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 = 0, int count = 0);
  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  * An 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 grouping-capabilities.
  56  *
  57  * Also optionally it is possible to provide a tree of items by implementing the methods
  58  * setExpanded(), isExpanded(), isExpandable() and expandedParentsCount().
  59  */
  60 class LIBDOLPHINPRIVATE_EXPORT KItemModelBase : public QObject
  61 {
  62     Q_OBJECT
  63
  64 public:
  65     KItemModelBase(QObject* parent = 0);
  66     explicit KItemModelBase(const QByteArray& sortRole, QObject* parent = 0);
  67     virtual ~KItemModelBase();
  68
  69     /** @return The number of items. */
  70     virtual int count() const = 0;
  71
  72     virtual QHash<QByteArray, QVariant> data(int index) const = 0;
  73
  74     /**
  75      * Sets the data for the item at \a index to the given \a values. Returns true
  76      * if the data was set on the item; returns false otherwise.
  77      *
  78      * The default implementation does not set the data, and will always return
  79      * false.
  80      */
  81     virtual bool setData(int index, const QHash<QByteArray, QVariant>& values);
  82
  83     /**
  84      * Enables/disables the grouped sorting. The method KItemModelBase::onGroupedSortingChanged() will be
  85      * called so that model-implementations can react on the grouped-sorting change. Afterwards the
  86      * signal groupedSortingChanged() will be emitted. If the grouped sorting is enabled, the method
  87      * KItemModelBase::groups() must be implemented.
  88      */
  89     void setGroupedSorting(bool grouped);
  90     bool groupedSorting() const;
  91
  92     /**
  93      * Sets the sort-role to \a role. The method KItemModelBase::onSortRoleChanged() will be
  94      * called so that model-implementations can react on the sort-role change. Afterwards the
  95      * signal sortRoleChanged() will be emitted.
  96      */
  97     void setSortRole(const QByteArray& role);
  98     QByteArray sortRole() const;
  99
 100     /**
 101      * Sets the sort order to \a order. The method KItemModelBase::onSortOrderChanged() will be
 102      * called so that model-implementations can react on the sort order change. Afterwards the
 103      * signal sortOrderChanged() will be emitted.
 104      */
 105     void setSortOrder(Qt::SortOrder order);
 106     Qt::SortOrder sortOrder() const;
 107
 108     /**
 109      * @return Translated description for the \p role. The description is e.g. used
 110      *         for the header in KItemListView.
 111      */
 112     virtual QString roleDescription(const QByteArray& role) const;
 113
 114     /**
 115      * @return List of group headers. Each list-item consists of the index of the item
 116      *         that represents the first item of a group and a value represented
 117      *         as QVariant. The value is shown by an instance of KItemListGroupHeader.
 118      *         Per default an empty list is returned.
 119      */
 120     virtual QList<QPair<int, QVariant> > groups() const;
 121
 122     /**
 123      * Expands the item with the index \a index if \a expanded is true.
 124      * If \a expanded is false the item will be collapsed.
 125      *
 126      * Per default no expanding of items is implemented. When implementing
 127      * this method it is mandatory to overwrite KItemModelBase::isExpandable()
 128      * and KItemListView::supportsExpandableItems() to return true.
 129      *
 130      * @return True if the operation has been successful.
 131      */
 132     virtual bool setExpanded(int index, bool expanded);
 133
 134     /**
 135      * @return True if the item with the index \a index is expanded.
 136      *         Per default no expanding of items is implemented. When implementing
 137      *         this method it is mandatory to overwrite KItemModelBase::isExpandable()
 138      *         and KItemListView::supportsExpandableItems() to return true.
 139      */
 140     virtual bool isExpanded(int index) const;
 141
 142     /**
 143      * @return True if expanding and collapsing of the item with the index \a index
 144      *         is supported. Per default false is returned.
 145      */
 146     virtual bool isExpandable(int index) const;
 147
 148     /**
 149      * @return Number of expanded parent items for the item with the given index.
 150      *         Per default 0 is returned.
 151      */
 152     virtual int expandedParentsCount(int index) const;
 153
 154     /**
 155      * @return MIME-data for the items given by \a indexes. The default implementation
 156      *         returns 0. The ownership of the returned instance is in the hand of the
 157      *         caller of this method. The method must be implemented if dragging of
 158      *         items should be possible.
 159      */
 160     virtual QMimeData* createMimeData(const QSet<int>& indexes) const;
 161
 162     /**
 163      * @return Reimplement this to return the index for the first item
 164      * beginning with string typed in through the keyboard, -1 if not found.
 165      * @param text              the text which has been typed in through the keyboard
 166      * @param startFromIndex    the index from which to start searching from
 167      */
 168     virtual int indexForKeyboardSearch(const QString& text, int startFromIndex = 0) const;
 169
 170     /**
 171      * @return True, if the item with the index \a index basically supports dropping.
 172      *         Per default false is returned.
 173      *
 174      *         The information is used only to give a visual feedback during a drag operation
 175      *         and not to decide whether a drop event gets emitted. It is it is still up to
 176      *         the receiver of KItemListController::itemDropEvent() to decide how to handle
 177      *         the drop event.
 178      */
 179     // TODO: Should the MIME-data be passed too so that the model can do a more specific
 180     // decision whether it accepts the drop?
 181     virtual bool supportsDropping(int index) const;
 182
 183 signals:
 184     /**
 185      * Is emitted if one or more items have been inserted. Each item-range consists
 186      * of:
 187      * - an index where items have been inserted
 188      * - the number of inserted items.
 189      * The index of each item-range represents the index of the model
 190      * before the items have been inserted.
 191      *
 192      * For the item-ranges it is assured that:
 193      * - They don't overlap
 194      * - The index of item-range n is smaller than the index of item-range n + 1.
 195      */
 196     void itemsInserted(const KItemRangeList& itemRanges);
 197
 198     /**
 199      * Is emitted if one or more items have been removed. Each item-range consists
 200      * of:
 201      * - an index where items have been inserted
 202      * - the number of inserted items.
 203      * The index of each item-range represents the index of the model
 204      * before the items have been removed.
 205      *
 206      * For the item-ranges it is assured that:
 207      * - They don't overlap
 208      * - The index of item-range n is smaller than the index of item-range n + 1.
 209      */
 210     void itemsRemoved(const KItemRangeList& itemRanges);
 211
 212     /**
 213      * Is emitted if one ore more items get moved.
 214      * @param itemRange      Item-range that gets moved to a new position.
 215      * @param movedToIndexes New positions for each element of the item-range.
 216      *
 217      * For example if the model has 10 items and the items 0 and 1 get exchanged
 218      * with the items 5 and 6 then the parameters look like this:
 219      * - itemRange: has the index 0 and a count of 7.
 220      * - movedToIndexes: Contains the seven values 5, 6, 2, 3, 4, 0, 1
 221      *
 222      * This signal implies that the groups might have changed. Therefore,
 223      * gropusChanged() is not emitted if this signal is emitted.
 224      */
 225     void itemsMoved(const KItemRange& itemRange, const QList<int>& movedToIndexes);
 226
 227     void itemsChanged(const KItemRangeList& itemRanges, const QSet<QByteArray>& roles);
 228
 229     /**
 230      * Is emitted if the groups have changed, even though the order of the
 231      * items has not been modified.
 232      */
 233     void groupsChanged();
 234
 235     void groupedSortingChanged(bool current);
 236     void sortRoleChanged(const QByteArray& current, const QByteArray& previous);
 237     void sortOrderChanged(Qt::SortOrder current, Qt::SortOrder previous);
 238
 239 protected:
 240     /**
 241      * Is invoked if the grouped sorting has been changed by KItemModelBase::setGroupedSorting(). Allows
 242      * to react on the changed grouped sorting  before the signal groupedSortingChanged() will be emitted.
 243      */
 244     virtual void onGroupedSortingChanged(bool current);
 245
 246     /**
 247      * Is invoked if the sort role has been changed by KItemModelBase::setSortRole(). Allows
 248      * to react on the changed sort role before the signal sortRoleChanged() will be emitted.
 249      * The implementation must assure that the items are sorted by the role given by \a current.
 250      * Usually the most efficient way is to emit a
 251      * itemsRemoved() signal for all items, reorder the items internally and to emit a
 252      * itemsInserted() signal afterwards.
 253      */
 254     virtual void onSortRoleChanged(const QByteArray& current, const QByteArray& previous);
 255
 256     /**
 257      * Is invoked if the sort order has been changed by KItemModelBase::setSortOrder(). Allows
 258      * to react on the changed sort order before the signal sortOrderChanged() will be emitted.
 259      * The implementation must assure that the items are sorted by the order given by \a current.
 260      * Usually the most efficient way is to emit a
 261      * itemsRemoved() signal for all items, reorder the items internally and to emit a
 262      * itemsInserted() signal afterwards.
 263      */
 264     virtual void onSortOrderChanged(Qt::SortOrder current, Qt::SortOrder previous);
 265
 266 private:
 267     bool m_groupedSorting;
 268     QByteArray m_sortRole;
 269     Qt::SortOrder m_sortOrder;
 270 };
 271
 272 inline Qt::SortOrder KItemModelBase::sortOrder() const
 273 {
 274     return m_sortOrder;
 275 }
 276
 277 #endif
 278
 279