src/views/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 <QApplication>
  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_keyPressed(false),
  35     m_initializedTimestamp(false),
  36     m_horizontalScrollInc(0),
  37     m_verticalScrollInc(0),
  38     m_itemView(parent),
  39     m_timer(0),
  40     m_timestamp()
  41 {
  42     m_itemView->setAutoScroll(false);
  43     m_itemView->viewport()->installEventFilter(this);
  44     m_itemView->installEventFilter(this);
  45
  46     m_timer = new QTimer(this);
  47     m_timer->setSingleShot(false);
  48     m_timer->setInterval(1000 / 25); // 25 frames per second
  49     connect(m_timer, SIGNAL(timeout()), this, SLOT(scrollViewport()));
  50 }
  51
  52 DolphinViewAutoScroller::~DolphinViewAutoScroller()
  53 {
  54 }
  55
  56 bool DolphinViewAutoScroller::isActive() const
  57 {
  58     return m_timer->isActive();
  59 }
  60
  61 void DolphinViewAutoScroller::handleCurrentIndexChange(const QModelIndex& current,
  62                                                        const QModelIndex& previous)
  63 {
  64     // When the autoscroller is inactive and a key has been pressed, it must be
  65     // assured that the current item stays visible. The check whether the previous
  66     // item is valid is important because of #197951. The keypress check is done
  67     // because of #199833.
  68     if (current.isValid() && (previous.isValid() || m_keyPressed) && !isActive()) {
  69         m_itemView->scrollTo(current);
  70     }
  71 }
  72
  73 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  74 {
  75     if (watched == m_itemView->viewport()) {
  76         switch (event->type()) {
  77         case QEvent::MouseButtonPress:
  78             if (static_cast<QMouseEvent*>(event)->button() == Qt::LeftButton) {
  79                 m_rubberBandSelection = true;
  80             }
  81             break;
  82
  83         case QEvent::MouseMove:
  84             if (m_rubberBandSelection) {
  85                 triggerAutoScroll();
  86             }
  87             break;
  88
  89         case QEvent::MouseButtonRelease:
  90             m_rubberBandSelection = false;
  91             stopAutoScroll();
  92             break;
  93
  94         case QEvent::DragEnter:
  95         case QEvent::DragMove:
  96             m_rubberBandSelection = false;
  97             triggerAutoScroll();
  98             break;
  99
 100         case QEvent::Drop:
 101         case QEvent::DragLeave:
 102             m_rubberBandSelection = false;
 103             stopAutoScroll();
 104             break;
 105
 106         default:
 107             break;
 108         }
 109     } else if (watched == m_itemView) {
 110         switch (event->type()) {
 111         case QEvent::KeyPress:
 112             m_keyPressed = true;
 113             break;
 114
 115         case QEvent::KeyRelease:
 116             m_keyPressed = false;
 117             break;
 118
 119         default:
 120             break;
 121         }
 122     }
 123
 124     return QObject::eventFilter(watched, event);
 125 }
 126
 127 void DolphinViewAutoScroller::scrollViewport()
 128 {
 129     if (m_timestamp.elapsed() < QApplication::startDragTime()) {
 130         return;
 131     }
 132
 133     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 134     if (verticalScrollBar != 0) {
 135         const int value = verticalScrollBar->value();
 136         verticalScrollBar->setValue(value + m_verticalScrollInc);
 137
 138     }
 139     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 140     if (horizontalScrollBar != 0) {
 141         const int value = horizontalScrollBar->value();
 142         horizontalScrollBar->setValue(value + m_horizontalScrollInc);
 143
 144     }
 145
 146     if (m_rubberBandSelection) {
 147         // The scrolling does not lead to an update of the rubberband
 148         // selection. Fake a mouse move event to let the QAbstractItemView
 149         // update the rubberband.
 150         QWidget* viewport = m_itemView->viewport();
 151         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 152         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, QApplication::keyboardModifiers());
 153         QCoreApplication::sendEvent(viewport, &event);
 154     }
 155 }
 156
 157 void DolphinViewAutoScroller::triggerAutoScroll()
 158 {
 159     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 160                                    m_itemView->verticalScrollBar()->isVisible();
 161     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 162                                      m_itemView->horizontalScrollBar()->isVisible();
 163     if (!verticalScrolling && !horizontalScrolling) {
 164         // no scrollbars are shown at all, so no autoscrolling is necessary
 165         stopAutoScroll();
 166         return;
 167     }
 168
 169     QWidget* viewport = m_itemView->viewport();
 170     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 171     if (verticalScrolling) {
 172         m_verticalScrollInc = calculateScrollIncrement(pos.y(), viewport->height());
 173     }
 174     if (horizontalScrolling) {
 175         m_horizontalScrollInc = calculateScrollIncrement(pos.x(), viewport->width());
 176     }
 177
 178     if (m_timer->isActive()) {
 179         if ((m_horizontalScrollInc == 0) && (m_verticalScrollInc == 0)) {
 180             stopAutoScroll();
 181         }
 182     } else if ((m_horizontalScrollInc != 0) || (m_verticalScrollInc != 0)) {
 183         if (!m_initializedTimestamp) {
 184             m_initializedTimestamp = true;
 185             m_timestamp.start();
 186         }
 187         m_timer->start();
 188     }
 189 }
 190
 191 void DolphinViewAutoScroller::stopAutoScroll()
 192 {
 193     m_timer->stop();
 194     m_horizontalScrollInc = 0;
 195     m_verticalScrollInc = 0;
 196     m_initializedTimestamp = false;
 197 }
 198
 199 int DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize) const
 200 {
 201     int inc = 0;
 202
 203     const int minSpeed = 4;
 204     const int maxSpeed = 768;
 205     const int speedLimiter = 48;
 206     const int autoScrollBorder = 64;
 207
 208     if (cursorPos < autoScrollBorder) {
 209         inc = -minSpeed + qAbs(cursorPos - autoScrollBorder) * (cursorPos - autoScrollBorder) / speedLimiter;
 210         if (inc < -maxSpeed) {
 211             inc = -maxSpeed;
 212         }
 213     } else if (cursorPos > rangeSize - autoScrollBorder) {
 214         inc = minSpeed + qAbs(cursorPos - rangeSize + autoScrollBorder) * (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 215         if (inc > maxSpeed) {
 216             inc = maxSpeed;
 217         }
 218     }
 219
 220     return inc;
 221 }
 222
 223 #include "dolphinviewautoscroller.moc"