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