Need to position a widget and make it semi-transparent

[franco.amato]

I have a QMainWindow derived object (BeastBurst) and I need to place a QWidget object (Game) at a specific position relative to the mainwindow, position is x = m_leftToolBar.width() and y = 81. I also need to make this widget semi transparent. I tried almost everything. I am using Qt 6.8

/* In mainwindow */

// selectedGame is the widget i want to place and is of type Game
selectedGame->setParent(this); // select the mainwindow as parent

// If I don't set the Qt::Window flag, then the position will be completely wrong
selectedGame->setWindowFlags(Qt::FramelessWindowHint | Qt::Window | Qt::WindowStaysOnTopHint);
// the 70% of transparency has no effect
selectedGame->setStyleSheet("QWidget{background-color: rgba(37, 38, 52, 0.7);}");
// this will move the selectedGame widget
selectedGame->moveRelativeToParent(this, m_leftToolBar->width(), 81);
selectedGame->show();

/* in Game */

void Game::moveRelativeToParent(QWidget *parent, int xOffset, int yOffset)
{
    if (!parent)
    {
        return;
    }

    QPoint parentGlobalPos = parent->mapToGlobal(QPoint(0, 0));
    move(parentGlobalPos.x() + xOffset, parentGlobalPos.y() + yOffset);
}

I also tried to set

setAttribute(Qt::WA_TranslucentBackground);

in the Game constructor but it will make completely transparent the widget and I don't want it, I want it semi transparent.
Any help please

[franco.amato]

I discovered a problem.
Removing the Qt::Window from the flags makes the widget to go behind other widgets that's why I cannot see it.
```
selectedGame->setParent(this);

selectedGame->setWindowFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint);
selectedGame->moveRelativeToParent(this, m_leftToolBar->width(), 81);
selectedGame->setStyleSheet("background-color: rgba(37, 38, 52, 0.7);");

selectedGame->show();
selectedGame->raise();

calling raise() didn't solve the problem

[Ronel_qtmaster]

@franco-amato hi. To make your widget semi transparent, you have to follow three steps:

1- setAttribute(Qt::WA_TranslucentBackground);
2- setWindowFlags(Qt::FramelessWindowHint);
3- Call paint Event and use painter.setOpacity(0.75); //exemple value

This is a demo project how you can achieve it https://github.com/jordanprog86/QtTransparentWindow.git

I hope it helps you

[franco.amato]

@Ronel_qtmaster I also have the problem of the positioning of the widget. If I don't set Qt::Window or Qt::Tool then the widget is placed behind other widgets even calling raise()

[Ronel_qtmaster]

@franco-amato i think you don't need to use show() when your widget has a parent , also you can use setGeometry alongside with setWindowFlags(Qt::WindowStaysOnTopHint);

[franco.amato]

@Ronel_qtmaster how to show it only when I need it without using show() ? The Qt::WindowStaysOnTopHint is already added

[Ronel_qtmaster]

@franco-amato If you have assigned a parent to your widget using "this" it is not necessary to call show() again

[franco.amato]

The widget must be shown only when I press a button and I have to place it to a specific position in the main window.:
This is the slot executed when I press the button (selectedGame is the widget I have to show)

void BeastBurst::onGameButtonClicked(GameButton *button)
{
    std::shared_ptr<Game> selectedGame;
    for (auto btn : m_gamesButtonGroup.buttons())
    {
        btn->setStyleSheet(
            "GameButton {"
            " border:none;"
            " background-color: transparent;"
            "}"
            "GameButton:hover {"
            " background-color: #30303d;"
            "}"
        );
    }

    for(auto game : m_games)
    {
        if(game->getGameId() == button->getGameId())
        {
            game->refresh();
            selectedGame = game;
            break;
        }
    }

    button->setStyleSheet("border:none; background-color: rgba(46, 58, 74, 0.7);");

    if (selectedGame->isVisible())
    {
        selectedGame->hide();
        return;
    }

    Qt::WindowFlags currentFlags = selectedGame->windowFlags();
    selectedGame->setWindowFlags(currentFlags | Qt::WindowStaysOnTopHint);
    selectedGame->move(m_leftToolBar->width(), 84);

    selectedGame->show();
    selectedGame->activateWindow();
    selectedGame->raise();
    ui->mainBody->setVisible(false);
}