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     m_itemView->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     } else if ((watched == m_itemView) && (event->type() == QEvent::KeyPress)) {
  88         const int key = static_cast<QKeyEvent*>(event)->key();
  89         const bool arrowKeyPressed = (key == Qt::Key_Up)   || (key == Qt::Key_Down) ||
  90                                      (key == Qt::Key_Left) || (key == Qt::Key_Right);
  91         if (arrowKeyPressed) {
  92             QMetaObject::invokeMethod(this, "scrollToCurrentIndex", Qt::QueuedConnection);
  93         }
  94     }
  95
  96
  97     return QObject::eventFilter(watched, event);
  98 }
  99
 100 void DolphinViewAutoScroller::scrollViewport()
 101 {
 102     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
 103     if (verticalScrollBar != 0) {
 104         const int value = verticalScrollBar->value();
 105         verticalScrollBar->setValue(value + m_scrollInc);
 106
 107     }
 108     QScrollBar* horizontalScrollBar = m_itemView->horizontalScrollBar();
 109     if (horizontalScrollBar != 0) {
 110         const int value = horizontalScrollBar->value();
 111         horizontalScrollBar->setValue(value + m_scrollInc);
 112
 113     }
 114
 115     if (m_rubberBandSelection) {
 116         // The scrolling does not lead to an update of the rubberband
 117         // selection. Fake a mouse move event to let the QAbstractItemView
 118         // update the rubberband.
 119         QWidget* viewport = m_itemView->viewport();
 120         const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 121         QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 122         QCoreApplication::sendEvent(viewport, &event);
 123     }
 124 }
 125
 126 void DolphinViewAutoScroller::scrollToCurrentIndex()
 127 {
 128      const QModelIndex index = m_itemView->currentIndex();
 129      m_itemView->scrollTo(index);
 130 }
 131
 132 void DolphinViewAutoScroller::triggerAutoScroll()
 133 {
 134     const bool verticalScrolling = (m_itemView->verticalScrollBar() != 0) &&
 135                                     m_itemView->verticalScrollBar()->isVisible();
 136     const bool horizontalScrolling = (m_itemView->horizontalScrollBar() != 0) &&
 137                                      m_itemView->horizontalScrollBar()->isVisible();
 138     if (!verticalScrolling && !horizontalScrolling) {
 139         // no scrollbars are shown at all, so no autoscrolling is necessary
 140         return;
 141     }
 142
 143     QWidget* viewport = m_itemView->viewport();
 144     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 145     if (verticalScrolling) {
 146         calculateScrollIncrement(pos.y(), viewport->height());
 147     }
 148     if (horizontalScrolling) {
 149         calculateScrollIncrement(pos.x(), viewport->width());
 150     }
 151
 152     if (m_timer->isActive()) {
 153         if (m_scrollInc == 0) {
 154             m_timer->stop();
 155         }
 156     } else if (m_scrollInc != 0) {
 157         m_timer->start();
 158     }
 159 }
 160
 161 void DolphinViewAutoScroller::stopAutoScroll()
 162 {
 163     m_timer->stop();
 164     m_scrollInc = 0;
 165 }
 166
 167 void DolphinViewAutoScroller::calculateScrollIncrement(int cursorPos, int rangeSize)
 168 {
 169     const int minSpeed = 2;
 170     const int maxSpeed = 32;
 171     const int speedLimiter = 8;
 172     const int autoScrollBorder = 32;
 173
 174     if (cursorPos < autoScrollBorder) {
 175         m_scrollInc = -minSpeed + (cursorPos - autoScrollBorder) / speedLimiter;
 176         if (m_scrollInc < -maxSpeed) {
 177             m_scrollInc = -maxSpeed;
 178         }
 179     } else if (cursorPos > rangeSize - autoScrollBorder) {
 180         m_scrollInc = minSpeed + (cursorPos - rangeSize + autoScrollBorder) / speedLimiter;
 181         if (m_scrollInc > maxSpeed) {
 182             m_scrollInc = maxSpeed;
 183         }
 184     } else {
 185         m_scrollInc = 0;
 186     }
 187 }
 188
 189 #include "dolphinviewautoscroller.moc"