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122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/*
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* ResourceProvider.h - header file for ResourceProvider
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*
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* Copyright (c) 2009-2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
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*
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* This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
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*
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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
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (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 GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program (see COPYING); if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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*/
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#ifndef _RESOURCE_PROVIDER_H
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#define _RESOURCE_PROVIDER_H
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#include <QtCore/QByteArray>
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#include <QtCore/QObject>
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#include <QtCore/QString>
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class ResourceDB;
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class ResourceItem;
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/*! \brief The ResourceProvider class provides an abstract API for various
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* backends that can serve a resource index and data of individual ResourceItems
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*
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* A ResourceProvider abstracts I/O of resource related data. It both serves
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* a resource index (in form of a ResourceDB) and functions such as
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* #fetchData(). Subclasses have to reimplement the pure virtual functions.
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*/
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class ResourceProvider : public QObject
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{
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Q_OBJECT
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public:
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/*! \brief Constructs a ResourceProvider object.
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* \param url A generic URL (can be e.g. a local path or a web URL)
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*/
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ResourceProvider( const QString & _url );
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/*! \brief Destroys the ResourceProvider object. */
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virtual ~ResourceProvider();
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/*! \brief Returns the name of subclass.
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*
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* Used for example for generating a unique file name for the local cache
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* file. */
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virtual QString providerName() const = 0;
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/*! \brief Triggers action to update the database.
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*
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* Subclasses can start to update their index e.g. by directory crawling
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* or downloading an index file from somewhere. */
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virtual void updateDatabase() = 0;
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/*! \brief Determines size of a ResourceItem (e.g. by stat()ing local file).
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* \param item The ResourceItem whose size to determine
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* \ret The determined size of the passed ResourceItem */
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virtual int dataSize( const ResourceItem * _item ) const = 0;
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/*! \brief Fetches data represented by a ResourceItem.
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* \param item The item whose data to fetch
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* \param maxSize A limit for the data size to fetch, -1 for no limit */
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virtual QByteArray fetchData( const ResourceItem * _item,
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int _maxSize = -1 ) const = 0;
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/*! \brief Returns wether this provider provides local resources.
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*
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* This can be important for code which fetches data using a ResourceProvider
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* and which wants to know whether it should cache the fetched data somehow. */
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virtual bool isLocal() const = 0;
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/*! \brief Returns whether the ResourceProvider base class should manage
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* caching of the database.
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*
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* Some special ResourceProvider subclasses that do some kind of proxying
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* should overload this and return false. */
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virtual bool cacheDatabase() const
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{
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return true;
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}
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/*! \brief Returns URL of this ResourceProvider object. */
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inline const QString & url() const
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{
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return m_url;
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}
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/*! \brief Returns full path to local cache file for this ResourceProvider. */
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QString localCacheFile() const;
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/*! \brief Returns pointer to internal ResourceDB. */
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ResourceDB * database()
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{
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return m_database;
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}
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private:
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ResourceDB * m_database;
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QString m_url;
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signals:
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void itemsChanged();
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} ;
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#endif
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