129 lines
3.4 KiB
C++

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