Fix overshoot, remove velocity

2 files changed, 40 insertions, 45 deletions

diff --git a/qkineticscroller.cpp b/qkineticscroller.cpp
index 7a378d1..eb6d0e9 100644
--- a/qkineticscroller.cpp
+++ b/qkineticscroller.cpp
@@ -479,7 +479,7 @@ void QKineticScroller::setDpiFromWidget(QWidget *widget)
 
 void QKineticScrollerPrivate::updateVelocity(const QPointF &deltaPixelRaw, qint64 deltaTime)
 {
-    qKSDebug() << "updateVelocity(dP = " << deltaPixelRaw << " [pix], dT = " << deltaTime << " [ms]) -- velocity: " << velocity << "[m/s]";
+    qKSDebug() << "updateVelocity(dP = " << deltaPixelRaw << " [pix], dT = " << deltaTime << " [ms]) -- velocity: " << releaseVelocity << "[m/s]";
 
     QPointF deltaPixel = deltaPixelRaw;
 
@@ -489,16 +489,16 @@ void QKineticScrollerPrivate::updateVelocity(const QPointF &deltaPixelRaw, qint6
 
     qreal inversSmoothingFactor = ((qreal(1) - dragVelocitySmoothingFactor) * qreal(deltaTime) / qreal(1000));
     QPointF newv = -deltaPixel / qreal(deltaTime) * qreal(1000) / pixelPerMeter;
-    newv = newv * (qreal(1) - inversSmoothingFactor) + velocity * inversSmoothingFactor;
+    newv = newv * (qreal(1) - inversSmoothingFactor) + releaseVelocity * inversSmoothingFactor;
 
     // newv = newv * dragVelocitySmoothingFactor + velocity * (qreal(1) - dragVelocitySmoothingFactor);
 
     if (deltaPixel.x())
-        velocity.setX(qBound(-maximumVelocity, newv.x(), maximumVelocity));
+        releaseVelocity.setX(qBound(-maximumVelocity, newv.x(), maximumVelocity));
     if (deltaPixel.y())
-        velocity.setY(qBound(-maximumVelocity, newv.y(), maximumVelocity));
+        releaseVelocity.setY(qBound(-maximumVelocity, newv.y(), maximumVelocity));
 
-    qKSDebug() << "resulting new velocity:" << velocity;
+    qKSDebug() << "resulting new velocity:" << releaseVelocity;
 }
 
 qreal QKineticScrollerPrivate::decelerate(qreal v, qreal t)
@@ -592,11 +592,11 @@ void QKineticScrollerPrivate::handleDrag(const QPointF &position, qint64 timesta
 
     if (!canScrollX) {
         deltaPixel.setX(0);
-        velocity.setX(0);
+        releaseVelocity.setX(0);
     }
     if (!canScrollY) {
         deltaPixel.setY(0);
-        velocity.setY(0);
+        releaseVelocity.setY(0);
     }
 
 //    if (firstDrag) {
@@ -716,33 +716,33 @@ bool QKineticScrollerPrivate::releaseWhileDragging(QKineticScroller::Input, cons
 
         // more than one fast swipe in a row: add fastSwipeVelocity
         int signX = 0, signY = 0;
-        if (velocity.x())
-            signX = (velocity.x() > 0) == (oldVelocity.x() > 0) ? 1 : -1;
-        if (velocity.y())
-            signY = (velocity.y() > 0) == (oldVelocity.y() > 0) ? 1 : -1;
+        if (releaseVelocity.x())
+            signX = (releaseVelocity.x() > 0) == (oldVelocity.x() > 0) ? 1 : -1;
+        if (releaseVelocity.y())
+            signY = (releaseVelocity.y() > 0) == (oldVelocity.y() > 0) ? 1 : -1;
 
-        velocity.setX(signX * (oldVelocity.x() + (oldVelocity.x() > 0 ? fastSwipeVelocity.x() : -fastSwipeVelocity.x())));
-        velocity.setY(signY * (oldVelocity.y() + (oldVelocity.y() > 0 ? fastSwipeVelocity.y() : -fastSwipeVelocity.y())));
+        releaseVelocity.setX(signX * (oldVelocity.x() + (oldVelocity.x() > 0 ? fastSwipeVelocity.x() : -fastSwipeVelocity.x())));
+        releaseVelocity.setY(signY * (oldVelocity.y() + (oldVelocity.y() > 0 ? fastSwipeVelocity.y() : -fastSwipeVelocity.y())));
 
-    } else if (velocity >= minimumVelocity) {
+    } else if (releaseVelocity >= minimumVelocity) {
 
         // if we have a fast swipe, accelerate it to the fastSwipe velocity
-        if ((qAbs(velocity.x()) > maximumNonAcceleratedVelocity) &&
+        if ((qAbs(releaseVelocity.x()) > maximumNonAcceleratedVelocity) &&
             (fastSwipeVelocity.x() > maximumNonAcceleratedVelocity)) {
-            velocity.setX(velocity.x() > 0 ? fastSwipeVelocity.x() : -fastSwipeVelocity.x());
+            releaseVelocity.setX(releaseVelocity.x() > 0 ? fastSwipeVelocity.x() : -fastSwipeVelocity.x());
         }
-        if ((qAbs(velocity.y()) > maximumNonAcceleratedVelocity) &&
+        if ((qAbs(releaseVelocity.y()) > maximumNonAcceleratedVelocity) &&
             (fastSwipeVelocity.y() > maximumNonAcceleratedVelocity)) {
-            velocity.setY(velocity.y() > 0 ? fastSwipeVelocity.y() : -fastSwipeVelocity.y());
+            releaseVelocity.setY(releaseVelocity.y() > 0 ? fastSwipeVelocity.y() : -fastSwipeVelocity.y());
         }
 
     }
 
-    qKSDebug() << "release While dragging, velocity: "<<velocity<<"minimum velocity"<<minimumVelocity;
+    qKSDebug() << "release While dragging, velocity: "<<releaseVelocity<<"minimum velocity"<<minimumVelocity;
     if (overshootX || overshootY) {
-        velocity = QPointF(0, 0);
+        releaseVelocity = QPointF(0, 0);
         setState(QKineticScroller::StateScrolling);
-    } else if (velocity >= minimumVelocity)
+    } else if (releaseVelocity >= minimumVelocity)
         setState(QKineticScroller::StateScrolling);
     else
         setState(QKineticScroller::StateInactive);
@@ -769,8 +769,6 @@ void QKineticScrollerPrivate::timerEventWhileScrolling()
 
 bool QKineticScrollerPrivate::pressWhileScrolling(QKineticScroller::Input, const QPointF &, qint64)
 {
-    oldVelocity = velocity;
-
     setState(QKineticScroller::StatePressed);
     return true;
 }
@@ -802,7 +800,7 @@ void QKineticScrollerPrivate::setState(QKineticScroller::State newstate)
                 qWarning() << "State change from " << stateName(state) << " to " << stateName(newstate) << ", but timer is not active.";
             }
         }
-        velocity = QPointF(0, 0);
+        releaseVelocity = QPointF(0, 0);
         break;
 
     case QKineticScroller::StatePressed:
@@ -812,7 +810,8 @@ void QKineticScrollerPrivate::setState(QKineticScroller::State newstate)
         }
         scrollToX = false;
         scrollToY = false;
-        velocity = QPointF(0, 0);
+        oldVelocity = releaseVelocity;
+        // releaseVelocity = QPointF(0, 0);
         break;
 
     case QKineticScroller::StateDragging:
@@ -832,19 +831,12 @@ void QKineticScrollerPrivate::setState(QKineticScroller::State newstate)
         }
         scrollRelativeTimer.start();
         scrollAbsoluteTimer.start();
-        releaseVelocity = velocity;
 
         if (state == QKineticScroller::StateDragging) {
-            QPointF oldPos = q->contentPosition();
-            QPointF maxPos = q->maximumContentPosition();
-            QPointF oldClampedPos;
-            oldClampedPos.setX(qBound(qreal(0), oldPos.x(), maxPos.x()));
-            oldClampedPos.setY(qBound(qreal(0), oldPos.y(), maxPos.y()));
-
-            QPointF overshootDistance = oldPos - oldClampedPos;
+            overshootPosition *= overshootDragResistanceFactor;
 
-            overshootStartTimeX = overshootStartTimeY = scrollAbsoluteTimer.elapsed() - M_PI / (overshootSpringConstantRoot * 2);
-            overshootVelocity = overshootDistance * overshootSpringConstantRoot;
+            overshootStartTimeX = overshootStartTimeY = qreal(scrollAbsoluteTimer.elapsed()) / 1000 - M_PI / (overshootSpringConstantRoot * 2);
+            overshootVelocity = overshootPosition * overshootSpringConstantRoot;
         }
 
         break;
@@ -916,7 +908,7 @@ void QKineticScroller::scrollTo(const QPointF &pos, int scrollTime)
     d->scrollToPosition = pos;
     d->scrollToX = true;
     d->scrollToY = true;
-    d->velocity = v;
+    d->releaseVelocity = v;
     d->setState(QKineticScroller::StateScrolling);
 }
 
@@ -966,7 +958,7 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
 {
     Q_Q(QKineticScroller);
 
-    QPointF oldPos = q->contentPosition();
+    QPointF oldPos = q->contentPosition() + overshootPosition;
     QPointF newPos = oldPos + deltaPos;
     QPointF maxPos = q->maximumContentPosition();
 
@@ -999,14 +991,15 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
     qDebug() << "oldOver: " << oldOvershootY << "  newOver: " << newOvershootY;
     // -- x axis
     if (oldOvershootX && (qSign(oldOvershootX) != qSign(newOvershootX))) {
+        newClampedPos.setX((oldOvershootX < 0) ? 0 : maxPos.x());
         realOvershootDistance.setX(0);
         releaseVelocity.setX(0);
         overshootX = false;
 
     } else if (newOvershootX) {
         if (!oldOvershootX) {
-            overshootStartTimeX = scrollAbsoluteTimer.elapsed();
-            overshootVelocity.setX(velocity.x());
+            overshootStartTimeX = qreal(scrollAbsoluteTimer.elapsed()) / 1000;
+            overshootVelocity.setX(calculateVelocity(overshootStartTimeX).x());
             scrollToX = false;
             overshootX = true;
         }
@@ -1019,14 +1012,15 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
 
     // -- y axis
     if (oldOvershootY && (qSign(oldOvershootY) != qSign(newOvershootY))) {
+        newClampedPos.setY((oldOvershootY < 0) ? 0 : maxPos.y());
         realOvershootDistance.setY(0);
         releaseVelocity.setY(0);
         overshootY = false;
 
     } else if (newOvershootY) {
         if (!oldOvershootY) {
-            overshootStartTimeY = scrollAbsoluteTimer.elapsed();
-            overshootVelocity.setY(velocity.y());
+            overshootStartTimeY = qreal(scrollAbsoluteTimer.elapsed()) / 1000;
+            overshootVelocity.setY(calculateVelocity(overshootStartTimeY).y());
             scrollToY = false;
             overshootY = true;
         }
@@ -1052,6 +1046,7 @@ void QKineticScrollerPrivate::setContentPositionHelper(const QPointF &deltaPos)
     }
 
     q->setContentPosition(newClampedPos, realOvershootDistance);
+    overshootPosition = newPos - newClampedPos;
 
     qDebug() << "setContentPositionHelper" << newClampedPos << " overshoot:" << realOvershootDistance;
 }
diff --git a/qkineticscroller_p.h b/qkineticscroller_p.h
index 1f5a564..ccaee6d 100644
--- a/qkineticscroller_p.h
+++ b/qkineticscroller_p.h
@@ -119,7 +119,6 @@ public:
     bool enabled;
     QKineticScroller::State state;
     QKineticScroller::OvershootPolicy overshootPolicy;
-    QPointF velocity;
     QPointF oldVelocity;
 
     QPointF pressPosition;
@@ -127,12 +126,13 @@ public:
     qint64  pressTimestamp;
     qint64  lastTimestamp;
 
-    QPointF dragDistance;
+    QPointF dragDistance; // the distance we should move during the next drag timer event
 
     QPointF scrollToPosition;
     bool    scrollToX;
     bool    scrollToY;
 
+    QPointF overshootPosition; // the number of pixels we are overshooting (before overshootDragResistanceFactor)
     bool    overshootX;
     bool    overshootY;
 
@@ -140,8 +140,8 @@ public:
 
     QElapsedTimer scrollRelativeTimer;
     QElapsedTimer scrollAbsoluteTimer;
-    QPointF releaseVelocity;
-    QPointF overshootVelocity;
+    QPointF releaseVelocity; // the starting velocity of the scrolling state
+    QPointF overshootVelocity; // the starting velocity when going into overshoot
     qreal overshootStartTimeX;
     qreal overshootStartTimeY;
     int timerId;