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import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Controls.Private 1.0

/*!
    \qmltype CheckBox
    \inqmlmodule QtQuick.Controls 1.0
    \since QtQuick.Controls 1.0
    \ingroup controls
    \brief A checkbox with a text label.

    A CheckBox is an option button that can be toggled on (checked) or off
    (unchecked). Checkboxes are typically used to represent features in an
    application that can be enabled or disabled without affecting others.

    The state of the checkbox can be set with the \l {AbstractCheckable::checked}{checked} property.

    In addition to the checked and unchecked states, there is a third state:
    partially checked. This state indicates that the
    regular checked/unchecked state can not be determined; generally because of
    other states that affect the checkbox. This state is useful when several
    child nodes are selected in a treeview, for example.

    The partially checked state can be made available to the user by setting
    \l partiallyCheckedEnabled to \c true, or set directly by setting
    \l checkedState to \c Qt.PartiallyChecked. \l checkedState behaves
    identically to \l {AbstractCheckable::checked}{checked} when \l partiallyCheckedEnabled
    is \c false; setting one will appropriately set the other.

    The label is shown next to the checkbox, and you can set the label text using its
    \l {AbstractCheckable::text}{text} property.

    \qml
    Column {
        CheckBox {
            text: qsTr("Breakfast")
        }
        CheckBox {
            text: qsTr("Lunch")
        }
        CheckBox {
            text: qsTr("Dinner")
        }
    }
    \endqml

    Whenever a CheckBox is clicked, it emits the \l {AbstractCheckable::clicked}{clicked()} signal.

    You can create a custom appearance for a CheckBox by
    assigning a \l CheckBoxStyle.
*/

AbstractCheckable {
    id: checkBox

    /*!
        \qmlproperty enumeration CheckBox::checkedState

        This property indicates the current checked state of the checkbox.

        Possible values:
        \c Qt.UnChecked - The checkbox is not checked (default).
        \c Qt.Checked - The checkbox is checked.
        \c Qt.PartiallyChecked - The checkbox is in a partially checked (or
        "mixed") state.

        The \l {AbstractCheckable::checked}{checked} property also determines whether
        this property is \c Qt.Checked or \c Qt.UnChecked, and vice versa.
    */
    property int checkedState: checked ? Qt.Checked : Qt.Unchecked

    /*!
        This property determines whether the \c Qt.PartiallyChecked state is
        available.

        A checkbox may be in a partially checked state when the regular checked
        state can not be determined.

        Setting \l checkedState to \c Qt.PartiallyChecked will implicitly set
        this property to \c true.

        If this property is \c true, \l {AbstractCheckable::checked}{checked} will be \c false.

        By default, this property is \c false.
    */
    property bool partiallyCheckedEnabled: false

    /*!
        \internal
        True if onCheckedChanged should be ignored because we were reacting
        to onCheckedStateChanged.
    */
    property bool __ignoreChecked: false

    style: Qt.createComponent(Settings.style + "/CheckBoxStyle.qml", checkBox)

    activeFocusOnTab: true

    Accessible.role: Accessible.CheckBox
    Accessible.name: text

    __cycleStatesHandler: __cycleCheckBoxStates

    onCheckedChanged: {
        if (!__ignoreChecked)
            checkedState = checked ? Qt.Checked : Qt.Unchecked;
    }

    onCheckedStateChanged: {
        __ignoreChecked = true;
        if (checkedState === Qt.PartiallyChecked) {
            partiallyCheckedEnabled = true;
            checked = false;
        } else {
            checked = checkedState === Qt.Checked;
        }
        __ignoreChecked = false;
    }

    onPartiallyCheckedEnabledChanged: {
        if (exclusiveGroup && partiallyCheckedEnabled) {
            console.warn("Cannot have partially checked boxes in an ExclusiveGroup.");
        }
    }

    onExclusiveGroupChanged: {
        if (exclusiveGroup && partiallyCheckedEnabled) {
            console.warn("Cannot have partially checked boxes in an ExclusiveGroup.");
        }
    }

    /*! \internal */
    function __cycleCheckBoxStates() {
        if (!partiallyCheckedEnabled) {
            checked = !checked;
        } else {
            switch (checkedState) {
                case Qt.Unchecked: checkedState = Qt.Checked; break;
                case Qt.Checked: checkedState = Qt.PartiallyChecked; break;
                case Qt.PartiallyChecked: checkedState = Qt.Unchecked; break;
            }
        }
    }
}
