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_horizontalScrollInc(0),
  34     m_verticalScrollInc(0),
  35     m_itemView(parent),
  36     m_timer()
  37 {
  38     m_itemView->setAutoScroll(false);
  39     m_itemView->viewport()->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::isActive() const
  52 {
  53     return m_timer->isActive();
  54 }
  55
  56 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  57 {
  58     if (watched == m_itemView->viewport()) {
  59         switch (event->type()) {
  60         case QEvent::MouseButtonPress:
  61             if (static_cast<QMouseEvent*>(event)->button() == Qt::LeftButton) {
  62                 m_rubberBandSelection = true;
  63             }
  64             break;
  65
  66         case QEvent::MouseMove:
  67             if (m_rubberBandSelection) {
  68                 triggerAutoScroll();
  69             }
  70             break;
  71
  72         case QEvent::MouseButtonRelease:
  73             m_rubberBandSelection = false;
  74             stopAutoScroll();
  75             break;
  76
  77         case QEvent::DragEnter:
  78         case QEvent::DragMove:
  79             m_rubberBandSelection = false;
  80             triggerAutoScroll();
  81             break;
  82
  83         case QEvent::Drop:
  84         case QEvent::DragLeave:
  85             m_rubberBandSelection = false;
  86             stopAutoScroll();
  87             break;
  88
  89         default:
  90             break;
  91         }
  92     }
  93
  94     return QObject::eventFilter(watched, event);
  95 }
  96
  97 void DolphinViewAutoScroller::scrollViewport()
  98 {
  99     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 100     if (verticalScrollBar != 0) {
 101         const int value = verticalScrollBar->value();
 102         verticalScrollBar->setValue(value + m_verticalScrollInc);
 103
 104     }
 105     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 106     if (horizontalScrollBar != 0) {
 107         const int value = horizontalScrollBar->value();
 108         horizontalScrollBar->setValue(value + m_horizontalScrollInc);
 109
 110     }
 111
 112     if (m_rubberBandSelection) {
 113         // The scrolling does not lead to an update of the rubberband
 114         // selection. Fake a mouse move event to let the QAbstractItemView
 115         // update the rubberband.
 116         QWidget* viewport = m_itemView->viewport();
 117         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 118         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 119         QCoreApplication::sendEvent(viewport, &event);
 120     }
 121 }
 122
 123 void DolphinViewAutoScroller::triggerAutoScroll()
 124 {
 125     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 126                                    m_itemView->verticalScrollBar()->isVisible();
 127     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 128                                      m_itemView->horizontalScrollBar()->isVisible();
 129     if (!verticalScrolling && !horizontalScrolling) {
 130         // no scrollbars are shown at all, so no autoscrolling is necessary
 131         return;
 132     }
 133
 134     QWidget* viewport = m_itemView->viewport();
 135     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 136     if (verticalScrolling) {
 137         m_verticalScrollInc = calculateScrollIncrement(pos.y(), viewport->height());
 138     }
 139     if (horizontalScrolling) {
 140         m_horizontalScrollInc = calculateScrollIncrement(pos.x(), viewport->width());
 141     }
 142
 143     if (m_timer->isActive()) {
 144         if ((m_horizontalScrollInc == 0) && (m_verticalScrollInc == 0)) {
 145             m_timer->stop();
 146         }
 147     } else if ((m_horizontalScrollInc != 0) || (m_verticalScrollInc != 0)) {
 148         m_timer->start();
 149     }
 150 }
 151
 152 void DolphinViewAutoScroller::stopAutoScroll()
 153 {
 154     m_timer->stop();
 155     m_horizontalScrollInc = 0;
 156     m_verticalScrollInc = 0;
 157 }
 158
 159 int DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize) const
 160 {
 161     int inc = 0;
 162
 163     const int minSpeed = 2;
 164     const int maxSpeed = 32;
 165     const int speedLimiter = 8;
 166     const int autoScrollBorder = 32;
 167
 168     if (cursorPos < autoScrollBorder) {
 169         inc = -minSpeed + (cursorPos - autoScrollBorder) / speedLimiter;
 170         if (inc < -maxSpeed) {
 171             inc = -maxSpeed;
 172         }
 173     } else if (cursorPos > rangeSize - autoScrollBorder) {
 174         inc = minSpeed + (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 175         if (inc > maxSpeed) {
 176             inc = maxSpeed;
 177         }
 178     }
 179
 180     return inc;
 181 }
 182
 183 #include "dolphinviewautoscroller.moc"