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