246 lines
9.0 KiB
C++
246 lines
9.0 KiB
C++
/*
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* Copyright 2006-2007 Aaron Seigo <aseigo@kde.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Library General Public License as
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* published by the Free Software Foundation; either version 2, or
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* (at your option) any later version.
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*
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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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*
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* You should have received a copy of the GNU Library General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef PLASMA_DATACONTAINER_H
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#define PLASMA_DATACONTAINER_H
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#include <QtCore/QHash>
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#include <QtCore/QObject>
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#include <plasma/plasma_export.h>
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#include <plasma/dataengine.h>
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namespace Plasma
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{
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class DataContainerPrivate;
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/**
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* @class DataContainer plasma/datacontainer.h <Plasma/DataContainer>
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*
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* @brief A set of data exported via a DataEngine
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*
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* Plasma::DataContainer wraps the data exported by a DataEngine
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* implementation, providing a generic wrapper for the data.
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*
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* A DataContainer may have zero or more associated pieces of data which
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* are keyed by strings. The data itself is stored as QVariants. This allows
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* easy and flexible retrieval of the information associated with this object
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* without writing DataContainer or DataEngine specific code in visualizations.
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*
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* If you are creating your own DataContainer objects (and are passing them to
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* DataEngine::addSource()), you normally just need to listen to the
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* updateRequested() signal (as well as any other methods you might have of
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* being notified of new data) and call setData() to actually update the data.
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* Then you need to either trigger the scheduleSourcesUpdated signal of the
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* parent DataEngine or call checkForUpdate() on the DataContainer.
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*
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* You also need to set a suitable name for the source with setObjectName().
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* See DataEngine::addSource() for more information.
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*
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* Note that there is normally no need to subclass DataContainer, except as
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* a way of encapsulating the data retreival for a source, since all notifications
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* are done via signals rather than virtual methods.
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**/
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class PLASMA_EXPORT DataContainer : public QObject
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{
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friend class DataEngine;
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friend class DataEnginePrivate;
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Q_OBJECT
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public:
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/**
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* Constructs a default DataContainer that has no name or data
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* associated with it
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**/
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explicit DataContainer(QObject *parent = 0);
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virtual ~DataContainer();
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/**
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* Returns the data for this DataContainer
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**/
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const DataEngine::Data data() const;
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/**
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* Set a value for a key.
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*
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* This also marks this source as needing to signal an update.
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*
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* If you call setData() directly on a DataContainer, you need to
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* either trigger the scheduleSourcesUpdated() slot for the
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* data engine it belongs to or call checkForUpdate() on the
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* DataContainer.
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*
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* @param key a string used as the key for the data
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* @param value a QVariant holding the actual data. If a invalid
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* QVariant is passed in and the key currently exists in the
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* data, then the data entry is removed
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**/
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void setData(const QString &key, const QVariant &value);
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/**
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* Removes all data currently associated with this source
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*
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* If you call removeAllData() on a DataContainer, you need to
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* either trigger the scheduleSourcesUpdated() slot for the
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* data engine it belongs to or call checkForUpdate() on the
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* DataContainer.
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**/
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void removeAllData();
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/**
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* @return true if the visualization is currently connected
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*/
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bool visualizationIsConnected(QObject *visualization) const;
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/**
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* Connects an object to this DataContainer.
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*
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* May be called repeatedly for the same visualization without
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* side effects
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*
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* @param visualization the object to connect to this DataContainer
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* @param pollingInterval the time in milliseconds between updates
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* @param alignment the clock position to align updates to
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**/
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void connectVisualization(QObject *visualization, uint pollingInterval,
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Plasma::IntervalAlignment alignment);
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/**
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* sets this data container to be automatically stored.
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* @param whether this data container should be stored
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*/
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void setStorageEnable(bool store);
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/**
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* @return true if the data container has been marked for storage
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*/
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bool isStorageEnabled() const;
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/**
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* @return true if the data container has been updated, but not stored
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*/
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bool needsToBeStored() const;
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/**
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* sets that the data container needs to be stored or not.
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* @param whether the data container needs to be stored
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*/
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void setNeedsToBeStored(bool store);
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public Q_SLOTS:
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/**
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* Disconnects an object from this DataContainer.
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*
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* Note that if this source was created by DataEngine::sourceRequestEvent(),
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* it will be deleted by DataEngine once control returns to the event loop.
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**/
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void disconnectVisualization(QObject *visualization);
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/**
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* Forces immediate update signals to all visualizations
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* @since 4.4
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*/
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void forceImmediateUpdate();
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Q_SIGNALS:
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/**
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* Emitted when the data has been updated, allowing visualizations to
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* reflect the new data.
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*
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* Note that you should not normally emit this directly. Instead, use
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* checkForUpdate() or the DataEngine::scheduleSourcesUpdated() slot.
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*
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* @param source the objectName() of the DataContainer (and hence the name
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* of the source) that updated its data
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* @param data the updated data
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**/
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void dataUpdated(const QString &source, const Plasma::DataEngine::Data &data);
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/**
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* Emitted when the last visualization is disconnected.
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*
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* Note that if this source was created by DataEngine::sourceRequestEvent(),
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* it will be deleted by DataEngine once control returns to the event loop
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* after this signal is emitted.
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*
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* @param source the name of the source that became unused
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**/
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void becameUnused(const QString &source);
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/**
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* Emitted when an update is requested.
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*
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* If a polling interval was passed connectVisualization(), this signal
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* will be emitted every time the interval expires.
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*
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* Note that if you create your own DataContainer (and pass it to
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* DataEngine::addSource()), you will need to listen to this signal
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* and refresh the data when it is triggered.
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*
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* @param source the datacontainer the update was requested for. Useful
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* for classes that update the data for several containers.
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**/
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void updateRequested(DataContainer *source);
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protected:
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/**
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* Checks whether any data has changed and, if so, emits dataUpdated().
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**/
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void checkForUpdate();
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/**
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* Returns how long ago, in msecs, that the data in this container was last updated.
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*
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* This is used by DataEngine to compress updates that happen more quickly than the
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* minimum polling interval by calling setNeedsUpdate() instead of calling
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* updateSourceEvent() immediately.
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**/
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uint timeSinceLastUpdate() const;
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/**
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* Indicates that the data should be treated as dirty the next time hasUpdates() is called.
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*
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* This is needed for the case where updateRequested() is triggered but we don't want to
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* update the data immediately because it has just been updated. The second request won't
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* be fulfilled in this case, because we never updated the data and so never called
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* checkForUpdate(). So we claim it needs an update anyway.
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**/
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void setNeedsUpdate(bool update = true);
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protected Q_SLOTS:
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/**
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* Check if the DataContainer is still in use.
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*
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* If not the signal "becameUnused" will be emitted.
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*
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* Warning: The DataContainer may be invalid after calling this function, because a listener
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* to becameUnused() may have deleted it.
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**/
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void checkUsage();
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private:
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friend class SignalRelay;
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DataContainerPrivate *const d;
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};
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} // Plasma namespace
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#endif // multiple inclusion guard
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