src/kitemviews/kfileitemmodelrolesupdater.h

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   This program is free software; you can redistribute it and/or modify  *
   5  *   it under the terms of the GNU General Public License as published by  *
   6  *   the Free Software Foundation; either version 2 of the License, or     *
   7  *   (at your option) any later version.                                   *
   8  *                                                                         *
   9  *   This program is distributed in the hope that it will be useful,       *
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  12  *   GNU General Public License for more details.                          *
  13  *                                                                         *
  14  *   You should have received a copy of the GNU General Public License     *
  15  *   along with this program; if not, write to the                         *
  16  *   Free Software Foundation, Inc.,                                       *
  17  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  18  ***************************************************************************/
  19
  20 #ifndef KFILEITEMMODELROLESUPDATER_H
  21 #define KFILEITEMMODELROLESUPDATER_H
  22
  23 #include <config-nepomuk.h>
  24
  25 #include <KFileItem>
  26 #include <kitemviews/kitemmodelbase.h>
  27
  28 #include <libdolphin_export.h>
  29
  30 #include <QObject>
  31 #include <QSet>
  32 #include <QSize>
  33 #include <QStringList>
  34
  35 class KDirectoryContentsCounter;
  36 class KFileItemModel;
  37 class KJob;
  38 class QPixmap;
  39 class QTimer;
  40
  41 #ifdef HAVE_NEPOMUK
  42     namespace Nepomuk2
  43     {
  44         class ResourceWatcher;
  45         class Resource;
  46         namespace Types
  47         {
  48             class Property;
  49         }
  50     }
  51 #else
  52     // Required for the slot applyChangedNepomukRoles() that
  53     // cannot be ifdefined due to moc.
  54     namespace Nepomuk2
  55     {
  56         class Resource;
  57         namespace Types
  58         {
  59             class Property;
  60         }
  61     }
  62 #endif
  63
  64 /**
  65  * @brief Resolves expensive roles asynchronously and applies them to the KFileItemModel.
  66  *
  67  * KFileItemModel only resolves roles that are inexpensive like e.g. the file name or
  68  * the permissions. Creating previews or determining the MIME-type can be quite expensive
  69  * and KFileItemModelRolesUpdater takes care to update such roles asynchronously.
  70  *
  71  * To prevent a huge CPU and I/O load, these roles are not updated for all
  72  * items, but only for the visible items, some items around the visible area,
  73  * and the items on the first and last pages of the view. This is a compromise
  74  * that aims to minimize the risk that the user sees items with unknown icons
  75  * in the view when scrolling or pressing Home or End.
  76  *
  77  * Determining the roles is done in several phases:
  78  *
  79  * 1.   If the sort role is "slow", it is determined for all items. If this
  80  *      cannot be finished synchronously in 200 ms, the remaining items are
  81  *      handled asynchronously by \a resolveNextSortRole().
  82  *
  83  * 2.   The function startUpdating(), which is called if either the sort role
  84  *      has been successfully determined for all items, or items are inserted
  85  *      in the view, or the visible items might have changed because items
  86  *      were removed or moved, tries to determine the icons for all visible
  87  *      items synchronously for 200 ms. Then:
  88  *
  89  *      (a) If previews are disabled, icons and all other roles are determined
  90  *          asynchronously for the interesting items. This is done by the
  91  *          function \a resolveNextPendingRoles().
  92  *
  93  *      (b) If previews are enabled, a \a KIO::PreviewJob is started that loads
  94  *          the previews for the interesting items. At the same time, the icons
  95  *          for these items are determined asynchronously as fast as possible
  96  *          by \a resolveNextPendingRoles(). This minimizes the risk that the
  97  *          user sees "unknown" icons when scrolling before the previews have
  98  *          arrived.
  99  *
 100  * 3.   Finally, the entire process is repeated for any items that might have
 101  *      changed in the mean time.
 102  */
 103 class LIBDOLPHINPRIVATE_EXPORT KFileItemModelRolesUpdater : public QObject
 104 {
 105     Q_OBJECT
 106
 107 public:
 108     explicit KFileItemModelRolesUpdater(KFileItemModel* model, QObject* parent = 0);
 109     virtual ~KFileItemModelRolesUpdater();
 110
 111     void setIconSize(const QSize& size);
 112     QSize iconSize() const;
 113
 114     /**
 115      * Sets the range of items that are visible currently. The roles
 116      * of visible items are resolved first.
 117      */
 118     void setVisibleIndexRange(int index, int count);
 119
 120     void setMaximumVisibleItems(int count);
 121
 122     /**
 123      * If \a show is set to true, the "iconPixmap" role will be filled with a preview
 124      * of the file. If \a show is false the MIME type icon will be used for the "iconPixmap"
 125      * role.
 126      */
 127     void setPreviewsShown(bool show);
 128     bool previewsShown() const;
 129
 130     /**
 131      * If enabled a small preview gets upscaled to the icon size in case where
 132      * the icon size is larger than the preview. Per default enlarging is
 133      * enabled.
 134      */
 135     void setEnlargeSmallPreviews(bool enlarge);
 136     bool enlargeSmallPreviews() const;
 137
 138     /**
 139      * If \a paused is set to true the asynchronous resolving of roles will be paused.
 140      * State changes during pauses like changing the icon size or the preview-shown
 141      * will be remembered and handled after unpausing.
 142      */
 143     void setPaused(bool paused);
 144     bool isPaused() const;
 145
 146     /**
 147      * Sets the roles that should be resolved asynchronously.
 148      */
 149     void setRoles(const QSet<QByteArray>& roles);
 150     QSet<QByteArray> roles() const;
 151
 152     /**
 153      * Sets the list of enabled thumbnail plugins that are used for previews.
 154      * Per default all plugins enabled in the KConfigGroup "PreviewSettings"
 155      * are used.
 156      *
 157      * For a list of available plugins, call KServiceTypeTrader::self()->query("ThumbCreator").
 158      *
 159      * @see enabledPlugins
 160      */
 161     void setEnabledPlugins(const QStringList& list);
 162
 163     /**
 164      * Returns the list of enabled thumbnail plugins.
 165      * @see setEnabledPlugins
 166      */
 167     QStringList enabledPlugins() const;
 168
 169 private slots:
 170     void slotItemsInserted(const KItemRangeList& itemRanges);
 171     void slotItemsRemoved(const KItemRangeList& itemRanges);
 172     void slotItemsMoved(const KItemRange& itemRange, QList<int> movedToIndexes);
 173     void slotItemsChanged(const KItemRangeList& itemRanges,
 174                           const QSet<QByteArray>& roles);
 175     void slotSortRoleChanged(const QByteArray& current,
 176                              const QByteArray& previous);
 177
 178     /**
 179      * Is invoked after a preview has been received successfully.
 180      * @see startPreviewJob()
 181      */
 182     void slotGotPreview(const KFileItem& item, const QPixmap& pixmap);
 183
 184     /**
 185      * Is invoked after generating a preview has failed.
 186      * @see startPreviewJob()
 187      */
 188     void slotPreviewFailed(const KFileItem& item);
 189
 190     /**
 191      * Is invoked when the preview job has been finished. Starts a new preview
 192      * job if there are any interesting items without previews left, or updates
 193      * the changed items otherwise.     *
 194      * @see startPreviewJob()
 195      */
 196     void slotPreviewJobFinished();
 197
 198     /**
 199      * Resolves the sort role of the next item in m_pendingSortRole, applies it
 200      * to the model, and invokes itself if there are any pending items left. If
 201      * that is not the case, \a startUpdating() is called.
 202      */
 203     void resolveNextSortRole();
 204
 205     /**
 206      * Resolves the icon name and (if previews are disabled) all other roles
 207      * for the next interesting item. If there are no pending items left, any
 208      * changed items are updated.
 209      */
 210     void resolveNextPendingRoles();
 211
 212     /**
 213      * Resolves items that have not been resolved yet after the change has been
 214      * notified by slotItemsChanged(). Is invoked if the m_changedItemsTimer
 215      * expires.
 216      */
 217     void resolveRecentlyChangedItems();
 218
 219     void applyChangedNepomukRoles(const Nepomuk2::Resource& resource, const Nepomuk2::Types::Property& property);
 220
 221     void slotDirectoryContentsCountReceived(const QString& path, int count);
 222
 223 private:
 224     /**
 225      * Starts the updating of all roles. The visible items are handled first.
 226      */
 227     void startUpdating();
 228
 229     /**
 230      * Loads the icons for the visible items. After 200 ms, the function
 231      * stops determining mime types and only loads preliminary icons.
 232      * This is a compromise that prevents that
 233      * (a) the GUI is blocked for more than 200 ms, and
 234      * (b) "unknown" icons could be shown in the view.
 235      */
 236     void updateVisibleIcons();
 237
 238     /**
 239      * Creates previews for the items starting from the first item in
 240      * m_pendingPreviewItems.
 241      * @see slotGotPreview()
 242      * @see slotPreviewFailed()
 243      * @see slotPreviewJobFinished()
 244      */
 245     void startPreviewJob();
 246
 247     /**
 248      * Ensures that icons, previews, and other roles are determined for any
 249      * items that have been changed.
 250      */
 251     void updateChangedItems();
 252
 253     /**
 254      * Resolves the sort role of the item and applies it to the model.
 255      */
 256     void applySortRole(int index);
 257
 258     void applySortProgressToModel();
 259
 260     enum ResolveHint {
 261         ResolveFast,
 262         ResolveAll
 263     };
 264     bool applyResolvedRoles(const KFileItem& item, ResolveHint hint);
 265     QHash<QByteArray, QVariant> rolesData(const KFileItem& item);
 266
 267     /**
 268      * @return The number of items of the path \a path.
 269      */
 270     int subItemsCount(const QString& path) const;
 271
 272     /**
 273      * Must be invoked if a property has been changed that affects
 274      * the look of the preview. Takes care to update all previews.
 275      */
 276     void updateAllPreviews();
 277
 278     void killPreviewJob();
 279
 280     QList<int> indexesToResolve() const;
 281
 282 private:
 283     enum State {
 284         Idle,
 285         Paused,
 286         ResolvingSortRole,
 287         ResolvingAllRoles,
 288         PreviewJobRunning
 289     };
 290
 291     State m_state;
 292
 293     // Property changes during pausing must be remembered to be able
 294     // to react when unpausing again:
 295     bool m_previewChangedDuringPausing;
 296     bool m_iconSizeChangedDuringPausing;
 297     bool m_rolesChangedDuringPausing;
 298
 299     // Property for setPreviewsShown()/previewsShown().
 300     bool m_previewShown;
 301
 302     // Property for setEnlargeSmallPreviews()/enlargeSmallPreviews()
 303     bool m_enlargeSmallPreviews;
 304
 305     // True if the role "iconPixmap" should be cleared when resolving the next
 306     // role with resolveRole(). Is necessary if the preview gets disabled
 307     // during the roles-updater has been paused by setPaused().
 308     bool m_clearPreviews;
 309
 310     // Remembers which items have been handled already, to prevent that
 311     // previews and other expensive roles are determined again.
 312     QSet<KFileItem> m_finishedItems;
 313
 314     KFileItemModel* m_model;
 315     QSize m_iconSize;
 316     int m_firstVisibleIndex;
 317     int m_lastVisibleIndex;
 318     int m_maximumVisibleItems;
 319     QSet<QByteArray> m_roles;
 320     QSet<QByteArray> m_resolvableRoles;
 321     QStringList m_enabledPlugins;
 322
 323     // Items for which the sort role still has to be determined.
 324     QSet<KFileItem> m_pendingSortRoleItems;
 325
 326     // Indexes of items which still have to be handled by
 327     // resolveNextPendingRoles().
 328     QList<int> m_pendingIndexes;
 329
 330     // Items which have been left over from the last call of startPreviewJob().
 331     // A new preview job will be started from them once the first one finishes.
 332     KFileItemList m_pendingPreviewItems;
 333
 334     KJob* m_previewJob;
 335
 336     // When downloading or copying large files, the slot slotItemsChanged()
 337     // will be called periodically within a quite short delay. To prevent
 338     // a high CPU-load by generating e.g. previews for each notification, the update
 339     // will be postponed until no file change has been done within a longer period
 340     // of time.
 341     QTimer* m_recentlyChangedItemsTimer;
 342     QSet<KFileItem> m_recentlyChangedItems;
 343
 344     // Items which have not been changed repeatedly recently.
 345     QSet<KFileItem> m_changedItems;
 346
 347     KDirectoryContentsCounter* m_directoryContentsCounter;
 348
 349 #ifdef HAVE_NEPOMUK
 350     Nepomuk2::ResourceWatcher* m_nepomukResourceWatcher;
 351     mutable QHash<QUrl, KUrl> m_nepomukUriItems;
 352 #endif
 353 };
 354
 355 #endif
 356
 357