Fixed MouseArea threshold with preventStealing

When preventStealing is true both keepMouseGrab() and
d->stealMouse are true. This in turn enable the dragging immediately
since the condition "keepMouseGrab() && d->stealMouse && !d->drag->active()"
is true.
Conversely when preventStealing is false the dragging is enabled in the
next move event since keepMouseGrab() and d->stealMouse are set true
inside the last "if" "!keepMouseGrab() && ...check threshold..".
This patch adds a new boolean flag for storing if we detected a drag motion
(so we exceeded the threshold) and enable the dragging iff this flag is true.
With this change:
- if preventStealing is true (and so keepMouseGrab() and d->stealMouse) the
additional d->overThresHold prevent the start of dragging. At the same time
the last if (!keepMouseGrab()) cannot be executed since keepMouseGrab is true
and we still check for the threshold being exceeded.
- if preventStealing is false, we still check for exceeding the threshold and
if this happen we enter in the last "if" since !keepMousegrab() && d->overThreshold
is true taking the mouseGrab as without this patch

Task-number: QTBUG-52534
Change-Id: I2b14d3048b6f8223c90ce5e2fd26e7ca706cb56a
Reviewed-by: Michael Brasser <michael.brasser@live.com>
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/quick/items/qquickmousearea_p_p.h b/src/quick/items/qquickmousearea_p_p.h
index 014729b651..f63c5f6092 100644
--- a/src/quick/items/qquickmousearea_p_p.h
+++ b/src/quick/items/qquickmousearea_p_p.h
@@ -86,6 +86,7 @@ public:
     bool doubleClick : 1;
     bool preventStealing : 1;
     bool propagateComposedEvents : 1;
+    bool overThreshold : 1;
     Qt::MouseButtons pressed;
 #ifndef QT_NO_DRAGANDDROP
     QQuickDrag *drag;