Restore value bindings when disabling a Binding element

We previously only restored script bindings that were replaced by
a Binding. Now we handle both.

[ChangeLog] QML Binding elements now support restoring previous values
of the bound property when the binding is disabled. This will be the
default behavior in Qt 5.15. Reliance on the old behavior of only
restoring binding, not literal values results in a warning now.

Fixes: QTBUG-33444
Change-Id: I833403b0645c08eee486fbd4acf5d3c7de2ef73a
Reviewed-by: Michael Brasser <michael.brasser@live.com>

4 files changed, 245 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlbinding/data/restoreBinding2.qml b/tests/auto/qml/qqmlbinding/data/restoreBinding2.qml
new file mode 100644
index 0000000000..b42f975fe0
--- /dev/null
+++ b/tests/auto/qml/qqmlbinding/data/restoreBinding2.qml
@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** 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 2.0
+import QtQml 2.14
+
+Rectangle {
+    height: 400
+    width: 400
+
+    Rectangle {
+        property bool when: true
+
+        id: myItem
+        objectName:  "myItem"
+        height: 300
+        width: 200
+    }
+
+    property var boundValue: 100
+
+    Binding {
+        restoreMode: Binding.RestoreValue
+        objectName: "theBinding"
+        target: myItem
+        property: "height"
+        when: myItem.when
+        value: boundValue
+    }
+}
diff --git a/tests/auto/qml/qqmlbinding/data/restoreBinding3.qml b/tests/auto/qml/qqmlbinding/data/restoreBinding3.qml
new file mode 100644
index 0000000000..1f63457ab6
--- /dev/null
+++ b/tests/auto/qml/qqmlbinding/data/restoreBinding3.qml
@@ -0,0 +1,56 @@
+/****************************************************************************
+**
+** 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 2.0
+import QtQml 2.14
+
+Rectangle {
+    height: 400
+    width: 400
+
+    Rectangle {
+        property bool when: true
+
+        id: myItem
+        objectName:  "myItem"
+        height: 300
+        width: 200
+        property var foo: 42
+    }
+
+    property var boundValue: 13
+
+    Binding {
+        restoreMode: Binding.RestoreBindingOrValue
+        objectName: "theBinding"
+        target: myItem
+        property: "foo"
+        when: myItem.when
+        value: boundValue
+    }
+}
diff --git a/tests/auto/qml/qqmlbinding/data/restoreBinding4.qml b/tests/auto/qml/qqmlbinding/data/restoreBinding4.qml
new file mode 100644
index 0000000000..f34c3b40cf
--- /dev/null
+++ b/tests/auto/qml/qqmlbinding/data/restoreBinding4.qml
@@ -0,0 +1,59 @@
+/****************************************************************************
+**
+** 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 2.0
+import QtQml 2.14
+
+Rectangle {
+    height: 400
+    width: 400
+
+    Rectangle {
+        property bool when: true
+
+        id: myItem
+        objectName:  "myItem"
+        height: 300
+        width: 200
+        property var foo: original
+        property bool fooCheck: foo === original && foo.bar() === 42
+    }
+
+    property var original: ({ bar: function() { return 42 } })
+
+    property var boundValue: 13
+
+    Binding {
+        restoreMode: Binding.RestoreBinding
+        objectName: "theBinding"
+        target: myItem
+        property: "foo"
+        when: myItem.when
+        value: boundValue
+    }
+}
diff --git a/tests/auto/qml/qqmlbinding/tst_qqmlbinding.cpp b/tests/auto/qml/qqmlbinding/tst_qqmlbinding.cpp
index 34cf21024d..717fd5dbd1 100644
--- a/tests/auto/qml/qqmlbinding/tst_qqmlbinding.cpp
+++ b/tests/auto/qml/qqmlbinding/tst_qqmlbinding.cpp
@@ -42,6 +42,9 @@ private slots:
     void binding();
     void whenAfterValue();
     void restoreBinding();
+    void restoreBindingValue();
+    void restoreBindingVarValue();
+    void restoreBindingJSValue();
     void restoreBindingWithLoop();
     void restoreBindingWithoutCrash();
     void deletedObject();
@@ -134,6 +137,78 @@ void tst_qqmlbinding::restoreBinding()
     delete rect;
 }
 
+void tst_qqmlbinding::restoreBindingValue()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("restoreBinding2.qml"));
+    QScopedPointer<QQuickRectangle> rect(qobject_cast<QQuickRectangle*>(c.create()));
+    QVERIFY(!rect.isNull());
+
+    auto myItem = qobject_cast<QQuickRectangle*>(rect->findChild<QQuickRectangle*>("myItem"));
+    QVERIFY(myItem != nullptr);
+
+    QCOMPARE(myItem->height(), 100);
+    myItem->setProperty("when", QVariant(false));
+    QCOMPARE(myItem->height(), 300); // make sure the original value was restored
+
+    myItem->setProperty("when", QVariant(true));
+    QCOMPARE(myItem->height(), 100); // make sure the value specified in Binding is set
+    rect->setProperty("boundValue", 200);
+    QCOMPARE(myItem->height(), 200); // make sure the changed binding value is set
+    myItem->setProperty("when", QVariant(false));
+    // make sure that the original value is back, not e.g. the value from before the
+    // change (i.e. 100)
+    QCOMPARE(myItem->height(), 300);
+}
+
+void tst_qqmlbinding::restoreBindingVarValue()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("restoreBinding3.qml"));
+    QScopedPointer<QQuickRectangle> rect(qobject_cast<QQuickRectangle*>(c.create()));
+    QVERIFY(!rect.isNull());
+
+    auto myItem = qobject_cast<QQuickRectangle*>(rect->findChild<QQuickRectangle*>("myItem"));
+    QVERIFY(myItem != nullptr);
+
+    QCOMPARE(myItem->property("foo"), 13);
+    myItem->setProperty("when", QVariant(false));
+    QCOMPARE(myItem->property("foo"), 42); // make sure the original value was restored
+
+    myItem->setProperty("when", QVariant(true));
+    QCOMPARE(myItem->property("foo"), 13); // make sure the value specified in Binding is set
+    rect->setProperty("boundValue", 31337);
+    QCOMPARE(myItem->property("foo"), 31337); // make sure the changed binding value is set
+    myItem->setProperty("when", QVariant(false));
+    // make sure that the original value is back, not e.g. the value from before the
+    // change (i.e. 100)
+    QCOMPARE(myItem->property("foo"), 42);
+}
+
+void tst_qqmlbinding::restoreBindingJSValue()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("restoreBinding4.qml"));
+    QScopedPointer<QQuickRectangle> rect(qobject_cast<QQuickRectangle*>(c.create()));
+    QVERIFY(!rect.isNull());
+
+    auto myItem = qobject_cast<QQuickRectangle*>(rect->findChild<QQuickRectangle*>("myItem"));
+    QVERIFY(myItem != nullptr);
+
+    QCOMPARE(myItem->property("fooCheck"), false);
+    myItem->setProperty("when", QVariant(false));
+    QCOMPARE(myItem->property("fooCheck"), true); // make sure the original value was restored
+
+    myItem->setProperty("when", QVariant(true));
+    QCOMPARE(myItem->property("fooCheck"), false); // make sure the value specified in Binding is set
+    rect->setProperty("boundValue", 31337);
+    QCOMPARE(myItem->property("fooCheck"), false); // make sure the changed binding value is set
+    myItem->setProperty("when", QVariant(false));
+    // make sure that the original value is back, not e.g. the value from before the change
+    QCOMPARE(myItem->property("fooCheck"), true);
+
+}
+
 void tst_qqmlbinding::restoreBindingWithLoop()
 {
     QQmlEngine engine;