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 #include <kdebug.h>
  51 bool DolphinViewAutoScroller::eventFilter(QObject* watched, QEvent* event)
  52 {
  53     if (watched == m_itemView->viewport()) {
  54         switch (event->type()) {
  55         case QEvent::MouseButtonPress:
  56             m_rubberBandSelection = true;
  57             break;
  58
  59         case QEvent::MouseMove:
  60             if (m_rubberBandSelection) {
  61                 triggerAutoScroll();
  62             }
  63             break;
  64
  65         case QEvent::MouseButtonRelease:
  66             m_rubberBandSelection = false;
  67             stopAutoScroll();
  68             break;
  69
  70         case QEvent::DragEnter:
  71         case QEvent::DragMove:
  72             m_rubberBandSelection = false;
  73             triggerAutoScroll();
  74             break;
  75
  76         case QEvent::DragLeave:
  77             m_rubberBandSelection = false;
  78             stopAutoScroll();
  79             break;
  80
  81         default:
  82             break;
  83         }
  84     }
  85
  86     return QObject::eventFilter(watched, event);
  87 }
  88
  89 void DolphinViewAutoScroller::scrollViewport()
  90 {
  91     // TODO: implement horizontal scrolling
  92     QScrollBar* verticalScrollBar = m_itemView->verticalScrollBar();
  93     if (verticalScrollBar != 0) {
  94         const int value = verticalScrollBar->value();
  95         verticalScrollBar->setValue(value + m_scrollInc);
  96
  97         if (m_rubberBandSelection) {
  98             // The scrolling does not lead to an update of the rubberband
  99             // selection. Fake a mouse move event to let the QAbstractItemView
 100             // update the rubberband.
 101             QWidget* viewport = m_itemView->viewport();
 102             const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 103             QMouseEvent event(QEvent::MouseMove, pos, Qt::LeftButton, Qt::LeftButton, Qt::NoModifier);
 104             QCoreApplication::sendEvent(viewport, &event);
 105         }
 106     }
 107 }
 108
 109 void DolphinViewAutoScroller::triggerAutoScroll()
 110 {
 111     // TODO: implement horizontal scrolling
 112
 113     const int startSpeed = 2;
 114     const int speedLimiter = 8;
 115     const int scrollIncMax = 32;
 116
 117     const int autoScrollBorder = 32;
 118
 119     QWidget* viewport = m_itemView->viewport();
 120     const QPoint pos = viewport->mapFromGlobal(QCursor::pos());
 121     if (pos.y() < autoScrollBorder) {
 122         // scroll up
 123         m_scrollInc = -startSpeed + (pos.y() - autoScrollBorder) / speedLimiter;
 124         if (m_scrollInc < -scrollIncMax) {
 125             m_scrollInc = -scrollIncMax;
 126         }
 127     } else if (pos.y() > viewport->height() - autoScrollBorder) {
 128         // scroll down
 129         m_scrollInc = startSpeed + (pos.y() - viewport->height() + autoScrollBorder) / speedLimiter;
 130         if (m_scrollInc > scrollIncMax) {
 131             m_scrollInc = scrollIncMax;
 132         }
 133     } else {
 134         // no scrolling
 135         m_scrollInc = 0;
 136     }
 137
 138     if (m_timer->isActive()) {
 139         if (m_scrollInc == 0) {
 140             m_timer->stop();
 141         }
 142     } else if (m_scrollInc != 0) {
 143         m_timer->start();
 144     }
 145 }
 146
 147 void DolphinViewAutoScroller::stopAutoScroll()
 148 {
 149     m_timer->stop();
 150     m_scrollInc = 0;
 151 }
 152
 153 #include "dolphinviewautoscroller.moc"