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 "scrollbar.h"
  24
  25 #include <QObject>
  26 #include <QDebug>
  27 #include <QGraphicsGridLayout>
  28 #include <QScrollBar>
  29 #include <QPropertyAnimation>
  30 #include <QTime>
  31
  32 /* TODO:
  33  * - fix velocity( create a new easing curve? )
  34  * - kinetic velocity parameterized upon count of list items
  35  * - horizontal scrolling
  36  * - parameterize dimensions
  37  * - ringbuffer (minimize number of items in the QGV).
  38  */
  39
  40 class KineticScrollingPrivate
  41 {
  42 public:
  43     KineticScrollingPrivate(): mScrollVelocity(0), timerID(0),
  44                                overshoot(40), bounceFlag(0), bounceStatus( Finished )
  45     { }
  46
  47     void count()
  48     {
  49         t = QTime::currentTime();
  50     }
  51
  52     unsigned int elapsed()
  53     {
  54         return t.msecsTo( QTime::currentTime() );
  55     }
  56
  57     void verticalScroll(int value)
  58     {
  59         widget->setPos(QPoint(0, -value*10));
  60     }
  61
  62     void horizontalScroll(int value)
  63     {
  64         widget->setPos(QPoint(-value*10, 0));
  65     }
  66
  67     /* Just for backport sake */
  68     int normalMovement()
  69     {
  70         return movement;
  71     }
  72
  73     int kinMovement()
  74     {
  75         return kin_movement;
  76     }
  77
  78     qreal duration()
  79     {
  80         return timeDelta;
  81     }
  82
  83     void mousePressEvent(QGraphicsSceneMouseEvent *event)
  84     {
  85         Q_UNUSED(event);
  86         count();
  87         scrollVelocity = 0;
  88         movement = 0;
  89         kin_movement = 0;
  90     }
  91
  92     void mouseMoveEvent(QGraphicsSceneMouseEvent *event)
  93     {
  94         int temp = event->lastPos().y() - event->pos().y();
  95         if (temp) {
  96             movement = temp;
  97             kin_movement += temp;
  98         }
  99     }
 100
 101     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 102     {
 103         timeDelta = elapsed();
 104         int temp = event->lastPos().y() - event->pos().y();
 105         if (temp)
 106             kin_movement += temp;
 107
 108         if (timeDelta > 200) {
 109             if (kin_movement > 0)
 110                 kin_movement = 3;
 111             else
 112                 kin_movement = -3;
 113         }
 114     }
 115
 116     void wheelReleaseEvent(QGraphicsSceneWheelEvent *event)
 117     {
 118         timeDelta = elapsed();
 119         int temp = event->delta();
 120         temp *= -1;
 121         kin_movement += temp;
 122     }
 123     /* Just for backport sake */
 124
 125     unsigned int timeDelta;
 126     qreal scrollVelocity;
 127     int movement;
 128     int kin_movement;
 129
 130     qreal mScrollVelocity;
 131     enum { None, Up, Down };
 132     enum BounceStatus{ Running, Finished };
 133     int timerID, overshoot, cposition, direction, minimalPos, maximumPos;
 134     char bounceFlag;
 135     BounceStatus bounceStatus;
 136
 137     QGraphicsWidget *widget;
 138     QGraphicsWidget *scrollingWidget;
 139
 140 protected:
 141     QTime t;
 142 };
 143
 144 KineticView::KineticView(QGraphicsWidget *parent)
 145     : QGraphicsWidget(parent)
 146 {
 147     d = new KineticScrollingPrivate;
 148     setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 149     d->scrollingWidget = new QGraphicsWidget(this);
 150     d->scrollingWidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 151     d->scrollingWidget->setFlag(QGraphicsItem::ItemClipsChildrenToShape, true);
 152     layout = new QGraphicsGridLayout(this);
 153     layout->addItem(d->scrollingWidget, 0, 0);
 154
 155     verticalScrollbar = new ScrollBar(this);
 156     connect(verticalScrollbar, SIGNAL(valueChanged(int)), this, SLOT(setVerticalScrollValue(int)));
 157     layout->addItem(verticalScrollbar, 0, 1);
 158
 159     setAcceptedMouseButtons(Qt::LeftButton);
 160 }
 161
 162 KineticView::~KineticView()
 163 {
 164     delete d->widget;
 165     delete d;
 166     delete scrollAnimation;
 167 }
 168
 169 void KineticView::adjustScrollBar()
 170 {
 171     verticalScrollbar->setMaximum( qMax( 0,
 172                 int( d->widget->size().height() - d->scrollingWidget->size().height())));
 173 }
 174
 175 void KineticView::setWidget(QGraphicsWidget *item)
 176 {
 177     d->widget = item;
 178     d->widget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
 179     d->widget->setParentItem(d->scrollingWidget);
 180     d->widget->setPos(0, 0);
 181     d->widget->setAcceptedMouseButtons(Qt::LeftButton);
 182
 183     scrollAnimation = new QPropertyAnimation(d->widget, "geometry");
 184     connect(scrollAnimation, SIGNAL(finished()), this, SLOT(overshoot()));
 185     scrollAnimation->setEasingCurve(QEasingCurve::OutCirc);
 186
 187     d->widget->installEventFilter( this );
 188     adjustScrollBar();
 189     update();
 190 }
 191
 192 void KineticView::overshoot()
 193 {
 194     /* Detect if bouncer */
 195     if( d->bounceStatus != KineticScrollingPrivate::Running ) {
 196         if( ( d->cposition > 0 ) || ( d->cposition < d->minimalPos + d->overshoot ) ) {
 197             int finalPosition;
 198             scrollAnimation->setEasingCurve( QEasingCurve::OutBounce );
 199
 200             if (d->cposition > 0)
 201                 finalPosition = 0;
 202             else
 203                 finalPosition = -d->widget->size().height( ) + d->scrollingWidget->size().height();
 204
 205             resetAnimation( finalPosition, 900 );
 206             d->bounceStatus = KineticScrollingPrivate::Running;
 207         }
 208     } else {
 209         d->bounceStatus = KineticScrollingPrivate::Finished;
 210         scrollAnimation->setEasingCurve( QEasingCurve::OutCirc );
 211     }
 212
 213 }
 214
 215 void KineticView::setVerticalScrollValue(int value)
 216 {
 217     const int pos = thresholdPosition( -value );
 218     d->widget->setPos(0, pos);
 219
 220     if( ( pos == d->overshoot ) || ( pos == d->minimalPos ) )
 221         overshoot();
 222 }
 223
 224 int KineticView::thresholdPosition(int value)
 225 {
 226
 227      d->minimalPos = -d->widget->size().height() + d->scrollingWidget->size().height()
 228          -d->overshoot;
 229      d->minimalPos = qMin(d->overshoot, d->minimalPos);
 230      d->maximumPos = value;
 231
 232      d->cposition = qBound(d->minimalPos, d->maximumPos, d->overshoot);
 233
 234      return d->cposition;
 235 }
 236
 237 void KineticView::resetAnimation(int finalPosition, int duration)
 238 {
 239     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 240         scrollAnimation->stop();
 241     d->cposition = finalPosition;
 242     QRectF tmpGeometry = d->widget->geometry();
 243     scrollAnimation->setStartValue(tmpGeometry);
 244     tmpGeometry.setY(d->cposition);
 245     scrollAnimation->setEndValue(tmpGeometry);
 246     scrollAnimation->setDuration(duration);
 247     scrollAnimation->start();
 248
 249 }
 250
 251
 252 void KineticView::mousePressEvent(QGraphicsSceneMouseEvent *event)
 253 {
 254     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 255         scrollAnimation->stop();
 256
 257     event->accept();
 258     scrollAnimation->setEasingCurve(QEasingCurve::OutCirc);
 259     d->mousePressEvent(event);
 260 }
 261
 262 void KineticView::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 263 {
 264     d->mouseMoveEvent(event);
 265     setVerticalScrollValue(-(d->widget->pos().y() - d->normalMovement()));
 266 }
 267
 268 void KineticView::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 269 {
 270
 271     if( scrollAnimation->state() != QAbstractAnimation::Running ) {
 272         d->mouseReleaseEvent(event);
 273
 274         const int finalPos = thresholdPosition(d->widget->pos().y() - d->kinMovement()*6);
 275         resetAnimation( finalPos, d->duration()*8 );
 276     }
 277 }
 278
 279 void KineticView::wheelEvent(QGraphicsSceneWheelEvent *event)
 280 {
 281     event->accept();
 282     scrollAnimation->setEasingCurve( QEasingCurve::OutCirc );
 283     d->mousePressEvent(NULL);
 284     d->wheelReleaseEvent(event);
 285     const int finalPos = thresholdPosition(d->widget->pos().y() - d->kinMovement()*6);
 286     resetAnimation( finalPos, 900 );
 287 }
 288
 289 void KineticView::resizeEvent(QGraphicsSceneResizeEvent *event)
 290 {
 291     if (d->widget)
 292         adjustScrollBar();
 293     QGraphicsWidget::resizeEvent(event);
 294 }
 295
 296 bool KineticView::eventFilter(QObject *watched, QEvent *event)
 297 {
 298     if (!d->widget) {
 299         return false;
 300     }
 301
 302     if (watched == d->widget && event->type() == QEvent::GraphicsSceneMove) {
 303         verticalScrollbar->blockSignals(true);
 304         verticalScrollbar->setValue(d->widget->pos().y());
 305         verticalScrollbar->blockSignals(false);
 306     }
 307
 308     return false;
 309 }