Fix going into overshoot with overshootMaximumDistance

1 files changed, 31 insertions, 6 deletions

diff --git a/qkineticscroller.cpp b/qkineticscroller.cpp
index 387db04..cace269 100644
--- a/qkineticscroller.cpp
+++ b/qkineticscroller.cpp
@@ -292,8 +292,6 @@ const char *QKineticScrollerPrivate::inputName(QKineticScroller::Input input)
 
 void QKineticScrollerPrivate::timerEvent(QTimerEvent *e)
 {
-    Q_Q(QKineticScroller);
-
     if (e->timerId() != timerId) {
         QObject::timerEvent(e);
         return;
@@ -315,8 +313,6 @@ void QKineticScrollerPrivate::timerEvent(QTimerEvent *e)
 
         if (state == te->state) {
             (this->*te->handler)();
-            if (debugHook)
-                debugHook(debugHookUser, releaseVelocity, q->contentPosition(), overshootPosition);
             return;
         }
     }
@@ -542,7 +538,10 @@ QPointF QKineticScrollerPrivate::calculateVelocity(qreal time)
 
     // -- x coordinate
     if (overshootX) {
-        velocity.setX(overshootVelocity.x() * qCos(overshootSpringConstantRoot * (time - overshootStartTimeX)));
+        if (overshootSpringConstantRoot * (time-overshootStartTimeX) < M_PI) // prevent swinging around
+            velocity.setX(overshootVelocity.x() * qCos(overshootSpringConstantRoot * (time - overshootStartTimeX)));
+        else
+            velocity.setX(-overshootVelocity.x());
 
     } else {
         qreal newVelocity = decelerate(releaseVelocity.x(), time);
@@ -561,7 +560,10 @@ QPointF QKineticScrollerPrivate::calculateVelocity(qreal time)
 
     // -- y coordinate
     if (overshootY) {
-        velocity.setY(overshootVelocity.y() * qCos(overshootSpringConstantRoot * (time - overshootStartTimeY)));
+        if (overshootSpringConstantRoot * (time-overshootStartTimeY) < M_PI) // prevent swinging around
+            velocity.setY(overshootVelocity.y() * qCos(overshootSpringConstantRoot * (time - overshootStartTimeY)));
+        else
+            velocity.setY(-overshootVelocity.y());
 
     } else {
         qreal newVelocity = decelerate(releaseVelocity.y(), time);
@@ -1069,6 +1071,16 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
         if (!oldOvershootX) {
             overshootStartTimeX = qreal(scrollAbsoluteTimer.elapsed()) / 1000;
             overshootVelocity.setX(calculateVelocity(overshootStartTimeX).x());
+
+            // restrict the overshoot to overshootMaximumDistance
+            qreal maxOvershootVelocity = overshootMaximumDistance.x() * overshootSpringConstantRoot;
+            if (overshootMaximumDistance.x() && qAbs(overshootVelocity.x()) > maxOvershootVelocity)
+                overshootVelocity.setX(maxOvershootVelocity * qSign(newOvershootX));
+
+            // -- prevent going into overshoot too far
+            if (state != QKineticScroller::StateDragging && overshootDragResistanceFactor)
+                newOvershootX = qSign(newOvershootX) * qreal(0.0001);
+
             scrollToX = false;
             overshootX = true;
         }
@@ -1092,6 +1104,16 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
         if (!oldOvershootY) {
             overshootStartTimeY = qreal(scrollAbsoluteTimer.elapsed()) / 1000;
             overshootVelocity.setY(calculateVelocity(overshootStartTimeY).y());
+
+            // -- restrict the overshoot to overshootMaximumDistance
+            qreal maxOvershootVelocity = overshootMaximumDistance.y() * overshootSpringConstantRoot;
+            if (overshootMaximumDistance.y() && (qAbs(overshootVelocity.y()) > maxOvershootVelocity))
+                overshootVelocity.setY(maxOvershootVelocity * qSign(newOvershootY));
+
+            // -- prevent going into overshoot too far
+            if (state != QKineticScroller::StateDragging && overshootDragResistanceFactor)
+                newOvershootY = qSign(newOvershootY) * qreal(0.0001);
+
             scrollToY = false;
             overshootY = true;
         }
@@ -1115,6 +1137,9 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
 
     q->setContentPosition(newClampedPos, realOvershootDistance);
 
+    if (debugHook)
+        debugHook(debugHookUser, calculateVelocity(qreal(scrollAbsoluteTimer.elapsed()) / 1000), newClampedPos, realOvershootDistance);
+
     qDebug() << "setContentPositionHelper" << newClampedPos << " overshoot:" << realOvershootDistance <<
     "Overshoot: "<<overshootX<<","<<overshootY<<"ScrollTo:"<<scrollToX<<","<<scrollToY;
 }