src/kfilepreviewgenerator.h

   1 /***************************************************************************
   2  *   Copyright (C) 2008 by Peter Penz <peter.penz@gmx.at>                  *
   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 KFILEPREVIEWGENERATOR_H
  21 #define KFILEPREVIEWGENERATOR_H
  22
  23 #include <QObject>
  24
  25 class KAbstractViewAdapter;
  26 class KDirModel;
  27 class QAbstractItemView;
  28 class QAbstractProxyModel;
  29
  30 /**
  31  * @brief Generates previews for files of an item view.
  32  *
  33  * Per default a preview is generated for each item.
  34  * Additionally the clipboard is checked for cut items.
  35  * The icon state for cut items gets dimmed automatically.
  36  *
  37  * The following strategy is used when creating previews:
  38  * - The previews for currently visible items are created before
  39  *   the previews for invisible items.
  40  * - If the user changes the visible area by using the scrollbars,
  41  *   all pending previews get paused. As soon as the user stays
  42  *   on the same position for a short delay, the previews are
  43  *   resumed. Also in this case the previews for the visible items
  44  *   are generated first.
  45  */
  46 class KFilePreviewGenerator : public QObject
  47 {
  48     Q_OBJECT
  49
  50 public:
  51     /**
  52      * @param parent  Item view containing the file items where previews should
  53      *                be generated. It is mandatory that the item view specifies
  54      *                an icon size by QAbstractItemView::setIconSize(), otherwise
  55      *                no previews will be generated.
  56      * @param model   Model of the item view.
  57      */
  58     KFilePreviewGenerator(QAbstractItemView* parent, QAbstractProxyModel* model);
  59
  60     /** @internal */
  61     KFilePreviewGenerator(KAbstractViewAdapter* parent, QAbstractProxyModel* model);
  62
  63     virtual ~KFilePreviewGenerator();
  64
  65     /**
  66      * If \a show is set to true, a preview is generated for each item. If \a show
  67      * is false, the MIME type icon of the item is shown instead. Per default showing
  68      * the preview is turned on. Note that it is mandatory that the item view
  69      * specifies an icon size by QAbstractItemView::setIconSize(), otherwise
  70      * KFilePreviewGenerator::showPreview() will always return false.
  71      */
  72     void setShowPreview(bool show);
  73     bool showPreview() const;
  74
  75     /**
  76      * Updates the previews for all already available items. Usually it is only
  77      * necessary to invoke this method when the icon size of the abstract item view
  78      * has been changed by QAbstractItemView::setIconSize().
  79      */
  80     void updatePreviews();
  81
  82     /** Cancels all pending previews. */
  83     void cancelPreviews();
  84
  85 private:
  86     class Private;
  87     Private* const d; /// @internal
  88     Q_DISABLE_COPY(KFilePreviewGenerator)
  89
  90     Q_PRIVATE_SLOT(d, void generatePreviews(const KFileItemList&))
  91     Q_PRIVATE_SLOT(d, void addToPreviewQueue(const KFileItem&, const QPixmap&))
  92     Q_PRIVATE_SLOT(d, void slotPreviewJobFinished(KJob*))
  93     Q_PRIVATE_SLOT(d, void updateCutItems())
  94     Q_PRIVATE_SLOT(d, void dispatchPreviewQueue())
  95     Q_PRIVATE_SLOT(d, void pausePreviews())
  96     Q_PRIVATE_SLOT(d, void resumePreviews())
  97 };
  98
  99 #endif