Transparency of QDeclarativeView containing QML on top of a QWidget playing a video (using either phonon or libvlc).

mimeit02

I am currently developing a video player.

1)
The GUI as the topmost layer is written in QML.
It should be transparent to lower layers.

It contains control elements, some Lists etc.,
It's displayed using a QDeclarativeView.

Source extract:

@ QDeclarativeView *upperLayer = new QDeclarativeView(this);
upperLayer->setSource(QUrl("/home/projects/QtVideo/qml/videoControl.qml"));
upperLayer->setStyleSheet(QString("background: transparent");
upperLayer->setResizeMode(QDeclarativeView::SizeRootObjectToView);
uperLayer->showFullScreen();@

2)

The layer underneath is a QWidget.

I use the libvlc to display the video content
in this widget.

Reason: I am receiving mpeg2-ts, which can not be decoded by phonon, afaik.
Therefore I need the libvlc to decode the incoming *.ts stream and put the output onto the display.

Source extract:

@QWidget *lowerLayer = new QWidget(this);
lowerLayer.setGeometry(QString("background: red"));
QUrl* url = new QUrl("file:///home/projects/QtVideo/video.ts");
libvlc_instance_t*vlcObject;
libvlc_media_t*vlcMedia;
libvlc_media_player_t*vlcPlayer;

vlcPlayer = NULL;
if(vlcObject = libvlc_new(argc, argv)) == NULL)
{
     printf("Not able to initialize";
     exit(1);
}

if(vlcPlayer && libvlc_media_player_is_playing(vlcPlayer))
{
     libvlc_media_player_stop(vlcPlayer);
}

vlcPlayer = libvlc_media_player_new(vlcObject);
vlcMedia = libvlc_media_new_location(vlcObject, url.toString().toUtf8().constData());
libvlc_media_player_set_media(vlcPlayer, vlcMedia);

#if defined(Q_OS_MAC)
     libvlc_media_player_set_nsobject(vlcPlayer, lowerLayer->winId());
#elif defined(Q_OS_UNIX)
     libvlc_media_player_set_x_window(vlcPlayer, lowerLayer->winId());
#elif defined(Q_OS_WIN)
     libvlc_media_player_set_hwnd(vlcPlayer, lowerLayer->winId());
#endif

libvlc_media_player_play(vlc_player);@

Both Elements, the QDeclarativeView and the QWidget
are embedded in a QMainWindow, lowerLayer created before the upperLayer,
upperLayer Transparent to the lowerLayer.

The Problem:

As long as the lowerLayer is displaying static elements such as a picture, or some colored shapes, everything works fine, full transparency and funtionality.

As soon as I start displaying a video, such as the described *.ts using the libvlc OR some random video using the Phonon::VideoPlayer, the parts of the upperLayer which are above the video parts of the lowerLayer are displayed in the color of the lowerLayer(default: gray),
the parts of the upperLayer which are positioned above parts of the lowerLayer or others which do not contain video elements are displayed in correct behaviour.

Question:

Is there any posibility and if so, how, to get the upperLayer transparent, even if there is a video playing?

Kind regards and thanks in advance,

Michael

flobe

I had the same problem and after some fiddling about I found out that setting the autoFillBackground property of the viewport to false helps at least for me. I have an ordinary widget underneath tough. Don't know whether it works with a video.

Just add
@
upperLayer->viewport()->setAutoFillBackground(false);
@ after setting the qml source.

helldrik

I am experiencing the same problem and
"upperLayer->viewport()->setAutoFillBackground(false)" doesn`t help.

Anyone found a solution so far?

flobe

Can you post a small example?