kfile/kfilepreviewgenerator.h

   1 /*******************************************************************************
   2  *   Copyright (C) 2008-2009 by Peter Penz <peter.penz@gmx.at>                 *
   3  *                                                                             *
   4  *   This library is free software; you can redistribute it and/or             *
   5  *   modify it under the terms of the GNU Library General Public               *
   6  *   License as published by the Free Software Foundation; either              *
   7  *   version 2 of the License, or (at your option) any later version.          *
   8  *                                                                             *
   9  *   This library 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 GNU         *
  12  *   Library General Public License for more details.                          *
  13  *                                                                             *
  14  *   You should have received a copy of the GNU Library General Public License *
  15  *   along with this library; see the file COPYING.LIB.  If not, write to      *
  16  *   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,      *
  17  *   Boston, MA 02110-1301, USA.                                               *
  18  *******************************************************************************/
  19
  20 #ifndef KFILEPREVIEWGENERATOR_H
  21 #define KFILEPREVIEWGENERATOR_H
  22
  23 #include <kfile_export.h>
  24
  25 #include <QtCore/QObject>
  26
  27 class KAbstractViewAdapter;
  28 class KDirModel;
  29 class QAbstractItemView;
  30 class QAbstractProxyModel;
  31
  32 /**
  33  * @brief Generates previews for files of an item view.
  34  *
  35  * Per default a preview is generated for each item.
  36  * Additionally the clipboard is checked for cut items.
  37  * The icon state for cut items gets dimmed automatically.
  38  *
  39  * The following strategy is used when creating previews:
  40  * - The previews for currently visible items are created before
  41  *   the previews for invisible items.
  42  * - If the user changes the visible area by using the scrollbars,
  43  *   all pending previews get paused. As soon as the user stays
  44  *   on the same position for a short delay, the previews are
  45  *   resumed. Also in this case the previews for the visible items
  46  *   are generated first.
  47  *
  48  * @since 4.2
  49  */
  50 class KFILE_EXPORT KFilePreviewGenerator : public QObject
  51 {
  52     Q_OBJECT
  53
  54 public:
  55     /**
  56      * @param parent  Item view containing the file items where previews should
  57      *                be generated. It is mandatory that the item view specifies
  58      *                an icon size by QAbstractItemView::setIconSize() and that
  59      *                the model of the view (or the source model of the proxy model)
  60      *                is an instance of KDirModel. Otherwise no previews will be generated.
  61      */
  62     KFilePreviewGenerator(QAbstractItemView* parent);
  63
  64     /** @internal */
  65     KFilePreviewGenerator(KAbstractViewAdapter* parent, QAbstractProxyModel* model);
  66
  67     virtual ~KFilePreviewGenerator();
  68
  69     /**
  70      * If \a show is set to true, a preview is generated for each item. If \a show
  71      * is false, the MIME type icon of the item is shown instead. Per default showing
  72      * the preview is turned on. Note that it is mandatory that the item view
  73      * specifies an icon size by QAbstractItemView::setIconSize(), otherwise
  74      * KFilePreviewGenerator::isPreviewShown() will always return false.
  75      */
  76     void setPreviewShown(bool show);
  77     bool isPreviewShown() const;
  78
  79     /**
  80      * Updates the previews for all already available items. Usually it is only
  81      * necessary to invoke this method when the icon size of the abstract item view
  82      * has been changed by QAbstractItemView::setIconSize().
  83      */
  84     void updatePreviews();
  85
  86     /** Cancels all pending previews. */
  87     void cancelPreviews();
  88
  89     /**
  90      * Sets the list of enabled thumbnail plugins.
  91      * If the list is empty, all plugins will be enabled.
  92      * All plugins are enabled by default.
  93      *
  94      * Note that this method doesn't cause already generated previews
  95      * to be regenerated.
  96      *
  97      * For a list of available plugins, call KServiceTypeTrader::self()->query("ThumbCreator").
  98      *
  99      * @see enabledPlugins
 100      */
 101     void setEnabledPlugins(const QStringList& list);
 102
 103     /**
 104      * Returns the list of enabled thumbnail plugins,
 105      * or an empty list if all plugins are enabled.
 106      *
 107      * @see setEnabledPlugins
 108      */
 109     QStringList enabledPlugins() const;
 110
 111 private:
 112     class Private;
 113     Private* const d; /// @internal
 114     Q_DISABLE_COPY(KFilePreviewGenerator)
 115
 116     Q_PRIVATE_SLOT(d, void updateIcons(const KFileItemList&))
 117     Q_PRIVATE_SLOT(d, void updateIcons(const QModelIndex&, const QModelIndex&))
 118     Q_PRIVATE_SLOT(d, void addToPreviewQueue(const KFileItem&, const QPixmap&))
 119     Q_PRIVATE_SLOT(d, void slotPreviewJobFinished(KJob*))
 120     Q_PRIVATE_SLOT(d, void updateCutItems())
 121     Q_PRIVATE_SLOT(d, void dispatchIconUpdateQueue())
 122     Q_PRIVATE_SLOT(d, void pauseIconUpdates())
 123     Q_PRIVATE_SLOT(d, void resumeIconUpdates())
 124     Q_PRIVATE_SLOT(d, void resolveMimeType())
 125 };
 126
 127 #endif