QQuickView/ QQuickWidget embeded in opacity QWidget

[xumuk]

Hi! I have problem with rendering QML using QQuickView /QQiuickWidget embeded in QWidget with attribute Qt::WA_TranslucentBackground. Usual widgets behavior is correct. Any ideas?

Container widget has this:

setWindowFlags(Qt::FramelessWindowHint | Qt::Tool );
setAttribute(Qt::WA_TranslucentBackground);

QML file looking like this:

import QtQuick 2.0 (or 1.0 for QDeclarativeView)

Rectangle {
    id: window
    color: "red"
}

Working code sample:

QDeclarativeView *view = new QDeclarativeView(QUrl("qrc:/qml/qmlcontent"));
view->setResizeMode(QDeclarativeView::SizeRootObjectToView);

Not working code sample:

QQuickWidget *view = new QQuickWidget(QUrl("qrc:/qml/qmlcontent"));
view->setResizeMode(QQuickWidget::SizeRootObjectToView);

One more not working code sample:

QQuickView *view = new QQuickView();
view->setResizeMode(QQuickView::SizeRootObjectToView);

QWidget *container = QWidget::createWindowContainer(view,  containerWidget);

view->setSource(QUrl("qrc:/qml/qmlcontent"));

[p3c0]

Hi @xumuk, That I guess is the limitation with both QQuickWidget and createWindowContainer as documented here.

Putting other widgets underneath and making the QQuickWidget transparent will not lead to the expected results: the widgets underneath will not be visible. This is because in practice the QQuickWidget is drawn before all other regular, non-OpenGL widgets, and so see-through types of solutions are not feasible.

With QtQuick 1.x it was different. It used the traditional QGraphics* backend. QtQuick 2.x uses Scenegraph based on OpenGL.

[Tadinu]

Please refer here for more information.
Besides, you may want to try running this example:
<Qt_Installatin_Folder>\5.4\Src\qtdeclarative\examples\quick\quickwidgets\qquickviewcomparison

[xumuk]

Thanks a lot for answers! But how to do semitransparent QQuickWidget on Windows/Linux using QML to get similar result like i can do this with:

QWidget *w = new QWidget;
w->setWindowFlags(Qt::FramelessWindowHint);
w->setAttribute(Qt::WA_TranslucentBackground);
w->resize(500, 400);

QHBoxLayout *layout = new QHBoxLayout(w);
layout->setContentsMargins(0,0,0,0);

QWidget *s = new QWidget(w);
s->setStyleSheet("background-color: rgba(128,128,128,128)");

layout->addWidget(s);

w->show();

[p3c0]

@xumuk As said earlier it is a limitation. But if you still need it you should have a look at the 2nd and 3rd paragraph in the link which I posted earlier. Basically you will have to do this:

QQuickWidget *wd = new QQuickWidget(this);
wd->setAttribute(Qt::WA_AlwaysStackOnTop);
wd->setClearColor(Qt::transparent);

//and the opacity can be set in QML istelf for eg. for a Rectangle
Rectangle {
    width: 300
    height: 300
    color: "green"
    opacity: 0.5
}

If you load this QML in the QQuickWIdget and put a QWidget in background it should be visible.