Introduce functions to set properties during creation

Change-Id: Idd4c8ab9e34b9bc3e00f21d7cf1e4f1a70586e7f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

14 files changed, 265 insertions, 11 deletions

diff --git a/src/qml/qml/qqmlapplicationengine.cpp b/src/qml/qml/qqmlapplicationengine.cpp
index e93cfcadb9..d04a89b514 100644
--- a/src/qml/qml/qqmlapplicationengine.cpp
+++ b/src/qml/qml/qqmlapplicationengine.cpp
@@ -131,7 +131,7 @@ void QQmlApplicationEnginePrivate::finishLoad(QQmlComponent *c)
         q->objectCreated(nullptr, c->url());
         break;
     case QQmlComponent::Ready: {
-        auto newObj = c->create();
+        auto newObj = initialProperties.empty() ? c->create() : c->createWithInitialProperties(initialProperties);
         objects << newObj;
         QObject::connect(newObj, &QObject::destroyed, q, [&](QObject *obj) { objects.removeAll(obj); });
         q->objectCreated(objects.constLast(), c->url());
@@ -279,6 +279,22 @@ void QQmlApplicationEngine::load(const QString &filePath)
 }
 
 /*!
+   Sets the initial properties with which the QML component gets initialized after
+   it gets loaded.
+
+
+   \sa QQmlComponent::setInitialProperties
+   \sa QQmlApplicationEngine::load
+   \sa QQmlApplicationEngine::loadData
+   \since 5.14
+*/
+void QQmlApplicationEngine::setInitialProperties(const QVariantMap &initialProperties)
+{
+    Q_D(QQmlApplicationEngine);
+    d->initialProperties = initialProperties;
+}
+
+/*!
   Loads the QML given in \a data. The object tree defined by \a data is
   instantiated immediately.
 
diff --git a/src/qml/qml/qqmlapplicationengine.h b/src/qml/qml/qqmlapplicationengine.h
index bb5d6b5d68..2b4de91154 100644
--- a/src/qml/qml/qqmlapplicationengine.h
+++ b/src/qml/qml/qqmlapplicationengine.h
@@ -66,6 +66,7 @@ public:
 public Q_SLOTS:
     void load(const QUrl &url);
     void load(const QString &filePath);
+    void setInitialProperties(const QVariantMap &initialProperties);
     void loadData(const QByteArray &data, const QUrl &url = QUrl());
 
 Q_SIGNALS:
diff --git a/src/qml/qml/qqmlapplicationengine_p.h b/src/qml/qml/qqmlapplicationengine_p.h
index 7a341847bd..1279e400e8 100644
--- a/src/qml/qml/qqmlapplicationengine_p.h
+++ b/src/qml/qml/qqmlapplicationengine_p.h
@@ -73,6 +73,7 @@ public:
     void loadTranslations(const QUrl &rootFile);
     void finishLoad(QQmlComponent *component);
     QList<QObject *> objects;
+    QVariantMap initialProperties;
 };
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index fefe2bc685..ed8c41a582 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -350,6 +350,32 @@ void QQmlComponentPrivate::clear()
     compilationUnit = nullptr;
 }
 
+QObject *QQmlComponentPrivate::doBeginCreate(QQmlComponent *q, QQmlContext *context)
+{
+    if (!engine) {
+        // ###Qt6: In Qt 6, it should be impossible for users to create a QQmlComponent without an engine, and we can remove this check
+        qWarning("QQmlComponent: Must provide an engine before calling create");
+        return nullptr;
+    }
+    if (!context)
+        context = engine->rootContext();
+    return q->beginCreate(context);
+}
+
+bool QQmlComponentPrivate::setInitialProperty(QObject *component, const QString& name, const QVariant &value)
+{
+    QQmlProperty prop(component, name);
+    auto privProp = QQmlPropertyPrivate::get(prop);
+    if (!prop.isValid() || !privProp->writeValueProperty(value, nullptr)) {
+        QQmlError error{};
+        error.setUrl(url);
+        error.setDescription(QLatin1String("Could not set property %1").arg(name));
+        state.errors.push_back(error);
+        return false;
+    } else
+        return true;
+}
+
 /*!
     \internal
 */
@@ -780,18 +806,28 @@ QObject *QQmlComponent::create(QQmlContext *context)
 {
     Q_D(QQmlComponent);
 
-    if (!d->engine) {
-        // ###Qt6: In Qt 6, it should be impossible for users to create a QQmlComponent without an engine, and we can remove this check
-        qWarning("QQmlComponent: Must provide an engine before calling create");
-        return nullptr;
-    }
+    QObject *rv = d->doBeginCreate(this, context);
+    if (rv)
+        completeCreate();
+    return rv;
+}
 
-    if (!context)
-        context = d->engine->rootContext();
+/*!
+    Create an object instance of this component, and initialize its toplevel properties according to initalPropertyValues.
 
-    QObject *rv = beginCreate(context);
-    if (rv)
+
+    \sa QQmlComponent::create
+    \since 5.14
+*/
+QObject *QQmlComponent::createWithInitialProperties(const QVariantMap& initialProperties, QQmlContext *context)
+{
+    Q_D(QQmlComponent);
+
+    QObject *rv = d->doBeginCreate(this, context);
+    if (rv) {
+        setInitialProperties(rv, initialProperties);
         completeCreate();
+    }
     return rv;
 }
 
@@ -1067,6 +1103,26 @@ void QQmlComponent::create(QQmlIncubator &incubator, QQmlContext *context,
     enginePriv->incubate(incubator, forContextData);
 }
 
+/*!
+   Set toplevel properties of the component.
+
+
+   This method provides advanced control over component instance creation.
+   In general, programmers should use
+   \l QQmlComponent::createWithInitialProperties to create a component.
+
+   Use this method after beginCreate and before completeCreate has been called.
+   If a provided property does not exist, a warning is issued.
+
+   \since 5.14
+*/
+void QQmlComponent::setInitialProperties(QObject *component, const QVariantMap &properties)
+{
+    Q_D(QQmlComponent);
+    for (auto it = properties.constBegin(); it != properties.constEnd(); ++it)
+        d->setInitialProperty(component, it.key(), it.value());
+}
+
 /*
     This is essentially a copy of QQmlComponent::create(); except it takes the QQmlContextData
     arguments instead of QQmlContext which means we don't have to construct the rather weighty
diff --git a/src/qml/qml/qqmlcomponent.h b/src/qml/qml/qqmlcomponent.h
index 39b6d4526f..f259c99b08 100644
--- a/src/qml/qml/qqmlcomponent.h
+++ b/src/qml/qml/qqmlcomponent.h
@@ -100,6 +100,8 @@ public:
     QUrl url() const;
 
     virtual QObject *create(QQmlContext *context = nullptr);
+    QObject *createWithInitialProperties(const QVariantMap& initialProperties, QQmlContext *context = nullptr);
+    void setInitialProperties(QObject *component, const QVariantMap &properties);
     virtual QObject *beginCreate(QQmlContext *);
     virtual void completeCreate();
 
diff --git a/src/qml/qml/qqmlcomponent_p.h b/src/qml/qml/qqmlcomponent_p.h
index 9a967501c9..2170646b89 100644
--- a/src/qml/qml/qqmlcomponent_p.h
+++ b/src/qml/qml/qqmlcomponent_p.h
@@ -143,6 +143,9 @@ public:
     static QQmlComponentPrivate *get(QQmlComponent *c) {
         return static_cast<QQmlComponentPrivate *>(QObjectPrivate::get(c));
     }
+
+    QObject *doBeginCreate(QQmlComponent *q, QQmlContext *context);
+    bool setInitialProperty(QObject *component, const QString &name, const QVariant& value);
 };
 
 QT_END_NAMESPACE
diff --git a/src/quick/items/qquickview.cpp b/src/quick/items/qquickview.cpp
index 61477360bf..17fc16d44b 100644
--- a/src/quick/items/qquickview.cpp
+++ b/src/quick/items/qquickview.cpp
@@ -240,6 +240,22 @@ void QQuickView::setSource(const QUrl& url)
 }
 
 /*!
+   Sets the initial properties with which the QML component gets initialized after
+   calling \l QQuickView::setSource.
+
+
+   Note that you can only use this function to initialize toplevel properties.
+
+   \sa QQmlComponent::createWithInitialProperties
+   \since 5.14
+*/
+void QQuickView::setInitialProperties(const QVariantMap &initialProperties)
+{
+    Q_D(QQuickView);
+    d->initialProperties = initialProperties;
+}
+
+/*!
     \internal
 
     Set the source \a url, \a component and content \a item (root of the QML object hierarchy) directly.
@@ -471,7 +487,7 @@ void QQuickView::continueExecute()
         return;
     }
 
-    QObject *obj = d->component->create();
+    QObject *obj = d->initialProperties.empty() ? d->component->create() : d->component->createWithInitialProperties(d->initialProperties);
 
     if (d->component->isError()) {
         const QList<QQmlError> errorList = d->component->errors();
diff --git a/src/quick/items/qquickview.h b/src/quick/items/qquickview.h
index ecae25e90b..4122fcac79 100644
--- a/src/quick/items/qquickview.h
+++ b/src/quick/items/qquickview.h
@@ -88,6 +88,7 @@ public:
 
 public Q_SLOTS:
     void setSource(const QUrl&);
+    void setInitialProperties(const QVariantMap &initialProperties);
     void setContent(const QUrl& url, QQmlComponent *component, QObject *item);
 
 Q_SIGNALS:
diff --git a/src/quick/items/qquickview_p.h b/src/quick/items/qquickview_p.h
index 3f284c0519..b1ab8d8e8c 100644
--- a/src/quick/items/qquickview_p.h
+++ b/src/quick/items/qquickview_p.h
@@ -108,6 +108,8 @@ public:
     QQuickView::ResizeMode resizeMode;
     QSize initialSize;
     QElapsedTimer frameTimer;
+
+    QVariantMap initialProperties;
 };
 
 QT_END_NAMESPACE
diff --git a/tests/auto/qml/qqmlapplicationengine/tst_qqmlapplicationengine.cpp b/tests/auto/qml/qqmlapplicationengine/tst_qqmlapplicationengine.cpp
index 8787a43884..0f5eea8b95 100644
--- a/tests/auto/qml/qqmlapplicationengine/tst_qqmlapplicationengine.cpp
+++ b/tests/auto/qml/qqmlapplicationengine/tst_qqmlapplicationengine.cpp
@@ -52,6 +52,7 @@ private slots:
     void removeObjectsWhenDestroyed();
     void loadTranslation_data();
     void loadTranslation();
+    void setInitialProperties();
 
 private:
     QString buildDir;
@@ -275,6 +276,23 @@ void tst_qqmlapplicationengine::loadTranslation()
     QCOMPARE(rootObject->property("translation").toString(), translation);
 }
 
+void tst_qqmlapplicationengine::setInitialProperties()
+{
+    QQmlApplicationEngine test {};
+    {
+        test.setInitialProperties(QVariantMap{{"success", false}});
+        test.load(testFileUrl("basicTest.qml"));
+        QVERIFY(!test.rootObjects().empty());
+        QCOMPARE(test.rootObjects().first()->property("success").toBool(), false);
+    }
+    {
+        test.setInitialProperties({{"success", true}});
+        test.load(testFileUrl("basicTest.qml"));
+        QCOMPARE(test.rootObjects().size(), 2);
+        QCOMPARE(test.rootObjects().at(1)->property("success").toBool(), true);
+    }
+}
+
 QTEST_MAIN(tst_qqmlapplicationengine)
 
 #include "tst_qqmlapplicationengine.moc"
diff --git a/tests/auto/qml/qqmlcomponent/data/allJSONTypes.qml b/tests/auto/qml/qqmlcomponent/data/allJSONTypes.qml
new file mode 100644
index 0000000000..0541c9b104
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/allJSONTypes.qml
@@ -0,0 +1,9 @@
+import QtQuick 2.14
+
+Item {
+    property int i
+    property bool b
+    property double d
+    property string s
+    property var nothing
+}
diff --git a/tests/auto/qml/qqmlcomponent/data/variantBasedInitialization.qml b/tests/auto/qml/qqmlcomponent/data/variantBasedInitialization.qml
new file mode 100644
index 0000000000..acf08e94d2
--- /dev/null
+++ b/tests/auto/qml/qqmlcomponent/data/variantBasedInitialization.qml
@@ -0,0 +1,21 @@
+import QtQuick 2.14
+
+Item {
+    property int i
+    property bool b
+    property double d
+    property string s
+    property var nothing
+    property url myurl
+    property color c
+    property font myfont
+    property date mydate
+    property point mypoint
+    property size mysize
+    property rect myrect
+    property matrix4x4 matrix
+    property quaternion quat
+    property vector2d vec2
+    property vector3d vec3
+    property vector4d vec4
+}
diff --git a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
index 71d3e8fe5f..79ec507388 100644
--- a/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
+++ b/tests/auto/qml/qqmlcomponent/tst_qqmlcomponent.cpp
@@ -121,6 +121,7 @@ private slots:
     void relativeUrl_data();
     void relativeUrl();
     void setDataNoEngineNoSegfault();
+    void testSetInitialProperties();
 
 private:
     QQmlEngine engine;
@@ -667,6 +668,101 @@ void tst_qqmlcomponent::setDataNoEngineNoSegfault()
     QVERIFY(!c);
 }
 
+void tst_qqmlcomponent::testSetInitialProperties()
+{
+    QQmlEngine eng;
+    {
+        // JSON based initialization
+        QQmlComponent comp(&eng);
+        comp.loadUrl(testFileUrl("allJSONTypes.qml"));
+        QScopedPointer<QObject> obj { comp.beginCreate(eng.rootContext()) };
+        QVERIFY(obj);
+        comp.setInitialProperties(obj.get(), QVariantMap {
+                {QLatin1String("i"), 42},
+                {QLatin1String("b"), true},
+                {QLatin1String("d"), 3.1416},
+                {QLatin1String("s"), QLatin1String("hello world")},
+                {QLatin1String("nothing"), QVariant::fromValue(nullptr)}
+        });
+        comp.completeCreate();
+        if (!comp.errors().empty())
+            qDebug() << comp.errorString() << comp.errors();
+        QVERIFY(comp.errors().empty());
+        QCOMPARE(obj->property("i"), 42);
+        QCOMPARE(obj->property("b"), true);
+        QCOMPARE(obj->property("d"), 3.1416);
+        QCOMPARE(obj->property("s"), QLatin1String("hello world"));
+        QCOMPARE(obj->property("nothing"), QVariant::fromValue(nullptr));
+    }
+    {
+        //  QVariant
+        QQmlComponent comp(&eng);
+        comp.loadUrl(testFileUrl("variantBasedInitialization.qml"));
+        QScopedPointer<QObject> obj { comp.beginCreate(eng.rootContext()) };
+        QVERIFY(obj);
+        QUrl myurl = comp.url();
+        QFont myfont;
+        QDateTime mydate = QDateTime::currentDateTime();
+        QPoint mypoint {1,2};
+        QSizeF mysize {0.5, 0.3};
+        QMatrix4x4 matrix {};
+        QQuaternion quat {5.0f, 0.3f, 0.2f, 0.1f};
+        QVector2D vec2 {2.0f, 3.1f};
+        QVector3D vec3 {1.0f, 2.0, 3.0f};
+        QVector4D vec4 {1.0f, 2.0f, 3.0f, 4.0f};
+#define ASJSON(NAME) {QLatin1String(#NAME), NAME}
+        comp.setInitialProperties(obj.get(), QVariantMap {
+                                                     {QLatin1String("i"), 42},
+                                                     {QLatin1String("b"), true},
+                                                     {QLatin1String("d"), 3.1416},
+                                                     {QLatin1String("s"), QLatin1String("hello world")},
+                                                     {QLatin1String("nothing"), QVariant::fromValue( nullptr)},
+                                                     ASJSON(myurl),
+                                                     ASJSON(myfont),
+                                                     ASJSON(mydate),
+                                                     ASJSON(mypoint),
+                                                     ASJSON(mysize),
+                                                     ASJSON(matrix),
+                                                     ASJSON(quat),
+                                                     ASJSON(vec2), ASJSON(vec3), ASJSON(vec4)
+                                             });
+#undef ASJSON
+        comp.completeCreate();
+        if (!comp.errors().empty())
+            qDebug() << comp.errorString() << comp.errors();
+        QVERIFY(comp.errors().empty());
+        QCOMPARE(obj->property("i"), 42);
+        QCOMPARE(obj->property("b"), true);
+        QCOMPARE(obj->property("d"), 3.1416);
+        QCOMPARE(obj->property("s"), QLatin1String("hello world"));
+        QCOMPARE(obj->property("nothing"), QVariant::fromValue(nullptr));
+#define COMPARE(NAME) QCOMPARE(obj->property(#NAME), NAME)
+        COMPARE(myurl);
+        COMPARE(myfont);
+        COMPARE(mydate);
+        COMPARE(mypoint);
+        COMPARE(mysize);
+        COMPARE(matrix);
+        COMPARE(quat);
+        COMPARE(vec2);
+        COMPARE(vec3);
+        COMPARE(vec4);
+#undef COMPARE
+
+    }
+    {
+        // createWithInitialProperties: setting a nonexistent property
+        QQmlComponent comp(&eng);
+        comp.loadUrl(testFileUrl("allJSONTypes.qml"));
+        QScopedPointer<QObject> obj {
+            comp.createWithInitialProperties(QVariantMap { {"notThePropertiesYoureLookingFor", 42} })
+        };
+        qDebug() << comp.errorString();
+        QVERIFY(obj);
+        QVERIFY(comp.errorString().contains("Could not set property notThePropertiesYoureLookingFor"));
+    }
+}
+
 QTEST_MAIN(tst_qqmlcomponent)
 
 #include "tst_qqmlcomponent.moc"
diff --git a/tests/auto/quick/qquickview/tst_qquickview.cpp b/tests/auto/quick/qquickview/tst_qquickview.cpp
index e259ed1ae7..dbce0d308c 100644
--- a/tests/auto/quick/qquickview/tst_qquickview.cpp
+++ b/tests/auto/quick/qquickview/tst_qquickview.cpp
@@ -49,6 +49,7 @@ private slots:
     void errors();
     void engine();
     void findChild();
+    void setInitialProperties();
 };
 
 
@@ -283,6 +284,17 @@ void tst_QQuickView::findChild()
     QVERIFY(!view.rootObject()->findChild<QObject *>("rootObject")); // self
 }
 
+void tst_QQuickView::setInitialProperties()
+{
+    QQuickView view;
+    view.setInitialProperties({{"z", 4}, {"width", 100}});
+    view.setSource(testFileUrl("resizemodeitem.qml"));
+    QObject *rootObject = view.rootObject();
+    QVERIFY(rootObject);
+    QCOMPARE(rootObject->property("z").toInt(), 4);
+    QCOMPARE(rootObject->property("width").toInt(), 100);
+}
+
 QTEST_MAIN(tst_QQuickView)
 
 #include "tst_qquickview.moc"