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    41 

    42 #include "flickable.h"

    43 

    44 #include <QtCore>

    45 #include <QtGui>

    46 

    47 class FlickableTicker: QObject

    48 {

    49 public:

    50     FlickableTicker(Flickable *scroller) {

    51         m_scroller = scroller;

    52     }

    53 

    54     void start(int interval) {

    55         if (!m_timer.isActive())

    56             m_timer.start(interval, this);

    57     }

    58 

    59     void stop() {

    60         m_timer.stop();

    61     }

    62 

    63 protected:

    64     void timerEvent(QTimerEvent *event) {

    65         Q_UNUSED(event);

    66         m_scroller->tick();

    67     }

    68 

    69 private:

    70     Flickable *m_scroller;

    71     QBasicTimer m_timer;

    72 };

    73 

    74 class FlickablePrivate

    75 {

    76 public:

    77     typedef enum {

    78         Steady,

    79         Pressed,

    80         ManualScroll,

    81         AutoScroll,

    82         Stop

    83     } State;

    84 

    85     State state;

    86     int threshold;

    87     QPoint pressPos;

    88     QPoint offset;

    89     QPoint delta;

    90     QPoint speed;

    91     FlickableTicker *ticker;

    92     QTime timeStamp;

    93     QWidget *target;

    94     QList<QEvent*> ignoreList;

    95 };

    96 

    97 Flickable::Flickable()

    98 {

    99     d = new FlickablePrivate;

   100     d->state = FlickablePrivate::Steady;

   101     d->threshold = 10;

   102     d->ticker = new FlickableTicker(this);

   103     d->timeStamp = QTime::currentTime();

   104     d->target = 0;

   105 }

   106 

   107 Flickable::~Flickable()

   108 {

   109     delete d;

   110 }

   111 

   112 void Flickable::setThreshold(int th)

   113 {

   114     if (th >= 0)

   115         d->threshold = th;

   116 }

   117 

   118 int Flickable::threshold() const

   119 {

   120     return d->threshold;

   121 }

   122 

   123 void Flickable::setAcceptMouseClick(QWidget *target)

   124 {

   125     d->target = target;

   126 }

   127 

   128 static QPoint deaccelerate(const QPoint &speed, int a = 1, int max = 64)

   129 {

   130     int x = qBound(-max, speed.x(), max);

   131     int y = qBound(-max, speed.y(), max);

   132     x = (x == 0) ? x : (x > 0) ? qMax(0, x - a) : qMin(0, x + a);

   133     y = (y == 0) ? y : (y > 0) ? qMax(0, y - a) : qMin(0, y + a);

   134     return QPoint(x, y);

   135 }

   136 

   137 void Flickable::handleMousePress(QMouseEvent *event)

   138 {

   139     event->ignore();

   140 

   141     if (event->button() != Qt::LeftButton)

   142         return;

   143 

   144     if (d->ignoreList.removeAll(event))

   145         return;

   146 

   147     switch (d->state) {

   148 

   149     case FlickablePrivate::Steady:

   150         event->accept();

   151         d->state = FlickablePrivate::Pressed;

   152         d->pressPos = event->pos();

   153         break;

   154 

   155     case FlickablePrivate::AutoScroll:

   156         event->accept();

   157         d->state = FlickablePrivate::Stop;

   158         d->speed = QPoint(0, 0);

   159         d->pressPos = event->pos();

   160         d->offset = scrollOffset();

   161         d->ticker->stop();

   162         break;

   163 

   164     default:

   165         break;

   166     }

   167 }

   168 

   169 void Flickable::handleMouseRelease(QMouseEvent *event)

   170 {

   171     event->ignore();

   172 

   173     if (event->button() != Qt::LeftButton)

   174         return;

   175 

   176     if (d->ignoreList.removeAll(event))

   177         return;

   178 

   179     QPoint delta;

   180 

   181     switch (d->state) {

   182 

   183     case FlickablePrivate::Pressed:

   184         event->accept();

   185         d->state = FlickablePrivate::Steady;

   186         if (d->target) {

   187             QMouseEvent *event1 = new QMouseEvent(QEvent::MouseButtonPress,

   188                                                   d->pressPos, Qt::LeftButton,

   189                                                   Qt::LeftButton, Qt::NoModifier);

   190             QMouseEvent *event2 = new QMouseEvent(*event);

   191             d->ignoreList << event1;

   192             d->ignoreList << event2;

   193             QApplication::postEvent(d->target, event1);

   194             QApplication::postEvent(d->target, event2);

   195         }

   196         break;

   197 

   198     case FlickablePrivate::ManualScroll:

   199         event->accept();

   200         delta = event->pos() - d->pressPos;

   201         if (d->timeStamp.elapsed() > 100) {

   202             d->timeStamp = QTime::currentTime();

   203             d->speed = delta - d->delta;

   204             d->delta = delta;

   205         }

   206         d->offset = scrollOffset();

   207         d->pressPos = event->pos();

   208         if (d->speed == QPoint(0, 0)) {

   209             d->state = FlickablePrivate::Steady;

   210         } else {

   211             d->speed /= 4;

   212             d->state = FlickablePrivate::AutoScroll;

   213             d->ticker->start(20);

   214         }

   215         break;

   216 

   217     case FlickablePrivate::Stop:

   218         event->accept();

   219         d->state = FlickablePrivate::Steady;

   220         d->offset = scrollOffset();

   221         break;

   222 

   223     default:

   224         break;

   225     }

   226 }

   227 

   228 void Flickable::handleMouseMove(QMouseEvent *event)

   229 {

   230     event->ignore();

   231 

   232     if (!(event->buttons() & Qt::LeftButton))

   233         return;

   234 

   235     if (d->ignoreList.removeAll(event))

   236         return;

   237 

   238     QPoint delta;

   239 

   240     switch (d->state) {

   241 

   242     case FlickablePrivate::Pressed:

   243     case FlickablePrivate::Stop:

   244         delta = event->pos() - d->pressPos;

   245         if (delta.x() > d->threshold || delta.x() < -d->threshold ||

   246                 delta.y() > d->threshold || delta.y() < -d->threshold) {

   247             d->timeStamp = QTime::currentTime();

   248             d->state = FlickablePrivate::ManualScroll;

   249             d->delta = QPoint(0, 0);

   250             d->pressPos = event->pos();

   251             event->accept();

   252         }

   253         break;

   254 

   255     case FlickablePrivate::ManualScroll:

   256         event->accept();

   257         delta = event->pos() - d->pressPos;

   258         setScrollOffset(d->offset - delta);

   259         if (d->timeStamp.elapsed() > 100) {

   260             d->timeStamp = QTime::currentTime();

   261             d->speed = delta - d->delta;

   262             d->delta = delta;

   263         }

   264         break;

   265 

   266     default:

   267         break;

   268     }

   269 }

   270 

   271 void Flickable::tick()

   272 {

   273     if (d->state == FlickablePrivate:: AutoScroll) {

   274         d->speed = deaccelerate(d->speed);

   275         setScrollOffset(d->offset - d->speed);

   276         d->offset = scrollOffset();

   277         if (d->speed == QPoint(0, 0)) {

   278             d->state = FlickablePrivate::Steady;

   279             d->ticker->stop();

   280         }

   281     } else {

   282         d->ticker->stop();

   283     }

   284 }