Component Creation

[romsharkov]

I am trying to dynamically create a QML object inside a predefined viewport object in C++ , even though the program works without any errors the actual component is not visible as if it were not there! I am struggling to understand why that is... am I missing something?

main.cpp

int main(int argc, char *argv[]) {
	QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
	QGuiApplication hostApp(argc, argv);

	QUrl mainUrl(QLatin1String("qrc:/main.qml"));
	QUrl placeholderUrl(QLatin1String("qrc:/placeholder.qml"));

	QQmlApplicationEngine *engine(new QQmlApplicationEngine());
	engine->load(mainUrl);
	QObject* viewport(engine->rootObjects().first()->findChild<QObject*>("viewport"));
	QQmlComponent newcomp(engine, placeholderUrl, viewport);
	QObject* obj(newcomp.create());
	return hostApp.exec();
}

qrc:/main.qml

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0
import QtGraphicalEffects 1.0

ApplicationWindow {
	visible: true
	width: 1024
	height: 768
	title: qsTr("Test")

	Rectangle {
		anchors.fill: parent
		color: Qt.rgba(.97,.97,.97,1)
	}

	Rectangle {
		id: appwindow
		anchors.centerIn: parent
		width: viewport.width
		height: titlebar.height + viewport.height
		Rectangle {
			id: titlebar
			anchors.left: parent.left
			anchors.right: parent.right
			height: 32
			anchors.top: parent.top
			Row {
				anchors.fill: parent
				anchors.leftMargin: 8
				spacing: 16
				Text {
					text: "Sample Application"
					font.pixelSize: 12
					anchors.verticalCenter: parent.verticalCenter
					color: Qt.rgba(0,0,0,.6)
				}
			}
			Rectangle {
				anchors.left: parent.left
				anchors.right: parent.right
				anchors.bottom: parent.bottom
				height: 1
				color: Qt.rgba(0,0,0,.05)
			}
		}
		Rectangle {
			objectName: "viewport"
			id: viewport
			anchors.top: titlebar.bottom
			width: 640
			height: 480
			color: Qt.rgba(1,1,1,1)
		}
	}
	DropShadow {
		anchors.fill: appwindow
		verticalOffset: 24
		radius: 64
		samples: 64
		color: Qt.rgba(0,0,0,.2)
		source: appwindow
	}
}

qrc:/placeholder.qml

import QtQuick 2.7

Item {
	id: container
	anchors.fill: parent
	Column {
		anchors.centerIn: parent
		spacing: 8
		Text {
			text: "Placeholder Component"
			anchors.horizontalCenter: parent.horizontalCenter
		}
		Text {
			text: container.width + " x " + container.height
			anchors.horizontalCenter: parent.horizontalCenter
		}
	}
}

[romsharkov]

I got it to work with the following line:

obj->setProperty("parent", QVariant::fromValue<QObject*>(viewport));

now everything's fine, anyway.. am I doing everything correctly here?

It's strange that it's not documented