函數(shù)調(diào)用流程為：
QObject::connect ->QObject::connectImpl
->
QObjectPrivate::connectImpl
->
QObjectPrivate::get(s)->addConnection

class QObject{ static inline QMetaObject::Connection connect(const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, const typename QtPrivate::FunctionPointer<Func2>::Object *receiver, Func2 slot,Qt::ConnectionType type = Qt::AutoConnection){...return connectImpl(sender, reinterpret_cast<void **>(&signal),receiver, reinterpret_cast<void **>(&slot),new QtPrivate::QSlotObject<Func2, typename QtPrivate::List_Left<typename SignalType::Arguments, SlotType::ArgumentCount>::Value,typename SignalType::ReturnType>(slot),type, types, &SignalType::Object::staticMetaObject); ... }QMetaObject::Connection QObject::connectImpl(const QObject *sender, void **signal,const QObject *receiver, void **slot,QtPrivate::QSlotObjectBase *slotObj, Qt::ConnectionType type,const int *types, const QMetaObject *senderMetaObject) {if (!signal) {qWarning("QObject::connect: invalid null parameter");if (slotObj)slotObj->destroyIfLastRef();return QMetaObject::Connection();}int signal_index = -1;void *args[] = { &signal_index, signal };for (; senderMetaObject && signal_index < 0; senderMetaObject = senderMetaObject->superClass()) {senderMetaObject->static_metacall(QMetaObject::IndexOfMethod, 0, args);if (signal_index >= 0 && signal_index < QMetaObjectPrivate::get(senderMetaObject)->signalCount)break;}if (!senderMetaObject) {qWarning("QObject::connect: signal not found in %s", sender->metaObject()->className());slotObj->destroyIfLastRef();return QMetaObject::Connection(0);}signal_index += QMetaObjectPrivate::signalOffset(senderMetaObject);return QObjectPrivate::connectImpl(sender, signal_index, receiver, slot, slotObj, type, types, senderMetaObject); }QMetaObject::Connection QObjectPrivate::connectImpl(const QObject *sender, int signal_index,const QObject *receiver, void **slot,QtPrivate::QSlotObjectBase *slotObj, Qt::ConnectionType type,const int *types, const QMetaObject *senderMetaObject) {if (!sender || !receiver || !slotObj || !senderMetaObject) {const char *senderString = sender ? sender->metaObject()->className(): senderMetaObject ? senderMetaObject->className(): "Unknown";const char *receiverString = receiver ? receiver->metaObject()->className(): "Unknown";qWarning("QObject::connect(%s, %s): invalid null parameter", senderString, receiverString);if (slotObj)slotObj->destroyIfLastRef();return QMetaObject::Connection();}QObject *s = const_cast<QObject *>(sender);QObject *r = const_cast<QObject *>(receiver);QOrderedMutexLocker locker(signalSlotLock(sender),signalSlotLock(receiver));if (type & Qt::UniqueConnection && slot) {QObjectConnectionListVector *connectionLists = QObjectPrivate::get(s)->connectionLists;if (connectionLists && connectionLists->count() > signal_index) {const QObjectPrivate::Connection *c2 =(*connectionLists)[signal_index].first;while (c2) {if (c2->receiver == receiver && c2->isSlotObject && c2->slotObj->compare(slot)) {slotObj->destroyIfLastRef();return QMetaObject::Connection();}c2 = c2->nextConnectionList;}}type = static_cast<Qt::ConnectionType>(type ^ Qt::UniqueConnection);}QScopedPointer<QObjectPrivate::Connection> c(new QObjectPrivate::Connection);c->sender = s;c->signal_index = signal_index;c->receiver = r;c->slotObj = slotObj;c->connectionType = type;c->isSlotObject = true;if (types) {c->argumentTypes.store(types);c->ownArgumentTypes = false;}QObjectPrivate::get(s)->addConnection(signal_index, c.data());QMetaObject::Connection ret(c.take());locker.unlock();QMetaMethod method = QMetaObjectPrivate::signal(senderMetaObject, signal_index);Q_ASSERT(method.isValid());s->connectNotify(method);return ret; }QMetaObject::Connection QMetaObject::connect(const QObject *sender, int signal_index,const QObject *receiver, int method_index, int type, int *types) {const QMetaObject *smeta = sender->metaObject();signal_index = methodIndexToSignalIndex(&smeta, signal_index);return Connection(QMetaObjectPrivate::connect(sender, signal_index, smeta,receiver, method_index,0, //FIXME, we could speed this connection up by computing the relative indextype, types)); }/*!\internalSame as the QMetaObject::connect, but \a signal_index must be the result of QObjectPrivate::signalIndexmethod_index is relative to the rmeta metaobject, if rmeta is null, then it is absolute indexthe QObjectPrivate::Connection* has a refcount of 2, so it must be passed to a QMetaObject::Connection*/ QObjectPrivate::Connection *QMetaObjectPrivate::connect(const QObject *sender,int signal_index, const QMetaObject *smeta,const QObject *receiver, int method_index,const QMetaObject *rmeta, int type, int *types) {QObject *s = const_cast<QObject *>(sender);QObject *r = const_cast<QObject *>(receiver);int method_offset = rmeta ? rmeta->methodOffset() : 0;Q_ASSERT(!rmeta || QMetaObjectPrivate::get(rmeta)->revision >= 6);QObjectPrivate::StaticMetaCallFunction callFunction =rmeta ? rmeta->d.static_metacall : 0;QOrderedMutexLocker locker(signalSlotLock(sender),signalSlotLock(receiver));if (type & Qt::UniqueConnection) {QObjectConnectionListVector *connectionLists = QObjectPrivate::get(s)->connectionLists;if (connectionLists && connectionLists->count() > signal_index) {const QObjectPrivate::Connection *c2 =(*connectionLists)[signal_index].first;int method_index_absolute = method_index + method_offset;while (c2) {if (!c2->isSlotObject && c2->receiver == receiver && c2->method() == method_index_absolute)return 0;c2 = c2->nextConnectionList;}}type &= Qt::UniqueConnection - 1;}QScopedPointer<QObjectPrivate::Connection> c(new QObjectPrivate::Connection);c->sender = s;c->signal_index = signal_index;c->receiver = r;c->method_relative = method_index;c->method_offset = method_offset;c->connectionType = type;c->isSlotObject = false;c->argumentTypes.store(types);c->nextConnectionList = 0;c->callFunction = callFunction;QObjectPrivate::get(s)->addConnection(signal_index, c.data());locker.unlock();QMetaMethod smethod = QMetaObjectPrivate::signal(smeta, signal_index);if (smethod.isValid())s->connectNotify(smethod);return c.take(); }

總結(jié)

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