1 // vim: set tabstop=4 shiftwidth=4 expandtab:
2 /*
3 Gwenview: an image viewer
4 Copyright 2008 Aurélien Gâteau <agateau@kde.org>
5 
6 This program is free software; you can redistribute it and/or
7 modify it under the terms of the GNU General Public License
8 as published by the Free Software Foundation; either version 2
9 of the License, or (at your option) any later version.
10 
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 GNU General Public License for more details.
15 
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street, Fifth Floor, Cambridge, MA 02110-1301, USA.
19 
20 */
21 #ifndef ABSTRACTSEMANTICINFOBACKEND_H
22 #define ABSTRACTSEMANTICINFOBACKEND_H
23 
24 #include <lib/gwenviewlib_export.h>
25 
26 // Qt
27 #include <QObject>
28 #include <QSet>
29 
30 // KF
31 
32 // Local
33 
34 class QUrl;
35 
36 namespace Gwenview
37 {
38 using SemanticInfoTag = QString;
39 
40 /**
41  * This class represents the set of tags associated to an url.
42  *
43  * It provides convenience methods to convert to and from QVariant, which are
44  * useful to communicate with SemanticInfoDirModel.
45  */
46 class GWENVIEWLIB_EXPORT TagSet : public QSet<SemanticInfoTag>
47 {
48 public:
49     TagSet();
50     TagSet(const QSet<SemanticInfoTag> &);
51 
52     QVariant toVariant() const;
53     static TagSet fromVariant(const QVariant &);
54     static TagSet fromList(const QList<SemanticInfoTag> &);
55 
56 private:
57     TagSet(const QList<SemanticInfoTag> &);
58 };
59 
60 /**
61  * A POD struct used by AbstractSemanticInfoBackEnd to store the metadata
62  * associated to an url.
63  */
64 struct SemanticInfo {
65     int mRating;
66     QString mDescription;
67     TagSet mTags;
68 };
69 
70 /**
71  * An abstract class, used by SemanticInfoDirModel to store and retrieve metadata.
72  */
73 class AbstractSemanticInfoBackEnd : public QObject
74 {
75     Q_OBJECT
76 public:
77     explicit AbstractSemanticInfoBackEnd(QObject *parent);
78 
79     virtual TagSet allTags() const = 0;
80 
81     virtual void refreshAllTags() = 0;
82 
83     virtual void storeSemanticInfo(const QUrl &, const SemanticInfo &) = 0;
84 
85     virtual void retrieveSemanticInfo(const QUrl &) = 0;
86 
87     virtual QString labelForTag(const SemanticInfoTag &) const = 0;
88 
89     /**
90      * Return a tag for a label. Will emit tagAdded() if the tag had to be
91      * created.
92      */
93     virtual SemanticInfoTag tagForLabel(const QString &) = 0;
94 
95 Q_SIGNALS:
96     void semanticInfoRetrieved(const QUrl &, const SemanticInfo &);
97 
98     /**
99      * Emitted whenever a new tag is added to allTags()
100      */
101     void tagAdded(const SemanticInfoTag &, const QString &label);
102 };
103 
104 } // namespace
105 
106 #endif /* ABSTRACTSEMANTICINFOBACKEND_H */
107