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
  30 DolphinViewAutoScroller::DolphinViewAutoScroller(QAbstractItemView* parent) :
  31     QObject(parent),
  32     m_rubberBandSelection(false),
  33     m_scrollInc(0),
  34     m_itemView(parent),
  35     m_timer()
  36 {
  37     m_itemView->setAutoScroll(false);
  38     m_itemView->viewport()->installEventFilter(this);
  39     m_itemView->installEventFilter(this);
  40
  41     m_timer = new QTimer(this);
  42     m_timer->setSingleShot(false);
  43     m_timer->setInterval(1000 / 25); // 25 frames per second
  44     connect(m_timer, SIGNAL(timeout()), this, SLOT(scrollViewport()));
  45 }
  46
  47 DolphinViewAutoScroller::~DolphinViewAutoScroller()
  48 {
  49 }
  50
  51 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  52 {
  53     if (watched == m_itemView->viewport()) {
  54         switch (event->type()) {
  55         case QEvent::MouseButtonPress:
  56             if (static_cast<QMouseEvent*>(event)->button() == Qt::LeftButton) {
  57                 m_rubberBandSelection = true;
  58             }
  59             break;
  60
  61         case QEvent::MouseMove:
  62             if (m_rubberBandSelection) {
  63                 triggerAutoScroll();
  64             }
  65             break;
  66
  67         case QEvent::MouseButtonRelease:
  68             m_rubberBandSelection = false;
  69             stopAutoScroll();
  70             break;
  71
  72         case QEvent::DragEnter:
  73         case QEvent::DragMove:
  74             m_rubberBandSelection = false;
  75             triggerAutoScroll();
  76             break;
  77
  78         case QEvent::Drop:
  79         case QEvent::DragLeave:
  80             m_rubberBandSelection = false;
  81             stopAutoScroll();
  82             break;
  83
  84         default:
  85             break;
  86         }
  87     } else if ((watched == m_itemView) && (event->type() == QEvent::KeyPress)) {
  88         switch (static_cast<QKeyEvent*>(event)->key()) {
  89         case Qt::Key_Up:
  90         case Qt::Key_Down:
  91         case Qt::Key_Left:
  92         case Qt::Key_Right:
  93         case Qt::Key_PageUp:
  94         case Qt::Key_PageDown:
  95         case Qt::Key_Home:
  96         case Qt::Key_End:
  97             QMetaObject::invokeMethod(this, "scrollToCurrentIndex", Qt::QueuedConnection);
  98             break;
  99         default:
 100             break;
 101         }
 102     }
 103
 104
 105     return QObject::eventFilter(watched, event);
 106 }
 107
 108 void DolphinViewAutoScroller::scrollViewport()
 109 {
 110     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 111     if (verticalScrollBar != 0) {
 112         const int value = verticalScrollBar->value();
 113         verticalScrollBar->setValue(value + m_scrollInc);
 114
 115     }
 116     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 117     if (horizontalScrollBar != 0) {
 118         const int value = horizontalScrollBar->value();
 119         horizontalScrollBar->setValue(value + m_scrollInc);
 120
 121     }
 122
 123     if (m_rubberBandSelection) {
 124         // The scrolling does not lead to an update of the rubberband
 125         // selection. Fake a mouse move event to let the QAbstractItemView
 126         // update the rubberband.
 127         QWidget* viewport = m_itemView->viewport();
 128         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 129         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 130         QCoreApplication::sendEvent(viewport, &event);
 131     }
 132 }
 133
 134 void DolphinViewAutoScroller::scrollToCurrentIndex()
 135 {
 136      const QModelIndex index = m_itemView->currentIndex();
 137      m_itemView->scrollTo(index);
 138 }
 139
 140 void DolphinViewAutoScroller::triggerAutoScroll()
 141 {
 142     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 143                                     m_itemView->verticalScrollBar()->isVisible();
 144     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 145                                      m_itemView->horizontalScrollBar()->isVisible();
 146     if (!verticalScrolling && !horizontalScrolling) {
 147         // no scrollbars are shown at all, so no autoscrolling is necessary
 148         return;
 149     }
 150
 151     QWidget* viewport = m_itemView->viewport();
 152     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 153     if (verticalScrolling) {
 154         calculateScrollIncrement(pos.y(), viewport->height());
 155     }
 156     if (horizontalScrolling) {
 157         calculateScrollIncrement(pos.x(), viewport->width());
 158     }
 159
 160     if (m_timer->isActive()) {
 161         if (m_scrollInc == 0) {
 162             m_timer->stop();
 163         }
 164     } else if (m_scrollInc != 0) {
 165         m_timer->start();
 166     }
 167 }
 168
 169 void DolphinViewAutoScroller::stopAutoScroll()
 170 {
 171     m_timer->stop();
 172     m_scrollInc = 0;
 173 }
 174
 175 void DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize)
 176 {
 177     const int minSpeed = 2;
 178     const int maxSpeed = 32;
 179     const int speedLimiter = 8;
 180     const int autoScrollBorder = 32;
 181
 182     if (cursorPos < autoScrollBorder) {
 183         m_scrollInc = -minSpeed + (cursorPos - autoScrollBorder) / speedLimiter;
 184         if (m_scrollInc < -maxSpeed) {
 185             m_scrollInc = -maxSpeed;
 186         }
 187     } else if (cursorPos > rangeSize - autoScrollBorder) {
 188         m_scrollInc = minSpeed + (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 189         if (m_scrollInc > maxSpeed) {
 190             m_scrollInc = maxSpeed;
 191         }
 192     } else {
 193         m_scrollInc = 0;
 194     }
 195 }
 196
 197 #include "dolphinviewautoscroller.moc"