QGraphicsView fitInView doesn't do anything on restore (down)

Sucharek

Hello, I'm having a problem with QGraphicsView.
I'm resizing an image on resize, but when I restore (down) the window, it keeps, and doesn't do anything:

I have to resize it to go back to normal.
Here's what I'm doing:

ui->graphicsView_LeftHand->fitInView(svgLeft, Qt::KeepAspectRatio);

SGaist

Hi,

When are you doing that call ?
Can you share your code ?

Sucharek

Hi @SGaist, I'm calling QResizeEvent. Here's how:

void MainWindow::resizeEvent(QResizeEvent*) {
      ui->graphicsView_LeftHand->fitInView(svgLeft, Qt::KeepAspectRatio);
}

SGaist

How do you do your restore ?

Sucharek

I don't know how the button is named. It's this one:

SGaist

Silly question, did you check that resizeEvent is properly called when you click the restore button ?

Sucharek

Hi @SGaist, yes, everytime I resize, restore the window, it activates

SGaist

Which version of Qt are you using ?
On which version of Windows ?
Can you provide a minimal compilable example that shows this behaviour ?

Sucharek

I'm using Qt 5.15.2
Windows 21H2
I don't know, only have an issue with resizing the picture, haven't found it in anything else

SGaist

Just for the sake of testing, what happens if you trigger a single shot QTimer in the resizeEvent to trigger the fitInView ?

Sucharek

Hi @SGaist, not sure what you meant by that, but I've got this:

QTimer timer;
timer.singleShot(1000, this, SLOT(QResizeEvent));
ui->graphicsView_LeftHand->fitInView(svgLeft, Qt::KeepAspectRatio);

And it prints:

QObject::connect: Parentheses expected, slot MainWindow::QResizeEvent
QObject::connect:  (receiver name: 'MainWindow')

JonB

@Sucharek
@SGaist meant more like:

QTimer timer;
timer.singleShot(1000, this, [this, svgLeft]() { ui->graphicsView_LeftHand->fitInView(svgLeft, Qt::KeepAspectRatio); });

Sucharek

That actually works.
Thank you @SGaist and @JonB for helping me.

Sucharek

Hi, just an improvement. Qt creator gave me errors, built anyway, but they were bothering me, so I've made a change:

timer.singleShot(0, this, [this]() {ui->graphicsView_LeftHand->fitInView(svgLeft, Qt::KeepAspectRatio);});

Thanks again for helping me.

SGaist

QTimer::singleShot is a static function so there's no need to create an instance for it.