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