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// vim: set tabstop=4 shiftwidth=4 noexpandtab
/*
Gwenview - A simple image viewer for KDE
Copyright 2000-2004 Aurélien Gâteau
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
// Qt
#include <qtimer.h>
// KDE
#include <kdebug.h>
// Local
#include "busylevelmanager.moc"
namespace Gwenview {
#undef ENABLE_LOG
#undef LOG
//#define ENABLE_LOG
#ifdef ENABLE_LOG
#define LOG(x) kdDebug() << k_funcinfo << x << endl
#else
#define LOG(x) ;
#endif
BusyLevelManager::BusyLevelManager()
: mCurrentBusyLevel( BUSY_NONE )
{
connect( &mDelayedBusyLevelTimer, SIGNAL( timeout()),
this, SLOT( delayedBusyLevelChanged()));
}
BusyLevelManager* BusyLevelManager::instance() {
static BusyLevelManager manager;
return &manager;
}
// How the busy level stuff works:
// This system allows suspending less important tasks while more important
// task are active, i.e. no thumbnails are generated when the viewed
// image is being loaded and painted.
// All objects responsible for operations set their busy level
// to the matching value when the operation starts and reset their busy
// level when the operation is done. They all connect to busyLevelChanged()
// signal and suspend their operation if the current busy level is higher
// than the busy level of their operation. If a new operation is started,
// it needs to be immediatelly suspended if the current busy level is higher!
// Note that there can be only one level per object,
// so if one object is responsible for more operations,
// it needs to use helper objects for setBusyLevel().
void BusyLevelManager::setBusyLevel( QObject* obj, BusyLevel level ) {
LOG("BUSY:" << level << ":" << obj << ":" << obj->className() );
if( level > BUSY_NONE ) {
if( mBusyLevels.contains( obj ) && mBusyLevels[ obj ] == level ) return;
if( !mBusyLevels.contains( obj )) {
connect( obj, SIGNAL( destroyed( QObject* )), this, SLOT( objectDestroyed( QObject* )));
}
mBusyLevels[ obj ] = level;
} else {
mBusyLevels.remove( obj );
disconnect( obj, SIGNAL( destroyed( QObject* )), this, SLOT( objectDestroyed( QObject* )));
}
mDelayedBusyLevelTimer.start( 0, true );
}
void BusyLevelManager::objectDestroyed( QObject* obj ) {
LOG("DESTROYED:" << obj );
mBusyLevels.remove( obj );
mDelayedBusyLevelTimer.start( 0, true );
}
void BusyLevelManager::delayedBusyLevelChanged() {
BusyLevel newLevel = BUSY_NONE;
for( QMap< QObject*, BusyLevel >::ConstIterator it = mBusyLevels.begin();
it != mBusyLevels.end();
++it ) {
newLevel = QMAX( newLevel, *it );
}
if( newLevel != mCurrentBusyLevel ) {
LOG("CHANGED BUSY:" << newLevel);
mCurrentBusyLevel = newLevel;
emit busyLevelChanged( newLevel );
}
}
BusyLevel BusyLevelManager::busyLevel() const {
return mCurrentBusyLevel;
}
} // namespace
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