Fix providing correct velocity when using index based scrolling

Index based scrolling does not enable moving and flicking properties.

Task-number: QTBUG-34576
Change-Id: Ief06d37115ca389027670c97ce6c0457a74d4872
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

4 files changed, 156 insertions, 5 deletions

diff --git a/src/quick/items/qquickflickable.cpp b/src/quick/items/qquickflickable.cpp
index 3462752370..e0f8b6de00 100644
--- a/src/quick/items/qquickflickable.cpp
+++ b/src/quick/items/qquickflickable.cpp
@@ -748,7 +748,8 @@ void QQuickFlickable::setContentX(qreal pos)
     d->hData.explicitValue = true;
     d->resetTimeline(d->hData);
     d->hData.vTime = d->timeline.time();
-    movementEnding(true, false);
+    if (isMoving() || isFlicking())
+        movementEnding(true, false);
     if (-pos != d->hData.move.value())
         d->hData.move.setValue(-pos);
 }
@@ -765,7 +766,8 @@ void QQuickFlickable::setContentY(qreal pos)
     d->vData.explicitValue = true;
     d->resetTimeline(d->vData);
     d->vData.vTime = d->timeline.time();
-    movementEnding(false, true);
+    if (isMoving() || isFlicking())
+        movementEnding(false, true);
     if (-pos != d->vData.move.value())
         d->vData.move.setValue(-pos);
 }
diff --git a/src/quick/items/qquickitemview.cpp b/src/quick/items/qquickitemview.cpp
index 66438ee37d..478499e209 100644
--- a/src/quick/items/qquickitemview.cpp
+++ b/src/quick/items/qquickitemview.cpp
@@ -926,7 +926,6 @@ void QQuickItemView::setDisplacedTransition(QQuickTransition *transition)
 
 void QQuickItemViewPrivate::positionViewAtIndex(int index, int mode)
 {
-    Q_Q(QQuickItemView);
     if (!isValid())
         return;
     if (mode < QQuickItemView::Beginning || mode > QQuickItemView::SnapPosition)
@@ -988,7 +987,6 @@ void QQuickItemViewPrivate::positionViewAtIndex(int index, int mode)
         qreal minExtent = calculatedMinExtent();
         pos = qMax(pos, minExtent);
         moveReason = QQuickItemViewPrivate::Other;
-        q->cancelFlick();
         setPosition(pos);
 
         if (highlight) {
@@ -1394,7 +1392,6 @@ void QQuickItemView::trackedPositionChanged()
                 pos = qMax(trackedPos, toItemPos);
         }
         if (viewPos != pos) {
-            cancelFlick();
             d->calcVelocity = true;
             d->setPosition(pos);
             d->calcVelocity = false;
diff --git a/tests/auto/quick/qquicklistview/data/qtbug34576.qml b/tests/auto/quick/qquicklistview/data/qtbug34576.qml
new file mode 100644
index 0000000000..f407d8ebe3
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/qtbug34576.qml
@@ -0,0 +1,102 @@
+/****************************************************************************
+**
+** 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 2.7
+
+Rectangle {
+    id: root
+    width: 320
+    height: 240
+    color: "black"
+
+    property int current: list.currentIndex
+    property int horizontalVelocityZeroCount: 0
+
+    ListView {
+        id: list
+        objectName: "list"
+        anchors.fill: parent
+
+        focus: true
+
+        orientation: ListView.Horizontal
+
+        snapMode: ListView.SnapToItem
+        flickableDirection: Flickable.HorizontalFlick
+
+        model: 10
+        delegate: Item {
+            width: root.width / 3
+            height: root.height
+            Rectangle {
+                anchors.centerIn: parent
+                width: 50
+                height: 50
+                color: list.currentIndex === index ? "red" : "white"
+            }
+        }
+
+        onHorizontalVelocityChanged:  {
+            if (list.horizontalVelocity === 0.0)
+                root.horizontalVelocityZeroCount++
+        }
+
+    }
+
+    Rectangle {
+        color: "red"
+        width: 50
+        height: 50
+        anchors.left: parent.left
+        anchors.bottom: parent.bottom
+
+        MouseArea {
+            anchors.fill: parent
+            onClicked: {
+                list.currentIndex--;
+            }
+        }
+    }
+
+    Rectangle {
+        color: "red"
+        width: 50
+        height: 50
+        anchors.right: parent.right
+        anchors.bottom: parent.bottom
+
+        MouseArea {
+            anchors.fill: parent
+            onClicked: {
+                list.currentIndex++;
+            }
+        }
+    }
+}
+
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 2e9c54c5a3..42049fa9ca 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -259,6 +259,8 @@ private slots:
     void itemFiltered();
     void releaseItems();
 
+    void QTBUG_34576_velocityZero();
+
 private:
     template <class T> void items(const QUrl &source);
     template <class T> void changed(const QUrl &source);
@@ -8607,6 +8609,54 @@ void tst_QQuickListView::releaseItems()
     listview->setModel(123);
 }
 
+void tst_QQuickListView::QTBUG_34576_velocityZero()
+{
+    QQuickView *window = new QQuickView(0);
+    window->setGeometry(0,0,240,320);
+
+    QQmlContext *ctxt = window->rootContext();
+
+    QString filename(testFile("qtbug34576.qml"));
+    window->setSource(QUrl::fromLocalFile(filename));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+
+    QQuickListView *listview = findItem<QQuickListView>(window->rootObject(), "list");
+    QTRY_VERIFY(listview != 0);
+    QQuickItem *contentItem = listview->contentItem();
+    QTRY_VERIFY(contentItem != 0);
+    QTRY_COMPARE(QQuickItemPrivate::get(listview)->polishScheduled, false);
+
+    QSignalSpy horizontalVelocitySpy(listview, SIGNAL(horizontalVelocityChanged()));
+
+    // currentIndex is initialized to 0
+    QCOMPARE(listview->currentIndex(), 0);
+
+    // set currentIndex to last item currently visible item
+    window->rootObject()->setProperty("horizontalVelocityZeroCount", QVariant(0));
+    listview->setCurrentIndex(2);
+    QTRY_COMPARE(window->rootObject()->property("current").toInt(), 2);
+    QTRY_COMPARE(horizontalVelocitySpy.count(), 0);
+    QTRY_COMPARE(window->rootObject()->property("horizontalVelocityZeroCount").toInt(), 0);
+
+    // click button which increases currentIndex
+    QTest::mousePress(window, Qt::LeftButton, 0, QPoint(295,215));
+    QTest::mouseRelease(window, Qt::LeftButton, 0, QPoint(295,215));
+
+    // verify that currentIndexChanged is triggered
+    QVERIFY(horizontalVelocitySpy.wait());
+
+    // set currentIndex to item out of view to cause listview scroll
+    QTRY_COMPARE(window->rootObject()->property("current").toInt(), 3);
+    QTRY_COMPARE(horizontalVelocitySpy.count() > 0, true);
+    QVERIFY(horizontalVelocitySpy.wait(1000));
+
+    // velocity should be always > 0.0
+    QTRY_COMPARE(window->rootObject()->property("horizontalVelocityZeroCount").toInt(), 0);
+
+    delete window;
+}
+
 QTEST_MAIN(tst_QQuickListView)
 
 #include "tst_qquicklistview.moc"