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