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