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::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     }
  88
  89     return QObject::eventFilter(watched, event);
  90 }
  91
  92 void DolphinViewAutoScroller::scrollViewport()
  93 {
  94     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
  95     if (verticalScrollBar != 0) {
  96         const int value = verticalScrollBar->value();
  97         verticalScrollBar->setValue(value + m_verticalScrollInc);
  98
  99     }
 100     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 101     if (horizontalScrollBar != 0) {
 102         const int value = horizontalScrollBar->value();
 103         horizontalScrollBar->setValue(value + m_horizontalScrollInc);
 104
 105     }
 106
 107     if (m_rubberBandSelection) {
 108         // The scrolling does not lead to an update of the rubberband
 109         // selection. Fake a mouse move event to let the QAbstractItemView
 110         // update the rubberband.
 111         QWidget* viewport = m_itemView->viewport();
 112         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 113         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 114         QCoreApplication::sendEvent(viewport, &event);
 115     }
 116 }
 117
 118 void DolphinViewAutoScroller::triggerAutoScroll()
 119 {
 120     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 121                                    m_itemView->verticalScrollBar()->isVisible();
 122     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 123                                      m_itemView->horizontalScrollBar()->isVisible();
 124     if (!verticalScrolling && !horizontalScrolling) {
 125         // no scrollbars are shown at all, so no autoscrolling is necessary
 126         return;
 127     }
 128
 129     QWidget* viewport = m_itemView->viewport();
 130     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 131     if (verticalScrolling) {
 132         m_verticalScrollInc = calculateScrollIncrement(pos.y(), viewport->height());
 133     }
 134     if (horizontalScrolling) {
 135         m_horizontalScrollInc = calculateScrollIncrement(pos.x(), viewport->width());
 136     }
 137
 138     if (m_timer->isActive()) {
 139         if ((m_horizontalScrollInc == 0) && (m_verticalScrollInc == 0)) {
 140             m_timer->stop();
 141         }
 142     } else if ((m_horizontalScrollInc != 0) || (m_verticalScrollInc != 0)) {
 143         m_timer->start();
 144     }
 145 }
 146
 147 void DolphinViewAutoScroller::stopAutoScroll()
 148 {
 149     m_timer->stop();
 150     m_horizontalScrollInc = 0;
 151     m_verticalScrollInc = 0;
 152 }
 153
 154 int DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize) const
 155 {
 156     int inc = 0;
 157
 158     const int minSpeed = 2;
 159     const int maxSpeed = 32;
 160     const int speedLimiter = 8;
 161     const int autoScrollBorder = 32;
 162
 163     if (cursorPos < autoScrollBorder) {
 164         inc = -minSpeed + (cursorPos - autoScrollBorder) / speedLimiter;
 165         if (inc < -maxSpeed) {
 166             inc = -maxSpeed;
 167         }
 168     } else if (cursorPos > rangeSize - autoScrollBorder) {
 169         inc = minSpeed + (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 170         if (inc > maxSpeed) {
 171             inc = maxSpeed;
 172         }
 173     }
 174
 175     return inc;
 176 }
 177
 178 #include "dolphinviewautoscroller.moc"