Please nominate your Qt Champions for 2021!

flickering when hiding and showing widget

  • I put a button and label in a widget, when I set visible to the widget, I will got same problem with this
    It is have better way to solve this problem?

    qt version : 5.9.5

  • Lifetime Qt Champion

    @OtisLin I don't know what your use case exactly is, but did you consider to use ?

  • Thanks your reply.
    螢幕快照 2020-02-07 下午2.04.15.png
    My question like this. Button_A will set area C visible false. add Button_B will set area C visible true.
    When the area C hidding and showing some times have flickering.

    It's look like layout problem. But still not found the key point. Maybe the QStackedWidget is the best way.

  • How is the connection between your buttons and the slots made ? This kind of issue often arises when there are several updates instead of one, which may be the case if A and B are grouped to be mutually exclusive. Do you use QPushButton::pressed or QPushButton::toggled ? It might be just because you simplified your issue to provide a minimal exemple, but it looks like you are using two buttons when you only need one (with a checked/unchecked state).

    Can you put some debug code in your "setVisible" slot, to check if it's called only once each time ?
    Does you still have that flickering is you put a breakpoint in the setVisible slot ?

    Last check : how is your layout made ? I guess C is a large widget that is inside a QVBoxLayout ? What happens when C is not visible ? Do A and B get lower, or is there a large bottom margin ? You may need a addStrech() at the end of your layout, if it's not already there.

  • @Andeol
    Thanks for your reply.
    When widgetC visible false. A and B will keep on top.
    Final I add a Spacer on the end. It's work.
    But as you said the maybe button call more than once. I will check this way.

Log in to reply