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