Velocities reported by Flickable in onFlickStarted can be 0

Change 55cfbdb7c64068ae68f7baaceb8acfb96cb0c07e manually applied
from Qt 4.7

Ensure the smoothed velocity is set at the start of the flick.  Ensure
that the smoothed velocity animation isn't restarted unless there is
new valid data.

Change-Id: Ia77249be9980aba268a1bfa0ea3f69c49fa09e5e
Reviewed-by: Bea Lam
Reviewed-on: http://codereview.qt-project.org/4712
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Martin Jones <martin.jones@nokia.com>

2 files changed, 42 insertions, 18 deletions

diff --git a/src/declarative/items/qsgflickable.cpp b/src/declarative/items/qsgflickable.cpp
index ce8afa1f4c..36d7db217c 100644
--- a/src/declarative/items/qsgflickable.cpp
+++ b/src/declarative/items/qsgflickable.cpp
@@ -962,18 +962,24 @@ void QSGFlickablePrivate::handleMouseReleaseEvent(QMouseEvent *event)
     qreal velocity = vData.velocity;
     if (vData.atBeginning || vData.atEnd)
         velocity /= 2;
-    if (qAbs(velocity) > MinimumFlickVelocity && qAbs(event->localPos().y() - pressPos.y()) > FlickThreshold)
+    if (q->yflick() && qAbs(velocity) > MinimumFlickVelocity && qAbs(event->localPos().y() - pressPos.y()) > FlickThreshold) {
+        velocityTimeline.reset(vData.smoothVelocity);
+        vData.smoothVelocity.setValue(-velocity);
         flickY(velocity);
-    else
+    } else {
         fixupY();
+    }
 
     velocity = hData.velocity;
     if (hData.atBeginning || hData.atEnd)
         velocity /= 2;
-    if (qAbs(velocity) > MinimumFlickVelocity && qAbs(event->localPos().x() - pressPos.x()) > FlickThreshold)
+    if (q->xflick() && qAbs(velocity) > MinimumFlickVelocity && qAbs(event->localPos().x() - pressPos.x()) > FlickThreshold) {
+        velocityTimeline.reset(hData.smoothVelocity);
+        hData.smoothVelocity.setValue(-velocity);
         flickX(velocity);
-    else
+    } else {
         fixupX();
+    }
 
     if (!timeline.isActive())
         q->movementEnding();
@@ -1156,19 +1162,25 @@ void QSGFlickable::viewportMoved()
 
     qreal prevX = d->lastFlickablePosition.x();
     qreal prevY = d->lastFlickablePosition.y();
-    d->velocityTimeline.clear();
     if (d->pressed || d->calcVelocity) {
         int elapsed = QSGItemPrivate::restart(d->velocityTime);
         if (elapsed > 0) {
             qreal horizontalVelocity = (prevX - d->hData.move.value()) * 1000 / elapsed;
+            if (qAbs(horizontalVelocity) > 0) {
+                d->velocityTimeline.reset(d->hData.smoothVelocity);
+                d->velocityTimeline.move(d->hData.smoothVelocity, horizontalVelocity, d->reportedVelocitySmoothing);
+                d->velocityTimeline.move(d->hData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            }
             qreal verticalVelocity = (prevY - d->vData.move.value()) * 1000 / elapsed;
-            d->velocityTimeline.move(d->hData.smoothVelocity, horizontalVelocity, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->hData.smoothVelocity, 0, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->vData.smoothVelocity, verticalVelocity, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->vData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            if (qAbs(verticalVelocity) > 0) {
+                d->velocityTimeline.reset(d->vData.smoothVelocity);
+                d->velocityTimeline.move(d->vData.smoothVelocity, verticalVelocity, d->reportedVelocitySmoothing);
+                d->velocityTimeline.move(d->vData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            }
         }
     } else {
         if (d->timeline.time() > d->vTime) {
+            d->velocityTimeline.clear();
             qreal horizontalVelocity = (prevX - d->hData.move.value()) * 1000 / (d->timeline.time() - d->vTime);
             qreal verticalVelocity = (prevY - d->vData.move.value()) * 1000 / (d->timeline.time() - d->vTime);
             d->hData.smoothVelocity.setValue(horizontalVelocity);
diff --git a/src/qtquick1/graphicsitems/qdeclarativeflickable.cpp b/src/qtquick1/graphicsitems/qdeclarativeflickable.cpp
index f145312334..6fa92b3bfa 100644
--- a/src/qtquick1/graphicsitems/qdeclarativeflickable.cpp
+++ b/src/qtquick1/graphicsitems/qdeclarativeflickable.cpp
@@ -913,18 +913,24 @@ void QDeclarative1FlickablePrivate::handleMouseReleaseEvent(QGraphicsSceneMouseE
     qreal velocity = vData.velocity;
     if (vData.atBeginning || vData.atEnd)
         velocity /= 2;
-    if (qAbs(velocity) > MinimumFlickVelocity && qAbs(event->pos().y() - pressPos.y()) > FlickThreshold)
+    if (q->yflick() && qAbs(velocity) > MinimumFlickVelocity && qAbs(event->pos().y() - pressPos.y()) > FlickThreshold) {
+        velocityTimeline.reset(vData.smoothVelocity);
+        vData.smoothVelocity.setValue(-velocity);
         flickY(velocity);
-    else
+    } else {
         fixupY();
+    }
 
     velocity = hData.velocity;
     if (hData.atBeginning || hData.atEnd)
         velocity /= 2;
-    if (qAbs(velocity) > MinimumFlickVelocity && qAbs(event->pos().x() - pressPos.x()) > FlickThreshold)
+    if (q->xflick() && qAbs(velocity) > MinimumFlickVelocity && qAbs(event->pos().x() - pressPos.x()) > FlickThreshold) {
+        velocityTimeline.reset(hData.smoothVelocity);
+        hData.smoothVelocity.setValue(-velocity);
         flickX(velocity);
-    else
+    } else {
         fixupX();
+    }
 
     if (!timeline.isActive())
         q->movementEnding();
@@ -1124,19 +1130,25 @@ void QDeclarative1Flickable::viewportMoved()
 
     qreal prevX = d->lastFlickablePosition.x();
     qreal prevY = d->lastFlickablePosition.y();
-    d->velocityTimeline.clear();
     if (d->pressed || d->calcVelocity) {
         int elapsed = QDeclarativeItemPrivate::restart(d->velocityTime);
         if (elapsed > 0) {
             qreal horizontalVelocity = (prevX - d->hData.move.value()) * 1000 / elapsed;
+            if (qAbs(horizontalVelocity) > 0) {
+                d->velocityTimeline.reset(d->hData.smoothVelocity);
+                d->velocityTimeline.move(d->hData.smoothVelocity, horizontalVelocity, d->reportedVelocitySmoothing);
+                d->velocityTimeline.move(d->hData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            }
             qreal verticalVelocity = (prevY - d->vData.move.value()) * 1000 / elapsed;
-            d->velocityTimeline.move(d->hData.smoothVelocity, horizontalVelocity, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->hData.smoothVelocity, 0, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->vData.smoothVelocity, verticalVelocity, d->reportedVelocitySmoothing);
-            d->velocityTimeline.move(d->vData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            if (qAbs(verticalVelocity) > 0) {
+                d->velocityTimeline.reset(d->vData.smoothVelocity);
+                d->velocityTimeline.move(d->vData.smoothVelocity, verticalVelocity, d->reportedVelocitySmoothing);
+                d->velocityTimeline.move(d->vData.smoothVelocity, 0, d->reportedVelocitySmoothing);
+            }
         }
     } else {
         if (d->timeline.time() > d->vTime) {
+            d->velocityTimeline.clear();
             qreal horizontalVelocity = (prevX - d->hData.move.value()) * 1000 / (d->timeline.time() - d->vTime);
             qreal verticalVelocity = (prevY - d->vData.move.value()) * 1000 / (d->timeline.time() - d->vTime);
             d->hData.smoothVelocity.setValue(horizontalVelocity);