how to Integrat QML in QWidget App ?

[Alex_wang]

I am new　to Qt and QML,so please in detail :

1. QQuickView
   2.QQuickWidget

[p3c0]

Hi @Alex_wang
The docs are quite self-explanatory (QQuickView and QQuickWidget.
QQuickView is used to load a QML scene given a URL whereas QQuickWidget also does the same but it can be embedded into existing QWidget. So if you want a mixture of QWidgets and QtQuick use QQuickWidget.

[mrjj]

Hi
Maybe this book
https://qmlbook.github.io/
would be great to browse first before coding.

[Alex_wang]

I want to render YUV video with QOpenglWidget，and render a control UI via QML that will display upon the video.
But the control UI should be translucent so that we can see the video under it.

If I use the QQuickWidget, have to the control UI translucent by the step:

QQuickWidget *view = new QQuickWidget(this);//this->QOpenglWidget
view->setAttribute(Qt::WA_AlwaysStackOnTop, true);
view->setClearColor(QColor(Qt::transparent));

this is valid， but I find a Transparent stripe inside the control UI.
anyone ideas ?

[p3c0]

@Alex_wang

This limitation only applies when there are other widgets underneath the QQuickWidget inside the same window. Making the window semi-transparent, with other applications and the desktop visible in the background, is done in the traditional way: Set Qt::WA_TranslucentBackground on the top-level window, request an alpha channel, and change the Qt Quick Scenegraph's clear color to Qt::transparent via setClearColor().

Not sure but can you try setting Qt::WA_TranslucentBackground (using setAttribute) as well as alpha channel using setFormat (QSurfaceFormat) ?

[Alex_wang]

I have tried,butt it is still failing!

QQuickWidget *view = new QQuickWidget(this);//this->QOpenglWidget
view->setAttribute(Qt::WA_AlwaysStackOnTop, true);
view->setClearColor(QColor(Qt::transparent));
view->setAttribute(Qt::WA_TranslucentBackground);
view->setSource(QUrl("qrc:/main.qml"));
view->show();

main.qml:

Item
{
       opacity: 0.8
}

I find that when I do not set opacity to 0.8 in QML , the control UI is not transparent;
but when I set opacity to 0.8 in QML, the control UI is slight transparent ,
and the error with a transparent stripe appears.

[p3c0]

@Alex_wang Can you also try to setFormat with alpha channel for QQuickWidget? Smthing like:

QSurfaceFormat format;
format.setAlphaBufferSize(8);

[Alex_wang]

QQuickWidget *view = new QQuickWidget(this);//this->QOpenglWidget
QSurfaceFormat format;
    format.setAlphaBufferSize(8);
    format.setDepthBufferSize(32);
    view->setFormat(format);
view->setAttribute(Qt::WA_AlwaysStackOnTop, true);
view->setClearColor(QColor(Qt::transparent));
view->setAttribute(Qt::WA_TranslucentBackground);
view->setSource(QUrl("qrc:/main.qml"));
view->show();

It is no effect! ..............when I not set opacity to 0.8 in QML

[p3c0]

@Alex_wang Hmm, as the docs says there are some limitations to it. There are ways which we tried but it still doesn't work. I would suggest to ask this question to mailing list.