QQuickItemView: Don't change the viewport while in layout

Moving the viewport in the middle of a layout operation is a bad idea as
it causes the visible items to change.

Task-number: QTBUG-49224
Change-Id: I45a214560e00b65ed53b9385e7a539bb4304b7d9
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

2 files changed, 104 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview/data/setpositiononlayout.qml b/tests/auto/quick/qquicklistview/data/setpositiononlayout.qml
new file mode 100644
index 0000000000..6e12eeafca
--- /dev/null
+++ b/tests/auto/quick/qquicklistview/data/setpositiononlayout.qml
@@ -0,0 +1,87 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.0
+
+Rectangle {
+    width: 200
+    height: 720
+
+    ListView {
+        anchors.fill: parent
+        focus: true
+        highlightMoveDuration: 200
+        model: 50
+        spacing: 10
+        delegate: FocusScope {
+            implicitHeight: col.height
+            Column {
+                id: col
+                Text {
+                    text: "YYYY"
+                }
+                ListView {
+                    id: list
+                    model: 1
+                    anchors.left: parent.left
+                    anchors.right: parent.right
+                    height: 250
+                    orientation: ListView.Horizontal
+                    delegate: Rectangle {
+                        id: self
+                        height: 250
+                        width: 150
+                        color: "blue"
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
index 1ca341fe66..a9be9d4fa4 100644
--- a/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
+++ b/tests/auto/quick/qquicklistview/tst_qquicklistview.cpp
@@ -270,6 +270,7 @@ private slots:
     void useDelegateChooserWithoutDefault();
 
     void addOnCompleted();
+    void setPositionOnLayout();
 
 private:
     template <class T> void items(const QUrl &source);
@@ -8860,6 +8861,22 @@ void tst_QQuickListView::addOnCompleted()
     }
 }
 
+void tst_QQuickListView::setPositionOnLayout()
+{
+    // Make sure we don't trigger a crash by removing items during layout from setPosition().
+    QScopedPointer<QQuickView> window(createView());
+    window->setSource(testFileUrl("setpositiononlayout.qml"));
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+    window->requestActivate();
+    QVERIFY(QTest::qWaitForWindowActive(window.data()));
+    for (int i = 0; i < 1000; ++i) {
+        QTest::keyPress(window.data(), Qt::Key_Down);
+        QTest::qWait(1);
+        QTest::keyRelease(window.data(), Qt::Key_Down);
+    }
+}
+
 void tst_QQuickListView::useDelegateChooserWithoutDefault()
 {
     // Check that the application doesn't crash