Flickable and MouseArea were too eager to take/keep mouse grab.

This meant that they would sometimes act upon a drag immediately,
rather than waiting for a nested area to take the grab.  This resulted
in a short jump before future events were handled by the nested item.

Task-number: QTBUG-15568
Reviewed-by: Bea Lam

1 files changed, 25 insertions, 12 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativemousearea.cpp b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
index d9edd11171..0a043a7967 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea.cpp
+++ b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
@@ -500,17 +500,9 @@ void QDeclarativeMouseArea::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
         const int dragThreshold = QApplication::startDragDistance();
         qreal dx = qAbs(curLocalPos.x() - startLocalPos.x());
         qreal dy = qAbs(curLocalPos.y() - startLocalPos.y());
-        if ((d->dragX && !(dx < dragThreshold)) || (d->dragY && !(dy < dragThreshold))) {
+
+        if (keepMouseGrab() && d->stealMouse)
             d->drag->setActive(true);
-            d->stealMouse = true;
-        }
-        if (!keepMouseGrab()) {
-            if ((!d->dragY && dy < dragThreshold && d->dragX && dx > dragThreshold)
-                || (!d->dragX && dx < dragThreshold && d->dragY && dy > dragThreshold)
-                || (d->dragX && d->dragY)) {
-                setKeepMouseGrab(true);
-            }
-        }
 
         if (d->dragX && d->drag->active()) {
             qreal x = (curLocalPos.x() - startLocalPos.x()) + d->startX;
@@ -528,6 +520,16 @@ void QDeclarativeMouseArea::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
                 y = drag()->ymax();
             drag()->target()->setY(y);
         }
+
+        if (!keepMouseGrab()) {
+            if ((!d->dragY && dy < dragThreshold && d->dragX && dx > dragThreshold)
+                || (!d->dragX && dx < dragThreshold && d->dragY && dy > dragThreshold)
+                || (d->dragX && d->dragY && (dx > dragThreshold || dy > dragThreshold))) {
+                setKeepMouseGrab(true);
+                d->stealMouse = true;
+            }
+        }
+
         d->moved = true;
     }
     QDeclarativeMouseEvent me(d->lastPos.x(), d->lastPos.y(), d->lastButton, d->lastButtons, d->lastModifiers, false, d->longPress);
@@ -618,6 +620,7 @@ bool QDeclarativeMouseArea::sceneEvent(QEvent *event)
             // if our mouse grab has been removed (probably by Flickable), fix our
             // state
             d->pressed = false;
+            d->stealMouse = false;
             setKeepMouseGrab(false);
             emit canceled();
             emit pressedChanged();
@@ -672,8 +675,18 @@ bool QDeclarativeMouseArea::sendMouseEvent(QGraphicsSceneMouseEvent *event)
         return stealThisEvent;
     }
     if (mouseEvent.type() == QEvent::GraphicsSceneMouseRelease) {
-        d->stealMouse = false;
-        ungrabMouse();
+        if (d->pressed) {
+            d->pressed = false;
+            d->stealMouse = false;
+            if (s && s->mouseGrabberItem() == this)
+                ungrabMouse();
+            emit canceled();
+            emit pressedChanged();
+            if (d->hovered) {
+                d->hovered = false;
+                emit hoveredChanged();
+            }
+        }
     }
     return false;
 }