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