Notify QQItem::mouseUngrabEvent() when an Event Handler steals grab

We already took care of cases when the handler is a child of the Item,
grab transitions involving Flickable etc.; but the bug is about a simpler
case when the handler is in the parent of the item that has the grab,
and steals from it.  Amends 38a016c7b1337d83d77879f45b4a2e6fec11d049

Fixes: QTBUG-71218
Fixes: QTBUG-75025
Change-Id: Id1d6d370e0db75c59ec7dce4a8e545701c501827
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

2 files changed, 93 insertions, 0 deletions

diff --git a/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/dragParentOfMPTA.qml b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/dragParentOfMPTA.qml
new file mode 100644
index 0000000000..dc7e5f6411
--- /dev/null
+++ b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/dragParentOfMPTA.qml
@@ -0,0 +1,50 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.12
+
+Item {
+    width: 640
+    height: 480
+    property alias touchpointPressed: tp1.pressed
+
+    Rectangle {
+        color: tp1.pressed ? "lightsteelblue" : drag.active ? "tomato" : "wheat"
+        width: 180
+        height: 180
+
+        DragHandler { id: drag }
+
+        MultiPointTouchArea {
+            anchors.fill: parent
+            touchPoints: [
+                TouchPoint { id: tp1 }
+            ]
+        }
+    }
+}
diff --git a/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/tst_multipointtoucharea_interop.cpp b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/tst_multipointtoucharea_interop.cpp
index bf582b820b..cd18580ccf 100644
--- a/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/tst_multipointtoucharea_interop.cpp
+++ b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/tst_multipointtoucharea_interop.cpp
@@ -56,6 +56,7 @@ private slots:
     void touchDrag();
     void touchesThenPinch();
     void unloadHandlerWithPassiveGrab();
+    void dragHandlerInParentStealingGrabFromItem();
 
 private:
     void createView(QScopedPointer<QQuickView> &window, const char *fileName);
@@ -301,6 +302,48 @@ void tst_MptaInterop::unloadHandlerWithPassiveGrab()
     QTest::mouseRelease(window, Qt::LeftButton, 0, point); // QTBUG-73819: don't crash
 }
 
+void tst_MptaInterop::dragHandlerInParentStealingGrabFromItem() // QTBUG-75025
+{
+    const int dragThreshold = QGuiApplication::styleHints()->startDragDistance();
+    QScopedPointer<QQuickView> windowPtr;
+    createView(windowPtr, "dragParentOfMPTA.qml");
+    QQuickView * window = windowPtr.data();
+    auto pointerEvent = QQuickWindowPrivate::get(window)->pointerEventInstance(QQuickPointerDevice::genericMouseDevice());
+
+    QPointer<QQuickPointerHandler> handler = window->rootObject()->findChild<QQuickPointerHandler*>();
+    QVERIFY(handler);
+    QQuickMultiPointTouchArea *mpta = window->rootObject()->findChild<QQuickMultiPointTouchArea*>();
+    QVERIFY(mpta);
+
+    // In QTBUG-75025 there is a QQ Controls Button; the MPTA here stands in for that,
+    // simply as an Item that grabs the mouse.  The bug has nothing to do with MPTA specifically.
+
+    QPoint point(20, 20);
+    QTest::mousePress(window, Qt::LeftButton, Qt::NoModifier, point);
+    QCOMPARE(window->mouseGrabberItem(), mpta);
+    QCOMPARE(window->rootObject()->property("touchpointPressed").toBool(), true);
+
+    // Start dragging
+    // DragHandler keeps monitoring, due to its passive grab,
+    // and eventually steals the exclusive grab from MPTA
+    int dragStoleGrab = 0;
+    for (int i = 0; i < 4; ++i) {
+        point += QPoint(dragThreshold / 2, 0);
+        QTest::mouseMove(window, point);
+        if (!dragStoleGrab && pointerEvent->point(0)->exclusiveGrabber() == handler)
+            dragStoleGrab = i;
+    }
+    if (dragStoleGrab)
+        qCDebug(lcPointerTests, "DragHandler stole the grab after %d events", dragStoleGrab);
+    QVERIFY(dragStoleGrab > 1);
+    QCOMPARE(handler->active(), true);
+    QCOMPARE(window->rootObject()->property("touchpointPressed").toBool(), false);
+
+    QTest::mouseRelease(window, Qt::LeftButton, Qt::NoModifier, point);
+    QCOMPARE(handler->active(), false);
+    QCOMPARE(window->rootObject()->property("touchpointPressed").toBool(), false);
+}
+
 QTEST_MAIN(tst_MptaInterop)
 
 #include "tst_multipointtoucharea_interop.moc"