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