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Diffstat (limited to 'src/webchannel/signalhandler_p.h')
| -rw-r--r-- | src/webchannel/signalhandler_p.h | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/src/webchannel/signalhandler_p.h b/src/webchannel/signalhandler_p.h new file mode 100644 index 0000000..2613f92 --- /dev/null +++ b/src/webchannel/signalhandler_p.h @@ -0,0 +1,278 @@ +/**************************************************************************** +** +** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). +** Copyright (C) 2013 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com> +** Contact: http://www.qt-project.org/legal +* +** This file is part of the QtWebChannel module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and Digia. For licensing terms and +** conditions see http://qt.digia.com/licensing. For further information +** use the contact form at http://qt.digia.com/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Digia gives you certain additional +** rights. These rights are described in the Digia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef SIGNALHANDLER_H +#define SIGNALHANDLER_H + +#include <QObject> +#include <QHash> +#include <QVector> +#include <QMetaMethod> +#include <QDebug> + +/** + * The signal handler is similar to QSignalSpy, but geared towards the usecase of the web channel. + * + * It allows connecting to any number of signals of arbitrary objects and forwards the signal + * invocations to the Receiver by calling its signalEmitted function, which takes the object, + * signal index and a QVariantList of arguments. + */ +template<class Receiver> +class SignalHandler : public QObject +{ +public: + SignalHandler(Receiver *receiver, QObject *parent = 0) + : QObject(parent) + , m_receiver(receiver) + { + } + + /** + * Connect to a signal of @p object identified by @p signalIndex. + * + * If the handler is already connected to the signal, an internal counter is increased, + * i.e. the handler never connects multiple times to the same signal. + */ + void connectTo(const QObject *object, const int signalIndex); + + /** + * Decrease the connection counter for the connection to the given signal. + * + * When the counter drops to zero, the connection is disconnected. + */ + void disconnectFrom(const QObject *object, const int signalIndex); + + /** + * @internal + * + * Custom implementation of qt_metacall which calls dispatch() for connected signals. + */ + int qt_metacall(QMetaObject::Call call, int methodId, void **args) Q_DECL_OVERRIDE; + + /** + * Reset all connections, useful for benchmarks. + */ + void clear(); + +private: + /** + * Exctract the arguments of a signal call and pass them to the receiver. + * + * The @p argumentData is converted to a QVariantList and then passed to the receiver's + * signalEmitted method. + */ + void dispatch(const QObject *object, const int signalIdx, void **argumentData); + + Receiver *m_receiver; + + // maps meta object -> signalIndex -> list of arguments + // NOTE: This data is "leaked" on disconnect until deletion of the handler, is this a problem? + typedef QVector<int> ArgumentTypeList; + typedef QHash<int, ArgumentTypeList> SignalArgumentHash; + QHash<const QMetaObject *, SignalArgumentHash > m_signalArgumentTypes; + + /* + * Tracks how many connections are active to object signals. + * + * Maps object -> signalIndex -> pair of connection and number of connections + * + * Note that the handler is connected to the signal only once, whereas clients + * may have connected multiple times. + * + * TODO: Move more of this logic to the HTML client side, esp. the connection counting. + */ + typedef QPair<QMetaObject::Connection, int> ConnectionPair; + typedef QHash<int, ConnectionPair> SignalConnectionHash; + typedef QHash<const QObject*, SignalConnectionHash> ConnectionHash; + ConnectionHash m_connectionsCounter; +}; + +/** + * Find and return the signal of index @p signalIndex in the meta object of @p object and return it. + * + * The return value is also verified to ensure it is a signal. + */ +QMetaMethod findSignal(const QMetaObject *metaObject, const int signalIndex) +{ + QMetaMethod signal = metaObject->method(signalIndex); + if (!signal.isValid()) { + qWarning("Cannot find signal with index %d of object %s", signalIndex, metaObject->className()); + return QMetaMethod(); + } + Q_ASSERT(signal.methodType() == QMetaMethod::Signal); + return signal; +} + +template<class Receiver> +void SignalHandler<Receiver>::connectTo(const QObject *object, const int signalIndex) +{ + const QMetaObject *metaObject = object->metaObject(); + const QMetaMethod &signal = findSignal(metaObject, signalIndex); + if (!signal.isValid()) { + return; + } + + ConnectionPair &connectionCounter = m_connectionsCounter[object][signalIndex]; + if (connectionCounter.first) { + // increase connection counter if already connected + ++connectionCounter.second; + return; + } // otherwise not yet connected, do so now + + const int memberOffset = QObject::staticMetaObject.methodCount(); + QMetaObject::Connection connection = QMetaObject::connect(object, signal.methodIndex(), this, memberOffset, Qt::DirectConnection, 0); + if (!connection) { + qWarning() << "SignalHandler: QMetaObject::connect returned false. Unable to connect to" << object << signal.name() << signal.methodSignature(); + return; + } + connectionCounter.first = connection; + connectionCounter.second = 1; + + if (!m_signalArgumentTypes.value(metaObject).contains(signal.methodIndex())) { + // find the type ids of the signal parameters, see also QSignalSpy::initArgs + QVector<int> args; + args.reserve(signal.parameterCount()); + for (int i = 0; i < signal.parameterCount(); ++i) { + int tp = signal.parameterType(i); + if (tp == QMetaType::UnknownType && object) { + void *argv[] = { &tp, &i }; + QMetaObject::metacall(const_cast<QObject *>(object), + QMetaObject::RegisterMethodArgumentMetaType, + signal.methodIndex(), argv); + if (tp == -1) { + tp = QMetaType::UnknownType; + } + } + if (tp == QMetaType::UnknownType) { + Q_ASSERT(tp != QMetaType::Void); // void parameter => metaobject is corrupt + qWarning("Don't know how to handle '%s', use qRegisterMetaType to register it.", + signal.parameterNames().at(i).constData()); + } + args << tp; + } + + m_signalArgumentTypes[metaObject][signal.methodIndex()] = args; + } +} + +template<class Receiver> +void SignalHandler<Receiver>::dispatch(const QObject *object, const int signalIdx, void **argumentData) +{ + Q_ASSERT(m_signalArgumentTypes.contains(object->metaObject())); + const QHash<int, QVector<int> > &objectSignalArgumentTypes = m_signalArgumentTypes.value(object->metaObject()); + QHash<int, QVector<int> >::const_iterator signalIt = objectSignalArgumentTypes.constFind(signalIdx); + if (signalIt == objectSignalArgumentTypes.constEnd()) { + // not connected to this signal, skip + return; + } + const QVector<int> &argumentTypes = *signalIt; + QVariantList arguments; + arguments.reserve(argumentTypes.count()); + // TODO: basic overload resolution based on number of arguments? + for (int i = 0; i < argumentTypes.count(); ++i) { + const QMetaType::Type type = static_cast<QMetaType::Type>(argumentTypes.at(i)); + QVariant arg; + if (type == QMetaType::QVariant) { + arg = *reinterpret_cast<QVariant *>(argumentData[i + 1]); + } else { + arg = QVariant(type, argumentData[i + 1]); + } + arguments.append(arg); + } + m_receiver->signalEmitted(object, signalIdx, arguments); +} + +template<class Receiver> +void SignalHandler<Receiver>::disconnectFrom(const QObject *object, const int signalIndex) +{ + Q_ASSERT(m_connectionsCounter.value(object).contains(signalIndex)); + ConnectionPair &connection = m_connectionsCounter[object][signalIndex]; + --connection.second; + if (!connection.second || !connection.first) { + QObject::disconnect(connection.first); + m_connectionsCounter[object].remove(signalIndex); + if (m_connectionsCounter[object].isEmpty()) { + m_connectionsCounter.remove(object); + } + } +} + +template<class Receiver> +int SignalHandler<Receiver>::qt_metacall(QMetaObject::Call call, int methodId, void **args) +{ + methodId = QObject::qt_metacall(call, methodId, args); + if (methodId < 0) + return methodId; + + if (call == QMetaObject::InvokeMetaMethod) { + if (methodId == 0) { + Q_ASSERT(sender()); + Q_ASSERT(senderSignalIndex() != -1); + dispatch(sender(), senderSignalIndex(), args); + static const int destroyedIndex = metaObject()->indexOfSignal("destroyed(QObject*)"); + if (senderSignalIndex() == destroyedIndex) { + ConnectionHash::iterator it = m_connectionsCounter.find(sender()); + Q_ASSERT(it != m_connectionsCounter.end()); + foreach (const ConnectionPair &connection, *it) { + QObject::disconnect(connection.first); + } + m_connectionsCounter.erase(it); + } + } + --methodId; + } + return methodId; +} + +template<class Receiver> +void SignalHandler<Receiver>::clear() +{ + foreach (const SignalConnectionHash &connections, m_connectionsCounter) { + foreach (const ConnectionPair &connection, connections) { + QObject::disconnect(connection.first); + } + } + m_connectionsCounter.clear(); + m_signalArgumentTypes.clear(); +} + +#endif // SIGNALHANDLER_H |