// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page qtquickcontrols-icons.html
    \keyword Icons in Qt Quick Controls 2
    \title Icons in Qt Quick Controls

    In Qt Quick Controls, buttons, item delegates, and menu items are capable
    of presenting an icon in addition to a text label.

    \section1 Using Icons

    \l {AbstractButton::icon}{AbstractButton} and \l {Action::icon}{Action} provide
    the following properties through which icons can be set:
    \list
        \li \c icon.name
        \li \c icon.source
        \li \c icon.width
        \li \c icon.height
        \li \c icon.color
        \li \c icon.cache
    \endlist

    Theme icons are referenced by a name, and regular icons by a source URL. Both
    \c icon.name and \c icon.source can be set to ensure that an icon will always
    be found. If the icon is found in the theme, it will always be used; even if
    \c icon.source is also set. If the icon is not found in the theme, \c icon.source
    will be used instead.

    \code
    Button {
        icon.name: "edit-cut"
        icon.source: "images/cut.png"
    }
    \endcode

    Each \l {Styling Qt Quick Controls}{Qt Quick Controls 2 style} requests a
    default icon size and color according to their guidelines, but it is possible
    to override these by setting the \c icon.width, \c icon.height, and \c icon.color
    properties.

    The image that is loaded by an icon whose \c width and \c height are not set
    depends on the type of icon in use. For theme icons, the closest available size
    will be chosen. For regular icons, the behavior is the same as the \l {Image::}
    {sourceSize} property of \l Image.

    The icon color is specified by default so that it matches the text color in
    different states. In order to use an icon with the original colors, set the
    color to \c "transparent".

    \code
    Button {
        icon.color: "transparent"
        icon.source: "images/logo.png"
    }
    \endcode

    For buttons, the \l {AbstractButton::}{display} property can be used to control
    how the icon and text are displayed within the button.

    The \c icon.cache property controls whether or not the icon image is cached.
    For more information, see \l {Image::}{cache}.

    \section1 Icon Themes

    Compliant icon themes must follow the freedesktop icon theme specification,
    which can be obtained here: \l {http://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html}.

    Traditionally, only Linux and UNIX support icon themes on the platform level,
    but it is possible to bundle a compliant icon theme in an application to use
    themed icons on any platform.

    The default \l {QIcon::themeSearchPaths()}{icon theme search paths} depend on
    the platform. On Linux and UNIX, the search path will use the \c XDG_DATA_DIRS
    environment variable if available. All platforms have the resource directory
    \c :/icons as a fallback. Custom icon theme search paths can be set with
    \l QIcon::setThemeSearchPaths().

    The following example bundles an icon theme called \e mytheme into the application's
    resources using \l {The Qt Resource System}{Qt's resource system}.

    \badcode
    <RCC>
        <qresource prefix="/">
            <file>icons/mytheme/index.theme</file>
            <file>icons/mytheme/32x32/myicon.png</file>
            <file>icons/mytheme/32x32@2/myicon.png</file>
        </qresource>
    </RCC>
    \endcode

    The \c index.theme file describes the general attributes of the icon theme, and
    lists the available theme icon directories:

    \badcode
    [Icon Theme]
    Name=mytheme
    Comment=My Icon Theme

    Directories=32x32,32x32@2

    [32x32]
    Size=32
    Type=Fixed

    [32x32@2]
    Size=32
    Scale=2
    Type=Fixed
    \endcode

    In order to use the bundled icon theme, an application should call \l QIcon::setThemeName()
    before loading the main QML file:

    \code
    #include <QGuiApplication>
    #include <QQmlApplicationEngine>
    #include <QIcon>

    int main(int argc, char *argv[])
    {
        QGuiApplication app(argc, argv);

        QIcon::setThemeName("mytheme"); // <--

        QQmlApplicationEngine engine;
        engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
        return app.exec();
    }
    \endcode

    Now it is possible to use named icons from the bundled icon theme without having
    to specify any fallback source:

    \code
    Button {
        icon.name: "myicon"
    }
    \endcode

    The \l {Qt Quick Controls - Gallery}{Gallery example} and \l {Qt Quick Controls 2 - Wearable Demo}
    {Wearable Demo} provide complete runnable applications with a bundled icon theme.
*/
