Animate window (top level widget) opacity

Borzh

I am trying to fade in a window. When the program starts, the window is shown as black and animates opacity as required. But I would like window to be shown completely transparent at the start and removing transparency to be shown completely. Here is the code I use:

QPropertyAnimation* a1 = NULL;
if (w) { // I checked, it is not null.
    QGraphicsOpacityEffect *eff = (QGraphicsOpacityEffect *)w->graphicsEffect();
    if (!eff) {
        eff = new QGraphicsOpacityEffect(w);
        from->setGraphicsEffect(eff);
    }
    if (dynamic_cast<QMainWindow*>(w))
        a1 = new QPropertyAnimation(eff, "windowOpacity"); // As top level window, uses this one.
    else
        a1 = new QPropertyAnimation(eff, "opacity");
    a1->setDuration(duration);
    a1->setStartValue(0.0);
    a1->setEndValue(1.0);
    a1->setEasingCurve(QEasingCurve::Linear);
    a1->start(QPropertyAnimation::DeleteWhenStopped);
}

BTW I tried both opacity and windowOpacity and effect is the same.
Window creation uses this code:

setWindowFlags(windowFlags() | Qt::WindowMinMaxButtonsHint | Qt::CustomizeWindowHint);
setAttribute(Qt::WA_TranslucentBackground);

mrjj

hi , i tried your code (win 7, qt 5.5)

MainWindow::MainWindow(QWidget* parent) :
QMainWindow(parent),
ui(new Ui::MainWindow) {
ui->setupUi(this);
setWindowOpacity(0.0);
QPropertyAnimation *a1 = new QPropertyAnimation(this, "windowOpacity"); // As top level window, uses this one.
a1->setDuration(3000);
a1->setStartValue(0.0);
a1->setEndValue(1.0);
a1->setEasingCurve(QEasingCurve::Linear);
a1->start(QPropertyAnimation::DeleteWhenStopped);
}

and it fade in very smooth.

So what platform are you on?

shanmugaraja

@mrjj - I tried the same code in Mac platform using Qt 5.12.6. But still it is not working.

mrjj

@shanmugaraja
Hi
This poster sounds like it does work on macOS
https://forum.qt.io/topic/59453/solved-widget-fade-in-effect-possible/3

so if not working on macOS, i guess its not supported if code is 100% the same.