qsignalmapper.cpp

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// Copyright (C) 2016 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 "qglobal.h"
 
#include "qsignalmapper.h"
#include "qhash.h"
#include "qobject_p.h"
 
QT_BEGIN_NAMESPACE
 
class QSignalMapperPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QSignalMapper)
public:
 
    template <class Signal, class Container>
    void emitMappedValue(QObject *sender, Signal signal, const Container &mappedValues)
    {
        Q_Q(QSignalMapper);
 
        auto it = mappedValues.find(sender);
        if (it != mappedValues.end())
            Q_EMIT(q->*signal)(*it);
    }
 
    void emitMappedValues(QObject *sender)
    {
        emitMappedValue(sender, &QSignalMapper::mappedInt, intHash);
        emitMappedValue(sender, &QSignalMapper::mappedString, stringHash);
        emitMappedValue(sender, &QSignalMapper::mappedObject, objectHash);
    }
 
    QHash<QObject *, int> intHash;
    QHash<QObject *, QString> stringHash;
    QHash<QObject *, QObject *> objectHash;
};
 
/*!
    \class QSignalMapper
    \inmodule QtCore
    \brief The QSignalMapper class bundles signals from identifiable senders.
 
    \ingroup objectmodel
 
 
    This class collects a set of parameterless signals, and re-emits
    them with integer, string or widget parameters corresponding to
    the object that sent the signal. Note that in most cases you can
    use lambdas for passing custom parameters to slots. This is less
    costly and will simplify the code.
 
    The class supports the mapping of particular strings, integers,
    objects and widgets with particular objects using setMapping().
    The objects' signals can then be connected to the map() slot which
    will emit a signal (it could be mappedInt(), mappedString()
    and mappedObject()) with a value associated with
    the original signalling object. Mappings can be removed later using
    removeMappings().
 
    Example: Suppose we want to create a custom widget that contains
    a group of buttons (like a tool palette). One approach is to
    connect each button's \c clicked() signal to its own custom slot;
    but in this example we want to connect all the buttons to a
    single slot and parameterize the slot by the button that was
    clicked.
 
    Here's the definition of a simple custom widget that has a single
    signal, \c clicked(), which is emitted with the text of the button
    that was clicked:
 
    \snippet qsignalmapper/buttonwidget.h 0
    \snippet qsignalmapper/buttonwidget.h 1
 
    The only function that we need to implement is the constructor:
 
    \snippet qsignalmapper/buttonwidget.cpp OpenCtor
    \snippet qsignalmapper/buttonwidget.cpp OldNotation
    \snippet qsignalmapper/buttonwidget.cpp CloseBrackets
 
    A list of texts is passed to the constructor. A signal mapper is
    constructed and for each text in the list a QPushButton is
    created. We connect each button's \c clicked() signal to the
    signal mapper's map() slot, and create a mapping in the signal
    mapper from each button to the button's text. Finally we connect
    the signal mapper's mappedString() signal to the custom widget's
    \c clicked() signal. When the user clicks a button, the custom
    widget will emit a single \c clicked() signal whose argument is
    the text of the button the user clicked.
 
    This class was mostly useful before lambda functions could be used as
    slots. The example above can be rewritten simpler without QSignalMapper
    by connecting to a lambda function.
 
    \snippet qsignalmapper/buttonwidget.cpp OpenCtor
    \snippet qsignalmapper/buttonwidget.cpp ModernNotation
    \snippet qsignalmapper/buttonwidget.cpp CloseBrackets
 
    \sa QObject, QButtonGroup, QActionGroup
*/
 
/*!
    Constructs a QSignalMapper with parent \a parent.
*/
QSignalMapper::QSignalMapper(QObject* parent)
    : QObject(*new QSignalMapperPrivate, parent)
{
}
 
/*!
    Destroys the QSignalMapper.
*/
QSignalMapper::~QSignalMapper()
{
}
 
/*!
    Adds a mapping so that when map() is signalled from the given \a
    sender, the signal mappedInt(\a id) is emitted.
 
    There may be at most one integer ID for each sender.
 
    \sa mapping()
*/
void QSignalMapper::setMapping(QObject *sender, int id)
{
    Q_D(QSignalMapper);
    d->intHash.insert(sender, id);
    connect(sender, &QObject::destroyed, this, &QSignalMapper::removeMappings);
}
 
/*!
    Adds a mapping so that when map() is signalled from the \a sender,
    the signal mappedString(\a text ) is emitted.
 
    There may be at most one text for each sender.
*/
void QSignalMapper::setMapping(QObject *sender, const QString &text)
{
    Q_D(QSignalMapper);
    d->stringHash.insert(sender, text);
    connect(sender, &QObject::destroyed, this, &QSignalMapper::removeMappings);
}
 
/*!
    Adds a mapping so that when map() is signalled from the \a sender,
    the signal mappedObject(\a object ) is emitted.
 
    There may be at most one object for each sender.
*/
void QSignalMapper::setMapping(QObject *sender, QObject *object)
{
    Q_D(QSignalMapper);
    d->objectHash.insert(sender, object);
    connect(sender, &QObject::destroyed, this, &QSignalMapper::removeMappings);
}
 
/*!
    Returns the sender QObject that is associated with the \a id.
 
    \sa setMapping()
*/
QObject *QSignalMapper::mapping(int id) const
{
    Q_D(const QSignalMapper);
    return d->intHash.key(id);
}
 
/*!
    \overload mapping()
*/
QObject *QSignalMapper::mapping(const QString &id) const
{
    Q_D(const QSignalMapper);
    return d->stringHash.key(id);
}
 
/*!
    \overload mapping()
 
    Returns the sender QObject that is associated with the \a object.
*/
QObject *QSignalMapper::mapping(QObject *object) const
{
    Q_D(const QSignalMapper);
    return d->objectHash.key(object);
}
 
/*!
    Removes all mappings for \a sender.
 
    This is done automatically when mapped objects are destroyed.
 
    \note This does not disconnect any signals. If \a sender is not destroyed
    then this will need to be done explicitly if required.
*/
void QSignalMapper::removeMappings(QObject *sender)
{
    Q_D(QSignalMapper);
 
    d->intHash.remove(sender);
    d->stringHash.remove(sender);
    d->objectHash.remove(sender);
}
 
/*!
    This slot emits signals based on which object sends signals to it.
*/
void QSignalMapper::map() { map(sender()); }
 
/*!
    This slot emits signals based on the \a sender object.
*/
void QSignalMapper::map(QObject *sender)
{
    d_func()->emitMappedValues(sender);
}
 
/*!
    \fn void QSignalMapper::mappedInt(int i)
    \since 5.15
 
    This signal is emitted when map() is signalled from an object that
    has an integer mapping set. The object's mapped integer is passed
    in \a i.
 
    \sa setMapping()
*/
 
/*!
    \fn void QSignalMapper::mappedString(const QString &text)
    \since 5.15
 
    This signal is emitted when map() is signalled from an object that
    has a string mapping set. The object's mapped string is passed in
    \a text.
 
    \sa setMapping()
*/
 
/*!
    \fn void QSignalMapper::mappedObject(QObject *object)
    \since 5.15
 
    This signal is emitted when map() is signalled from an object that
    has an object mapping set. The object provided by the map is passed in
    \a object.
 
    \sa setMapping()
*/
 
QT_END_NAMESPACE
 
#include "moc_qsignalmapper.cpp"