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 #include "kineticscroll.h"
  24 #include "scrollbar.h"
  25
  26 #include <QObject>
  27 #include <QDebug>
  28 #include <QGraphicsGridLayout>
  29 #include <QScrollBar>
  30 #include <QPropertyAnimation>
  31
  32 /* TODO:
  33  * - fix velocity( create a new easing curve? )
  34  * - fix scrollbar
  35  * - kinetic velocity parameterized upon count of list items
  36  * - horizontal scrolling
  37  * - parameterize dimensions
  38  * - ringbuffer (minimize number of items in the QGV).
  39  */
  40
  41 KineticView::KineticView( QGraphicsWidget *parent )
  42     : QGraphicsWidget( parent ), mWindow( 0 ), mScrollVelocity( 0 ),
  43       timerID( 0 ), overshut( 40 ), bounceFlag( 0 )
  44 {
  45     setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding);
  46
  47     mViewPort = new QGraphicsWidget( this );
  48     mViewPort->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Expanding );
  49     mViewPort->setFlag( QGraphicsItem::ItemClipsChildrenToShape, true);
  50     layout = new QGraphicsGridLayout( this );
  51     layout->addItem( mViewPort, 0, 0 );
  52
  53     verticalScrollbar = new ScrollBar( this );
  54     connect( verticalScrollbar, SIGNAL( valueChanged( int ) ), this, SLOT( setVerticalScrollValue( int ) ) );
  55
  56     layout->addItem( verticalScrollbar, 0, 1 );
  57
  58     setAcceptedMouseButtons( Qt::LeftButton );
  59     scroller = new KineticScrolling;
  60 }
  61
  62 KineticView::~KineticView()
  63 {
  64     delete mWindow;
  65     delete scroller;
  66     delete scrollAnimation;
  67 }
  68
  69 void KineticView::adjustScrollBar()
  70 {
  71     verticalScrollbar->setMaximum( qMax( 0,
  72                 int( mWindow->size().height() - mViewPort->size().height() ) ) );
  73 }
  74
  75 void KineticView::setWidget( QGraphicsWidget *item)
  76 {
  77     mWindow = item;
  78     mWindow->setSizePolicy( QSizePolicy::Expanding, QSizePolicy::Fixed );
  79     mWindow->setParentItem( mViewPort );
  80     mWindow->setPos( 0, 0 );
  81     mWindow->setAcceptedMouseButtons(  Qt::LeftButton );
  82
  83     scrollAnimation = new QPropertyAnimation( mWindow, "geometry" );
  84     scrollAnimation->setEasingCurve( QEasingCurve::OutCirc );
  85
  86     adjustScrollBar();
  87     update();
  88 }
  89
  90 void KineticView::setVerticalScrollValue( int value )
  91 {
  92     mWindow->setPos( 0, -value );
  93 }
  94
  95 void KineticView::mousePressEvent( QGraphicsSceneMouseEvent *event )
  96 {
  97     event->accept();
  98     scroller->mousePressEvent( event );
  99 }
 100
 101 void KineticView::mouseMoveEvent( QGraphicsSceneMouseEvent *event )
 102 {
 103     scroller->mouseMoveEvent( event );
 104     setVerticalScrollValue( -( mWindow->pos().y() - scroller->movement() ) );
 105     QGraphicsWidget::mouseMoveEvent( event );
 106 }
 107
 108 int KineticView::thresholdPosition( int value )
 109 {
 110
 111      int minimalPos = -mWindow->size( ).height( ) + mViewPort->size( ).height( );
 112      minimalPos = qMin(  0, minimalPos );
 113      int maximumPos = value;
 114
 115      int cposition = qBound(  minimalPos, maximumPos, 0);
 116
 117      return cposition;
 118 }
 119
 120 void KineticView::mouseReleaseEvent( QGraphicsSceneMouseEvent *event )
 121 {
 122     if( scrollAnimation->state() != QAbstractAnimation::Stopped )
 123         scrollAnimation->stop();
 124
 125     scroller->mouseReleaseEvent( event );
 126
 127     QRectF tmpGeometry = mWindow->geometry();
 128     scrollAnimation->setStartValue( tmpGeometry );
 129
 130     int position = thresholdPosition( tmpGeometry.y() - scroller->kin_movement()*6 );
 131     tmpGeometry.setY( position );
 132     scrollAnimation->setEndValue( tmpGeometry );
 133     scrollAnimation->setDuration( scroller->duration()*5 );
 134     scrollAnimation->start();
 135 }
 136
 137 void KineticView::wheelEvent(QGraphicsSceneWheelEvent *event)
 138 {
 139     if( scrollAnimation->state() != QAbstractAnimation::Stopped )
 140         scrollAnimation->stop();
 141     event->accept();
 142     scroller->mousePressEvent( NULL );
 143     scroller->wheelReleaseEvent( event );
 144     mScrollVelocity = scroller->kin_movement();
 145
 146     QRectF tmpGeometry = mWindow->geometry();
 147     scrollAnimation->setStartValue( tmpGeometry );
 148
 149     int position = thresholdPosition( tmpGeometry.y() - scroller->kin_movement()*6 );
 150     tmpGeometry.setY( position );
 151     scrollAnimation->setEndValue( tmpGeometry );
 152     scrollAnimation->setDuration( 900  );
 153
 154     scrollAnimation->start();
 155 }
 156
 157 void KineticView::resizeEvent( QGraphicsSceneResizeEvent *event )
 158 {
 159     if( mWindow )
 160         adjustScrollBar();
 161     QGraphicsWidget::resizeEvent( event );
 162 }