src/dolphinviewautoscroller.cpp

   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 #include "dolphinviewautoscroller.h"
  21
  22 #include <QAbstractItemView>
  23 #include <QCoreApplication>
  24 #include <QCursor>
  25 #include <QEvent>
  26 #include <QMouseEvent>
  27 #include <QScrollBar>
  28 #include <QTimer>
  29 #include <math.h>
  30
  31 DolphinViewAutoScroller::DolphinViewAutoScroller(QAbstractItemView* parent) :
  32     QObject(parent),
  33     m_rubberBandSelection(false),
  34     m_horizontalScrollInc(0),
  35     m_verticalScrollInc(0),
  36     m_itemView(parent),
  37     m_timer(0)
  38 {
  39     m_itemView->setAutoScroll(false);
  40     m_itemView->viewport()->installEventFilter(this);
  41
  42     m_timer = new QTimer(this);
  43     m_timer->setSingleShot(false);
  44     m_timer->setInterval(1000 / 25); // 25 frames per second
  45     connect(m_timer, SIGNAL(timeout()), this, SLOT(scrollViewport()));
  46 }
  47
  48 DolphinViewAutoScroller::~DolphinViewAutoScroller()
  49 {
  50 }
  51
  52 bool DolphinViewAutoScroller::isActive() const
  53 {
  54     return m_timer->isActive();
  55 }
  56
  57 void DolphinViewAutoScroller::handleCurrentIndexChange(const QModelIndex& current,
  58                                                        const QModelIndex& previous)
  59 {
  60     // When the autoscroller is inactive and a key has been pressed, it must be
  61     // assured that the current item stays visible. The check whether the previous
  62     // item is valid is important because of #197951.
  63     if (current.isValid() && previous.isValid() && !isActive()) {
  64         m_itemView->scrollTo(current);
  65     }
  66 }
  67
  68 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  69 {
  70     if (watched == m_itemView->viewport()) {
  71         switch (event->type()) {
  72         case QEvent::MouseButtonPress:
  73             if (static_cast<QMouseEvent*>(event)->button() == Qt::LeftButton) {
  74                 m_rubberBandSelection = true;
  75             }
  76             break;
  77
  78         case QEvent::MouseMove:
  79             if (m_rubberBandSelection) {
  80                 triggerAutoScroll();
  81             }
  82             break;
  83
  84         case QEvent::MouseButtonRelease:
  85             m_rubberBandSelection = false;
  86             stopAutoScroll();
  87             break;
  88
  89         case QEvent::DragEnter:
  90         case QEvent::DragMove:
  91             m_rubberBandSelection = false;
  92             triggerAutoScroll();
  93             break;
  94
  95         case QEvent::Drop:
  96         case QEvent::DragLeave:
  97             m_rubberBandSelection = false;
  98             stopAutoScroll();
  99             break;
 100
 101         default:
 102             break;
 103         }
 104     }
 105
 106     return QObject::eventFilter(watched, event);
 107 }
 108
 109 void DolphinViewAutoScroller::scrollViewport()
 110 {
 111     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 112     if (verticalScrollBar != 0) {
 113         const int value = verticalScrollBar->value();
 114         verticalScrollBar->setValue(value + m_verticalScrollInc);
 115
 116     }
 117     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 118     if (horizontalScrollBar != 0) {
 119         const int value = horizontalScrollBar->value();
 120         horizontalScrollBar->setValue(value + m_horizontalScrollInc);
 121
 122     }
 123
 124     if (m_rubberBandSelection) {
 125         // The scrolling does not lead to an update of the rubberband
 126         // selection. Fake a mouse move event to let the QAbstractItemView
 127         // update the rubberband.
 128         QWidget* viewport = m_itemView->viewport();
 129         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 130         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 131         QCoreApplication::sendEvent(viewport, &event);
 132     }
 133 }
 134
 135 void DolphinViewAutoScroller::triggerAutoScroll()
 136 {
 137     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 138                                    m_itemView->verticalScrollBar()->isVisible();
 139     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 140                                      m_itemView->horizontalScrollBar()->isVisible();
 141     if (!verticalScrolling && !horizontalScrolling) {
 142         // no scrollbars are shown at all, so no autoscrolling is necessary
 143         return;
 144     }
 145
 146     QWidget* viewport = m_itemView->viewport();
 147     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 148     if (verticalScrolling) {
 149         m_verticalScrollInc = calculateScrollIncrement(pos.y(), viewport->height());
 150     }
 151     if (horizontalScrolling) {
 152         m_horizontalScrollInc = calculateScrollIncrement(pos.x(), viewport->width());
 153     }
 154
 155     if (m_timer->isActive()) {
 156         if ((m_horizontalScrollInc == 0) && (m_verticalScrollInc == 0)) {
 157             m_timer->stop();
 158         }
 159     } else if ((m_horizontalScrollInc != 0) || (m_verticalScrollInc != 0)) {
 160         m_timer->start();
 161     }
 162 }
 163
 164 void DolphinViewAutoScroller::stopAutoScroll()
 165 {
 166     m_timer->stop();
 167     m_horizontalScrollInc = 0;
 168     m_verticalScrollInc = 0;
 169 }
 170
 171 int DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize) const
 172 {
 173     int inc = 0;
 174
 175     const int minSpeed = 4;
 176     const int maxSpeed = 768;
 177     const int speedLimiter = 48;
 178     const int autoScrollBorder = 64;
 179
 180     if (cursorPos < autoScrollBorder) {
 181         inc = -minSpeed + qAbs(cursorPos - autoScrollBorder) * (cursorPos - autoScrollBorder) / speedLimiter;
 182         if (inc < -maxSpeed) {
 183             inc = -maxSpeed;
 184         }
 185     } else if (cursorPos > rangeSize - autoScrollBorder) {
 186         inc = minSpeed + qAbs(cursorPos - rangeSize + autoScrollBorder) * (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 187         if (inc > maxSpeed) {
 188             inc = maxSpeed;
 189         }
 190     }
 191
 192     return inc;
 193 }
 194
 195 #include "dolphinviewautoscroller.moc"