Ensure that HoverHandler reacts if a touchpoint moves out of bounds

We rely on QQuickDeliveryAgentPrivate::flushFrameSynchronousEvents()
mostly, but it doesn't get invoked without a window update request.
So there is a special case when a touchpoint moves _out_ of an item
that has a HoverHandler but is not reacting to touch in other ways:
we just need to send another artificial hover event for each touchpoint
to each hovered item to inform handlers about the new hover position.

Fixes: QTBUG-120346
Pick-to: 6.2 6.5 6.6 6.7
Change-Id: I479362a2663943eb495fe0be418009165c7134bd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Santhosh Kumar <santhosh.kumar.selvaraj@qt.io>

src/quick/util/qquickdeliveryagent.cpp

@@ -2092,6 +2092,16 @@ void QQuickDeliveryAgentPrivate::deliverUpdatedPoints(QPointerEvent *event)
         }
         if (!relevantPassiveGrabbers.isEmpty())
             deliverToPassiveGrabbers(relevantPassiveGrabbers, event);
+
+        // Ensure that HoverHandlers are updated, in case no items got dirty so far and there's no update request
+        if (event->type() == QEvent::TouchUpdate) {
+            for (auto hoverItem : hoverItems) {
+                if (auto item = hoverItem.first) {
+                    deliverHoverEventToItem(item, point.scenePosition(), point.sceneLastPosition(),
+                                            event->modifiers(), event->timestamp(), false);
+                }
+            }
+        }
     }
 
     if (done)

tests/auto/quick/pointerhandlers/qquickhoverhandler/data/hoverHandler.qml

@@ -0,0 +1,17 @@
+import QtQuick
+
+Item {
+    width: 320
+    height: 240
+
+    Rectangle {
+        width: 100
+        height: 100
+        anchors.centerIn: parent
+        color: hh.hovered ? "lightsteelblue" : "beige"
+
+        HoverHandler {
+            id: hh
+        }
+    }
+}

tests/auto/quick/pointerhandlers/qquickhoverhandler/tst_qquickhoverhandler.cpp

@@ -49,9 +49,12 @@ private slots:
     void addHandlerFromCpp();
     void ensureHoverHandlerWorksWhenItemHasHoverDisabled();
     void changeCursor();
+    void touchDrag();
 
 private:
     void createView(QScopedPointer<QQuickView> &window, const char *fileName);
+
+    QScopedPointer<QPointingDevice> touchscreen = QScopedPointer<QPointingDevice>(QTest::createTouchDevice());
 };
 
 void tst_HoverHandler::createView(QScopedPointer<QQuickView> &window, const char *fileName)
@@ -700,6 +703,46 @@ void tst_HoverHandler::changeCursor()
 #endif
 }
 
+void tst_HoverHandler::touchDrag()
+{
+    QQuickView window;
+    QVERIFY(QQuickTest::showView(window, testFileUrl("hoverHandler.qml")));
+    const QQuickItem *root = window.rootObject();
+    QQuickHoverHandler *handler = root->findChild<QQuickHoverHandler *>();
+    QVERIFY(handler);
+
+    // polishAndSync() calls flushFrameSynchronousEvents() before emitting afterAnimating()
+    QSignalSpy frameSyncSpy(&window, &QQuickWindow::afterAnimating);
+
+    const QPoint out(root->width() - 1, root->height() / 2);
+    QPoint in(root->width() / 2, root->height() / 2);
+
+    QTest::touchEvent(&window, touchscreen.get()).press(0, out, &window);
+    QQuickTouchUtils::flush(&window);
+    QCOMPARE(handler->isHovered(), false);
+
+    frameSyncSpy.clear();
+    QTest::touchEvent(&window, touchscreen.get()).move(0, in, &window);
+    QQuickTouchUtils::flush(&window);
+    QTRY_COMPARE(handler->isHovered(), true);
+    QCOMPARE(handler->point().scenePosition(), in);
+
+    in += {10, 10};
+    QTest::touchEvent(&window, touchscreen.get()).move(0, in, &window);
+    QQuickTouchUtils::flush(&window);
+    // ensure that the color change is visible
+    QTRY_COMPARE_GE(frameSyncSpy.size(), 1);
+    QCOMPARE(handler->isHovered(), true);
+    QCOMPARE(handler->point().scenePosition(), in);
+
+    QTest::touchEvent(&window, touchscreen.get()).move(0, out, &window);
+    QQuickTouchUtils::flush(&window);
+    QTRY_COMPARE_GE(frameSyncSpy.size(), 2);
+    QCOMPARE(handler->isHovered(), false);
+
+    QTest::touchEvent(&window, touchscreen.get()).release(0, out, &window);
+}
+
 QTEST_MAIN(tst_HoverHandler)
 
 #include "tst_qquickhoverhandler.moc"