kineticview.cpp

   1 /////////////////////////////////////////////////////////////////////////
   2 // kineticview.cpp                                                     //
   3 //                                                                     //
   4 // Copyright(C) 2009 Igor Trindade Oliveira <igor.oliveira@indt.org.br>//
   5 // Copyright(C) 2009 Adenilson Cavalcanti <adenilson.silva@idnt.org.br>//
   6 //                                                                     //
   7 // This library is free software; you can redistribute it and/or       //
   8 // modify it under the terms of the GNU Lesser General Public          //
   9 // License as published by the Free Software Foundation; either        //
  10 // version 2.1 of the License, or (at your option) any later version.  //
  11 //                                                                     //
  12 // This library is distributed in the hope that it will be useful,     //
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of      //
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   //
  15 // Lesser General Public License for more details.                     //
  16 //                                                                     //
  17 // You should have received a copy of the GNU Lesser General Public    //
  18 // License along with this library; if not, write to the Free Software //
  19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA       //
  20 // 02110-1301  USA                                                     //
  21 /////////////////////////////////////////////////////////////////////////
  22 #include "kineticview.h"
  23
  24 #include <QObject>
  25 #include <QDebug>
  26 #include <QGraphicsGridLayout>
  27
  28 /* TODO:
  29  * - bump effect when rolling (twice should be enough)
  30  * - add a scrollbar for reference
  31  * - kinetic velocity parameterized upon count of list items
  32  * - ringbuffer (minimize number of items in the QGV).
  33  * - parameterize dimensions
  34  */
  35
  36 KineticView::KineticView( QGraphicsWidget *parent )
  37     : QGraphicsWidget( parent ), mScrollVelocity( 0 ),
  38       timerID( 0 ), overshut( 30 )
  39 {
  40     setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding);
  41
  42     mViewPort = new QGraphicsWidget( this );
  43     mViewPort->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
  44     mViewPort->setFlag( QGraphicsItem::ItemClipsChildrenToShape, true);
  45     layout = new QGraphicsGridLayout( this );
  46     layout->addItem( mViewPort, 0, 0 );
  47
  48     setAcceptedMouseButtons( Qt::LeftButton );
  49 }
  50
  51 KineticView::~KineticView()
  52 {
  53     delete mWindow;
  54 }
  55
  56 void KineticView::startTimer(int interval)
  57 {
  58     timerID = QObject::startTimer( interval );
  59 }
  60 void KineticView::setWidget( QGraphicsWidget *item)
  61 {
  62     mWindow = item;
  63     mWindow->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Fixed );
  64     mWindow->setParentItem( mViewPort );
  65     mWindow->setPos( 0, 0 );
  66     mWindow->setAcceptedMouseButtons(  Qt::LeftButton );
  67
  68     update();
  69 }
  70
  71 void KineticView::bounceTimer()
  72 {
  73     int delta = -5;
  74     if ( direction == DOWN )
  75         delta = 5;
  76     cposition += delta;
  77     mWindow->setPos( 0, cposition );
  78
  79     if ( ( direction == UP ) && ( cposition < 0 ) ) {
  80         cposition = 0;
  81         goto done;
  82
  83     } else if ( ( direction == DOWN ) &&
  84                 ( ( cposition - overshut) > minimalPos ) ) {
  85         cposition = minimalPos + overshut;
  86         goto done;
  87     }
  88
  89     return;
  90
  91 done:
  92     direction = NONE;
  93     mScrollVelocity = 0;
  94     killTimer( timerID );
  95     timerID = 0;
  96 }
  97
  98 void KineticView::setScrollValue( int value )
  99 {
 100     minimalPos = -mWindow->size().height() + mViewPort->size().height()
 101                  - overshut;
 102     minimalPos = qMin( overshut, minimalPos );
 103     maximumPos = mWindow->pos().y() - value;
 104
 105     cposition = qBound( minimalPos, maximumPos, overshut );
 106     mWindow->setPos( 0, cposition );
 107
 108     if ( cposition == overshut ) {
 109         direction = UP;
 110         goto overshut;
 111     } else if ( cposition == minimalPos ) {
 112         direction = DOWN;
 113         goto overshut;
 114     } else
 115         direction = NONE;
 116
 117     return;
 118
 119
 120 overshut:
 121     mScrollVelocity = 5;
 122     startTimer( 20 );
 123 }
 124
 125 void KineticView::mousePressEvent( QGraphicsSceneMouseEvent *event )
 126 {
 127     event->accept();
 128     killTimer( timerID );
 129     timerID = 0;
 130     KineticScrolling::mousePressEvent( static_cast<QGraphicsSceneMouseEvent*>(event) );
 131 }
 132
 133 void KineticView::mouseMoveEvent( QGraphicsSceneMouseEvent *event )
 134 {
 135     KineticScrolling::mouseMoveEvent( static_cast<QGraphicsSceneMouseEvent*>(event) );
 136     QGraphicsWidget::mouseMoveEvent( static_cast<QGraphicsSceneMouseEvent*>(event) );
 137     setScrollValue( movement() );
 138 }
 139
 140 void KineticView::mouseReleaseEvent( QGraphicsSceneMouseEvent *event )
 141 {
 142     KineticScrolling::mouseReleaseEvent(
 143     static_cast<QGraphicsSceneMouseEvent*>( event ) );
 144     mScrollVelocity = kin_movement();
 145     startTimer( 50 );
 146 }
 147
 148 void KineticView::timerEvent( QTimerEvent *event )
 149 {
 150     if ( ( direction == NONE ) && ( timerID != 0 ) ) {
 151         mScrollVelocity *= 0.9;
 152         if ( qAbs( mScrollVelocity ) < 5.0 ) {
 153             if ( timerID ) {
 154                 killTimer( timerID );
 155             }
 156         }
 157         setScrollValue( qRound( mScrollVelocity ) );
 158     } else if ( timerID != 0 ) {
 159         bounceTimer();
 160     } else {
 161         killTimer( event->timerId() );
 162     }
 163 }