[SOLVED]Show qml file in qwidget

[A Former User]

Hi ,I use qt 5.3 on mac. i want to show qml file in qwidget. look at the codes:

@
//mainwindow.cpp

void MainWindow::createQMLWindow()
{
QQmlEngine engine;
QQmlComponent component = new QQmlComponent(&engine);
component->loadUrl(QUrl("qrc:///main.qml"));
if(!component->isReady())
{
qDebug() << "Component Error:" << component->errorString();
}
QQuickWindow * mywin = qobject_cast<QQuickWindow>(component->create()); //the error occures here
QWidget *container = QWidget::createWindowContainer(mywin , this);
setCentralWidget(container);
QVBoxLayout *layout = new QVBoxLayout;
container->setLayout(layout);
container->setMinimumSize(200,200);
container->setMaximumSize(200,200);
}
@

when i run my program , after a few seconds, the program crashed:
this error: the program has unexpectedly finished.

please help me to fix it. Thanks

[edit: cleaned use of coding tags SGaist]

[sierdzio]

engine is deleted when createQMLWindow() goes out of scope - maybe that is the problem.

[A Former User]

Thanks for your answer. I've tried to move code to main.cpp, but i doesn't work.
@
//main.cpp

MainWindow w;
QQmlEngine engine;
QQmlComponent component = new QQmlComponent(&engine);
component->loadUrl(QUrl("qrc:///main.qml"));
if(!component->isReady())
{
qDebug() << "Component Error:" << component->errorString();
}
QQuickWindow * mywin = qobject_cast<QQuickWindow>(component->create());
w.createQMLWindow();
w.show();

//mainwindow.cpp
 
void MainWindow::createQMLWindow(QQuickWindow * mywin)
{  
  QWidget *container = QWidget::createWindowContainer(mywin , this);
  setCentralWidget(container);
  QVBoxLayout *layout = new QVBoxLayout;
  container->setLayout(layout);
  container->setMinimumSize(200,200);
  container->setMaximumSize(200,200);
}

@

[sierdzio]

Please put your code between '@' tags here on the forum, otherwise it's hard to read.

Why not use "QQuickView":http://qt-project.org/doc/qt-5/qquickview.html, which is a QWindow? The code is much simpler there:
@
MainWindow w;
QVBoxLayout *layout = new QVBoxLayout(w);
w.setLayout(layout);

QQuickView *view = new QQuickView;
view->setSource(QUrl::fromLocalFile("myqmlfile.qml"));

QWidget container *cont = QWidget::createWindowContainer(view, w);
layout->addWidget(container);
w.show();
@

[A Former User]

If i use QQuickView like you said, i get this error:

QQuickView only supports loading of root objects that derive from QQuickItem.
In my qml file i've used window type.

[sierdzio]

[quote author="hasti66" date="1414389434"]If i use QQuickView like you said, i get this error:

QQuickView only supports loading of root objects that derive from QQuickItem.
In my qml file i've used window type.[/quote]

Then that is not necessary, remove Window and use Rectangle instead :-)

[A Former User]

I used window type in qml because i want to use UIImagePickerController to pick an image from photo library.

[A Former User]

finally i found another way to use UIImagePickerController in qt5.3 (on mac) without using qml window type.I created a subclass of UIViewController in .mm file and implemented an UIImagePickerController in that and defined a cpp bridge method. So i don't need to embed a qml file in QWidget anymore.
Thank you very much.