Handle press events without release gracefully

In the old code, touch point grabbers would be ignored in case of a
press without release for a point. To make sure not to break existing
bad test code or clash with broken devices, warn, but reset the grabber
for new press events.

Change-Id: Ia76ed4d3ee32c983c451f760837e83f8d90dab41
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/quick/items/qquickevents.cpp b/src/quick/items/qquickevents.cpp
index bc9e5d0ad2..59faafa023 100644
--- a/src/quick/items/qquickevents.cpp
+++ b/src/quick/items/qquickevents.cpp
@@ -624,7 +624,13 @@ QQuickPointerEvent *QQuickPointerTouchEvent::reset(QEvent *event)
     for (int i = 0; i < newPointCount; ++i) {
         auto point = m_touchPoints.at(i);
         point->reset(tps.at(i), ev->timestamp());
-        point->setGrabber(grabbers.at(i));
+        if (point->state() == QQuickEventPoint::Pressed) {
+            if (grabbers.at(i))
+                qWarning() << "TouchPointPressed without previous release event" << point;
+            point->setGrabber(nullptr);
+        } else {
+            point->setGrabber(grabbers.at(i));
+        }
     }
     m_pointCount = newPointCount;
     return this;