// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page windows.html
    \title Qt for Windows
    \brief Platform support for Windows.
    \ingroup supportedplatform

    Qt's support for different Windows platforms is extensive and mature.

    To download and install Qt for Windows, follow the instructions on the
    \l{Getting Started with Qt} page.

    \target windows-supported-configurations
    \section1 Supported Configurations

    The following Windows configurations are supported in Qt \QtVer:

    \include supported-platforms.qdocinc windows

    \section1 Building from Source

    For details on how to build Qt itself from sources, see
    \l{Qt for Windows - Building from Source}.

    \section1 Deployment and Other Issues

    The pages below covers specific issues and recommendations for creating
    Windows applications.

    \list
    \li \l{Qt for Windows - Deployment}
    \li \l{Qt for Windows - Graphics Acceleration}
    \li \l{Qt for Windows - Specific Issues}
    \endlist

    \section1 Where to Go from Here

    We invite you to explore the rest of Qt. We prepared overviews which help
    you decide which APIs to use and our examples demonstrate how to use our
    API.

    \list
    \li \l{Qt Overviews} - list of topics about application development
    \li \l{Qt Examples and Tutorials}{Examples and Tutorials} - code samples and tutorials
    \li \l{Qt Reference Pages} - a listing of C++ and QML APIs
    \li \l{ActiveX in Qt}
    \endlist

    Qt's vibrant and active community site, \l{http://qt.io} houses
    a wiki, a forum, and additional learning guides and presentations.

    \section2 Visual Studio Tools

    \l {Qt VS Tools} enables programmers to create, build, debug, and run
    Qt applications from Microsoft Visual Studio. It contains project wizards,
    Qt project import and export support, integrated Qt resource manager,
    and automated build setup for the Qt Meta-Object Compiler, User Interface
    Compiler, and Resource Compiler.

*/

/*!
    \page windows-graphics.html
    \title Qt for Windows - Graphics Acceleration
    \brief Using graphics acceleration with Qt for Windows

    For \l{Qt Quick} to work, a graphics driver that provides Direct 3D 11.1,
    Vulkan 1.0, or OpenGL 2.1 or higher is required. As of Qt 6, the default
    for Qt Quick on Windows is Direct3D 11. This is different from Qt 5, where
    the default was OpenGL, either directly, or through ANGLE, an OpenGL to
    Direct3D translator. ANGLE is no longer shipped with Qt in Qt 6.

    To force using Direct3D's software rasterizer (WARP), set the environment
    variable \c{QSG_RHI_PREFER_SOFTWARE_RENDERER} to \c 1.

    To request using Vulkan or OpenGL, both of which require a Vulkan or OpenGL
    driver to be installed, set the environment variable \c{QSG_RHI_BACKEND} to
    \c vulkan or \c opengl, or use the equivalent
    \l{QQuickWindow::setGraphicsApi()}{C++ API} in \c{main()}.

    While not the default for \l{Qt Quick}, OpenGL is still commonly used in
    many Qt applications, for example in QWidget-based applications building on
    QOpenGLWindow or QOpenGLWidget. The following sections cover some OpenGL
    specifics of a Qt build.

    \section1 Dynamically Loading OpenGL

    Qt supports choosing and loading the OpenGL implementation at runtime. This
    mode is the default, and can be explicitly requested by passing \c{-opengl
    dynamic} to the configure script.

    \badcode
    configure -opengl dynamic
    \endcode

    This configuration is the most flexible because no dependencies or
    assumptions are hardcoded about the OpenGL implementation during build
    time. It allows robust application deployment. When a given environment
    fails to provide a proper OpenGL 2.0 implementation, it will fall back
    automatically to load an alternative to \c{opengl32.dll}, the default name
    of which is \c{opengl32sw.dll}. The pre-built Qt packages ship a build of
    Mesa llvmpipe, a software rasterizer implementation of OpenGL, under that
    name.

    When configured with \c{-opengl dynamic}, neither Qt nor the applications
    built using \c qmake or \c CMake will link to opengl32.lib. Instead, the
    library is chosen and loaded at runtime. By default, Qt will determine
    whether the system's opengl32.dll provides OpenGL 2 functions. If these are
    present, opengl32.dll is used, otherwise it attempts to load
    \c{opengl32sw.dll}. See below for details.

    The loading mechanism can be configured through the \c{QT_OPENGL}
    environment variable and the following application attributes:

    \list
    \li \c Qt::AA_UseDesktopOpenGL Equivalent to setting \c{QT_OPENGL} to \c{desktop}.
    \li \c Qt::AA_UseOpenGLES Has no effect in Qt 6.
    \li \c Qt::AA_UseSoftwareOpenGL Equivalent to setting \c{QT_OPENGL} to \c{software}.
    \endlist

    When a certain configuration is requested explicitly, no checks are done at
    application startup, that is, the system-provided opengl32.dll will not be
    examined.

    The dynamic loading has a significant impact on applications that contain
    native OpenGL calls: they may fail to link since opengl32.lib is not
    automatically specified to the linker. Instead, applications are expected
    to use the OpenGL functions via the QOpenGLFunctions class. Thus the direct
    dependency on the OpenGL library is removed and all calls will be routed
    during runtime to the implementation chosen by Qt. Alternatively,
    applications are free to make direct OpenGL function calls if they add
    opengl32.lib to their .pro project files: \e{LIBS += opengl32.lib} (Visual
    Studio) or \e{LIBS += -lopengl32} (MinGW). The result is, from the
    application's perspective, equivalent to the \c{-opengl desktop} build
    configuration of Qt.

    \c Qt::AA_UseSoftwareOpenGL is special in the sense that it will try to load
    an OpenGL implementation with a non-standard name. The default name is
    \c{opengl32sw.dll}. This allows shipping a software-only OpenGL
    implementation, for example a build of
    \l{http://www.mesa3d.org/llvmpipe.html}{Mesa with llvmpipe}, under this
    name. If necessary, the filename can be overridden by setting the
    \c{QT_OPENGL_DLL} environment variable.

    It is possible to provide a JSON-format configuration file specifying which
    OpenGL implementation to use depending on the graphics card and driver version.
    The location is given by the environment variable \c{QT_OPENGL_BUGLIST}. Relative
    paths are resolved using \c {QLibraryInfo::SettingsPath} or
    \c {QStandardPaths::ConfigLocation}. The file utilizes the format of the
    driver bug list used in \l{The Chromium Projects}. It consists of a list of
    entries each of which specifies a set of conditions and a list of feature keywords.
    Typically, device id and vendor id are used to match a specific graphics card.
    They can be found in the output of the \c qtdiag6 or \c dxdiag tool.

    The following feature keywords are relevant for choosing the OpenGL implementation:

    \note In Qt 6, the legacy ANGLE related keywords (\c disable_angle, \c disable_d3d11,
    \c disable_d3d9) are accepted, but have no effect.

    \list
        \li \c disable_desktopgl - Disables OpenGL. This ensures that Qt does not attempt
        to use regular OpenGL (opengl32.dll), and that it starts with ANGLE right
        away. This is useful to prevent bad OpenGL drivers from crashing the application.

        \li \c disable_rotation - Forces the application to run in landscape orientation
        always. It has no effect when using a software OpenGL implementation. This is
        intended for drivers that have issues with rotation.

        \li \c disable_program_cache - Disable storing shader program binaries on
        disk.
    \endlist

    A sample file looks like:

    \badcode
    {
    "entries": [
    {
      "id": 1,
      "description": "Disable D3D11 on older nVidia drivers",
      "os": {
        "type": "win"
      },
      "vendor_id": "0x10de",
      "device_id": ["0x0DE9"],
      "driver_version": {
        "op": "<=",
        "value": "8.17.12.6973"
      },
      "features": [
        "disable_d3d11"
      ]
    },
    ...
    \endcode

    When \c{QT_OPENGL_BUGLIST} is not specified, a built-in list will be used.
    This typically includes some older, less-capable graphics cards with \c
    disable_desktopgl set, in order to prevent Qt from using their unstable
    desktop OpenGL implementations and instead fall back to attempting to load
    the software-based alternative library right away.

    In practice the most common combinations are expected to be the following:

    \list
        \li \c disable_desktopgl - In case the system provides OpenGL 2.0 or newer, but
        the driver is known to be unstable and prone to crash.

        \li \c disable_desktopgl, disable_angle - When no accelerated path is
        desired. This ensures that the only option Qt tries is the software rasterizer
        (opengl32sw.dll). Can be useful in virtual machines and applications that are
        deployed on a wide range of old systems.
    \endlist

    The supported keys for matching a given card or driver are the following. Note that
    some of these are specific to Qt.

    \list
        \li \c os.type - Operating system: \c win, \c linux, \c macosx, \c android
        \li \c os.version - Kernel version
        \li \c os.release - Specifies a list of operating system releases on Windows:
        \c xp, \c vista, \c 7, \c 8, \c 8.1, \c 10.

        \li \c vendor_id - Vendor from the adapter identifier

        \li \c device_id - List of PCI device IDs.

        \li \c driver_version - Driver version from the adapter identifier

        \li \c driver_description - Matches when the value is a substring of the driver
        description from the adapter identifier

        \li \c gl_vendor - Matches when the value is a substring of the \c GL_VENDOR string
    \endlist

    To disable all blacklisting, set the environment variable \c{QT_NO_OPENGL_BUGLIST} to
    any value. This will skip reading any configuration files, and instead will assume that
    nothing is disabled, regardless of the driver or OS.

    \note While not typically needed, \c{QT_NO_OPENGL_BUGLIST} can become relevant in
    certain virtualized environments, with multiple, possibly virtual, graphics adapters
    present. If the logs from categories like \c{qt.qpa.gl} indicate that the detection of
    the driver and display adapter leads to incorrectly disabling OpenGL, it is then
    recommended to set this environment variable in order to enable the application to run
    normally. This environment variable was introduced in Qt 5.15.

    \section1 Direct dependency to opengl32.dll

    An alternative to the default \c dynamic OpenGL builds is to depend
    directly on opengl32.dll. For this mode, pass the command line options
    \c{-opengl desktop} to the configure script.

    \badcode
    configure -opengl desktop
    \endcode

    \note Using EGL and OpenGL ES is not supported on Windows. In Qt 6, OpenGL
    on Windows always implies using WGL as the windowing system interface.

    In such Qt builds, many Qt shared libraries, and also Qt applications will
    have a dependency to opengl32.dll, and therefore using an alternative
    library is not possible.
*/

/*!
    \page windows-issues.html
    \title Qt for Windows - Specific Issues
    \brief A description of issues with Qt that are specific to Windows.

    This page contains information about \l{Qt for Windows}.

    \section1 Installation location

    Installing Qt into a directory with spaces, for example,
    \e{C:\\Program Files}, may cause issues with qmake.

    Install Qt into a sub-directory without spaces to avoid this problem.

    \section1 Maximum path length

    The Win32 API that both Qt and compiler tools use has a built-in maximum
    file path length of 260 characters (\c MAX_PATH). This can hit you in
    various forms if either your absolute or relative directory structures
    are too verbose.
    It is therefore recommended to keep the file system paths within limits,
    and put build directories nearby the source directories.

    \section1 Visual Studio

    If you are experiencing strange problems with using special flags that
    modify the alignment of structure and union members (such as \c{/Zp2})
    then you will need to recompile Qt with the flags set for the
    application as well.

    \section1 Fullscreen OpenGL Based Windows

    When a window is using an OpenGL based surface and is appearing in full
    screen mode, problems can occur with other top-level windows which are
    part of the application. Due to limitations of the Windows DWM,
    compositing is not handled correctly for OpenGL based windows when going
    into full screen mode. As a result, other top-level windows are not placed
    on top of the full screen window when they are made visible. For example,
    menus may not appear correctly, or dialogs fail to show up.

    A window can use an OpenGL based surface either explicitly when
    \l {QWindow::}{setSurfaceType()} is called, or when something that
    requires OpenGL is used inside the window, causing the whole window to be
    OpenGL based. For example, QOpenGLWidget or QQuickWidget can trigger this.
    However, if the surface is contained in a QWindow which is hosted with
    \l {QWidget::}{createWindowContainer()}, or the obsoleted QGLWidget is
    used and it does cover the entire full screen window, then this problem
    does not occur.

    To solve this problem, native APIs can be used to enable the \c WS_BORDER
    attribute when showing in full screen mode. This can be utilized as follows:

    \code
        bool Widget::event(QEvent *e) {
        #if defined(Q_OS_WIN)
            if (e->type() == QEvent::WinIdChange) {
                if (windowHandle()) {
                    HWND handle = reinterpret_cast<HWND>(windowHandle()->winId());
                    SetWindowLongPtr(handle, GWL_STYLE, GetWindowLongPtr(handle, GWL_STYLE) | WS_BORDER);
                }
            }
        #endif
            return QWidget::event(e);
        }
    \endcode

    This will give the full screen window a 1-pixel border, thus enabling the
    other top level windows to appear on top.
*/

/*!
    \page windows-deployment.html
    \title Qt for Windows - Deployment

    This documentation describes deployment process for \l{Qt for
    Windows}{Windows}. We refer to the \l{Plug & Paint Example}{Plug & Paint}
    example application through out the document to demonstrate the deployment
    process.

    \section1 The Windows Deployment Tool
    \target windeployqt
    The Windows deployment tool \c windeployqt is designed to automate the
    process of creating a deployable folder containing the \l{Qt}-related
    dependencies (libraries, QML imports, plugins, and translations) required
    to run the application from that folder.
    It creates an installation tree for Windows desktop applications, which can be
    easily bundled into an installation package.

    The tool can be found in \c{QTDIR/bin/windeployqt}. It needs to be run
    within the build environment in order to function correctly. When using
    Qt Installer, the script \c{QTDIR/bin/qtenv2.bat} should be used to set it up.

    \c windeployqt takes an \c .exe file or a directory that contains an \c .exe
    file as an argument, and scans the executable for dependencies. If a
    directory is passed with the \c{--qmldir} argument, \c windeployqt uses the
    \c qmlimportscanner tool to scan QML files inside the directory for QML import
    dependencies. Identified dependencies are then copied to the executable's
    directory.

    In case Qt was built with the configure switch \c{-relocatable} turned off,
    \c windeployqt replaces the hardcoded local paths in Qt6Core.dll by
    relative ones.

    For Windows desktop applications, the required runtime files for the compiler
    are also copied to the deployable folder by default (unless the option
    \c --no-compiler-runtime is specified). In the case of release builds using
    Microsoft Visual C++, these consist of the Visual C++ Redistributable Packages,
    which are intended for recursive installation by the application's installer on
    the target machine. Otherwise, the shared libraries of the compiler runtime are used.

    The application may require additional 3rd-party libraries (for example,
    database libraries), which are not taken into account by windeployqt.

    Additional arguments are described in the tools' help output:

    \badcode
    Usage: windeployqt [options] [files]
    Qt Deploy Tool 6.0.0

    The simplest way to use windeployqt is to add the bin directory of your Qt
    installation (e.g. <QT_DIR\bin>) to the PATH variable and then run:
      windeployqt <path-to-app-binary>
    If ICU, etc. are not in the bin directory, they need to be in the PATH
    variable. If your application uses Qt Quick, run:
      windeployqt --qmldir <path-to-app-qml-files> <path-to-app-binary>

    Options:
      -?, -h, --help              Displays help on commandline options.
      --help-all                  Displays help including Qt specific options.
      -v, --version               Displays version information.
      --dir <directory>           Use directory instead of binary directory.
      --qmake <path>              Use specified qmake instead of qmake from PATH.
      --libdir <path>             Copy libraries to path.
      --plugindir <path>          Copy plugins to path.
      --debug                     Assume debug binaries.
      --release                   Assume release binaries.
      --pdb                       Deploy .pdb files (MSVC).
      --force                     Force updating files.
      --dry-run                   Simulation mode. Behave normally, but do not
                                  copy/update any files.
      --no-patchqt                Do not patch the Qt6Core library.
      --ignore-library-errors     Ignore errors when libraries cannot be found.
      --no-plugins                Skip plugin deployment.
      --no-libraries              Skip library deployment.
      --qmldir <directory>        Scan for QML-imports starting from directory.
      --qmlimport <directory>     Add the given path to the QML module search
                                  locations.
      --no-quick-import           Skip deployment of Qt Quick imports.
      --translations <languages>  A comma-separated list of languages to deploy
                                  (de,fi).
      --no-translations           Skip deployment of translations.
      --no-system-d3d-compiler    Skip deployment of the system D3D compiler.
      --compiler-runtime          Deploy compiler runtime (Desktop only).
      --no-virtualkeyboard        Disable deployment of the Virtual Keyboard.
      --no-compiler-runtime       Do not deploy compiler runtime (Desktop only).
      --json                      Print to stdout in JSON format.
      --no-opengl-sw              Do not deploy the software rasterizer library.
      --list <option>             Print only the names of the files copied.
                                  Available options:
                                   source:   absolute path of the source files
                                   target:   absolute path of the target files
                                   relative: paths of the target files, relative
                                             to the target directory
                                   mapping:  outputs the source and the relative
                                             target, suitable for use within an
                                             Appx mapping file
      --verbose <level>           Verbose level (0-2).

    Qt libraries can be added by passing their name (-xml) or removed by passing
    the name prepended by --no- (--no-xml). Available libraries:
    bluetooth concurrent core declarative designer designercomponents gui qthelp
    multimedia multimediawidgets multimediaquick network nfc opengl openglwidgets
    positioning printsupport qml qmltooling quick quickparticles quickwidgets script
    scripttools sensors serialport sql svg svgwidgets test websockets widgets xml
    webenginecore webengine webenginewidgets 3dcore 3drenderer 3dquick
    3dquickrenderer 3dinput 3danimation 3dextras geoservices webchannel serialbus
    webview

    Arguments:
      [files]                     Binaries or directory containing the binary.
\endcode

    \section1 Static Linking

    To build static applications, build Qt statically by configuring Qt with
    \c -static:

    \snippet snippets/code/doc_src_deployment.qdoc 11

    If you later need to reconfigure and rebuild Qt from the
    same location, ensure that all traces of the previous configuration are
    removed by entering the build directory and running \c{nmake distclean} or
    \c{mingw32-make distclean} before running \c configure again.

    \section2 Linking the Application to the Static Version of Qt

    As an example, this section will build the \l{tools/plugandpaint/app}{Plug & Paint}
    example statically.

    Once Qt finishes building, build the \l{tools/plugandpaint/app}{Plug & Paint}
    application. First we must go into the directory that contains the
    application:

    \snippet snippets/code/doc_src_deployment.qdoc 13

    Run \c qmake to create a new makefile for the
    application, and perform a clean build to create the statically linked
    executable:

    \snippet snippets/code/doc_src_deployment.qdoc 14

    You probably want to link against the release libraries, and you can specify
    this when invoking \c qmake. Now, provided that everything compiled and
    linked without any errors, we should have a \c plugandpaint.exe file that is
    ready for deployment. To check that the application has the required
    libraries, copy the executable to a machine that does not have Qt or any Qt
    applications installed, and run it on that machine.

    Remember that if your application depends on compiler specific
    libraries, these must still be redistributed along with your
    application. You can check which libraries your application is
    linking against by using the \c depends tool. For more
    information, read the \l {Application Dependencies} section.

    Since we cannot deploy plugins using the static linking
    approach, the application we have prepared is incomplete. It will
    run, but the functionality will be disabled due to the missing
    plugins. To deploy plugin-based applications we should use the
    shared library approach.

    \section1 Shared Libraries

    We have two challenges when deploying the \l
    {tools/plugandpaint/app}{Plug & Paint} application using the shared
    libraries approach: The Qt runtime has to be correctly
    redistributed along with the application executable, and the
    plugins have to be installed in the correct location on the target
    system so that the application can find them.

    \section2 Building Qt as a Shared Library

    For this example, we assume that Qt is installed as a shared library,
    which is the default when installing Qt, in the \e{C:\\path\\to\\Qt}
    directory.

    \section2 Linking the Application to Qt as a Shared Library

    After ensuring that Qt is built as a shared library, we can build
    the \l {tools/plugandpaint/app}{Plug & Paint} application. First, we
    must go into the directory that contains the application:

    \snippet snippets/code/doc_src_deployment.qdoc 15

    Now run \c qmake to create a new makefile for the application, and
    do a clean build to create the dynamically linked executable:

    \snippet snippets/code/doc_src_deployment.qdoc 16

    This builds the core application, the following will build the
    plugins:

    \snippet snippets/code/doc_src_deployment.qdoc 17

    If everything compiled and linked without any errors, we will get
    a \c plugandpaint.exe executable and the \c pnp_basictools.dll and
    \c pnp_extrafilters.dll plugin files.

    \section2 Creating the Application Package

    To deploy the application, we must make sure that we copy the
    relevant Qt DLLs (corresponding to the Qt modules used in
    the application) and the Windows platform plugin, \c {qwindows.dll},
    as well as the executable to the same directory tree in the \c release
    subdirectory.

    In contrast to user plugins, Qt plugins must be put into subdirectories
    matching the plugin type. The correct location for the platform plugin
    is a subdirectory named \c {platforms}. \l{Qt Plugins} section has
    additional information about plugins and how Qt searches for them.

    If dynamic OpenGL is used, you may additionally want to include the library
    required software-based OpenGL, if the application is compatible with it.

    If Qt was configured to link against ICU or OpenSSL, the respective DLL's
    need to be added to the \c release folder, too.

    \omit
    \note \l{Qt WebEngine} applications have additional requirements that are
    listed in \l{Deploying Qt WebEngine Applications}.
    \endomit

    Remember that if your application depends on compiler specific
    libraries, these must be redistributed along with your
    application. You can check which libraries your application is
    linking against by using the \c depends tool. For more
    information, see the \l {Application Dependencies} section.

    We'll cover the plugins shortly, but first we'll check that the
    application will work in a deployed environment: Either copy the
    executable and the Qt DLLs to a machine that doesn't have Qt
    or any Qt applications installed, or if you want to test on the
    build machine, ensure that the machine doesn't have Qt in its
    environment.

    If the application starts without any problems, then we have
    successfully made a dynamically linked version of the \l
    {tools/plugandpaint/app}{Plug & Paint} application. But the
    application's functionality will still be missing since we have
    not yet deployed the associated plugins.

    Plugins work differently to normal DLLs, so we can't just
    copy them into the same directory as our application's executable
    as we did with the Qt DLLs.  When looking for plugins, the
    application searches in a \c plugins subdirectory inside the
    directory of the application executable.

    So to make the plugins available to our application, we have to
    create the \c plugins subdirectory and copy over the relevant DLLs:

    \snippet snippets/code/doc_src_deployment.qdoc 18

    An archive distributing all the Qt DLLs and application
    specific plugins required to run the \l {tools/plugandpaint/app}{Plug
    & Paint} application, would have to include the following files:

    \table 100%
    \header
        \li Component \li {2, 1} File Name
    \row
        \li The executable
        \li {2, 1} \c plugandpaint.exe
    \row
        \li The Basic Tools plugin
        \li {2, 1} \c plugins\pnp_basictools.dll
    \row
        \li The ExtraFilters plugin
        \li {2, 1} \c plugins\pnp_extrafilters.dll
    \row
        \li The Qt Windows platform plugin
        \li {2, 1} \c platforms\qwindows.dll
    \row
        \li The Qt Windows Vista style plugin
        \li {2, 1} \c styles\qwindowsvistastyle.dll
    \row
        \li The Qt Core module
        \li {2, 1} \c Qt6Core.dll
    \row
        \li The Qt GUI module
        \li {2, 1} \c Qt6Gui.dll
    \row
        \li The Qt Widgets module
        \li {2, 1} \c Qt6Widgets.dll
    \endtable

    Other plugins might be required depending on the features the application uses
    (\c iconengines, \c imageformats).

    In addition, the archive must contain the following compiler
    specific libraries (assuming Visual Studio 16 (2019)):

    \table 100%
    \header
        \li Component \li {2, 1} File Name
    \row
        \li The C run-time
        \li {2, 1} \c vcruntime140.dll
    \row
        \li The C++ run-time
        \li {2, 1} \c msvcp160.dll
    \endtable

    If dynamic OpenGL was used, then the archive may additionally contain:

    \table 100%
    \header
        \li Component \li {2, 1} File Name
    \row
        \li OpenGL Software renderer library
        \li opengl32sw.dll
    \endtable

    Finally, if Qt was configured to use ICU, the archive must contain:

    \table 100%
    \header
        \li{3,1} File Name
    \row
        \li icudtXX.dll
        \li icuinXX.dll
        \li icuucXX.dll
    \endtable

    To verify that the application now can be successfully deployed,
    you can extract this archive on a machine without Qt and without
    any compiler installed, and try to run it.

    An alternative to putting the plugins in the plugins subdirectory
    is to add a custom search path when you start your application
    using QCoreApplication::addLibraryPath() or
    QCoreApplication::setLibraryPaths().

    \snippet snippets/code/doc_src_deployment.cpp 19

    One benefit of using plugins is that they can easily be made
    available to a whole family of applications.

    It's often most convenient to add the path in the application's \c
    main() function, right after the QApplication object is
    created. Once the path is added, the application will search it
    for plugins, in addition to looking in the \c plugins subdirectory
    in the application's own directory. Any number of additional paths
    can be added.

    \section2 Manifest files

    When deploying an application compiled with Visual Studio, there are some
    additional steps to be taken.

    First, we need to copy the manifest file created when linking the
    application. This manifest file contains information about the
    application's dependencies on side-by-side assemblies, such as the runtime
    libraries.

    The manifest file needs to be copied into the \b same folder as the
    application executable. You do not need to copy the manifest files for
    shared libraries (DLLs), since they are not used.

    If the shared library has dependencies that are different from the
    application using it, the manifest file needs to be embedded into the DLL
    binary. Since Qt 4.1.3, the following \c CONFIG options are available for
    embedding manifests:

    \snippet snippets/code/doc_src_deployment.qdoc 20

    Both options are enabled by default. To remove \c{embed_manifest_exe}, add

    \snippet snippets/code/doc_src_deployment.pro 21

    to your .pro file.

    You can find more information about manifest files and side-by-side
    assemblies at the
    \l {https://docs.microsoft.com/en-us/previous-versions//aa376307(v=vs.85)}
    {Side-by-side Assemblies documentation page}.

    The correct way to include the runtime libraries with your application
    is to ensure that they are installed on the end-user's system.

    To install the runtime libraries on the end-user's system, you need to
    include the appropriate Visual C++ Redistributable Package (VCRedist)
    executable with your application and ensure that it is executed when the
    user installs your application.

    The redistributable is named \c vc_redist.x64.exe (64-bit) and can be found
    in the folder \c{<Visual Studio install path>/VC/redist/<language-code>}.

    Alternatively, it can be downloaded from the web, for example
    \l{https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads}.

    \note The application you ship must be compiled with exactly the same
    compiler version against the same C runtime version. This prevents
    deploying errors caused by different versions of the C runtime libraries.

    \section1 Application Dependencies

    \section2 Additional Libraries

    Depending on configuration, compiler specific libraries must be
    redistributed along with your application.

    You can check which
    libraries your application is linking against by using the
    \l{Dependency Walker} tool. All you need to do is to run it like
    this:

    \snippet snippets/code/doc_src_deployment.qdoc 24

    This will provide a list of the libraries that your application
    depends on and other information.

    When looking at the release build of the Plug & Paint executable
    (\c plugandpaint.exe) with the \c depends tool, the tool lists the
    following immediate dependencies to non-system libraries:

    \table 100%
        \header
            \li Qt
            \li Visual Studio 16 (2019)
            \li MinGW
        \row
        \li \list
               \li QT6CORE.DLL - The QtCore runtime
               \li QT6GUI.DLL - The QtGui runtime
               \li QT6WIDGETS.DLL - The QtWidgets runtime
           \endlist
        \li \list
               \li VCCORLIB140.DLL, VCRUNTIME140D.DLL - The C runtime
               \li MSVCP140.DLL - The C++ runtime
           \endlist
        \li \list
               \li LIBWINPTHREAD-1.DLL
               \li LIBGCC_S_SEH-1.DLL
               \li LIBSTDC++-6.DLL
           \endlist
    \endtable

    When looking at the plugin DLLs the exact same dependencies
    are listed.

    From Qt version 5.2 onwards, the officially supported version
    for OpenSSL is 1.0.0 or later. Versions >= 0.9.7 and < 1.0.0 might
    work, but are not guaranteed to.

    \section2 Qt Plugins

    All Qt GUI applications require a plugin that implements the \l {Qt
    Platform Abstraction} (QPA) layer in Qt. For Windows, the name of the
    platform plugin is \c {qwindows.dll}. This file must be located within a
    specific subdirectory (by default, \c platforms) under your distribution
    directory. Alternatively, it is possible to adjust the search path Qt
    uses to find its plugins, as described below.

    Your application may also depend on one or more Qt plugins, such
    as the print support plugin, the JPEG image format plugin or a SQL driver
    plugin. Be sure to distribute any Qt plugins that you need with your
    application. Similar to the platform plugin, each type of plugin must
    be located within a specific subdirectory (such as \c printsupport,
    \c imageformats or \c sqldrivers) within your distribution directory.

    As of Qt 5.14, the libraries are relocatable unless Qt was built with
    the configure switch \c{-relocatable} turned off. The search paths for
    Qt plugins are relative to the location of the QtCore library and no
    further steps are required to ensure plugins are found after installing
    the application on the target machine.

    \section2 Ensuring Plugins Are Found when Using Non-Relocatable Builds

    For non-relocatable builds, additional steps must be taken to ensure
    plugins are found after the application has been installed on the target
    machine.

    In this case, the search path for Qt plugins is hard-coded into the QtCore
    library. By default, the plugins subdirectory of the Qt installation is
    the first plugin search path. However, pre-determined paths like the
    default one have certain disadvantages. For example, they may not
    exist on the target machine. For that reason, you need to examine various
    alternatives to make sure that the Qt plugins are found:

    \list

    \li \l{qt-conf.html}{Using \c qt.conf}. This approach is the recommended
    if you have executables in different places sharing the same plugins.

    \li Using QApplication::addLibraryPath() or
    QApplication::setLibraryPaths(). This approach is recommended if you only
    have one executable that will use the plugin.

    \li Using a third party installation utility to change the
    hard-coded paths in the QtCore library.

    \endlist

    If you add a custom path using QApplication::addLibraryPath it could
    look like this:

    \snippet snippets/code/doc_src_deployment.qdoc 54

    Then QCoreApplication::libraryPaths() would return something like this:

    \list
    \li \c{C:/customPath/plugins}
    \li \c{C:/Qt/%VERSION%/plugins}
    \li \c{E:/myApplication/directory}
    \endlist

    The executable will look for the plugins in these directories and
    the same order as the QStringList returned by QCoreApplication::libraryPaths().
    The newly added path is prepended to the QCoreApplication::libraryPaths() which
    means that it will be searched through first. However, if you use
    QCoreApplication::setLibraryPaths(), you will be able to determine which paths
    and in which order they will be searched.

    The \l{How to Create Qt Plugins} document outlines the issues you
    need to pay attention to when building and deploying plugins for
    Qt applications.

*/

/*!
    \page windows-building.html
    \title Qt for Windows - Building from Source
    \brief Configuring and building Qt for Windows.

    This page describes the process of configuring and building
    \l{Qt for Windows}. To download and install a pre-built Qt for Windows,
    follow the instructions on the \l{Getting Started with Qt} page.

    \section1 Step 1: Getting the Sources

    Qt sources can be installed in the Qt Online Installer. Source packages are
    also available as \l{https://code.qt.io}{Git repositories}, as archives in
    the \l{Qt Account} (commercial users), and on
    \l{https://download.qt.io}{download.qt.io} (open-source users).

    If you install the sources through the Qt Online Installer, they will
    be available in the Qt installation directory, for instance
    \tt{C:\\Qt\\\QtVersion\\Src}.

    If you downloaded the source archive, extract it to a directory of your
    choice, for instance \c{C:\dev\Qt\src}.

    \note The path to the source directory must not contain any spaces or
    Windows specific file system characters. The path should also be kept short.
    This avoids issues with too long file paths in the compilation phase.

    \section1 Step 2: Install Build Requirements

    To build Qt from sources you need a build environment with
    a supported compiler and various build tools available:

    \section2 Build Tools

    \table 80%
    \header \li Tool \li Supported Versions \li Description
    \row
        \li CMake
        \li Version 3.16 and newer (3.17 and newer for \c{-debug-and-release} builds
            3.21 and newer for \c{-static} builds).
        \li Required for configuring the Qt build. Available in the Qt Online
            Installer and on \l{https://cmake.org}{cmake.org}.
    \row
        \li Ninja
        \li -
        \li Recommended tool for building Qt. Available in the Qt Online
            Installer and on \l{https://ninja-build.org}{ninja-build.org}.
    \row
        \li Perl
        \li -
        \li Required build tool. Popular Windows installers are
            \l{https://www.activestate.com/products/perl/downloads/}{ActiveState Perl}
            and \l{https://strawberryperl.com/}{Strawberry Perl}. Perl is also
            installed as part of \l{https://git-scm.com/download/win}{Git}.
    \row
        \li Python
        \li Version 3
        \li Required build tool. Windows installers are available on
            \l{https://www.python.org/downloads/windows/}{python.org}, or from the
            \l{https://docs.python.org/3/using/windows.html#windows-store}{Microsoft Store}.
    \endtable

    The executables \c{cmake.exe}, \c{ninja.exe}, \c{perl.exe}, and \c{python.exe}
    must be available in your build environment. You achieve this by adding the
    respective directory to your \c{PATH} environment variable.

    \section2 Compilers

    The following compilers and configurations are supported in Qt \QtVer:

    \include supported-platforms.qdocinc windows

    \omit
    \section2 Building Qt WebEngine

    \l{Qt WebEngine} has additional build requirements which are listed in the
    \l{Qt WebEngine Platform Notes}.
    \endomit

    \section2 QDoc Dependencies
    \l {QDoc Manual}{QDoc} uses Clang to parse C++ code.
    If you wish to build QDoc manually, refer to \l {Installing Clang for QDoc}
    for specific build requirements.

    \section1 Step 3: Set the Environment Variables

        We recommend creating a desktop link that opens a command
        prompt with the environment set up similar to the
        \uicontrol{Command Prompt} menu entries provided by Visual Studio.
        This is done by creating an application link passing a \c .cmd file setting
        up the environment and the command line option \c /k (remain open)
        to \c cmd.exe.

        Assuming the file is called \c{qt6vars.cmd}
        and the Qt folder is called \tt{C:\\Qt\\\QtVersion\\Src}:

        \badcode \QtVersion
        REM Set up Microsoft Visual Studio 2019, where <arch> is amd64, x86, etc.
        CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Auxiliary\Build\vcvarsall.bat" <arch>
        SET _ROOT=C:\Qt\\1\Src
        SET PATH=%_ROOT%\qtbase\bin;%PATH%
        SET _ROOT=
        \endcode

        A desktop link can then be created by specifying the command
        \c{%SystemRoot%\system32\cmd.exe /E:ON /V:ON  /k C:\Qt\qt6vars.cmd}
        as application.

        Depending on your individual setup, you might also need to make the
        installation directories of CMake, Ninja, Perl, and Python part of the
        \c{SET %PATH%} line above.

        \note Setups for MinGW are similar; they differ
        only in that the \c bin folder of the installation should be added to the
        path instead of calling the Visual Studio setup script. For MinGW, please make
        sure that no \c sh.exe can be found in the path, as it affects \c {mingw32-make}.

    \section1 Step 4: Build the Qt Library

        To configure the Qt library for your machine type, run the
        \c{configure.bat} script in the source directory.

        By default, Qt is configured for installation in the
        \c{C:\Program Files\Qt} directory, but this can be
        changed by using the \c{-prefix} option.

        The \l{Qt Configure Options}{Configure Options} page contains more
        information about the configure options.
        See \l{Qt for Windows - Graphics Acceleration} for specific options
        regarding graphics acceleration.
*/
