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  * - 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 class KineticScrollingPrivate
  42 {
  43 public:
  44     KineticScrollingPrivate(): mScrollVelocity(0), timerID(0),
  45                                overshoot(40), bounceFlag(0)
  46     { }
  47
  48     void count()
  49     {
  50         t = QTime::currentTime();
  51         t.start();
  52     }
  53
  54     unsigned int elapsed()
  55     {
  56         return t.restart();
  57     }
  58
  59     void verticalScroll(int value)
  60     {
  61         widget->setPos(QPoint(0, -value*10));
  62     }
  63
  64     void horizontalScroll(int value)
  65     {
  66         widget->setPos(QPoint(-value*10, 0));
  67     }
  68
  69     /* Just for backport sake */
  70     int normalMovement()
  71     {
  72         return movement;
  73     }
  74
  75     int kinMovement()
  76     {
  77         return kin_movement;
  78     }
  79
  80     qreal duration()
  81     {
  82         return timeDelta;
  83     }
  84
  85     void mousePressEvent(QGraphicsSceneMouseEvent *event)
  86     {
  87         Q_UNUSED(event);
  88         count();
  89         scrollVelocity = 0;
  90         movement = 0;
  91         kin_movement = 0;
  92     }
  93
  94     void mouseMoveEvent(QGraphicsSceneMouseEvent *event)
  95     {
  96         int temp = event->lastPos().y() - event->pos().y();
  97         if (temp) {
  98             movement = temp;
  99             kin_movement += temp;
 100         }
 101     }
 102
 103     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 104     {
 105         timeDelta = elapsed();
 106         int temp = event->lastPos().y() - event->pos().y();
 107         if (temp)
 108             kin_movement += temp;
 109
 110         if (timeDelta > 200) {
 111             if (kin_movement > 0)
 112                 kin_movement = 3;
 113             else
 114                 kin_movement = -3;
 115         }
 116     }
 117
 118     void wheelReleaseEvent(QGraphicsSceneWheelEvent *event)
 119     {
 120         timeDelta = elapsed();
 121         int temp = event->delta();
 122         temp *= -1;
 123         kin_movement += temp;
 124     }
 125     /* Just for backport sake */
 126
 127     unsigned int timeDelta;
 128     qreal scrollVelocity;
 129     int movement;
 130     int kin_movement;
 131
 132     qreal mScrollVelocity;
 133     enum { None, Up, Down };
 134     int timerID, overshoot, cposition, direction, minimalPos, maximumPos;
 135     char bounceFlag;
 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     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 void KineticView::mousePressEvent(QGraphicsSceneMouseEvent *event)
 202 {
 203     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 204         scrollAnimation->stop();
 205
 206     event->accept();
 207     d->mousePressEvent(event);
 208 }
 209
 210 void KineticView::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 211 {
 212     d->mouseMoveEvent(event);
 213     setVerticalScrollValue(-(d->widget->pos().y() - d->normalMovement()));
 214     QGraphicsWidget::mouseMoveEvent(event);
 215 }
 216
 217 int KineticView::thresholdPosition(int value)
 218 {
 219
 220      int minimalPos = -d->widget->size().height() + d->scrollingWidget->size().height();
 221      minimalPos = qMin( 0, minimalPos);
 222      int maximumPos = value;
 223
 224      int cposition = qBound( minimalPos, maximumPos, 0);
 225
 226      return cposition;
 227 }
 228
 229 void KineticView::resetAnimation(int duration)
 230 {
 231     if (scrollAnimation->state() != QAbstractAnimation::Stopped)
 232         scrollAnimation->stop();
 233     QRectF tmpGeometry = d->widget->geometry();
 234     scrollAnimation->setStartValue(tmpGeometry);
 235     int position = thresholdPosition(tmpGeometry.y() - d->kinMovement()*6);
 236     tmpGeometry.setY(position);
 237     scrollAnimation->setEndValue(tmpGeometry);
 238     scrollAnimation->setEndValue(tmpGeometry);
 239     scrollAnimation->setDuration(duration);
 240     scrollAnimation->start();
 241 }
 242
 243 void KineticView::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 244 {
 245
 246     d->mouseReleaseEvent(event);
 247     resetAnimation(d->duration()*8);
 248
 249 }
 250
 251 void KineticView::wheelEvent(QGraphicsSceneWheelEvent *event)
 252 {
 253     event->accept();
 254     d->mousePressEvent(NULL);
 255     d->wheelReleaseEvent(event);
 256     resetAnimation(900);
 257 }
 258
 259 void KineticView::resizeEvent(QGraphicsSceneResizeEvent *event)
 260 {
 261     if (d->widget)
 262         adjustScrollBar();
 263     QGraphicsWidget::resizeEvent(event);
 264 }