plasma-framework/datacontainer.h

143 lines
4.6 KiB
C++

/*
* Copyright 2006-2007 Aaron Seigo <aseigo@kde.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2, 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 Library General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef PLASMA_DATACONTAINER_H
#define PLASMA_DATACONTAINER_H
#include <QtCore/QHash>
#include <QtCore/QObject>
#include <plasma/plasma_export.h>
#include <plasma/dataengine.h>
namespace Plasma
{
/**
* @brief A set of data exported via a DataEngine
*
* Plasma::DataContainer wraps the data exported by a DataEngine
* implementation, providing a generic wrapper for the data.
*
* A DataContainer may have zero or more associated pieces of data which
* are keyed by strings. The data itself is stored as QVariants. This allows
* easy and flexible retrieval of the information associated with this object
* without writing DataContainer or DataEngine specific code in visualizations.
**/
class PLASMA_EXPORT DataContainer : public QObject
{
Q_OBJECT
public:
//typedef QHash<QString, DataEngine::SourceDict> Grouping;
/**
* Constructs a default DataContainer, which has no name or data
* associated with it
**/
explicit DataContainer(QObject* parent = 0);
virtual ~DataContainer();
/**
* Returns the data for this DataContainer
**/
const DataEngine::Data data() const;
/**
* Set a value for a key. This also marks this source as needing
* to signal an update. After calling this, a call to checkForUpdate()
* is done by the engine. This allows for batching updates.
*
* @param key a string used as the key for the data
* @param value a QVariant holding the actual data. If a null or invalid
* QVariant is passed in and the key currently exists in the
* data, then the data entry is removed
**/
void setData(const QString& key, const QVariant& value);
/**
* Clears all data currently associated with this source
**/
void clearData();
/**
* Checks for whether the data has changed and therefore an update
* signal needs to be emitted.
**/
void checkForUpdate();
/**
* Returns how long ago, in msecs, that the data in this container was last updated
**/
int timeSinceLastUpdate() const;
/**
* @internal
**/
bool hasUpdates() const;
public Q_SLOTS:
/**
* Check if the DataContainer is still in use.
* If not the signal "unused" will be emitted.
* Warning: The DataContainer may be invalid after calling this function.
*/
void checkUsage();
/**
* Connects an object to this DataContainer. May be called repeatedly
* for the same visualization without side effects
*
* @param visualization the object to connect to this DataContainer
* @param updateInterval the time in milliseconds between updates
**/
void connectVisualization(QObject* visualization, uint updateInterval, Plasma::IntervalAlignment alignment);
/**
* Disconnects an object from this DataContainer.
**/
void disconnectVisualization(QObject* visualization);
Q_SIGNALS:
/**
* Emitted when the data has been updated, allowing visualization to
* reflect the new data.
**/
void dataUpdated(const QString& source, const Plasma::DataEngine::Data& data);
/**
* Emitted when this source becomes unused
**/
void unused(const QString& source);
/**
* Emitted when the source, usually due to an internal timer firing,
* requests to be updated.
**/
void requestUpdate(DataContainer *source);
private:
friend class SignalRelay;
class Private;
Private* const d;
};
} // Plasma namespace
#endif // multiple inclusion guard