CODEWITHSUNDEEP
c++qtuser-interfaceresizewidget
JBentley
JBentley

Reputation: 6260

Widget same size as it's children?

In Qt, how can I have a widget which automatically sizes itself according to the size of it's children?

For example, if I have a QGroupBox which contains a QHBoxLayout which contains some QPushButtons, I would like the QGroupBox to automatically calculate it's size so that it is no bigger and no smaller than necessary to fit all of the QPushButtons.

Ideally I would like to be able to do this in Qt Designer so that I can create a .ui file which already knows how to size the QGroupBox, however I am also opening to deriving from a class inside a .ui file and doing the resizing manually.

I have tried placing the QGroupBox inside it's own layout (with and without a spacer) but this just resizes the QGroupBox to the smallest possible size so that none of the children are visible.

Upvotes: 0

Views: 938

Answers (2)

Thadeux
Thadeux

Reputation: 144

You'll probably have the most luck by sub classing QGroupBox and overriding sizeHint or other sizing functions to loop through children and calculate the minimum bounding rectangle. Depending on how dynamic the group box is, managing connections to new widgets might be a small challenge.

Upvotes: 0

Kuba hasn't forgotten Monica
Kuba hasn't forgotten Monica

Reputation: 98425

There are two things to pay attention to:

  1. Set the size policies appropriately on the children in the groupbox. You literally need to think what the buttons can do - most likely, you do not want the buttons to either grow or shrink, so setting both of their size policies to Fixed is the right thing to do. You could, possibly, let the buttons expand horizontally, so the horizontal policy of MinimumExpanding is an option.

  2. Set the size constraint on the layout in the groupbox to act according to your objective:

    ui->groupbox->layout()->setConstraint(QLayout::SetMinAndMaxSize);

Of course, the groupbox will be inside of some layout in its parent window, but that doesn't matter.

Upvotes: 1

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