src/dolphinviewautoscroller.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 DOLPHINVIEWAUTOSCROLLER_H
  21 #define DOLPHINVIEWAUTOSCROLLER_H
  22
  23 #include <QObject>
  24
  25 class QAbstractItemView;
  26 class QModelIndex;
  27 class QTimer;
  28
  29 /**
  30  * @brief Assures that an autoscrolling is done for item views.
  31  *
  32  * This is a workaround as QAbstractItemView::setAutoScroll() is not usable
  33  * when selecting items (see Qt issue #214542).
  34  */
  35 class DolphinViewAutoScroller : public QObject
  36 {
  37     Q_OBJECT
  38
  39 public:
  40     DolphinViewAutoScroller(QAbstractItemView* parent);
  41     virtual ~DolphinViewAutoScroller();
  42     bool isActive() const;
  43
  44     /**
  45      * Must be invoked by the parent item view, when QAbstractItemView::currentChanged()
  46      * has been called. Assures that the current item stays visible when it has been
  47      * changed by the keyboard.
  48      */
  49     void handleCurrentIndexChange(const QModelIndex& current, const QModelIndex& previous);
  50
  51 protected:
  52     virtual bool eventFilter(QObject* watched, QEvent* event);
  53
  54 private slots:
  55     void scrollViewport();
  56
  57 private:
  58     void triggerAutoScroll();
  59     void stopAutoScroll();
  60
  61     /**
  62      * Calculates the scroll increment dependent from
  63      * the cursor position \a cursorPos and the range 0 - \a rangeSize - 1.
  64      */
  65     int calculateScrollIncrement(int cursorPos, int rangeSize) const;
  66
  67 private:
  68     bool m_rubberBandSelection;
  69     bool m_keyPressed;
  70     int m_horizontalScrollInc;
  71     int m_verticalScrollInc;
  72     QAbstractItemView* m_itemView;
  73     QTimer* m_timer;
  74 };
  75
  76 #endif