strawberry-audio-player-win.../src/smartplaylists/playlistgenerator.h

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/*
* Strawberry Music Player
* This file was part of Clementine.
* Copyright 2010, David Sansome <me@davidsansome.com>
*
* Strawberry 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 3 of the License, or
* (at your option) any later version.
*
* Strawberry 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 Strawberry. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef PLAYLISTGENERATOR_H
#define PLAYLISTGENERATOR_H
#include "config.h"
#include <memory>
#include <QObject>
#include <QByteArray>
#include <QString>
#include "playlist/playlistitem.h"
class CollectionBackend;
class PlaylistGenerator : public QObject, public std::enable_shared_from_this<PlaylistGenerator> {
Q_OBJECT
public:
explicit PlaylistGenerator();
static const int kDefaultLimit;
static const int kDefaultDynamicHistory;
static const int kDefaultDynamicFuture;
enum Type {
Type_None = 0,
Type_Query = 1
};
// Creates a new PlaylistGenerator of the given type
static std::shared_ptr<PlaylistGenerator> Create(const Type type = Type_Query);
// Should be called before Load on a new PlaylistGenerator
void set_collection(CollectionBackend *backend) { backend_ = backend; }
void set_name(const QString &name) { name_ = name; }
CollectionBackend *collection() const { return backend_; }
QString name() const { return name_; }
// Name of the subclass
virtual Type type() const = 0;
// Serializes the PlaylistGenerator's settings
// Called on UI-thread.
virtual void Load(const QByteArray &data) = 0;
// Called on UI-thread.
virtual QByteArray Save() const = 0;
// Creates and returns a playlist
// Called from non-UI thread.
virtual PlaylistItemList Generate() = 0;
// If the generator can be used as a dynamic playlist then GenerateMore should return the next tracks in the sequence.
// The subclass should remember the last GetDynamicHistory() + GetDynamicFuture() tracks,
// and ensure that the tracks returned from this method are not in that set.
virtual bool is_dynamic() const { return false; }
virtual void set_dynamic(const bool dynamic) { Q_UNUSED(dynamic); }
// Called from non-UI thread.
virtual PlaylistItemList GenerateMore(int count) {
Q_UNUSED(count);
return PlaylistItemList();
}
virtual int GetDynamicHistory() { return kDefaultDynamicHistory; }
virtual int GetDynamicFuture() { return kDefaultDynamicFuture; }
signals:
void Error(const QString& message);
protected:
CollectionBackend *backend_;
private:
QString name_;
};
#include "playlistgenerator_fwd.h"
#endif // PLAYLISTGENERATOR_H