129 lines
3.4 KiB
C++
129 lines
3.4 KiB
C++
// vim: set tabstop=4 shiftwidth=4 expandtab:
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/*
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Gwenview: an image viewer
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Copyright 2009 Aurélien Gâteau <agateau@kde.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
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*/
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#ifndef BINDER_H
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#define BINDER_H
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#include <lib/gwenviewlib_export.h>
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// Qt
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#include <QObject>
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namespace Gwenview
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{
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/**
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* @internal
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*
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* Necessary helper class because a QObject class cannot be a template
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*/
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class GWENVIEWLIB_EXPORT BinderInternal : public QObject
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{
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Q_OBJECT
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public:
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explicit BinderInternal(QObject *parent);
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~BinderInternal() override;
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protected Q_SLOTS:
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virtual void callMethod()
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{
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}
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};
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/**
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* The Binder and BinderRef classes make it possible to "connect" a
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* parameter-less signal with a slot which accepts one argument. The
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* argument must be known at connection time.
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*
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* Example:
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*
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* Assuming a class like this:
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*
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* class Receiver
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* {
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* public:
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* void doSomething(Param* p);
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* };
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*
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* This code:
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*
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* Binder<Receiver, Param*>::bind(emitter, SIGNAL(somethingHappened()), receiver, &Receiver::doSomething, p)
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*
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* Will result in receiver->doSomething(p) being called when emitter emits
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* the somethingHappened() signal.
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*
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* Just like a regular QObject connection, the connection will last until
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* either emitter or receiver are deleted.
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*
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* Using this system avoids creating an helper slot and adding a member to
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* the Receiver class to store the argument of the method to call.
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*
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* To call a method which accept a pointer or a value argument, use Binder.
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* To call a method which accept a const reference argument, use BinderRef.
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*
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* Note: the method does not need to be a slot.
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*/
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template<class Receiver, class Arg, typename MethodArg>
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class BaseBinder : public BinderInternal
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{
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public:
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using Method = void (Receiver::*)(MethodArg);
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static void bind(QObject *emitter, const char *signal, Receiver *receiver, Method method, MethodArg arg)
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{
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auto *binder = new BaseBinder<Receiver, Arg, MethodArg>(emitter);
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binder->mReceiver = receiver;
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binder->mMethod = method;
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binder->mArg = arg;
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QObject::connect(emitter, signal, binder, SLOT(callMethod()));
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QObject::connect(receiver, SIGNAL(destroyed(QObject *)), binder, SLOT(deleteLater()));
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}
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protected:
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void callMethod() override
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{
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(mReceiver->*mMethod)(mArg);
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}
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private:
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BaseBinder(QObject *emitter)
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: BinderInternal(emitter)
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, mReceiver(nullptr)
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, mMethod(nullptr)
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{
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}
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Receiver *mReceiver;
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Method mMethod;
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Arg mArg;
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};
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template<class Receiver, class Arg>
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class Binder : public BaseBinder<Receiver, Arg, Arg>
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{
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};
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template<class Receiver, class Arg>
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class BinderRef : public BaseBinder<Receiver, Arg, const Arg &>
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{
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};
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} // namespace
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#endif /* BINDER_H */
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