src/views/dolphinviewautoscroller.h

   1 /***************************************************************************
   2  *   Copyright (C) 2008 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 DOLPHINVIEWAUTOSCROLLER_H
  21 #define DOLPHINVIEWAUTOSCROLLER_H
  22
  23 #include <QTime>
  24 #include <QObject>
  25
  26 class QAbstractItemView;
  27 class QModelIndex;
  28 class QTimer;
  29
  30 /**
  31  * @brief Assures that an autoscrolling is done for item views.
  32  *
  33  * This is a workaround as QAbstractItemView::setAutoScroll() is not usable
  34  * when selecting items (see Qt issue #214542).
  35  */
  36 class DolphinViewAutoScroller : public QObject
  37 {
  38     Q_OBJECT
  39
  40 public:
  41     DolphinViewAutoScroller(QAbstractItemView* parent);
  42     virtual ~DolphinViewAutoScroller();
  43     bool isActive() const;
  44
  45     /**
  46      * Must be invoked by the parent item view, when QAbstractItemView::currentChanged()
  47      * has been called. Assures that the current item stays visible when it has been
  48      * changed by the keyboard.
  49      */
  50     void handleCurrentIndexChange(const QModelIndex& current, const QModelIndex& previous);
  51
  52 protected:
  53     virtual bool eventFilter(QObject* watched, QEvent* event);
  54
  55 private slots:
  56     void scrollViewport();
  57
  58 private:
  59     void triggerAutoScroll();
  60     void stopAutoScroll();
  61
  62     /**
  63      * Calculates the scroll increment dependent from
  64      * the cursor position \a cursorPos and the range 0 - \a rangeSize - 1.
  65      */
  66     int calculateScrollIncrement(int cursorPos, int rangeSize) const;
  67
  68 private:
  69     bool m_rubberBandSelection;
  70     bool m_keyPressed;
  71     bool m_initializedTimestamp;
  72     int m_horizontalScrollInc;
  73     int m_verticalScrollInc;
  74     QAbstractItemView* m_itemView;
  75     QTimer* m_timer;
  76     QTime m_timestamp;
  77 };
  78
  79 #endif