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)
  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     int timerID, overshoot, cposition, direction, minimalPos, maximumPos;
 134     char bounceFlag;
 135
 136     QGraphicsWidget *widget;
 137     QGraphicsWidget *scrollingWidget;
 138
 139 protected:
 140     QTime t;
 141 };
 142
 143 KineticView::KineticView(QGraphicsWidget *parent)
 144     : QGraphicsWidget(parent)
 145 {
 146     d = new KineticScrollingPrivate;
 147     setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 148     d->scrollingWidget = new QGraphicsWidget(this);
 149     d->scrollingWidget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 150     d->scrollingWidget->setFlag(QGraphicsItem::ItemClipsChildrenToShape, true);
 151     layout = new QGraphicsGridLayout(this);
 152     layout->addItem(d->scrollingWidget, 0, 0);
 153
 154     verticalScrollbar = new ScrollBar(this);
 155     connect(verticalScrollbar, SIGNAL(valueChanged(int)), this, SLOT(setVerticalScrollValue(int)));
 156     layout->addItem(verticalScrollbar, 0, 1);
 157
 158     setAcceptedMouseButtons(Qt::LeftButton);
 159 }
 160
 161 KineticView::~KineticView()
 162 {
 163     delete d->widget;
 164     delete d;
 165     delete scrollAnimation;
 166 }
 167
 168 void KineticView::adjustScrollBar()
 169 {
 170     verticalScrollbar->setMaximum( qMax( 0,
 171                 int( d->widget->size().height() - d->scrollingWidget->size().height())));
 172 }
 173
 174 void KineticView::setWidget(QGraphicsWidget *item)
 175 {
 176     d->widget = item;
 177     d->widget->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
 178     d->widget->setParentItem(d->scrollingWidget);
 179     d->widget->setPos(0, 0);
 180     d->widget->setAcceptedMouseButtons(Qt::LeftButton);
 181
 182     scrollAnimation = new QPropertyAnimation(d->widget, "geometry");
 183     connect(scrollAnimation, SIGNAL(finished()), this, SLOT(overshoot()));
 184     scrollAnimation->setEasingCurve(QEasingCurve::OutCirc);
 185
 186     d->widget->installEventFilter( this );
 187     adjustScrollBar();
 188     update();
 189 }
 190
 191 void KineticView::overshoot()
 192 {
 193     qDebug() << "animation is over...";
 194 }
 195
 196 void KineticView::setVerticalScrollValue(int value)
 197 {
 198     d->widget->setPos(0, -value);
 199 }
 200
 201 int KineticView::thresholdPosition(int value)
 202 {
 203
 204      int minimalPos = -d->widget->size().height() + d->scrollingWidget->size().height();
 205      minimalPos = qMin( 0, minimalPos);
 206      int maximumPos = value;
 207
 208      int cposition = qBound( minimalPos, maximumPos, 0);
 209
 210      return cposition;
 211 }
 212
 213 void KineticView::resetAnimation(int duration)
 214 {
 215     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 216         scrollAnimation->stop();
 217     QRectF tmpGeometry = d->widget->geometry();
 218     scrollAnimation->setStartValue(tmpGeometry);
 219     int position = thresholdPosition(tmpGeometry.y() - d->kinMovement()*6);
 220     tmpGeometry.setY(position);
 221     scrollAnimation->setEndValue(tmpGeometry);
 222     scrollAnimation->setEndValue(tmpGeometry);
 223     scrollAnimation->setDuration(duration);
 224     scrollAnimation->start();
 225 }
 226
 227
 228 void KineticView::mousePressEvent(QGraphicsSceneMouseEvent *event)
 229 {
 230     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 231         scrollAnimation->stop();
 232
 233     event->accept();
 234     d->mousePressEvent(event);
 235 }
 236
 237 void KineticView::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 238 {
 239     d->mouseMoveEvent(event);
 240     setVerticalScrollValue(-(d->widget->pos().y() - d->normalMovement()));
 241     QGraphicsWidget::mouseMoveEvent(event);
 242 }
 243
 244 void KineticView::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 245 {
 246
 247     d->mouseReleaseEvent(event);
 248     resetAnimation(d->duration()*8);
 249
 250 }
 251
 252 void KineticView::wheelEvent(QGraphicsSceneWheelEvent *event)
 253 {
 254     event->accept();
 255     d->mousePressEvent(NULL);
 256     d->wheelReleaseEvent(event);
 257     resetAnimation(900);
 258 }
 259
 260 void KineticView::resizeEvent(QGraphicsSceneResizeEvent *event)
 261 {
 262     if (d->widget)
 263         adjustScrollBar();
 264     QGraphicsWidget::resizeEvent(event);
 265 }
 266
 267 bool KineticView::eventFilter(QObject *watched, QEvent *event)
 268 {
 269     if (!d->widget) {
 270         return false;
 271     }
 272
 273     if (watched == d->widget && event->type() == QEvent::GraphicsSceneMove) {
 274         verticalScrollbar->blockSignals(true);
 275         verticalScrollbar->setValue(d->widget->pos().y());
 276         verticalScrollbar->blockSignals(false);
 277     }
 278
 279     return false;
 280 }