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/*!
    \page qtquickcontrols2-fileselectors.html
    \title Using File Selectors with Qt Quick Controls 2

    \l {QFileSelector}{File selectors} provide a convenient way of selecting
    file variants. Qt offers the platform name and the locale as built-in
    selectors. Qt Quick Controls 2 extends the built-in selectors with the name
    (lowercase) of the style that an application is running with.

    By using file selectors, style-specific tweaks can be applied without
    creating a hard dependency to a style. From the available file variants,
    only the selected QML file is loaded by the QML engine. Each file variant
    can assume the context, that is, a specific style. This typically leads
    to some code duplication, but on the other hand, cuts the aforementioned
    hard dependency to the style, and leads to simpler and more efficient
    QML code. The same technique is used to implement the \l {Styling Qt
    Quick Controls 2}{Qt Quick Controls 2 styles}.

    The following example demonstrates a custom rounded button that has a
    styled drop shadow in the \l {Material Style}{Material style}, and looks
    flat in other styles. The files are organized so that the Material version
    of \c CustomButton.qml is placed into a \c +material sub-directory.

    \code
    :/main.qml
    :/CustomButton.qml
    :/+material/CustomButton.qml
    \endcode

    By default, \c main.qml will use \c CustomButton.qml for the \c CustomButton
    type. However, when the application is run with the Material style, the
    \c material selector will be present and the \c +material/CustomButton.qml
    version will be used instead.

    \code
    // main.qml
    import QtQuick 2.6
    import QtQuick.Controls 2.1

    ApplicationWindow {
        id: window
        visible: true

        CustomButton {
            text: "Button"
            anchors.centerIn: parent
        }
    }
    \endcode

    The base implementation of the custom button is a simple rounded
    flat button.

    \code
    // CustomButton.qml
    import QtQuick 2.6
    import QtQuick.Controls 2.1

    Button {
        id: control

        background: Rectangle {
            radius: width / 2
            implicitWidth: 36
            implicitHeight: 36
            color: control.pressed ? "#ccc" : "#eee"
        }
    }
    \endcode

    The Material style's implementation of the custom button imports the
    Material style, requests a dark theme to get light text, and creates
    a drop shadow for the background.

    \code
    // +material/CustomButton.qml
    import QtQuick 2.6
    import QtGraphicalEffects 1.0
    import QtQuick.Controls 2.1
    import QtQuick.Controls.Material 2.1

    Button {
        id: control

        Material.theme: Material.Dark

        background: Rectangle {
            implicitWidth: 48
            implicitHeight: 48
            color: Material.accentColor
            radius: width / 2

            layer.enabled: control.enabled
            layer.effect: DropShadow {
                verticalOffset: 1
                color: Material.dropShadowColor
                samples: control.pressed ? 20 : 10
                spread: 0.5
            }
        }
    }
    \endcode

    \note It is recommended to use \l QQmlApplicationEngine, which internally
    creates a \l QQmlFileSelector instance. This is all that is needed to take
    QML file selectors into use.

    \section1 Related Information
    \list
      \li \l {QFileSelector}
      \li \l {QQmlFileSelector}
      \li \l {Styling Qt Quick Controls 2}
    \endlist
*/