prepend PointerHandler children of Items so the last is visited first

This helps with overriding behavior: when a QML control implementation
has handlers encapsulated inside, but the user tries to override
behavior by declaring more handler instances in instances of the
control, the user's handlers must be visited before the encapsulated
handlers.  Likewise, this reverse-ordering corresponds to intuition
after having used MouseHandlers: the one which is declared last inside
an Item will have a higher effective Z order, and thus will be visited
first during event delivery.

Task-number: QTBUG-64692
Change-Id: I9bf18218a1887d0297c71ebf81dde0956394b72a
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

3 files changed, 86 insertions, 5 deletions

diff --git a/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/pinchDragMPTA.qml b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/pinchDragMPTA.qml
index eebeb22201..084cc25414 100644
--- a/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/pinchDragMPTA.qml
+++ b/tests/auto/quick/pointerhandlers/multipointtoucharea_interop/data/pinchDragMPTA.qml
@@ -90,6 +90,11 @@ Rectangle {
             // In order to get the touchpoints first, it has to be on top of the Z order: i.e. come last in paintOrderChildItems().
             // This is the opposite situation as with filtersChildMouseEvents: e.g. PinchArea would have wanted to be the parent,
             // if it even knew that trick (which it doesn't).
+            DragHandler {
+                id: dragHandler
+                objectName: "DragHandler"
+                target: container
+            }
             PinchHandler {
                 id: pinch3
                 objectName: "3-finger pinch"
@@ -98,11 +103,6 @@ Rectangle {
                 minimumScale: 0.1
                 maximumScale: 10
             }
-            DragHandler {
-                id: dragHandler
-                objectName: "DragHandler"
-                target: container
-            }
         }
     }
 }
diff --git a/tests/auto/quick/pointerhandlers/qquicktaphandler/data/buttonOverrideHandler.qml b/tests/auto/quick/pointerhandlers/qquicktaphandler/data/buttonOverrideHandler.qml
new file mode 100644
index 0000000000..14a8d67300
--- /dev/null
+++ b/tests/auto/quick/pointerhandlers/qquicktaphandler/data/buttonOverrideHandler.qml
@@ -0,0 +1,45 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 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 2.0
+import Qt.labs.handlers 1.0
+
+Item {
+    width: 320
+    height: 240
+    Button {
+        id: button
+        objectName: "Overridden"
+        label: "Overridden"
+        x: 10; y: 10; width: parent.width - 20; height: 40
+        TapHandler {
+            objectName: "override"
+            onTapped: button.tapped()
+        }
+    }
+}
diff --git a/tests/auto/quick/pointerhandlers/qquicktaphandler/tst_qquicktaphandler.cpp b/tests/auto/quick/pointerhandlers/qquicktaphandler/tst_qquicktaphandler.cpp
index d7eda5e19c..9e3261f7b2 100644
--- a/tests/auto/quick/pointerhandlers/qquicktaphandler/tst_qquicktaphandler.cpp
+++ b/tests/auto/quick/pointerhandlers/qquicktaphandler/tst_qquicktaphandler.cpp
@@ -68,6 +68,7 @@ private slots:
     void touchLongPress();
     void mouseLongPress();
     void buttonsMultiTouch();
+    void componentUserBehavioralOverride();
 
 private:
     void createView(QScopedPointer<QQuickView> &window, const char *fileName);
@@ -585,6 +586,41 @@ void tst_TapHandler::buttonsMultiTouch()
     QVERIFY(buttonReleaseWithinBounds->property("pressed").toBool());
 }
 
+void tst_TapHandler::componentUserBehavioralOverride()
+{
+    QScopedPointer<QQuickView> windowPtr;
+    createView(windowPtr, "buttonOverrideHandler.qml");
+    QQuickView * window = windowPtr.data();
+
+    QQuickItem *button = window->rootObject()->findChild<QQuickItem*>("Overridden");
+    QVERIFY(button);
+    QQuickTapHandler *innerTapHandler = button->findChild<QQuickTapHandler*>("Overridden");
+    QVERIFY(innerTapHandler);
+    QQuickTapHandler *userTapHandler = button->findChild<QQuickTapHandler*>("override");
+    QVERIFY(userTapHandler);
+    QSignalSpy tappedSpy(button, SIGNAL(tapped()));
+    QSignalSpy innerGrabChangedSpy(innerTapHandler, SIGNAL(grabChanged(QQuickEventPoint *)));
+    QSignalSpy userGrabChangedSpy(userTapHandler, SIGNAL(grabChanged(QQuickEventPoint *)));
+    QSignalSpy innerPressedChangedSpy(innerTapHandler, SIGNAL(pressedChanged()));
+    QSignalSpy userPressedChangedSpy(userTapHandler, SIGNAL(pressedChanged()));
+
+    // Press
+    QPoint p1 = button->mapToScene(button->clipRect().center()).toPoint();
+    QTest::mousePress(window, Qt::LeftButton, Qt::NoModifier, p1);
+    QTRY_COMPARE(userPressedChangedSpy.count(), 1);
+    QCOMPARE(innerPressedChangedSpy.count(), 0);
+    QCOMPARE(innerGrabChangedSpy.count(), 0);
+    QCOMPARE(userGrabChangedSpy.count(), 1);
+
+    // Release
+    QTest::mouseRelease(window, Qt::LeftButton, Qt::NoModifier, p1);
+    QTRY_COMPARE(userPressedChangedSpy.count(), 2);
+    QCOMPARE(innerPressedChangedSpy.count(), 0);
+    QCOMPARE(tappedSpy.count(), 1); // only because the override handler makes that happen
+    QCOMPARE(innerGrabChangedSpy.count(), 0);
+    QCOMPARE(userGrabChangedSpy.count(), 2);
+}
+
 QTEST_MAIN(tst_TapHandler)
 
 #include "tst_qquicktaphandler.moc"