klayout/src/gsiqt/gsiQtHelper.cc

122 lines
3.1 KiB
C++

/*
KLayout Layout Viewer
Copyright (C) 2006-2018 Matthias Koefferlein
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 St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "gsiQtHelper.h"
#include "tlObject.h"
#include <QMetaType>
namespace qt_gsi
{
/**
* @brief A tiny object being both a gsi::ObjectBase for lifetime monitoring and tl::Object for shared pointer management
*
* See QtWatcher for details.
*/
class QtLifetimeMonitor
: public tl::Object, public gsi::ObjectBase
{
// .. nothing yet ..
};
/**
* @brief A helper object that is attached to a QObject to monitor it's lifetime
*
* This object will be put into the properties table of the QObject (more precisely: a copy).
* When the QObject is destroyed, it's properties are destroyed too and through reference
* counting the destruction of the QObject is detected. The monitoring itself is implemented
* through a gsi::ObjectBase object which plugs seamlessly into the gsi type system:
*
* QObject -> QtWatcher (+ temp copies) -> gsi::ObjectBase -> plugs into script objects
*
* NOTE: the initial idea was to use child objects attached to QObject. However, these
* interfere too much with Qt's internals - for example, attaching a child object emits
* a QChildEvent. That gets filtered in some eventFilter function which itself may cause
* QObjects to be decorated with helper objects ... resulting in a infinte recursion.
*
* Decoration by properties is a leaner solution.
*/
class QtWatcher
{
public:
QtWatcher ()
{
// .. nothing yet ..
}
QtWatcher (QtLifetimeMonitor *monitor)
: mp_monitor (monitor)
{
// .. nothing yet ..
}
gsi::ObjectBase *gsi_object ()
{
if (mp_monitor) {
return static_cast<gsi::ObjectBase *> (mp_monitor.get ());
} else {
return 0;
}
}
private:
QtWatcher (size_t id, gsi::ObjectBase *obj);
tl::shared_ptr<QtLifetimeMonitor> mp_monitor;
};
}
Q_DECLARE_METATYPE (qt_gsi::QtWatcher)
namespace qt_gsi
{
/**
* @brief Attaches a watcher object to a native QObject
*/
gsi::ObjectBase *get_watcher_object (QObject *qobject, bool required)
{
const char *watcher_prop_name = "_gsi_qt::watcher";
QVariant prop = qobject->property (watcher_prop_name);
if (prop.isValid ()) {
return prop.value<QtWatcher> ().gsi_object ();
} else if (required) {
QtWatcher w (new QtLifetimeMonitor ());
qobject->setProperty (watcher_prop_name, QVariant::fromValue<QtWatcher> (w));
return w.gsi_object ();
} else {
return 0;
}
}
}