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             triggerAutoScroll();
  72             break;
  73
  74         case QEvent::DragLeave:
  75             stopAutoScroll();
  76             break;
  77
  78         default:
  79             break;
  80         }
  81     }
  82
  83     return QObject::eventFilter(watched, event);
  84 }
  85
  86 void DolphinViewAutoScroller::scrollViewport()
  87 {
  88     // TODO: implement horizontal scrolling
  89     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
  90     if (verticalScrollBar != 0) {
  91         const int value = verticalScrollBar->value();
  92         verticalScrollBar->setValue(value + m_scrollInc);
  93
  94         if (m_rubberBandSelection) {
  95             // The scrolling does not lead to an update of the rubberband
  96             // selection. Fake a mouse move event to let the QAbstractItemView
  97             // update the rubberband.
  98             QWidget* viewport = m_itemView->viewport();
  99             const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 100             QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 101             QCoreApplication::sendEvent(viewport, &event);
 102         }
 103     }
 104 }
 105
 106 void DolphinViewAutoScroller::triggerAutoScroll()
 107 {
 108     // TODO: implement horizontal scrolling
 109
 110     const int startSpeed = 2;
 111     const int speedLimiter = 8;
 112     const int scrollIncMax = 32;
 113
 114     const int autoScrollBorder = 32;
 115
 116     QWidget* viewport = m_itemView->viewport();
 117     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 118     if (pos.y() < autoScrollBorder) {
 119         // scroll up
 120         m_scrollInc = -startSpeed + (pos.y() - autoScrollBorder) / speedLimiter;
 121         if (m_scrollInc < -scrollIncMax) {
 122             m_scrollInc = -scrollIncMax;
 123         }
 124     } else if (pos.y() > viewport->height() - autoScrollBorder) {
 125         // scroll down
 126         m_scrollInc = startSpeed + (pos.y() - viewport->height() + autoScrollBorder) / speedLimiter;
 127         if (m_scrollInc > scrollIncMax) {
 128             m_scrollInc = scrollIncMax;
 129         }
 130     } else {
 131         // no scrolling
 132         m_scrollInc = 0;
 133     }
 134
 135     if (m_timer->isActive()) {
 136         if (m_scrollInc == 0) {
 137             m_timer->stop();
 138         }
 139     } else if (m_scrollInc != 0) {
 140         m_timer->start();
 141     }
 142 }
 143
 144 void DolphinViewAutoScroller::stopAutoScroll()
 145 {
 146     m_timer->stop();
 147     m_scrollInc = 0;
 148 }
 149
 150 #include "dolphinviewautoscroller.moc"