src/kitemviews/kitemmodelbase.h

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   Based on the Itemviews NG project from Trolltech Labs:                *
   5  *   http://qt.gitorious.org/qt-labs/itemviews-ng                          *
   6  *                                                                         *
   7  *   This program is free software; you can redistribute it and/or modify  *
   8  *   it under the terms of the GNU General Public License as published by  *
   9  *   the Free Software Foundation; either version 2 of the License, or     *
  10  *   (at your option) any later version.                                   *
  11  *                                                                         *
  12  *   This program is distributed in the hope that it will be useful,       *
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  15  *   GNU General Public License for more details.                          *
  16  *                                                                         *
  17  *   You should have received a copy of the GNU General Public License     *
  18  *   along with this program; if not, write to the                         *
  19  *   Free Software Foundation, Inc.,                                       *
  20  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  21  ***************************************************************************/
  22
  23 #ifndef KITEMMODELBASE_H
  24 #define KITEMMODELBASE_H
  25
  26 #include <libdolphin_export.h>
  27
  28 #include <QHash>
  29 #include <QObject>
  30 #include <QSet>
  31 #include <QVariant>
  32
  33 class QMimeData;
  34
  35 struct KItemRange
  36 {
  37     KItemRange(int index, int count);
  38     int index;
  39     int count;
  40
  41     bool operator == (const KItemRange& other) const;
  42 };
  43 typedef QList<KItemRange> KItemRangeList;
  44
  45 /**
  46  * @brief Base class for model implementations used by KItemListView and KItemListController.
  47  *
  48  * A item-model consists of a variable number of items. The number of items
  49  * is given by KItemModelBase::count(). The data of an item is accessed by a unique index
  50  * with KItemModelBase::data(). The indexes are integer-values counting from 0 to the
  51  * KItemModelBase::count() - 1.
  52  *
  53  * One item consists of a variable number of role/value-pairs.
  54  *
  55  * A model can optionally provide sorting- and/or grouping-capabilities.
  56  */
  57 class LIBDOLPHINPRIVATE_EXPORT KItemModelBase : public QObject
  58 {
  59     Q_OBJECT
  60
  61 public:
  62     KItemModelBase(QObject* parent = 0);
  63     KItemModelBase(const QByteArray& groupRole, const QByteArray& sortRole, QObject* parent = 0);
  64     virtual ~KItemModelBase();
  65
  66     /** @return The number of items. */
  67     virtual int count() const = 0;
  68
  69     virtual QHash<QByteArray, QVariant> data(int index) const = 0;
  70
  71     /**
  72      * Sets the data for the item at \a index to the given \a values. Returns true
  73      * if the data was set on the item; returns false otherwise.
  74      *
  75      * The default implementation does not set the data, and will always return
  76      * false.
  77      */
  78     virtual bool setData(int index, const QHash<QByteArray, QVariant>& values);
  79
  80     /**
  81      * @return True if the model supports grouping of data. Per default false is returned.
  82      *         If the model should support grouping it is necessary to overwrite
  83      *         this method to return true and to implement KItemModelBase::onGroupRoleChanged().
  84      */
  85     virtual bool supportsGrouping() const;
  86
  87     /**
  88      * Sets the group-role to \a role. The method KItemModelBase::onGroupRoleChanged() will be
  89      * called so that model-implementations can react on the group-role change. Afterwards the
  90      * signal groupRoleChanged() will be emitted.
  91      */
  92     void setGroupRole(const QByteArray& role);
  93     QByteArray groupRole() const;
  94
  95     /**
  96      * @return True if the model supports sorting of data. Per default false is returned.
  97      *         If the model should support sorting it is necessary to overwrite
  98      *         this method to return true and to implement KItemModelBase::onSortRoleChanged().
  99      */
 100     virtual bool supportsSorting() const;
 101
 102     /**
 103      * Sets the sor-role to \a role. The method KItemModelBase::onSortRoleChanged() will be
 104      * called so that model-implementations can react on the sort-role change. Afterwards the
 105      * signal sortRoleChanged() will be emitted.
 106      */
 107     void setSortRole(const QByteArray& role);
 108     QByteArray sortRole() const;
 109
 110     virtual QString roleDescription(const QByteArray& role) const;
 111
 112     /**
 113      * @return MIME-data for the items given by \a indexes. The default implementation
 114      *         returns 0. The ownership of the returned instance is in the hand of the
 115      *         caller of this method.
 116      */
 117     virtual QMimeData* createMimeData(const QSet<int>& indexes) const;
 118
 119     /**
 120      * @return Reimplement this to return the index for the first item
 121      * beginning with string typed in through the keyboard, -1 if not found.
 122      * @param text              the text which has been typed in through the keyboard
 123      * @param startFromIndex    the index from which to start searching from
 124      */
 125     virtual int indexForKeyboardSearch(const QString& text, int startFromIndex = 0) const;
 126
 127     /**
 128      * @return True, if the item with the index \a index basically supports dropping.
 129      *         Per default false is returned.
 130      *
 131      *         The information is used only to give a visual feedback during a drag operation
 132      *         and not to decide whether a drop event gets emitted. It is it is still up to
 133      *         the receiver of KItemListController::itemDropEvent() to decide how to handle
 134      *         the drop event.
 135      */
 136     // TODO: Should the MIME-data be passed too so that the model can do a more specific
 137     // decision whether it accepts the drop?
 138     virtual bool supportsDropping(int index) const;
 139
 140 signals:
 141     /**
 142      * Is emitted if one or more items have been inserted. Each item-range consists
 143      * of:
 144      * - an index where items have been inserted
 145      * - the number of inserted items.
 146      * The index of each item-range represents the index of the model
 147      * before the items have been inserted.
 148      *
 149      * For the item-ranges it is assured that:
 150      * - They don't overlap
 151      * - The index of item-range n is smaller than the index of item-range n + 1.
 152      */
 153     void itemsInserted(const KItemRangeList& itemRanges);
 154
 155     /**
 156      * Is emitted if one or more items have been removed. Each item-range consists
 157      * of:
 158      * - an index where items have been inserted
 159      * - the number of inserted items.
 160      * The index of each item-range represents the index of the model
 161      * before the items have been removed.
 162      *
 163      * For the item-ranges it is assured that:
 164      * - They don't overlap
 165      * - The index of item-range n is smaller than the index of item-range n + 1.
 166      */
 167     void itemsRemoved(const KItemRangeList& itemRanges);
 168
 169     /**
 170      * Is emitted if one ore more items get moved.
 171      * @param itemRanges     Item-ranges that get moved to a new position.
 172      * @param movedToIndexes New position of the ranges.
 173      * It is assured that the itemRanges list has the same size as the movedToIndexes list.
 174      *
 175      * For the item-ranges it is assured that:
 176      * - They don't overlap
 177      * - The index of item-range n is smaller than the index of item-range n + 1.
 178      */
 179     void itemsMoved(const KItemRangeList& itemRanges, const QList<int> movedToIndexes);
 180
 181     void itemsChanged(const KItemRangeList& itemRanges, const QSet<QByteArray>& roles);
 182
 183     void groupRoleChanged(const QByteArray& current, const QByteArray& previous);
 184     void sortRoleChanged(const QByteArray& current, const QByteArray& previous);
 185
 186 protected:
 187     /**
 188      * Is invoked if the group role has been changed by KItemModelBase::setGroupRole(). Allows
 189      * to react on the changed group role before the signal groupRoleChanged() will be emitted.
 190      * The implementation must assure that the items are sorted in a way that they are grouped
 191      * by the role given by \a current. Usually the most efficient way is to emit a
 192      * itemsRemoved() signal for all items, reorder the items internally and to emit a
 193      * itemsInserted() signal afterwards.
 194      */
 195     virtual void onGroupRoleChanged(const QByteArray& current, const QByteArray& previous);
 196
 197     /**
 198      * Is invoked if the sort role has been changed by KItemModelBase::setSortRole(). Allows
 199      * to react on the changed sort role before the signal sortRoleChanged() will be emitted.
 200      * The implementation must assure that the items are sorted by the role given by \a current.
 201      * Usually the most efficient way is to emit a
 202      * itemsRemoved() signal for all items, reorder the items internally and to emit a
 203      * itemsInserted() signal afterwards.
 204      */
 205     virtual void onSortRoleChanged(const QByteArray& current, const QByteArray& previous);
 206
 207 private:
 208     QByteArray m_groupRole;
 209     QByteArray m_sortRole;
 210 };
 211
 212 #endif
 213
 214