Insert QML in a QQuickWidget

AntoineLet

Hi everyone,
I am very new to QT5.9. I looked on the forum and QT documentation but I couldnt find a way to solve my problem.

I am trying to set up a software which controls a Arduino with uart. This part work fine, and is written in C++. I would now like to add a visual feedback of what is happening with a usb webcam. I found this code

https://github.com/alex-spataru/QCCTV

which is exactly what I need to add to my software (many thanks to Alex Spataru).

I was able to merge my code and his, but I am not sure how to put the qml code (from QCCTV project) into a widget. I my mainWindow constructor I added the lines from QCCTV project :

/*From QCCTV*/
QGuiApplication::setApplicationName("Awake Monitoring");//("QCCTV Camera");
QGuiApplication::setOrganizationName("Labeo Technologies"); //("Alex Spataru");
QGuiApplication::setApplicationVersion("1.0");
QGuiApplication::setOrganizationDomain("www.labeotech.com"); //(APP_WEBSITE);

/* Set application attributes */
QGuiApplication::setAttribute (Qt::AA_ShareOpenGLContexts);
QGuiApplication::setAttribute (Qt::AA_EnableHighDpiScaling);

/* Initialize application */
QQuickStyle::setStyle ("Material");
QCCTV_LocalCamera* qcctvCamera = new QCCTV_LocalCamera();

bool mobile = false;    // Not on mobile device

QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty ("isMobile", mobile);
engine.rootContext()->setContextProperty ("AppDspName", "Awake Monitoring");
engine.rootContext()->setContextProperty ("AppVersion", "1.0");
engine.rootContext()->setContextProperty ("QCCTVCamera", qcctvCamera);

/* Add QCCTV image provider */
QCCTV_ImageProvider* provider = new QCCTV_ImageProvider (qcctvCamera);
engine.addImageProvider ("qcctv", provider);

/* Load QML interface */
engine.load (QUrl(QStringLiteral ("qrc:/main_default.qml")));

And replaced the last line with

/*My line*/
ui->cameraFeed_qw->setSource(QUrl(QStringLiteral("qrc:/main_default.qml")));

in which cameraFeed_qw is a quickWidget I added into Designer. This launches two screen, one with my arduino controls and one with the QCCTV project. My QuickWidget is left as a white blank square.

I also have "QQuickWidget does not support using windows as a root item.

If you wish to create your root window from QML, consider using QQmlApplicationEngine instead. " warning.

Can someone help me with this ? Many thanks in advance,

Antoine

Fheanor

ui->cameraFeed_qw->setSource(QUrl(QStringLiteral("qrc:/main_default.qml"))); should be fine.

Usually, I write it like that:
ui->cameraFeed_qw->setSource(QUrl::fromLocalFile(QML_FILE_DEFINITION));

What is wrong about your code is in QML. As it says QQuickWidget does not support using windows as a root item, you probably wrote something like ApplicationWindow{Item {....}} .
So if you read carefully, you will understand that QQuickWidget does not support ApplicationWindow as a root.

So basically, you just need to delete it from your code.
Now your Qml will be something like that :

//ApplicationWindow {
Item {
...
}
//}