add virtual QQuickPointerHandler::onGrabChanged and signal grabChanged

Some handlers will need to react to gaining or losing a grab, in both
C++ and QML.

Change-Id: I25b94800e3eaeabb0782315c679813ec735d4d51
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/quick/handlers/qquickpointerhandler.cpp b/src/quick/handlers/qquickpointerhandler.cpp
index da8fccbfa0..77f0db41b7 100644
--- a/src/quick/handlers/qquickpointerhandler.cpp
+++ b/src/quick/handlers/qquickpointerhandler.cpp
@@ -70,8 +70,12 @@ void QQuickPointerHandler::setGrab(QQuickEventPoint *point, bool grab)
         if (oldGrabber && oldGrabber != this)
             oldGrabber->handleGrabCancel(point);
         point->setGrabberPointerHandler(this);
+        onGrabChanged(point);
+        emit grabChanged(point);
     } else if (point->grabberPointerHandler() == this) {
         point->setGrabberPointerHandler(nullptr);
+        onGrabChanged(point);
+        emit grabChanged(point);
     }
 }