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109 lines
3.3 KiB
109 lines
3.3 KiB
// vim: set tabstop=4 shiftwidth=4 noexpandtab
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/*
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Gwenview - A simple image viewer for KDE
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Copyright 2000-2004 Aurélien Gâteau
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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, Boston, MA 02110-1301, USA.
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*/
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// Qt
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#include <qtimer.h>
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// KDE
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#include <kdebug.h>
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// Local
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#include "busylevelmanager.moc"
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namespace Gwenview {
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#undef ENABLE_LOG
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#undef LOG
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//#define ENABLE_LOG
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#ifdef ENABLE_LOG
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#define LOG(x) kdDebug() << k_funcinfo << x << endl
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#else
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#define LOG(x) ;
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#endif
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BusyLevelManager::BusyLevelManager()
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: mCurrentBusyLevel( BUSY_NONE )
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{
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connect( &mDelayedBusyLevelTimer, SIGNAL( timeout()),
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this, SLOT( delayedBusyLevelChanged()));
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}
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BusyLevelManager* BusyLevelManager::instance() {
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static BusyLevelManager manager;
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return &manager;
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}
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// How the busy level stuff works:
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// This system allows suspending less important tasks while more important
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// task are active, i.e. no thumbnails are generated when the viewed
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// image is being loaded and painted.
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// All objects responsible for operations set their busy level
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// to the matching value when the operation starts and reset their busy
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// level when the operation is done. They all connect to busyLevelChanged()
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// signal and suspend their operation if the current busy level is higher
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// than the busy level of their operation. If a new operation is started,
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// it needs to be immediatelly suspended if the current busy level is higher!
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// Note that there can be only one level per object,
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// so if one object is responsible for more operations,
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// it needs to use helper objects for setBusyLevel().
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void BusyLevelManager::setBusyLevel( QObject* obj, BusyLevel level ) {
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LOG("BUSY:" << level << ":" << obj << ":" << obj->className() );
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if( level > BUSY_NONE ) {
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if( mBusyLevels.contains( obj ) && mBusyLevels[ obj ] == level ) return;
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if( !mBusyLevels.contains( obj )) {
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connect( obj, SIGNAL( destroyed( QObject* )), this, SLOT( objectDestroyed( QObject* )));
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}
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mBusyLevels[ obj ] = level;
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} else {
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mBusyLevels.remove( obj );
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disconnect( obj, SIGNAL( destroyed( QObject* )), this, SLOT( objectDestroyed( QObject* )));
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}
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mDelayedBusyLevelTimer.start( 0, true );
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}
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void BusyLevelManager::objectDestroyed( QObject* obj ) {
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LOG("DESTROYED:" << obj );
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mBusyLevels.remove( obj );
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mDelayedBusyLevelTimer.start( 0, true );
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}
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void BusyLevelManager::delayedBusyLevelChanged() {
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BusyLevel newLevel = BUSY_NONE;
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for( QMap< QObject*, BusyLevel >::ConstIterator it = mBusyLevels.begin();
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it != mBusyLevels.end();
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++it ) {
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newLevel = QMAX( newLevel, *it );
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}
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if( newLevel != mCurrentBusyLevel ) {
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LOG("CHANGED BUSY:" << newLevel);
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mCurrentBusyLevel = newLevel;
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emit busyLevelChanged( newLevel );
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}
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}
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BusyLevel BusyLevelManager::busyLevel() const {
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return mCurrentBusyLevel;
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}
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} // namespace
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