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 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  58 {
  59     if (watched == m_itemView->viewport()) {
  60         switch (event->type()) {
  61         case QEvent::MouseButtonPress:
  62             if (static_cast<QMouseEvent*>(event)->button() == Qt::LeftButton) {
  63                 m_rubberBandSelection = true;
  64             }
  65             break;
  66
  67         case QEvent::MouseMove:
  68             if (m_rubberBandSelection) {
  69                 triggerAutoScroll();
  70             }
  71             break;
  72
  73         case QEvent::MouseButtonRelease:
  74             m_rubberBandSelection = false;
  75             stopAutoScroll();
  76             break;
  77
  78         case QEvent::DragEnter:
  79         case QEvent::DragMove:
  80             m_rubberBandSelection = false;
  81             triggerAutoScroll();
  82             break;
  83
  84         case QEvent::Drop:
  85         case QEvent::DragLeave:
  86             m_rubberBandSelection = false;
  87             stopAutoScroll();
  88             break;
  89
  90         default:
  91             break;
  92         }
  93     }
  94
  95     return QObject::eventFilter(watched, event);
  96 }
  97
  98 void DolphinViewAutoScroller::scrollViewport()
  99 {
 100     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 101     if (verticalScrollBar != 0) {
 102         const int value = verticalScrollBar->value();
 103         verticalScrollBar->setValue(value + m_verticalScrollInc);
 104
 105     }
 106     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 107     if (horizontalScrollBar != 0) {
 108         const int value = horizontalScrollBar->value();
 109         horizontalScrollBar->setValue(value + m_horizontalScrollInc);
 110
 111     }
 112
 113     if (m_rubberBandSelection) {
 114         // The scrolling does not lead to an update of the rubberband
 115         // selection. Fake a mouse move event to let the QAbstractItemView
 116         // update the rubberband.
 117         QWidget* viewport = m_itemView->viewport();
 118         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 119         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 120         QCoreApplication::sendEvent(viewport, &event);
 121     }
 122 }
 123
 124 void DolphinViewAutoScroller::triggerAutoScroll()
 125 {
 126     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 127                                    m_itemView->verticalScrollBar()->isVisible();
 128     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 129                                      m_itemView->horizontalScrollBar()->isVisible();
 130     if (!verticalScrolling && !horizontalScrolling) {
 131         // no scrollbars are shown at all, so no autoscrolling is necessary
 132         return;
 133     }
 134
 135     QWidget* viewport = m_itemView->viewport();
 136     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 137     if (verticalScrolling) {
 138         m_verticalScrollInc = calculateScrollIncrement(pos.y(), viewport->height());
 139     }
 140     if (horizontalScrolling) {
 141         m_horizontalScrollInc = calculateScrollIncrement(pos.x(), viewport->width());
 142     }
 143
 144     if (m_timer->isActive()) {
 145         if ((m_horizontalScrollInc == 0) && (m_verticalScrollInc == 0)) {
 146             m_timer->stop();
 147         }
 148     } else if ((m_horizontalScrollInc != 0) || (m_verticalScrollInc != 0)) {
 149         m_timer->start();
 150     }
 151 }
 152
 153 void DolphinViewAutoScroller::stopAutoScroll()
 154 {
 155     m_timer->stop();
 156     m_horizontalScrollInc = 0;
 157     m_verticalScrollInc = 0;
 158 }
 159
 160 int DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize) const
 161 {
 162     int inc = 0;
 163
 164     const int minSpeed = 4;
 165     const int maxSpeed = 768;
 166     const int speedLimiter = 48;
 167     const int autoScrollBorder = 64;
 168
 169     if (cursorPos < autoScrollBorder) {
 170         inc = -minSpeed + fabs(cursorPos - autoScrollBorder) * (cursorPos - autoScrollBorder) / speedLimiter;
 171         if (inc < -maxSpeed) {
 172             inc = -maxSpeed;
 173         }
 174     } else if (cursorPos > rangeSize - autoScrollBorder) {
 175         inc = minSpeed + fabs(cursorPos - rangeSize + autoScrollBorder) * (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 176         if (inc > maxSpeed) {
 177             inc = maxSpeed;
 178         }
 179     }
 180
 181     return inc;
 182 }
 183
 184 #include "dolphinviewautoscroller.moc"