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>

2 files changed, 63 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
+        }
+    }
+}
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index ff796a5bd8..fddba77f35 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -37,6 +37,7 @@
 #include <QtQml/qqmlincubator.h>
 #include <QtQuick/private/qquickitemview_p_p.h>
 #include <QtQuick/private/qquicklistview_p.h>
+#include <QtQuick/private/qquickmousearea_p.h>
 #include <QtQuick/private/qquicktext_p.h>
 #include <QtQml/private/qqmlobjectmodel_p.h>
 #include <QtQml/private/qqmllistmodel_p.h>
@@ -273,6 +274,7 @@ private slots:
 
     void addOnCompleted();
     void setPositionOnLayout();
+    void touchCancel();
 
 private:
     template <class T> void items(const QUrl &source);
@@ -328,6 +330,7 @@ private:
 
     QQuickView *m_view;
     QString testForView;
+    QTouchDevice *touchDevice = QTest::createTouchDevice();
 };
 
 class TestObject : public QObject
@@ -8944,6 +8947,37 @@ void tst_QQuickListView::useDelegateChooserWithoutDefault()
     window->show();
 };
 
+void tst_QQuickListView::touchCancel() // QTBUG-74679
+{
+    QScopedPointer<QQuickView> window(createView());
+    window->setSource(testFileUrl("delegateWithMouseArea.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+
+    QQuickListView *listview = qobject_cast<QQuickListView *>(window->rootObject());
+    QVERIFY(listview);
+    QQuickMouseArea *mouseArea = listview->currentItem()->findChild<QQuickMouseArea *>();
+    QVERIFY(mouseArea);
+
+    QPoint p1(300, 300);
+    QTest::touchEvent(window.data(), touchDevice).press(0, p1, window.data());
+    QQuickTouchUtils::flush(window.data());
+    QTRY_VERIFY(mouseArea->pressed());
+    // and because Flickable filtered it, QQuickFlickablePrivate::pressed
+    // should be true, but it's not easily tested here
+
+    QTouchEvent cancelEvent(QEvent::TouchCancel);
+    cancelEvent.setDevice(touchDevice);
+    QCoreApplication::sendEvent(window.data(), &cancelEvent);
+    // now QQuickWindowPrivate::sendUngrabEvent() will be called, Flickable will filter it,
+    // QQuickFlickablePrivate::pressed will be set to false, and that will allow setCurrentIndex() to make it move
+    QQuickTouchUtils::flush(window.data());
+
+    listview->setCurrentIndex(1);
+    // ensure that it actually moves (animates) to the second delegate
+    QTRY_COMPARE(listview->contentY(), 500.0);
+}
+
 QTEST_MAIN(tst_QQuickListView)
 
 #include "tst_qquicklistview.moc"