c make command with the \c sudo command.

    \section1 Building on Windows

    To build Qt for Android under a Windows environment, follow the steps below:

    \section2 Preparing the Build Environment

    In addition to the requirements from \c {Prepare the Build Environment}, you
    need the following on Windows:

    \list
        \li \b {MinGW 7.3} toolchain
        \li \l{Perl}
    \endlist

    Then set the respective environment variables from the \uicontrol{Environment Variables}
    system UI, or from the build command line prompt. For the default \c {Command prompt}:

    \badcode
    set JDK_ROOT=<JDK_ROOT_PATH>\bin
    set MINGW_ROOT=<MINGW_ROOT_PATH>\bin
    set PERL_ROOT=<PERL_ROOT_PATH>\bin
    set CMAKE_ROOT=C:\Qt\Tools\CMake\bin
    set NINJA_ROOT=C:\Qt\Tools\Ninja\
    set PATH=%MINGW_ROOT%;%CMAKE_ROOT%;%NINJA_ROOT%;%PERL_ROOT%;%JDK_ROOT%;%PATH%
    \endcode

    Then, in the command line prompt, verify that:

    \badcode
    where mingw32-make.exe
    \endcode

    The command should list mingw32-make.exe under the path \e {<MINGW_ROOT>} first.

    \badcode
    where javac.exe
    \endcode

    The command should list javac.exe under the path \e {<JDK_ROOT>} first.

    \note JDK 11 or earlier must be used to properly build Qt for Android.

    \note Qt for Android does not support building with Microsoft Visual C++ (MSVC),
    we only support building with MinGW.

    \section2 Configuring and Building on Windows

    If you have downloaded the source code archive from \l {Qt Downloads}, unpack
    the archive. Uncompress the files into a temporary folder, for example,
    \c {C:\Qt\Build\Src_%VERSION%}. This path must not contain any spaces or
    Windows-specific file system characters.

    Run the following command to configure Qt:

    \badcode
    mkdir C:\Qt\Build\build-qt
    cd C:\Qt\Build\build-qt

    ..\Src_%VERSION%\configure.bat -platform android-clang -prefix <\path\to\install> -android-sdk <ANDROID_SDK_PATH> -android-ndk <ANDROID_SDK_PATH>\ndk\<ndk_version> -qt-host-path <path_to_host_qt_installation> -android-abis arm64-v8a
    \endcode

    \l{Qt Configure Options} contains more information about the configure options.

    You can customize your build configuration in a more advanced manner. For
    more information, see \l {Advanced Build Arguments}.

    \note For more information about building Qt 6 with CMake, see \l {Building with CMake}.

    To build the configured Qt for Android code, run the following:

    \badcode
    cmake --build . --parallel
    \endcode

    Also, the following is possible instead:

    \badcode
    ninja -j<N>
    \endcode

    \note \e{<N>} is optional. It represents the number of parallel jobs your
    system can do.

    Now, to install Qt, run the following command:

    \badcode
    cmake --install .
    \endcode

    \section1 Advanced Build Arguments

    Qt for Android contains Java code which is compiled into *.jar files with
    \e javac. To set the \e javac version for source and target, use \e -android-javac-source
    and \e -android-javac-target respectively:

    \badcode
    -android-javac-source 8 -android-javac-target 8
    \endcode

    To debug Qt with a developer build instead of a prefix build, use the following
    instead of \c -prefix argument:

    \badcode
    -developer-build
    \endcode

    A developer build is meant to be used directly from the build directory.

    \note A developer build takes more storage than a prefix build.

    \section2 Building Separate Modules

    It is possible to build specific Qt modules only. There are two options:

    \list
        \li Use the configured \e qt5 build with the following command:
            \code
            ninja -j$(nproc) module-qtbase
            \endcode

            The to install those modules, use:

            \code
            ninja -j$(nproc) module-qtbase-install_subtargets
            \endcode

        \li Configure and build \e qtbase only, then use the resulting
            \e qt-configure-module to configure any other module. The only
            difference is that the configure script in \e qtbase directory has to be used:

            \badcode
            mkdir <path_to_build_dir>/build-qt/qtbase
            cd <path_to_build_dir>/build-qt/qtbase
            <path_to_qt_source>/qtbase/configure [...]
            \endcode

            Then to configure \c qtdeclarative for example:

            \badcode
            mkdir <build_directory>/build-qtdeclarative
            cd <build_directory>/build-qtdeclarative
            <qt_for_android_install_path>/bin/qt-configure-module <qt_source_path>/qtdeclarative
            cmake --build . --parallel
            cmake --install .
            \endcode
    \endlist

    \section1 Building User Projects

    To build CMake projects with the resulting Qt installation, use
    \c qt-cmake wrapper. For Android the following has to be be provided:

    \badcode
    <qt_for_android_install_path>/bin/qt-cmake -DANDROID_SDK_ROOT=<android_sdk_path> -DANDROID_NDK_ROOT=<android_ndk_path> -S <source_dir> -B <build_dir>
    \endcode

    Additionally, you can still use \c qmake to build user projects as before in Qt 5.
*/
