Avoid emitting release when the mouse is ungrabbed

Added an onCanceled signal to mouse area, which is triggered when the
mouse area rejects the event (propagates to the nearest
mouse area beneath) or some other element steals the mouse grab
(flickable, for example).

Task-number: QTBUG-10162
Reviewed-by: Michael Brasser

2 files changed, 17 insertions, 3 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativemousearea.cpp b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
index c5a995e..74f2338 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea.cpp
+++ b/src/declarative/graphicsitems/qdeclarativemousearea.cpp
@@ -288,6 +288,17 @@ QDeclarativeMouseAreaPrivate::~QDeclarativeMouseAreaPrivate()
 */
 
 /*!
+    \qmlsignal MouseArea::onCanceled()
+
+    This handler is called when the mouse events are canceled, either because the event was not accepted or
+    another element stole the mouse event handling. This signal is for advanced users, it's useful in case there
+    is more than one mouse areas handling input, or when there is a mouse area inside a flickable. In the latter
+    case, if you do some logic on pressed and then start dragging, the flickable will steal the mouse handling
+    from the mouse area. In these cases, to reset the logic when there is no mouse handling anymore, you should
+    use onCanceled, in addition to onReleased.
+*/
+
+/*!
     \internal
     \class QDeclarativeMouseArea
     \brief The QDeclarativeMouseArea class provides a simple mouse handling abstraction for use within Qml.
@@ -562,10 +573,12 @@ bool QDeclarativeMouseArea::sceneEvent(QEvent *event)
             // state
             d->pressed = false;
             setKeepMouseGrab(false);
-            QDeclarativeMouseEvent me(d->lastPos.x(), d->lastPos.y(), d->lastButton, d->lastButtons, d->lastModifiers, false, false);
-            emit released(&me);
+            emit canceled();
             emit pressedChanged();
-            setHovered(false);
+            if (d->hovered) {
+                d->hovered = false;
+                emit hoveredChanged();
+            }
         }
     }
     return rv;
diff --git a/src/declarative/graphicsitems/qdeclarativemousearea_p.h b/src/declarative/graphicsitems/qdeclarativemousearea_p.h
index e3f523b..df77ac6 100644
--- a/src/declarative/graphicsitems/qdeclarativemousearea_p.h
+++ b/src/declarative/graphicsitems/qdeclarativemousearea_p.h
@@ -163,6 +163,7 @@ Q_SIGNALS:
     void doubleClicked(QDeclarativeMouseEvent *mouse);
     void entered();
     void exited();
+    void canceled();
 
 protected:
     void setHovered(bool);