In response to touch cancel, don't just ungrab, send an ungrab event

QQuickWindowPrivate::sendUngrabEvent() sends an UngrabMouse event, and
that can be filtered by parent filters.  If a touch cancel happens to a
MouseArea in a ListView delegate, we need the ListView to filter the
UngrabMouse event so that QQuickFlickable::childMouseEventFilter() will
call QQuickFlickable::mouseUngrabEvent() and
QQuickFlickablePrivate::cancelInteraction() will set pressed to false.
The pressed state became true because Flickable filtered the press
event; so for symmetry, it also needs to filter the touch cancel (in the
form of a mouse ungrab), to avoid being stuck in a state where it can't
move programmatically.

Fixes: QTBUG-74679
Change-Id: I6c0ed364d2bc1f45c7e7b17846a09f6b53f91d0a
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

1 files changed, 29 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/data/delegateWithMouseArea.qml b/tests/auto/quick/qquicklistview/data/delegateWithMouseArea.qml
new file mode 100644
index 0000000000..e0b8222bfb
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/delegateWithMouseArea.qml
@@ -0,0 +1,29 @@
+import QtQuick 2.12
+
+ListView {
+    id: root
+    objectName: "view"
+    width: 600
+    height: 600
+    model: 3
+    snapMode: ListView.SnapOneItem
+    boundsBehavior: Flickable.StopAtBounds
+    highlightRangeMode: ListView.StrictlyEnforceRange
+    preferredHighlightBegin: 0
+    preferredHighlightEnd: 0
+    highlightMoveDuration: 100
+    delegate: Rectangle {
+        id: delegateRect
+        width: 500
+        height: 500
+        color: Qt.rgba(Math.random(), Math.random(), Math.random(), 1)
+        Text {
+            text: index
+            font.pixelSize: 128
+            anchors.centerIn: parent
+        }
+        MouseArea {
+            anchors.fill: parent
+        }
+    }
+}