How to keep horizontalScrollBar at the rightmost side?

feiyuhuahuo

I have a QScrollArea, and every time I push a button, a new QLabel will be added into it.

I tried these codes to keep the horizontalScrollBar at the rightmost side, but there's still some sapce left and thus the newest added QLabel can not show completely.

    def button_back(self):
        self.marquees_layout.addWidget(self.marquee_label())
        aa = self.main_ui.scrollArea.horizontalScrollBar().maximum()
        self.main_ui.scrollArea.horizontalScrollBar().setValue(aa)

JonB

@feiyuhuahuo
I wonder whether: you have just added a new widget, but perhaps Qt has not yet recalculated the layout for that and so it has not adjusted horizontalScrollBar().maximum() to be a bigger value?

    def button_back(self):
        print(self.main_ui.scrollArea.horizontalScrollBar().maximum())
        self.marquees_layout.addWidget(self.marquee_label())
        print(self.main_ui.scrollArea.horizontalScrollBar().maximum())

Does the second print() show a greater value or the same value?

You might test the principle by moving the horizontalScrollBar().setValue(horizontalScrollBar().maximum()) into a QTimer::singleShot(), which you set off after the addWidget(), to give it time to show and adjust the scrollbar for the new widget. If that works you can then find a better way of recognising the added widget.

feiyuhuahuo

@JonB said in How to keep horizontalScrollBar at the rightmost side?:

QTimer::singleShot()

@JonB
I tried your code, and the second value is the same as the first one.
I also tried code:

    def print_max(self):
        print(self.main_ui.scrollArea.horizontalScrollBar().maximum())

    def button_back(self):
        QTimer.singleShot(50, self.print_max)
        self.marquees_layout.addWidget(self.marquee_label())
        QTimer.singleShot(50, self.print_max)
        QTimer.singleShot(50, self.print_max)
        QTimer.singleShot(50, self.print_max)

All the values are the same.
And yet I also tried:

    def button_back(self):
        self.marquees_layout.addWidget(self.marquee_label())
        # aa = self.main_ui.scrollArea.horizontalScrollBar().maximum()
        self.main_ui.scrollArea.horizontalScrollBar().setValue(99999)

The result is the same. There's still some space left and the space is always just for a Qlabel.