Improve interaction of nested Flickables and PathView

Don't require a flick to come to a complete stop before
allowing another flickable element to begin its
gesture.

Change-Id: I74c1998e01e04c70c76253cd09edc02f593123d0
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>

src/quick/items/qquickcanvas.cpp

@@ -376,10 +376,8 @@ void QQuickCanvasPrivate::translateTouchToMouse(QTouchEvent *event)
 {
     if (event->type() == QEvent::TouchCancel) {
         touchMouseId = -1;
-        if (!mouseGrabberItem)
-            return;
-        mouseGrabberItem->ungrabMouse();
-        mouseGrabberItem = 0;
+        if (mouseGrabberItem)
+            mouseGrabberItem->ungrabMouse();
         return;
     }
     for (int i = 0; i < event->touchPoints().count(); ++i) {
@@ -447,7 +445,8 @@ void QQuickCanvasPrivate::translateTouchToMouse(QTouchEvent *event)
                 me.setTimestamp(event->timestamp());
                 me.setCapabilities(event->device()->capabilities());
                 deliverMouseEvent(&me);
-                mouseGrabberItem = 0;
+                if (mouseGrabberItem)
+                    mouseGrabberItem->ungrabMouse();
             }
             break;
         }
@@ -947,13 +946,13 @@ bool QQuickCanvasPrivate::deliverInitialMousePressEvent(QQuickItem *item, QMouse
             QMouseEvent me(event->type(), p, event->windowPos(), event->screenPos(),
                            event->button(), event->buttons(), event->modifiers());
             me.accept();
-            mouseGrabberItem = item;
+            item->grabMouse();
             q->sendEvent(item, &me);
             event->setAccepted(me.isAccepted());
             if (me.isAccepted())
                 return true;
-            mouseGrabberItem->ungrabMouse();
-            mouseGrabberItem = 0;
+            if (mouseGrabberItem)
+                mouseGrabberItem->ungrabMouse();
         }
     }
 
@@ -1023,7 +1022,8 @@ void QQuickCanvas::mouseReleaseEvent(QMouseEvent *event)
     }
 
     d->deliverMouseEvent(event);
-    d->mouseGrabberItem = 0;
+    if (d->mouseGrabberItem)
+        d->mouseGrabberItem->ungrabMouse();
 }
 
 /*! \reimp */
@@ -1560,6 +1560,12 @@ bool QQuickCanvas::sendEvent(QQuickItem *item, QEvent *e)
             QQuickItemPrivate::get(item)->deliverMouseEvent(static_cast<QMouseEvent *>(e));
         }
         break;
+    case QEvent::UngrabMouse:
+        if (!d->sendFilteredMouseEvent(item->parentItem(), item, e)) {
+            e->accept();
+            item->mouseUngrabEvent();
+        }
+        break;
     case QEvent::Wheel:
         QQuickItemPrivate::get(item)->deliverWheelEvent(static_cast<QWheelEvent *>(e));
         break;

src/quick/items/qquickflickable.cpp

@@ -107,7 +107,7 @@ static const int FlickThreshold = 20;
 
 // RetainGrabVelocity is the maxmimum instantaneous velocity that
 // will ensure the Flickable retains the grab on consecutive flicks.
-static const int RetainGrabVelocity = 15;
+static const int RetainGrabVelocity = 100;
 
 QQuickFlickableVisibleArea::QQuickFlickableVisibleArea(QQuickFlickable *parent)
     : QObject(parent), flickable(parent), m_xPosition(0.), m_widthRatio(0.)
@@ -823,8 +823,8 @@ void QQuickFlickablePrivate::handleMousePressEvent(QMouseEvent *event)
     Q_Q(QQuickFlickable);
     QQuickItemPrivate::start(timer);
     if (interactive && timeline.isActive()
-        && (qAbs(hData.smoothVelocity.value()) > RetainGrabVelocity
-            || qAbs(vData.smoothVelocity.value()) > RetainGrabVelocity)) {
+        && ((qAbs(hData.smoothVelocity.value()) > RetainGrabVelocity && !hData.fixingUp && !hData.inOvershoot)
+            || (qAbs(vData.smoothVelocity.value()) > RetainGrabVelocity && !vData.fixingUp && !vData.inOvershoot))) {
         stealMouse = true; // If we've been flicked then steal the click.
         int flickTime = timeline.time();
         if (flickTime > 600) {
@@ -846,7 +846,10 @@ void QQuickFlickablePrivate::handleMousePressEvent(QMouseEvent *event)
     }
     q->setKeepMouseGrab(stealMouse);
     pressed = true;
-    timeline.clear();
+    if (!hData.fixingUp)
+        timeline.reset(hData.move);
+    if (!vData.fixingUp)
+        timeline.reset(vData.move);
     hData.reset();
     vData.reset();
     hData.dragMinBound = q->minXExtent();
@@ -910,6 +913,7 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
                 }
             }
             if (!rejectY && stealMouse && dy != 0.0) {
+                timeline.clear();
                 vData.move.setValue(newY);
                 vMoved = true;
             }
@@ -942,6 +946,7 @@ void QQuickFlickablePrivate::handleMouseMoveEvent(QMouseEvent *event)
                 }
             }
             if (!rejectX && stealMouse && dx != 0.0) {
+                timeline.clear();
                 hData.move.setValue(newX);
                 hMoved = true;
             }
@@ -1753,6 +1758,7 @@ void QQuickFlickable::mouseUngrabEvent()
     if (d->pressed) {
         // if our mouse grab has been removed (probably by another Flickable),
         // fix our state
+        d->clearDelayedPress();
         d->pressed = false;
         d->draggingEnding();
         d->stealMouse = false;
@@ -1845,6 +1851,12 @@ bool QQuickFlickable::childMouseEventFilter(QQuickItem *i, QEvent *e)
     case QEvent::MouseMove:
     case QEvent::MouseButtonRelease:
         return sendMouseEvent(static_cast<QMouseEvent *>(e));
+    case QEvent::UngrabMouse:
+        if (d->canvas && d->canvas->mouseGrabberItem() && d->canvas->mouseGrabberItem() != this) {
+            // The grab has been taken away from a child and given to some other item.
+            mouseUngrabEvent();
+        }
+        break;
     default:
         break;
     }

src/quick/items/qquickitem.cpp

@@ -4743,8 +4743,10 @@ void QQuickItem::grabMouse()
 
     QQuickItem *oldGrabber = canvasPriv->mouseGrabberItem;
     canvasPriv->mouseGrabberItem = this;
-    if (oldGrabber)
-        oldGrabber->mouseUngrabEvent();
+    if (oldGrabber) {
+        QEvent ev(QEvent::UngrabMouse);
+        d->canvas->sendEvent(oldGrabber, &ev);
+    }
 }
 
 void QQuickItem::ungrabMouse()
@@ -4759,7 +4761,9 @@ void QQuickItem::ungrabMouse()
     }
 
     canvasPriv->mouseGrabberItem = 0;
-    mouseUngrabEvent();
+
+    QEvent ev(QEvent::UngrabMouse);
+    d->canvas->sendEvent(this, &ev);
 }
 
 bool QQuickItem::keepMouseGrab() const

src/quick/items/qquickpathview.cpp

@@ -1224,7 +1224,8 @@ void QQuickPathViewPrivate::handleMousePressEvent(QMouseEvent *event)
             return;
     }
 
-    if (tl.isActive() && flicking)
+
+    if (tl.isActive() && flicking && flickDuration && qreal(tl.time())/flickDuration < 0.8)
         stealMouse = true; // If we've been flicked then steal the click.
     else
         stealMouse = false;
@@ -1335,6 +1336,7 @@ void QQuickPathViewPrivate::handleMouseReleaseEvent(QMouseEvent *)
         } else {
             dist = qMin(qreal(modelCount-1), qreal(v2 / (accel * 2.0)));
         }
+        flickDuration = static_cast<int>(1000 * qAbs(velocity) / accel);
         offsetAdj = 0.0;
         moveOffset.setValue(offset);
         tl.accel(moveOffset, velocity, accel, dist);

src/quick/items/qquickpathview_p_p.h

@@ -81,7 +81,7 @@ class QQuickPathViewPrivate : public QQuickItemPrivate, public QQuickItemChangeL
         , autoHighlight(true), highlightUp(false), layoutScheduled(false)
         , moving(false), flicking(false), requestedOnPath(false), inRequest(false)
         , dragMargin(0), deceleration(100)
-        , moveOffset(this, &QQuickPathViewPrivate::setAdjustedOffset)
+        , moveOffset(this, &QQuickPathViewPrivate::setAdjustedOffset), flickDuration(0)
         , firstIndex(-1), pathItems(-1), requestedIndex(-1), requestedZ(0)
         , moveReason(Other), moveDirection(Shortest), attType(0), highlightComponent(0), highlightItem(0)
         , moveHighlight(this, &QQuickPathViewPrivate::setHighlightPosition)
@@ -171,6 +171,7 @@ class QQuickPathViewPrivate : public QQuickItemPrivate, public QQuickItemChangeL
     qreal deceleration;
     QQuickTimeLine tl;
     QQuickTimeLineValueProxy<QQuickPathViewPrivate> moveOffset;
+    int flickDuration;
     int firstIndex;
     int pathItems;
     int requestedIndex;