qquickbuttongroup.cpp

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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickbuttongroup_p.h"
 
#include <QtCore/private/qobject_p.h>
#include <QtCore/qmetaobject.h>
#include <QtCore/qvariant.h>
#include <QtQml/qqmlinfo.h>
 
#include "qquickabstractbutton_p_p.h"
 
QT_BEGIN_NAMESPACE
 
/*!
    \qmltype ButtonGroup
    \inherits QtObject
//!     \nativetype QQuickButtonGroup
    \inqmlmodule QtQuick.Controls
    \since 5.7
    \ingroup utilities
    \brief Mutually-exclusive group of checkable buttons.
 
    ButtonGroup is a non-visual, mutually exclusive group of buttons.
    It is used with controls such as RadioButton, where only one of the options
    can be selected at a time.
 
    The most straight-forward way to use ButtonGroup is to assign
    a list of buttons. For example, the list of children of a
    \l{Item Positioners}{positioner} or a \l{Qt Quick Layouts}{layout}
    that manages a group of mutually exclusive buttons.
 
    \code
    ButtonGroup {
        buttons: column.children
    }
 
    Column {
        id: column
 
        RadioButton {
            checked: true
            text: qsTr("DAB")
        }
 
        RadioButton {
            text: qsTr("FM")
        }
 
        RadioButton {
            text: qsTr("AM")
        }
    }
    \endcode
 
    Mutually exclusive buttons do not always share the same parent item,
    or the parent layout may sometimes contain items that should not be
    included in the button group. Such cases are best handled using
    the \l group attached property.
 
    \code
    ButtonGroup { id: radioGroup }
 
    Column {
        Label {
            text: qsTr("Radio:")
        }
 
        RadioButton {
            checked: true
            text: qsTr("DAB")
            ButtonGroup.group: radioGroup
        }
 
        RadioButton {
            text: qsTr("FM")
            ButtonGroup.group: radioGroup
        }
 
        RadioButton {
            text: qsTr("AM")
            ButtonGroup.group: radioGroup
        }
    }
    \endcode
 
    Another option is to filter the list of children. This is especially handy
    if you're using a repeater to populate it, since the repeater will also be
    a child of the parent layout:
 
    \code
    ButtonGroup {
        buttons: column.children.filter((child) => child !== repeater)
    }
 
    Column {
        id: column
 
        Repeater {
            id: repeater
            model: [ qsTr("DAB"), qsTr("AM"), qsTr("FM") ]
            RadioButton {
                required property string modelData
                text: modelData
            }
        }
    }
    \endcode
 
    More advanced use cases can be handled using the \c addButton() and
    \c removeButton() methods.
 
    \sa RadioButton, {Button Controls}
*/
 
/*!
    \qmlsignal QtQuick.Controls::ButtonGroup::clicked(AbstractButton button)
    \since QtQuick.Controls 2.1 (Qt 5.8)
 
    This signal is emitted when a \a button in the group has been clicked.
 
    This signal is convenient for implementing a common signal handler for
    all buttons in the same group.
 
    \code
    ButtonGroup {
        buttons: column.children
        onClicked: button => {
            console.log("clicked:", button.text)
        }
    }
 
    Column {
        id: column
        Button { text: "First" }
        Button { text: "Second" }
        Button { text: "Third" }
    }
    \endcode
 
    \sa AbstractButton::clicked()
*/
 
class QQuickButtonGroupPrivate : public QObjectPrivate
{
public:
    Q_DECLARE_PUBLIC(QQuickButtonGroup)
 
    void clear();
    void buttonClicked();
    void _q_updateCurrent();
    void updateCheckState();
    void setCheckState(Qt::CheckState state);
 
    static void buttons_append(QQmlListProperty<QQuickAbstractButton> *prop, QQuickAbstractButton *obj);
    static qsizetype buttons_count(QQmlListProperty<QQuickAbstractButton> *prop);
    static QQuickAbstractButton *buttons_at(QQmlListProperty<QQuickAbstractButton> *prop, qsizetype index);
    static void buttons_clear(QQmlListProperty<QQuickAbstractButton> *prop);
 
    bool complete = true;
    bool exclusive = true;
    bool settingCheckState = false;
    Qt::CheckState checkState = Qt::Unchecked;
    QPointer<QQuickAbstractButton> checkedButton;
    QList<QQuickAbstractButton*> buttons;
};
 
void QQuickButtonGroupPrivate::clear()
{
    for (QQuickAbstractButton *button : std::as_const(buttons)) {
        auto *attached = qobject_cast<QQuickButtonGroupAttached *>(
            qmlAttachedPropertiesObject<QQuickButtonGroup>(button, false));
        if (attached) {
            attached->setGroup(nullptr);
        } else {
            QQuickAbstractButtonPrivate::get(button)->group = nullptr;
            QObjectPrivate::disconnect(button, &QQuickAbstractButton::clicked, this, &QQuickButtonGroupPrivate::buttonClicked);
            QObjectPrivate::disconnect(button, &QQuickAbstractButton::checkedChanged, this, &QQuickButtonGroupPrivate::_q_updateCurrent);
        }
    }
    buttons.clear();
}
 
void QQuickButtonGroupPrivate::buttonClicked()
{
    Q_Q(QQuickButtonGroup);
    QQuickAbstractButton *button = qobject_cast<QQuickAbstractButton*>(q->sender());
    if (button)
        emit q->clicked(button);
}
 
void QQuickButtonGroupPrivate::_q_updateCurrent()
{
    Q_Q(QQuickButtonGroup);
    if (exclusive) {
        QQuickAbstractButton *button = qobject_cast<QQuickAbstractButton*>(q->sender());
        if (button && button->isChecked())
            q->setCheckedButton(button);
        else if (!buttons.contains(checkedButton))
            q->setCheckedButton(nullptr);
    }
    updateCheckState();
}
 
void QQuickButtonGroupPrivate::updateCheckState()
{
    if (!complete || settingCheckState)
        return;
 
    bool anyChecked = false;
    bool allChecked = !buttons.isEmpty();
    for (QQuickAbstractButton *button : std::as_const(buttons)) {
        const bool isChecked = button->isChecked();
        anyChecked |= isChecked;
        allChecked &= isChecked;
    }
    setCheckState(Qt::CheckState(anyChecked + allChecked));
}
 
void QQuickButtonGroupPrivate::setCheckState(Qt::CheckState state)
{
    Q_Q(QQuickButtonGroup);
    if (checkState == state)
        return;
 
    checkState = state;
    emit q->checkStateChanged();
}
 
void QQuickButtonGroupPrivate::buttons_append(QQmlListProperty<QQuickAbstractButton> *prop, QQuickAbstractButton *obj)
{
    QQuickButtonGroup *q = static_cast<QQuickButtonGroup *>(prop->object);
    q->addButton(obj);
}
 
qsizetype QQuickButtonGroupPrivate::buttons_count(QQmlListProperty<QQuickAbstractButton> *prop)
{
    QQuickButtonGroupPrivate *p = static_cast<QQuickButtonGroupPrivate *>(prop->data);
    return p->buttons.size();
}
 
QQuickAbstractButton *QQuickButtonGroupPrivate::buttons_at(QQmlListProperty<QQuickAbstractButton> *prop, qsizetype index)
{
    QQuickButtonGroupPrivate *p = static_cast<QQuickButtonGroupPrivate *>(prop->data);
    return p->buttons.value(index);
}
 
void QQuickButtonGroupPrivate::buttons_clear(QQmlListProperty<QQuickAbstractButton> *prop)
{
    QQuickButtonGroupPrivate *p = static_cast<QQuickButtonGroupPrivate *>(prop->data);
    if (!p->buttons.isEmpty()) {
        p->clear();
        QQuickButtonGroup *q = static_cast<QQuickButtonGroup *>(prop->object);
        // QTBUG-52358: don't clear the checked button immediately
        QMetaObject::invokeMethod(q, "_q_updateCurrent", Qt::QueuedConnection);
        emit q->buttonsChanged();
    }
}
 
QQuickButtonGroup::QQuickButtonGroup(QObject *parent)
    : QObject(*(new QQuickButtonGroupPrivate), parent)
{
}
 
QQuickButtonGroup::~QQuickButtonGroup()
{
    Q_D(QQuickButtonGroup);
    d->clear();
}
 
QQuickButtonGroupAttached *QQuickButtonGroup::qmlAttachedProperties(QObject *object)
{
    return new QQuickButtonGroupAttached(object);
}
 
/*!
    \qmlproperty AbstractButton QtQuick.Controls::ButtonGroup::checkedButton
 
    This property holds the currently selected button in an exclusive group,
    or \c null if there is none or the group is non-exclusive.
 
    By default, it is the first checked button added to an exclusive button group.
 
    \sa exclusive
*/
QQuickAbstractButton *QQuickButtonGroup::checkedButton() const
{
    Q_D(const QQuickButtonGroup);
    return d->checkedButton;
}
 
void QQuickButtonGroup::setCheckedButton(QQuickAbstractButton *checkedButton)
{
    Q_D(QQuickButtonGroup);
    if (d->checkedButton == checkedButton)
        return;
 
    if (d->checkedButton)
        d->checkedButton->setChecked(false);
    d->checkedButton = checkedButton;
    if (checkedButton)
        checkedButton->setChecked(true);
    emit checkedButtonChanged();
}
 
/*!
    \qmlproperty list<AbstractButton> QtQuick.Controls::ButtonGroup::buttons
 
    This property holds the list of buttons.
 
    \code
    ButtonGroup {
        buttons: column.children
    }
 
    Column {
        id: column
 
        RadioButton {
            checked: true
            text: qsTr("Option A")
        }
 
        RadioButton {
            text: qsTr("Option B")
        }
    }
    \endcode
 
    \sa group
*/
QQmlListProperty<QQuickAbstractButton> QQuickButtonGroup::buttons()
{
    Q_D(QQuickButtonGroup);
    return QQmlListProperty<QQuickAbstractButton>(this, d,
        QQuickButtonGroupPrivate::buttons_append,
        QQuickButtonGroupPrivate::buttons_count,
        QQuickButtonGroupPrivate::buttons_at,
        QQuickButtonGroupPrivate::buttons_clear);
}
 
/*!
    \since QtQuick.Controls 2.3 (Qt 5.10)
    \qmlproperty bool QtQuick.Controls::ButtonGroup::exclusive
 
    This property holds whether the button group is exclusive. The default value is \c true.
 
    If this property is \c true, then only one button in the group can be checked at any given time.
    The user can click on any button to check it, and that button will replace the existing one as
    the checked button in the group.
 
    In an exclusive group, the user cannot uncheck the currently checked button by clicking on it;
    instead, another button in the group must be clicked to set the new checked button for that group.
 
    In a non-exclusive group, checking and unchecking buttons does not affect the other buttons in
    the group. Furthermore, the value of the \l checkedButton property is \c null.
*/
bool QQuickButtonGroup::isExclusive() const
{
    Q_D(const QQuickButtonGroup);
    return d->exclusive;
}
 
void QQuickButtonGroup::setExclusive(bool exclusive)
{
    Q_D(QQuickButtonGroup);
    if (d->exclusive == exclusive)
        return;
 
    d->exclusive = exclusive;
    emit exclusiveChanged();
}
 
/*!
    \since QtQuick.Controls 2.4 (Qt 5.11)
    \qmlproperty enumeration QtQuick.Controls::ButtonGroup::checkState
 
    This property holds the combined check state of the button group.
 
    Available states:
    \value Qt.Unchecked None of the buttons are checked.
    \value Qt.PartiallyChecked Some of the buttons are checked.
    \value Qt.Checked All of the buttons are checked.
 
    Setting the check state of a non-exclusive button group to \c Qt.Unchecked
    or \c Qt.Checked unchecks or checks all buttons in the group, respectively.
    \c Qt.PartiallyChecked is ignored.
 
    Setting the check state of an exclusive button group to \c Qt.Unchecked
    unchecks the \l checkedButton. \c Qt.Checked and \c Qt.PartiallyChecked
    are ignored.
*/
Qt::CheckState QQuickButtonGroup::checkState() const
{
    Q_D(const QQuickButtonGroup);
    return d->checkState;
}
 
void QQuickButtonGroup::setCheckState(Qt::CheckState state)
{
    Q_D(QQuickButtonGroup);
    if (d->checkState == state || state == Qt::PartiallyChecked)
        return;
 
    d->settingCheckState = true;
    if (d->exclusive) {
        if (d->checkedButton && state == Qt::Unchecked)
            setCheckedButton(nullptr);
    } else {
        for (QQuickAbstractButton *button : std::as_const(d->buttons))
            button->setChecked(state == Qt::Checked);
    }
    d->settingCheckState = false;
    d->setCheckState(state);
}
 
/*!
    \qmlmethod void QtQuick.Controls::ButtonGroup::addButton(AbstractButton button)
 
    Adds a \a button to the button group.
 
    \note Manually adding objects to a button group is typically unnecessary.
          The \l buttons property and the \l group attached property provide a
          convenient and declarative syntax.
 
    \sa buttons, group
*/
void QQuickButtonGroup::addButton(QQuickAbstractButton *button)
{
    Q_D(QQuickButtonGroup);
    if (!button || d->buttons.contains(button))
        return;
 
    QQuickAbstractButtonPrivate::get(button)->group = this;
    QObjectPrivate::connect(button, &QQuickAbstractButton::clicked, d, &QQuickButtonGroupPrivate::buttonClicked);
    QObjectPrivate::connect(button, &QQuickAbstractButton::checkedChanged, d, &QQuickButtonGroupPrivate::_q_updateCurrent);
 
    if (d->exclusive && button->isChecked())
        setCheckedButton(button);
 
    d->buttons.append(button);
    d->updateCheckState();
    emit buttonsChanged();
}
 
/*!
    \qmlmethod void QtQuick.Controls::ButtonGroup::removeButton(AbstractButton button)
 
    Removes a \a button from the button group.
 
    \note Manually removing objects from a button group is typically unnecessary.
          The \l buttons property and the \l group attached property provide a
          convenient and declarative syntax.
 
    \sa buttons, group
*/
void QQuickButtonGroup::removeButton(QQuickAbstractButton *button)
{
    Q_D(QQuickButtonGroup);
    if (!button || !d->buttons.contains(button))
        return;
 
    QQuickAbstractButtonPrivate::get(button)->group = nullptr;
    QObjectPrivate::disconnect(button, &QQuickAbstractButton::clicked, d, &QQuickButtonGroupPrivate::buttonClicked);
    QObjectPrivate::disconnect(button, &QQuickAbstractButton::checkedChanged, d, &QQuickButtonGroupPrivate::_q_updateCurrent);
 
    if (d->checkedButton == button)
        setCheckedButton(nullptr);
 
    d->buttons.removeOne(button);
    d->updateCheckState();
    emit buttonsChanged();
}
 
void QQuickButtonGroup::classBegin()
{
    Q_D(QQuickButtonGroup);
    d->complete = false;
}
 
void QQuickButtonGroup::componentComplete()
{
    Q_D(QQuickButtonGroup);
    d->complete = true;
    if (!d->buttons.isEmpty())
        d->updateCheckState();
}
 
class QQuickButtonGroupAttachedPrivate : public QObjectPrivate
{
public:
    QQuickButtonGroup *group = nullptr;
};
 
QQuickButtonGroupAttached::QQuickButtonGroupAttached(QObject *parent)
    : QObject(*(new QQuickButtonGroupAttachedPrivate), parent)
{
}
 
/*!
    \qmlattachedproperty ButtonGroup QtQuick.Controls::ButtonGroup::group
 
    This property attaches a button to a button group.
 
    \code
    ButtonGroup { id: group }
 
    RadioButton {
        checked: true
        text: qsTr("Option A")
        ButtonGroup.group: group
    }
 
    RadioButton {
        text: qsTr("Option B")
        ButtonGroup.group: group
    }
    \endcode
 
    \sa buttons
*/
QQuickButtonGroup *QQuickButtonGroupAttached::group() const
{
    Q_D(const QQuickButtonGroupAttached);
    return d->group;
}
 
void QQuickButtonGroupAttached::setGroup(QQuickButtonGroup *group)
{
    Q_D(QQuickButtonGroupAttached);
    if (d->group == group)
        return;
 
    auto *button = qobject_cast<QQuickAbstractButton *>(parent());
    if (d->group)
        d->group->removeButton(button);
    d->group = group;
    if (group)
        group->addButton(button);
    emit groupChanged();
}
 
QT_END_NAMESPACE
 
#include "moc_qquickbuttongroup_p.cpp"