Unsolved Qt Widgets + GStreamer + Overlay + Screen Capture

[SeeRich]

@SGaist would it be helpful if I provided a CMakeLists.txt file to compile this example code?

[JoeCFD]

@SeeRich Use a QLabel(not QWidget) as your overlay widget and make it transparent. Then, the black background will be gone.

[SeeRich]

@JoeCFD Thank you for the suggestion! Unfortunately, it gave me the same result. I specifically changed the overlay code to be this:

class OverlayWidget : public QLabel
{
    Q_OBJECT
public:
    OverlayWidget(QWidget* parent) : QLabel(parent)
    {
        // setAttribute(Qt::WA_TranslucentBackground);
        // setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint);
        setStyleSheet("background-color: transparent");
    }

Is this what you were suggesting?

[JoeCFD]

@SeeRich Yes, something like that. Can you try
setStyleSheet("background-color: green");
to see if the background color is green?

if the green color works, try the following:
QLabel * _overlayLabel{nullptr}; /* no need to create a overlay widget class */
_overlayLabel = new Qlabel( this );
_overlayLabel->setStyleSheet("border:none; background:transparent;");

[SeeRich]

@JoeCFD The green background did work; however, the _overlayLabel still has a black background. Could this be because Qt isn't aware of what gstreamer is rendering?

[JoeCFD]

@SeeRich your mainwindow has a black background stylesheet which affects its children. Assign its object name to its stylesheet and its children will not be affected anymore.

    MainWindow()
    {
        resize(720, 600);
        setAttribute(Qt::WA_StyledBackground);
        setObjectName( "mainWindiw" );
        setStyleSheet( QString( "MainWindow#%1 { background-color: black; }" ) .arg( objectName() );

[SeeRich]

@JoeCFD I really thought that was going to fix it, but unfortunately, same result.

[JoeCFD]

@SeeRich Change the background-color to blue to make sure the color from mainwindow stylesheet

    MainWindow()
    {
        resize(720, 600);
        setAttribute(Qt::WA_StyledBackground);
        setObjectName( "mainWindow" );
        setStyleSheet( QString( "MainWindow#%1 { background-color: blue; }" ) .arg( objectName() );

also try the following:

_overlayLabel = new Qlabel( this );
_overlayLabel->setAttribute(Qt::WA_StyledBackground);
_overlayLabel->setStyleSheet("border:none; background:transparent;");

[SeeRich]

@JoeCFD Sorry for the delay...

It is definitely the mainwindow background as the change to blue causes the text background box to change colors as well.

Setting the Qt::WA_StyledBackground attribute didn't change anything either.

[JoeCFD]

@SeeRich
can you change

        setAttribute(Qt::WA_StyledBackground);
        setObjectName( "mainWindow" );
        setStyleSheet( QString( "MainWindow#%1 { background-color: blue; }" ) .arg( objectName() );

to

        setAttribute(Qt::WA_StyledBackground);
        setObjectName( "mainWindow" );
        setStyleSheet( QString( "QWidget#%1 { background-color: blue; }" ) .arg( objectName() );

there is no MainWindow stylesheet. It should be QMainWindow.