// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page appicon.html
    \title Setting the Application Icon
    \brief How to set your application's icon.

    \ingroup best-practices

    The application icon, typically displayed in the top-left corner of an
    application's top-level windows, is set by calling the
    QWindow::setIcon() method.

    In order to change the icon of the executable application file
    itself, as it is presented on the desktop (that is, prior to
    application launch), it is necessary to employ another,
    platform-dependent technique.

    \section1 Setting the Application Icon on Windows

    First, create an ICO format bitmap file that contains the icon
    image. This can be done using Microsoft Visual Studio: Select
    \uicontrol{File >> New}, and choose the \uicontrol{Icon File}.

    \note You need not load the application into the Visual Studio IDE as you
    are using the icon editor only.

    Alternatively, an \c .ico file can be created from a set of images using
    ImageMagick's \l {https://imagemagick.org/script/convert.php}{convert}
    tool:

    \badcode
    magick.exe convert icon-16.png icon-32.png icon-256.png icon.ico
    \endcode

    Store the ICO file in your application's source code directory,
    for example, with the name \c appico.ico.

    \section2 Using CMake on Windows

    To configure your application's icon, a resource file containing
    information about the icon is required. A resource file is a text
    file that contains information about the application
    resources, such as icons, cursors, fonts, and so on. For
    more information about resource files and what it can contain, see
    \l{https://docs.microsoft.com/en-us/windows/win32/menurc/about-resource-files}{About Resource Files}.

    Once you have the \c .rc file, add information about the ICO file to it and
    use it to configure your application icon.

    The following snippet demonstrates how the \l{Photo Surface}
    example application uses CMake to set up an application icon:

    \snippet demos/photosurface/CMakeLists.txt appicon_windows

    Notice that the \c set command, defines the \c app_icon_windows
    variable, which contains the path of the RC file. This variable is used
    with the \c add_executable command to set the application's icon.

    \section2 Using qmake on Windows

    If you are still using qmake to generate your makefiles,
    you need to add a single line to your \c .pro project file:

    \snippet snippets/code/doc_src_appicon.pro 0

    Finally, regenerate your makefile and your application. The \c .exe file
    will now be represented by your icon in Explorer.

    However, if you already have an \c .rc file, for example, with the name
    \c myapp.rc, which you want to reuse, the following two steps will be
    required. First, put a single line of text to the \c myapp.rc file:

    \snippet snippets/code/doc_src_appicon.qdoc 0

    Then, add this line to your \c myapp.pro file:

    \snippet snippets/code/doc_src_appicon.pro 1

    If you do not use \c qmake, the necessary steps are: first, create an
    \c .rc file and run the \c rc or \c windres program on the \c .rc file,
    then link your application with the resulting \c .res file.

    \section1 Setting the Application Icon on \macos

    The application icon, typically displayed in the application dock
    area, is set by calling \l QWindow::setIcon() on a window. It is
    possible that the program could appear in the application dock area
    before the function call, in which case a default icon will appear
    during the bouncing animation.

    To ensure that the correct icon appears, both when the application is
    being launched, and in the Finder, it is necessary to employ a
    platform-dependent technique.

    Although many programs can create icon files (\c .icns), the
    recommended approach is to use the \e{iconutil} program
    supplied by Apple.  \e{iconutil} is a command-line tool that
    converts iconset folders to deployment-ready, high-resolution
    icns files. Using this tool also compresses the resulting icns file,
    so there is no need for you to perform additional compression.

    \section2 Using CMake on \macos

    To configure the application's icon, the \c Info.plist file generated
    by CMake must contain the icon information. This can be achieved by
    setting the \c .icns file name to the \c MACOSX_BUNDLE_ICON_FILE variable.

    The following snippet demonstrates how the \l{Photo Surface}
    example application uses CMake to set up an application icon:

    \snippet demos/photosurface/CMakeLists.txt appicon_macOS

    Notice that the first \c set command defines the \c MACOSX_BUNDLE_ICON_FILE
    variable, which is required to add the icon file to the \c Info.plist file.
    The second \c set command defines the \c app_icon_macos variable with the
    absolute path to the icon file. This variable is then used to configure
    MACOSX_PACKAGE_LOCATION, which defines the icon file's install location.
    Finally, the \c add_executable uses the \c app_icon_macOS variable to set
    the application's icon.

    \section2 Using qmake on \macos

    If you are still using qmake to generate your makefiles, you only need
    to add a single line to your \c .pro project file. For example,
    if the name of your icon file is \c{myapp.icns}, and your project
    file is \c{myapp.pro}, add this line to \c{myapp.pro}:

    \snippet snippets/code/doc_src_appicon.pro 2

    This will ensure that \c qmake puts your icons in the proper
    place and creates an \c{Info.plist} entry for the icon.

    If you do not use \c qmake, you must do the following manually:
    \list 1
    \li Create an \c Info.plist file for your application (using the
       \c PropertyListEditor, found in \c Developer/Applications).
    \li Associate your \c .icns record with the \c CFBundleIconFile record in the
       \c Info.plist file (again, using the \c PropertyListEditor).
    \li Copy the \c Info.plist file into your application bundle's \c Contents
       directory.
    \li Copy the \c .icns file into your application bundle's \c Contents/Resources
       directory.
    \endlist

    \section1 Setting the Application Icon on Common Linux Desktops

    In this section we briefly describe the issues involved in providing
    icons for applications for two common Linux desktop environments:
    \l{https://www.kde.org/}{KDE} and \l{https://www.gnome.org/}{GNOME}.
    The core technology used to describe application icons
    is the same for both desktops, and may also apply to others, but there
    are details which are specific to each. The main source of information
    on the standards used by these Linux desktops is
    \l{https://www.freedesktop.org/}{freedesktop.org}. For information
    on other Linux desktops please refer to the documentation for the
    desktops you are interested in.

    Often, users do not use executable files directly, but instead launch
    applications by clicking icons on the desktop. These icons are
    representations of "desktop entry files" that contain a description of
    the application that includes information about its icon. Both desktop
    environments are able to retrieve the information in these files, and
    they use it to generate shortcuts to applications on the desktop, in
    the start menu, and on the panel.

    More information about desktop entry files can be found in the
    \l{https://www.freedesktop.org/wiki/Specifications/desktop-entry-spec/}{Desktop Entry Specification}.

    Although desktop entry files can usefully encapsulate the application's details,
    we still need to store the icons in the conventional location for each desktop
    environment. A number of locations for icons are given in the
    \l{https://www.freedesktop.org/wiki/Specifications/icon-theme-spec/}{Icon Theme Specification}.

    Although the path used to locate icons depends on the desktop in use,
    and on its configuration, the directory structure beneath each of
    these should follow the same pattern: subdirectories are arranged by
    theme, icon size, and application type. Generally, application icons
    are added to the hicolor theme, so a square application icon 32 pixels
    in size would be stored in the \c hicolor/32x32/apps directory beneath
    the icon path.

    \section2 K Desktop Environment (KDE)

    Application icons can be installed for use by all users, or on a per-user basis.
    A user currently logged into their KDE 4 desktop can discover these locations
    by using kde4-config, for example, by typing the following in a terminal window:

    \snippet snippets/code/doc_src_appicon.qdoc 3

    Applications using Qt 5 and KDE Frameworks 5 will find their icons in the list
    returned by this command:

    \snippet snippets/code/doc_src_appicon.qdoc 5

    Typically, the list of colon-separated paths printed to stdout includes the
    user-specific icon path and the system-wide path. Beneath these
    directories, it should be possible to locate and install icons according
    to the conventions described in the
    \l{https://www.freedesktop.org/wiki/Specifications/icon-theme-spec/}{Icon Theme Specification}.

    If you are developing exclusively for KDE, you may wish to take
    advantage of the \l{https://techbase.kde.org/Development/CMake/Addons_for_KDE}{KDE build system} to configure your application. This ensures
    that your icons are installed in the appropriate locations for KDE.

    The KDE developer website is at \l{https://techbase.kde.org/}.

    \section2 GNOME

    Application icons are stored within a standard system-wide
    directory containing architecture-independent files. This
    location can be determined by using \c gnome-config, for example
    by typing the following in a terminal window:

    \snippet snippets/code/doc_src_appicon.qdoc 4

    The path printed on stdout refers to a location that should contain a directory
    called \c{pixmaps}; the directory structure within the \c pixmaps
    directory is described in the
    \l{https://www.freedesktop.org/wiki/Specifications/icon-theme-spec/}{Icon Theme Specification}.

    If you are developing exclusively for GNOME, you may want to use the
    standard set of GNU Build Tools. For more information, see the
    \l{https://developer.gnome.org/documentation/guidelines/maintainer/integrating.html?highlight=application%20icons#icons}{Integration Guidelines}
    section. This ensures that your icons are installed in the
    appropriate locations for GNOME.

    The GNOME developer website, \l{https://developer.gnome.org/}, provides
    more insight into developing applications.
*/
